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  • Parent Football Nutrition Guide: Fuelling Young Players Effectively

    Parent Football Nutrition Guide: Fuelling Young Players Effectively

    Youth football nutrition plays a key role in energy levels, recovery, focus, and consistency across the training week. Many young players are not underperforming because of fitness or talent, but because of inconsistent fuelling and hydration patterns across the day. This guide explains how parents can support practical, realistic nutrition habits that directly improve performance, recovery, and wellbeing.

    Why youth football nutrition matters

    Football is a high-intensity intermittent sport involving repeated sprints, rapid changes of direction, physical contact, and constant decision-making under fatigue. These actions rely heavily on muscle glycogen, the body’s stored form of carbohydrate. When glycogen levels drop, performance declines, particularly in repeated sprint ability and late-game intensity (Bangsbo et al., 2006; Burke et al., 2011). This often presents as players starting strongly but fading in the second half, reduced reaction speed, and slower decision-making under pressure.

    In children and adolescents, this is compounded by growth demands, meaning energy is also required for:

    • Muscle repair and adaptation
    • Bone growth
    • Hormonal development
    • Cognitive function

    (Gibson et al., 2011)

    1. Pre-training and pre-match nutrition (football pre match meal)

    The goal before football is to ensure sufficient carbohydrate availability to support high-intensity performance throughout the session or match (Burke et al., 2011). Think of this as “fuel loading” rather than just eating to stop hunger.

    2–3 hours before training or match (main meal)

    This meal should:

    • Top up carbohydrate stores (main fuel source)
    • Provide moderate protein for muscle support
    • Be low in fat and easy to digest

    Examples:

    • Pasta with chicken in tomato sauce
    • Rice with chicken or turkey
    • Wraps with chicken and light sauce + fruit
    • Cereal with milk, banana, and yoghurt
    • Toast with scrambled eggs and fruit juice

    Avoid meals that are too light (e.g. fruit or yogurt alone), as they do not provide enough energy for high-intensity performance.

    30–60 minutes before exercise (optional snack)

    Useful if there is a long gap since the last meal or the player feels hungry.

    Examples:

    • Banana
    • Cereal bar
    • Yogurt pouch
    • Toast with honey

    This helps maintain blood glucose availability early in exercise (Jeukendrup, 2014).

    2. Hydration for young footballers

    Even mild dehydration can reduce reaction time, concentration, and endurance performance (Thomas et al., 2016). Children are especially vulnerable because they often:

    • Forget to drink during school
    • Don’t recognise early thirst
    • Become distracted during play

    Practical approach:

    • Encourage regular drinking throughout the day
    • Use small, frequent sips during training
    • Rehydrate after sessions at home

    Simple check:

    • Pale yellow urine usually indicates good hydration status

    3. During training and matches

    For most youth football sessions under 90 minutes:

    • Water is sufficient
    • No structured fuelling is needed

    For tournaments or hot conditions:

    • Hydration becomes more important
    • Fluid loss can significantly impact later performance

    A common issue is performance drop-off in later games due to cumulative dehydration and reduced energy availability (Burke et al., 2011).

    4. Football recovery nutrition (post training nutrition)

    Recovery is where many young players lose performance consistency without realising it. After football, the body needs to:

    • Refill muscle glycogen
    • Repair muscle tissue
    • Restore fluid balance

    Recovery is most effective when nutrition is consumed within 1–2 hours post exercise (Burke et al., 2017).

    Best recovery approach: carbohydrate + protein

    Examples:

    • Chicken and rice
    • Tuna sandwich + fruit + yogurt
    • Milk smoothie with banana and oats
    • Eggs on toast + milk
    • Yogurt with granola and berries

    Poor recovery nutrition can lead to:

    • Increased fatigue
    • Reduced performance in next session
    • Slower weekly recovery cycle

    5. Daily youth athlete nutrition habits

    Consistency across the week is more important than match-day nutrition strategies (Desbrow et al., 2014).

    Key habits:

    • Eat breakfast every day
    • Avoid long gaps between meals
    • Include carbohydrates at most meals
    • Include protein for growth and repair
    • Eat fruit and vegetables daily
    • Maintain regular hydration

    Many young athletes under-fuel during school hours, which reduces evening training quality (Gibson et al., 2011).

    6. Travel nutrition for football matches

    Away games often disrupt normal eating routines, which can negatively affect performance (Burke et al., 2011).

    Common issues:

    • Missed meals before travel
    • Long gaps without food
    • Reliance on convenience snacks
    • Nervous appetite suppression

    Practical strategy:

    • Eat a carbohydrate-based meal before leaving home
    • Bring familiar, easy-to-eat foods

    Examples:

    • Sandwiches
    • Fruit
    • Cereal bars
    • Yogurts
    • Water

    Avoid relying on unfamiliar venue food options.

    7. Common youth football nutrition mistakes

    • Under-fuelling disguised as “healthy eating” (fruit or yogurt alone is not enough energy)
    • Skipping recovery meals after training (reduces glycogen restoration)
    • Hydration only on match days rather than daily
    • Over-reliance on supplements instead of food-first nutrition (Thomas et al., 2016)

    8. Warning signs of poor football nutrition

    Look for:

    • Early fatigue in training
    • Drop-off in second-half performance
    • Poor concentration late in sessions
    • Slow recovery between training days
    • Frequent minor illness
    • Heavy legs during warm-ups

    These are often nutrition-related rather than fitness-related (Gibson et al., 2011).

    9. Energy availability and development

    Energy availability is the energy left after exercise that supports growth and normal body function.

    Low energy availability can affect:

    • Growth and development
    • Bone health
    • Recovery capacity
    • Injury risk
    • Training adaptation

    (Gibson et al., 2011; Thomas et al., 2016)

    This usually develops gradually through small daily deficits rather than intentional restriction.

    Conclusion

    Effective youth football nutrition is built on:

    • Adequate fuelling before activity (Burke et al., 2011)
    • Consistent hydration habits (Thomas et al., 2016)
    • Structured recovery nutrition (Burke et al., 2017)

    Small improvements in these areas can significantly improve performance, recovery, and enjoyment of football.

    Final note for parents

    Every young footballer is different, and nutrition needs vary based on training load, growth stage, and individual response. If you are unsure whether your child is fuelling correctly for football, or you would like personalised support tailored to their schedule and development, you can get in touch for expert nutrition guidance.

    Contact me

  • Creatine Supplementation in Male and Female Athletes: An Evidence-Based Review of Mechanisms, Performance, Recovery and Sex-Specific Responses

    Creatine Supplementation in Male and Female Athletes: An Evidence-Based Review of Mechanisms, Performance, Recovery and Sex-Specific Responses

    Introduction

    Creatine monohydrate is one of the most extensively researched and scientifically supported ergogenic aids in sport and exercise science. Contemporary consensus statements confirm that creatine is effective for improving high-intensity exercise performance, increasing lean mass and enhancing training adaptations across a wide range of populations (Kreider et al., 2022; Antonio et al., 2021). Unlike many supplements in sport, creatine has a consistently strong evidence base supported by systematic reviews and meta-analyses, particularly when combined with resistance training (Chilibeck et al., 2017; Candow et al., 2019; Forbes et al., 2021). Although the physiological mechanisms are similar between males and females, emerging evidence suggests sex-specific differences in creatine metabolism, baseline muscle creatine stores and hormonal regulation may influence responsiveness and practical application (Smith-Ryan et al., 2021; Delpino et al., 2022).

    Physiological Role and Mechanisms of Action

    Creatine functions primarily within the phosphagen energy system, supporting rapid ATP regeneration during high-intensity exercise. During maximal effort, ATP is rapidly depleted and resynthesised via phosphocreatine (PCr), catalysed by creatine kinase. Contemporary evidence confirms that creatine supplementation increases intramuscular total creatine and phosphocreatine stores, enhancing ATP resynthesis during repeated high-intensity efforts (Kreider et al., 2022; Forbes et al., 2021). Key physiological effects include increased phosphocreatine availability, enhanced sprint and resistance performance, improved training volume tolerance, intracellular hydration and upregulation of anabolic signalling pathways associated with hypertrophy (Kreider et al., 2022; Antonio et al., 2021). Cell swelling is considered an anabolic stimulus contributing to protein synthesis and reduced protein breakdown (Forbes et al., 2021).

    Creatine and Performance in Males

    Meta-analytical evidence consistently demonstrates creatine improves maximal strength, lean body mass, training volume and muscular hypertrophy when combined with resistance training (Chilibeck et al., 2017; Candow et al., 2019). A meta-analysis reported significantly greater increases in lean mass with creatine supplementation alongside resistance training compared with training alone (Chilibeck et al., 2017). More recent evidence confirms increases in lean body mass of approximately ~1 kg in trained and untrained populations (Delpino et al., 2022). Creatine also improves repeated sprint ability, peak power output and anaerobic performance capacity, making it highly relevant to team sports such as football, rugby and hockey (Kreider et al., 2022; Antonio et al., 2021).

    Creatine and Performance in Females

    Although historically underrepresented in research, recent systematic reviews demonstrate that females benefit from creatine supplementation in strength, high-intensity performance and lean mass adaptations (Smith-Ryan et al., 2021; Delpino et al., 2022). Females typically have lower baseline intramuscular creatine stores and dietary intake, which may influence responsiveness (Smith-Ryan et al., 2021). While absolute gains in lean mass are often smaller than in males, relative improvements are comparable when adjusted for baseline differences (Delpino et al., 2022). Evidence suggests creatine may be particularly relevant in female athletes due to hormonal influences on energy metabolism and creatine kinase activity across the menstrual cycle (Smith-Ryan et al., 2021).

    Creatine and the Menstrual Cycle

    Oestrogen and progesterone fluctuations influence substrate utilisation, neuromuscular performance, thermoregulation and fatigue perception. These hormonal changes may also influence creatine kinase activity and energy metabolism (Smith-Ryan et al., 2021). Although phase-specific intervention studies remain limited, creatine’s role in ATP resynthesis suggests potential benefits during phases of increased fatigue or reduced energy availability.

    Creatine, Recovery and Training Adaptation

    Creatine supplementation may enhance recovery between training sessions and improve tolerance to high training loads. Evidence suggests improvements in training volume capacity, reductions in muscle damage markers in some contexts and enhanced glycogen resynthesis when combined with carbohydrate intake (Antonio et al., 2021; Kreider et al., 2022). These effects are most pronounced when creatine is combined with structured resistance or high-intensity training programmes (Candow et al., 2019).

    Creatine and Cognitive Function

    Creatine plays a role in brain energy metabolism, and supplementation may improve working memory, processing speed and cognitive resilience under stress or sleep deprivation (Antonio et al., 2021; Kreider et al., 2022). These effects are most evident in conditions of metabolic stress, making creatine relevant for athletes experiencing travel, congestion, sleep disruption or high cognitive load. This may also be relevant for female athletes experiencing cyclical fatigue or hormonal fluctuations (Smith-Ryan et al., 2021).

    Creatine Across the Female Lifespan

    In adolescence, creatine supports strength and power development alongside training. During reproductive years, it supports high-intensity performance and recovery. In perimenopause and menopause, creatine combined with resistance training improves lean mass, strength and functional performance (Candow et al., 2019; Delpino et al., 2022). Bone health outcomes remain inconclusive, but functional improvements are consistently reported.

    Safety and Long-Term Use

    Consensus statements confirm creatine monohydrate is safe when used at recommended doses in healthy individuals (Kreider et al., 2022). Evidence does not support adverse effects on kidney function, liver function, hydration status or cramping risk (Antonio et al., 2021; Kreider et al., 2022). Long-term studies support its safety in both male and female populations.

    Practical Application

    Loading phase (optional): 20 g/day split into 4 doses for 5–7 days. Maintenance: 3–5 g/day. Alternatively, 3–5 g/day without loading achieves full saturation over ~3–4 weeks. Timing is not critical; total daily intake is the key factor (Antonio et al., 2021). Creatine monohydrate remains the gold standard due to its efficacy, safety, cost-effectiveness and evidence base (Kreider et al., 2022).

    Conclusion

    Creatine monohydrate is one of the most effective and well-supported supplements in sport science. Evidence demonstrates consistent benefits for strength, lean mass, high-intensity performance, recovery and cognition in both males and females. While males show greater absolute gains in lean mass, this is largely due to baseline physiological differences rather than differences in responsiveness. In females, creatine may have additional relevance due to hormonal fluctuations and lower baseline creatine stores. Overall, creatine should be considered a foundational evidence-based supplement for athletes across sexes and performance levels.

    References

    Antonio, J. et al. (2021) Journal of the International Society of Sports Nutrition, 18, pp.1–17.
    Candow, D.G. et al. (2019) Journal of Clinical Medicine, 8, 488.
    Chilibeck, P.D. et al. (2017) Open Access Journal of Sports Medicine, 8, pp.213–226.
    Delpino, F.M. et al. (2022) Nutrition, 103–104, 111791.
    Forbes, S.C. et al. (2021) Nutrients, 13(6), 1915.
    Kreider, R.B. et al. (2022) Journal of the International Society of Sports Nutrition, 19(1), pp.1–46.
    Smith-Ryan, A.E. et al. (2021) Nutrients, 13(3), 877.

  • Bone Health in Athletes: The Role of Energy Availability, Training Load and Stress Fracture Risk

    Bone Health in Athletes: The Role of Energy Availability, Training Load and Stress Fracture Risk

    Introduction

    Bone is a dynamic tissue that responds continuously to mechanical and metabolic stimuli. In athletic populations, bone health is determined by the interaction between mechanical loading, endocrine function, and energy availability rather than isolated nutrient intake alone (Turner, 1998; Tenforde and Fredericson, 2011).

    Although sports participation is generally associated with higher bone mineral density (BMD), certain training environments particularly those characterised by low energy availability are associated with impaired bone turnover and increased risk of stress injury (Mountjoy et al., 2018; Logue et al., 2020). This makes bone health a critical but often under-monitored determinant of long-term athletic performance and injury resilience.

    Bone Remodelling and Mechanotransduction in Sport

    Bone adapts to mechanical loading via remodelling, a process regulated by osteoblast and osteoclast activity. According to mechanostat theory, bone tissue responds to strain magnitude, rate, and frequency, increasing its structural strength when subjected to sufficient mechanical stress (Turner, 1998).

    High-impact, multidirectional loading sports stimulate osteogenesis more effectively than low-impact endurance activities. Evidence consistently shows higher BMD in athletes participating in sports involving jumping, sprinting, and rapid changes of direction compared with cycling or swimming (Tenforde and Fredericson, 2011).

    However, bone adaptation is not solely dependent on mechanical stimulus. Energy availability and endocrine function significantly modulate the remodelling response, with low energy availability attenuating bone formation despite mechanical loading exposure (Ihle and Loucks, 2004).

    Energy Availability as a Central Regulator of Bone Health

    Energy availability (EA), defined as dietary energy intake minus exercise energy expenditure relative to fat-free mass, is a primary determinant of physiological function in athletes (Loucks et al., 2011).

    Low energy availability impairs bone health through multiple mechanisms including suppression of bone formation markers such as osteocalcin and procollagen type 1 N-terminal propeptide (P1NP), alongside increased bone resorption markers such as C-terminal telopeptide (CTX) (Ihle and Loucks, 2004; Logue et al., 2020).

    Endocrine disruption is also central to this process. Low EA reduces insulin-like growth factor-1 (IGF-1), leptin, oestrogen, and testosterone, all of which are essential regulators of bone metabolism (Mountjoy et al., 2018). These hormonal changes shift bone turnover towards net resorption and impair recovery from microdamage accumulation.

    Stress Fractures and Bone Stress Injuries

    Bone stress injuries represent a continuum from periosteal oedema to cortical fracture and occur when repetitive submaximal loading exceeds the bone’s capacity for remodelling and repair (Warden et al., 2014).

    Key risk factors consistently identified in peer-reviewed literature include low energy availability, rapid increases in training load, prior stress fracture history, hormonal disturbances, and low bone mineral density (Mountjoy et al., 2018; Tenforde et al., 2015).

    Athletes with low energy availability exhibit significantly increased incidence of stress fractures due to impaired bone formation and delayed microdamage repair processes (Logue et al., 2020).

    Hormonal Regulation of Bone Metabolism in Athletes

    Bone remodelling is tightly regulated by endocrine signalling. Oestrogen and testosterone are critical for maintaining bone formation and inhibiting resorption (Mountjoy et al., 2018).

    In low energy availability states, oestrogen concentrations may decrease in female athletes, particularly in cases of functional hypothalamic amenorrhoea, while testosterone may also decline in male athletes. Insulin-like growth factor-1 (IGF-1) is suppressed, reducing osteoblastic activity, while cortisol may increase, promoting catabolic effects on bone tissue (Mountjoy et al., 2018).

    These endocrine changes collectively shift bone metabolism towards increased resorption and reduced formation.

    Mechanical Loading: Protective and Dose-Dependent Effects

    Mechanical loading remains one of the most potent stimuli for bone formation. High-impact loading generates strain-induced deformation and fluid flow within the bone matrix, triggering osteogenic responses (Turner, 1998).

    High-impact sports consistently demonstrate greater bone mineral density compared with low-impact endurance sports (Tenforde and Fredericson, 2011). Furthermore, plyometric and resistance training enhance site-specific bone strength adaptations (Tenforde et al., 2015).

    However, excessive repetitive loading without adequate recovery or energy availability results in microdamage accumulation and increased risk of bone stress injury (Warden et al., 2014).

    Nutrition and Bone Health: Beyond Calcium

    Energy availability is the primary nutritional determinant of bone health in athletes. Low energy availability suppresses bone formation even when calcium and vitamin D intake are adequate (Loucks et al., 2011; Mountjoy et al., 2018).

    Calcium plays a key role in bone mineralisation, but its effectiveness is dependent on hormonal status and energy balance. Vitamin D is essential for calcium absorption and bone metabolism, with deficiency associated with increased fracture risk in athletes (Close et al., 2013).

    Protein intake supports bone matrix formation and collagen synthesis. Evidence indicates that higher protein intakes do not negatively impact bone health when calcium intake is sufficient and may enhance IGF-1-mediated anabolic signalling (Shams-White et al., 2017).

    RED-S and Bone Health

    Relative Energy Deficiency in Sport (RED-S) describes impaired physiological function resulting from low energy availability. Bone health is one of the most significantly affected systems (Mountjoy et al., 2018).

    RED-S is associated with reduced bone formation markers, increased bone resorption, impaired attainment of peak bone mass, and increased stress fracture risk. Persistent low energy availability during key developmental periods may result in long-term deficits in bone mineral density (Mountjoy et al., 2018).

    Integration of Training Load and Energy Availability

    Bone adaptation is dependent on the interaction between mechanical loading and energy availability. Mechanical loading is only osteogenic when sufficient energy is available to support remodelling processes.

    When energy availability is low, the osteogenic response to loading is blunted, bone resorption exceeds formation, and adaptation to training is impaired. This explains the high incidence of bone stress injuries in athletes experiencing high training loads without adequate fuelling (Logue et al., 2020; Warden et al., 2014).

    Practical Implications for Athlete Management

    Optimising bone health in athletes requires a multi-factorial approach that includes maintaining adequate energy availability, structured mechanical loading, and appropriate nutritional support.

    Early identification of RED-S risk factors such as menstrual dysfunction, recurrent stress injury, fatigue, and rapid training load increases is essential for prevention (Mountjoy et al., 2018).

    Conclusion

    Bone health in athletes is governed primarily by the interaction between energy availability, endocrine function, and mechanical loading rather than isolated nutrient intake. Low energy availability is the most significant modifiable risk factor for impaired bone metabolism and stress injury development. Maintaining adequate energy availability alongside structured loading strategies is essential for optimal skeletal adaptation and injury prevention.

    References

    Close, G.L., Leckey, J., Patterson, M., et al. (2013) ‘Vitamin D and skeletal muscle strength in athletes’, Scandinavian Journal of Medicine & Science in Sports.

    Ihle, R. and Loucks, A.B. (2004) ‘Dose-response relationships between energy availability and bone turnover’, Journal of Bone and Mineral Research.

    Logue, D.M., Madigan, S.M., Melin, A., et al. (2020) ‘Low energy availability in athletes’, Sports Medicine.

    Loucks, A.B., Kiens, B. and Wright, H.H. (2011) ‘Energy availability in athletes’, Journal of Sports Sciences.

    Mountjoy, M., Sundgot-Borgen, J., Burke, L., et al. (2018) ‘IOC consensus statement on RED-S’, British Journal of Sports Medicine.

    Shams-White, M.M., Chung, M., et al. (2017) ‘Protein intake and bone health’, American Journal of Clinical Nutrition.

    Tenforde, A.S. and Fredericson, M. (2011) ‘Influence of sports participation on bone health’, Sports Health.

    Tenforde, A.S., et al. (2015) ‘Impact activity and bone density’, PM&R.

    Turner, C.H. (1998) ‘Three rules for bone adaptation’, Bone.

    Warden, S.J., Davis, I.S. and Fredericson, M. (2014) ‘Stress fracture biomechanics’, British Journal of Sports Medicine

  • Continuous Glucose Monitoring in Healthy Individuals: Evidence, Interpretation, and Practical Value Beyond Clinical Use

    Continuous Glucose Monitoring in Healthy Individuals: Evidence, Interpretation, and Practical Value Beyond Clinical Use

    Introduction

    Continuous glucose monitoring (CGM) systems are well established in diabetes care, where strong evidence demonstrates improvements in glycaemic variability, time in range, and hypoglycaemia prevention in both type 1 and insulin-treated type 2 diabetes populations (Battelino et al., 2019; Beck et al., 2017). In recent years, CGMs have increasingly been adopted by individuals without diabetes for purposes such as dietary optimisation, metabolic health tracking, and performance monitoring. This expansion reflects interest in precision nutrition, although evidence supporting clinical benefit in healthy populations remains limited (Liao et al., 2026). The key question is whether additional metabolic data improves outcomes in already well-regulated physiology.

    Physiological Basis of CGM Technology

    CGMs measure glucose in interstitial fluid using enzymatic sensors. Interstitial glucose is physiologically linked to blood glucose but is not identical. A consistent limitation is the time lag between blood and interstitial compartments, typically 5–15 minutes depending on metabolic state and perfusion (Torimoto and Okada, 2021). This lag becomes more pronounced during rapid changes such as postprandial absorption or exercise. Accuracy is also influenced by sensor kinetics, calibration algorithms, and tissue-level variability. Facchinetti (2016) notes that CGM accuracy is generally acceptable in diabetic ranges but is reduced at lower glucose levels and during rapid glycaemic shifts, which are more typical in healthy individuals. This means CGM outputs in normoglycaemic populations should be interpreted as trend-based estimates rather than precise biochemical measurements.

    Inter-Individual Variability in Glycaemic Response

    A key rationale for CGM use in personalised nutrition is inter-individual variability in postprandial glycaemic responses (PPGRs). Zeevi et al. (2015) demonstrated that identical meals produce highly variable glucose responses driven by factors including microbiome composition, insulin sensitivity, sleep, and anthropometrics. Their machine-learning model was able to predict PPGRs and showed that personalised dietary interventions could reduce postprandial glucose excursions. Mendes-Soares et al. (2019) replicated these findings in an independent cohort, confirming that glycaemic responses are highly individualised. Mechanistically, variability reflects differences in gastric emptying, insulin secretion dynamics, hepatic glucose output, and peripheral glucose uptake. However, variability in physiological response does not necessarily imply that reducing all glucose excursions improves long-term health outcomes.

    CGM Effects in Non-Diabetic Populations

    The most comprehensive synthesis of evidence is provided by Liao et al. (2026), who conducted a systematic review and meta-analysis of CGM use in non-diabetic populations. They reported small reductions in mean glucose and improved dietary awareness, but no consistent improvements in BMI, glycaemic variability, or long-term metabolic outcomes in healthy individuals. Benefits were more evident in individuals with impaired glucose regulation, suggesting CGM utility may be dependent on baseline metabolic status. These findings indicate CGMs function more effectively as behavioural feedback tools than as metabolic intervention devices in healthy populations.

    Do Postprandial Glucose Spikes Matter?

    Postprandial increases in glucose are a normal physiological response to carbohydrate ingestion. In healthy individuals, glucose homeostasis is maintained through coordinated insulin secretion, hepatic regulation, and peripheral uptake. DeFronzo et al. (2015) describe these responses as central to metabolic flexibility rather than pathological dysfunction. While glycaemic variability has been associated with adverse outcomes in diabetic populations, causality in healthy individuals is not established. No randomised controlled trials demonstrate that reducing physiological glucose excursions improves cardiovascular outcomes, body composition, or longevity in normoglycaemic populations.

    CGM Accuracy and Interpretation Limitations

    CGM interpretation is limited by both physiological and technical factors. Interstitial lag introduces temporal discrepancy between blood and tissue glucose (Torimoto and Okada, 2021). Sensor accuracy decreases during rapid glucose fluctuations and at lower glucose ranges (Facchinetti, 2016). In healthy individuals, where glucose variability is relatively small, these limitations may disproportionately influence interpretation, increasing the risk of misclassifying normal physiological variation as meaningful metabolic disturbance.

    Behavioural and Psychological Considerations

    CGMs provide continuous physiological feedback, which can influence behaviour. Vettoretti et al. (2020) highlight that while CGMs may improve awareness of dietary patterns, continuous monitoring can also increase cognitive load and attention bias toward short-term fluctuations. This may lead to over-interpretation of normal glucose variability, increased dietary restriction, and reduced dietary flexibility in some individuals. Importantly, there is no evidence that focusing on minimising all glucose excursions improves dietary quality or long-term health outcomes in healthy populations.

    CGMs in Sport and Exercise

    CGMs are increasingly used in athletic populations to monitor carbohydrate availability, fuelling strategies, and recovery nutrition. However, exercise significantly alters glucose kinetics through catecholamine-mediated hepatic glucose output, increased skeletal muscle uptake, and changes in insulin sensitivity. These physiological responses complicate interpretation of CGM data during training and recovery. Jeukendrup (2017) notes that while carbohydrate availability is central to performance, there is no strong evidence that CGM-guided nutrition improves athletic performance outcomes in controlled trials.

    Future Directions: Precision Nutrition

    CGMs are being integrated into precision nutrition models alongside microbiome and dietary data. Zeevi et al. (2015) and Mendes-Soares et al. (2019) demonstrated that machine-learning approaches can predict individual glycaemic responses with moderate accuracy, supporting the concept of metabolic phenotyping. However, translation into clinical practice remains limited due to lack of long-term outcome data, limited external validity, and absence of large-scale randomised controlled trials demonstrating clinical benefit.

    Practical Implications

    Current evidence suggests CGMs may improve short-term dietary awareness and engagement behaviours (Liao et al., 2026). Individual variability in glycaemic response is well established (Zeevi et al., 2015), but does not justify routine intervention in healthy populations. Physiological glucose excursions are not inherently harmful (DeFronzo et al., 2015). CGM data must be interpreted cautiously due to physiological lag and measurement limitations (Facchinetti, 2016). Behavioural effects may be beneficial or maladaptive depending on the individual context (Vettoretti et al., 2020).

    Are CGMs Worth Using in Healthy Individuals?

    In healthy individuals, CGMs are not currently supported as a routine metabolic optimisation tool. Evidence suggests their primary value is educational and behavioural rather than clinical. They may help increase awareness of dietary patterns and individual variability but do not currently demonstrate improvements in body composition, performance, or long-term health outcomes (Liao et al., 2026). In individuals with impaired glucose regulation, CGMs may have greater utility as part of lifestyle intervention strategies. In athletes, CGMs may provide descriptive insights into fuelling responses but lack evidence for performance enhancement. Overall, CGMs should be considered informational rather than interventional tools in healthy populations.

    Conclusion

    Continuous glucose monitoring is a well-established clinical tool in diabetes management and an emerging technology in personalised nutrition. However, current evidence does not support routine use in healthy individuals for improving metabolic health, performance, or body composition. While CGMs provide valuable insight into inter-individual variability in glycaemic responses, physiological glucose excursions in healthy individuals are not inherently pathological, and the clinical significance of modifying them remains unproven. CGMs are best viewed as research and educational tools rather than essential health optimisation devices in normoglycaemic populations.

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    References

    Battelino, T., Danne, T., Bergenstal, R.M., Amiel, S.A., Beck, R., Biester, T., et al. (2019) ‘Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range’, Diabetes Care, 42(8), pp. 1593–1603.

    Beck, R.W., Riddlesworth, T.D., Ruedy, K., Ahmann, A., Bergenstal, R., Haller, S. (2017) ‘Effect of continuous glucose monitoring on glycemic control in adults with type 1 diabetes using insulin injections’, Annals of Internal Medicine, 167(6), pp. 365–374.

    DeFronzo, R.A., Ferrannini, E., Groop, L., Henry, R.R., Herman, W.H., Holst, J.J., et al. (2015) ‘Type 2 diabetes mellitus’, Diabetes Care, 38(1), pp. 142–150.

    Facchinetti, A. (2016) ‘Continuous glucose monitoring sensors: past, present and future algorithmic challenges’, Sensors, 16(12), 2098.

    Jeukendrup, A.E. (2017) ‘Periodized nutrition for athletes’, Sports Medicine, 47(S1), pp. 51–63.

    Liao, X., et al. (2026) ‘Continuous glucose monitoring in non-diabetic individuals: systematic review and meta-analysis’, European Journal of Medical Research, 31, pp. 1–15.

    Mendes-Soares, H., et al. (2019) ‘Assessment of a personalized approach to predicting postprandial glycemic responses’, Cell Host & Microbe, 26(3), pp. 424–435.

    Torimoto, K. and Okada, Y. (2021) ‘Accuracy and limitations of continuous glucose monitoring systems’, Diabetology International, 12, pp. 1–10.

    Vettoretti, M., Facchinetti, A. and Sparacino, G. (2020) ‘Continuous glucose monitoring: interpretation and behavioural implications’, Diabetes Technology & Therapeutics, 22(9), pp. 1–10.

    Zeevi, D., Korem, T., Zmora, N., Israeli, D., Rothschild, D., Weinberger, A., et al. (2015) ‘Personalized nutrition by prediction of glycemic responses’, Cell, 163(5), pp. 1079–1094

  • Sleep Optimisation for Athletes: A Critical Evidence-Based Review of Recovery, Behaviour and Performance

    Sleep Optimisation for Athletes: A Critical Evidence-Based Review of Recovery, Behaviour and Performance

    Introduction

    Sleep is widely recognised as a foundational biological process underpinning recovery, cognitive performance and physiological adaptation. In athletic populations, sleep is increasingly considered a modifiable performance variable alongside training load and nutrition. A consensus statement on sleep and the athlete reports that many athletes fail to achieve recommended sleep durations, particularly during periods of travel, competition and intensified training (Walsh et al., 2021). This article critically evaluates peer-reviewed evidence on sleep and athletic performance, with emphasis on physiological mechanisms, behavioural constraints and applied strategies relevant to coaches and athletes.

    Sleep Physiology and Performance-Relevant Functions

    Sleep consists of non-rapid eye movement (NREM) and rapid eye movement (REM) stages, both contributing to recovery and adaptation. Evidence indicates NREM sleep is associated with tissue repair, immune regulation and growth hormone secretion (Dattilo et al., 2011; Halson, 2014) while REM sleep is associated with memory consolidation and motor learning (Walker and Stickgold, 2006; Rasch and Born, 2013). Sleep is therefore involved in neuromuscular adaptation, cognitive processing and recovery from training load (Fullagar et al., 2015; Halson, 2014).

    Consequences of Sleep Restriction

    Sleep restriction has been associated with:

    • Impaired cognitive performance and reaction time (Lim and Dinges, 2010; Pilcher and Huffcutt, 1996)
    • Reduced endurance performance and increased perceived exertion (Fullagar et al., 2015; Halson, 2014)
    • Reduced sprint and sport-specific performance (Mah et al., 2011; Waterhouse et al., 2007)
    • Increased injury risk in youth athletes (Milewski et al., 2014; Watson, 2017)
    • Impaired glucose regulation and insulin sensitivity (Spiegel et al., 1999; Tasali et al., 2008)
    • Altered appetite regulation and increased energy intake (Taheri et al., 2004; St-Onge et al., 2016)

    Why Athletes Experience Sleep Disruption

    Evening training, elevated sympathetic activity, increased core temperature and travel all contribute to disrupted sleep patterns (Fullagar et al., 2015; Samuels, 2012).

    Lifestyle Behaviours and Sleep

    Video gaming, social media use, streaming and bedtime procrastination are all associated with delayed sleep onset and reduced sleep duration (Weaver et al., 2010; Levenson et al., 2017; Exelmans and Van den Bulck, 2016).

    Caffeine and Alcohol

    Caffeine reduces sleep duration and quality even when consumed up to 6 hours pre-bed (Drake et al., 2013). Alcohol disrupts REM sleep and increases nocturnal awakenings (Ebrahim et al., 2013).

    Sleep Extension and Napping

    Sleep extension improves sprint performance and reaction time in athletes (Mah et al., 2011). Short naps improve alertness and cognitive performance (Waterhouse et al., 2007).

    Sleep Hygiene

    Consistent routines and reduced evening stimulation improve subjective sleep quality but show variable objective effects (Irish et al., 2015).

    Nutritional Interventions and Sleep

    Nutrition may influence sleep via neurotransmitter synthesis, thermoregulation, glucose metabolism and circadian signalling, although the evidence base remains heterogeneous.

    Carbohydrate Timing and Glycaemic Response

    High glycaemic carbohydrate intake may reduce sleep onset latency via insulin-mediated amino acid shifts increasing tryptophan availability (Afaghi et al., 2007). However, systematic reviews highlight inconsistent findings and strong dependence on timing, dose and individual variability (St-Onge et al., 2016). In practice, carbohydrate intake should prioritise performance recovery rather than sleep manipulation.

    Protein Intake and Pre-Sleep Nutrition

    Pre-sleep protein ingestion does not impair sleep architecture and may support overnight muscle protein synthesis (Res et al., 2012; Trommelen and van Loon, 2016). However, there is no evidence that protein directly improves sleep quality, reinforcing its role in recovery rather than sleep optimisation.

    Tart Cherry Juice

    Tart cherry supplementation may improve sleep duration and efficiency, potentially via melatonin content and anti-inflammatory effects (Howatson et al., 2012; Pigeon et al., 2010). Evidence remains limited by small sample sizes and short trial durations.

    Glycine Supplementation

    Glycine may improve subjective sleep quality and reduce fatigue via thermoregulatory and inhibitory neurotransmission pathways (Inagawa et al., 2006; Bannai and Kawai, 2012). However, replication in athletic populations is lacking.

    Magnesium

    Magnesium influences neuromuscular excitability and stress regulation relevant to sleep physiology (Boyle et al., 2017). A randomised controlled trial showed improved sleep quality in older adults with insomnia symptoms (Abbasi et al., 2012). However, systematic reviews highlight limited and inconsistent evidence, with poor generalisability to young athletic populations (Boyle et al., 2017). Magnesium should therefore be targeted primarily at individuals with low dietary intake rather than used universally.

    Melatonin

    Melatonin is effective for circadian disruption such as jet lag but shows inconsistent benefits in healthy non-shifted populations (Herxheimer and Petrie, 2002; Ferracioli-Oda et al., 2013).

    Caffeine–Sleep Interaction

    Caffeine significantly impairs sleep duration and quality even when consumed 6 hours before bedtime (Drake et al., 2013; Clark and Landolt, 2017).

    Wearable Sleep Tracking

    Wearable devices are widely used in sport for sleep monitoring but show only moderate accuracy for total sleep time and poor accuracy for sleep staging compared with polysomnography (de Zambotti et al., 2018; Chinoy et al., 2021). Their primary value lies in tracking behavioural metrics such as sleep opportunity, bedtime consistency and wake timing rather than physiological sleep architecture. Athletic populations may experience further inaccuracies due to elevated heart rate and training stress. Psychological effects such as orthosomnia may also influence sleep perception. Wearables should therefore be used as behavioural monitoring tools rather than diagnostic instruments.

    Practical Recommendations (Evidence-Graded)

    Strong Evidence

    • Aim for 8–10 hours sleep opportunity per night (Walsh et al., 2021)
    • Avoid caffeine within 6 hours of sleep (Drake et al., 2013)
    • Avoid alcohol before bedtime (Ebrahim et al., 2013)
    • Maintain consistent sleep–wake schedules (Irish et al., 2015)

    Moderate Evidence

    • Sleep extension during heavy training (Mah et al., 2011)
    • Short naps (~20–30 min) for performance and alertness (Waterhouse et al., 2007)
    • Sleep hygiene strategies (Irish et al., 2015)
    • Reduce evening digital stimulation (Levenson et al., 2017)

    Emerging Evidence

    • Tart cherry supplementation (Howatson et al., 2012)
    • Glycine supplementation (Inagawa et al., 2006)
    • Melatonin for jet lag/circadian disruption (Ferracioli-Oda et al., 2013)

    Conclusion

    Sleep is a key recovery modulator in athletic performance, with strong evidence linking restriction to impaired cognitive, metabolic and physical outcomes. However, sleep is influenced by behavioural, nutritional and environmental factors including caffeine, alcohol, digital media use and training schedules. The strongest interventions remain behavioural: increasing sleep opportunity, reducing evening stimulation and maintaining consistent routines. Nutritional and technological interventions may offer adjunct support but remain secondary to foundational sleep behaviours.

    REFERENCES

    Abbasi, B. et al. (2012) ‘The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial’, Journal of Research in Medical Sciences.


    Afaghi, A. et al. (2007) ‘High-glycemic-index carbohydrate meals and sleep onset’, American Journal of Clinical Nutrition.


    Bannai, M. and Kawai, N. (2012) ‘New therapeutic strategy for amino acids in sleep’, Journal of Pharmacological Sciences.


    Boyle, N.B. et al. (2017) ‘The effects of magnesium supplementation on subjective anxiety and stress’, Nutrients.


    Clark, I. and Landolt, H. (2017) ‘Coffee, caffeine, and sleep’, Journal of Sleep Research.


    Dattilo, M. et al. (2011) ‘Sleep and muscle recovery’, Sports Medicine.


    de Zambotti, M. et al. (2018) ‘Wearable sleep technology accuracy’, Journal of Clinical Sleep Medicine.


    Drake, C. et al. (2013) ‘Caffeine effects on sleep’, Journal of Clinical Sleep Medicine.


    Ebrahim, I.O. et al. (2013) ‘Alcohol and sleep architecture’, Alcoholism: Clinical and Experimental Research.


    Exelmans, L. and Van den Bulck, J. (2016) ‘Bedtime procrastination’, Journal of Sleep Research.


    Ferracioli-Oda, E. et al. (2013) ‘Melatonin and sleep outcomes’, PLoS One.


    Fullagar, H.H.K. et al. (2015) ‘Sleep and athletic performance’, Sports Medicine.


    Halson, S.L. (2014) ‘Sleep in elite athletes’, Sports Medicine.


    Herxheimer, A. and Petrie, K.J. (2002) ‘Melatonin for jet lag’, Cochrane Database.


    Howatson, G. et al. (2012) ‘Tart cherry juice and recovery’, Scandinavian Journal of Medicine & Science in Sports.


    Inagawa, K. et al. (2006) ‘Glycine and sleep quality’, Journal of Pharmacological Sciences.


    Irish, L.A. et al. (2015) ‘Sleep hygiene review’, Sleep Medicine Reviews.


    King, D.L. et al. (2013) ‘Gaming and sleep’, Journal of Clinical Sleep Medicine.


    Kredlow, M.A. et al. (2015) ‘Sleep hygiene effectiveness’, Journal of Behavioral Medicine.


    Levenson, J.C. et al. (2017) ‘Social media use and sleep’, Preventive Medicine.


    Lim, J. and Dinges, D.F. (2010) ‘Sleep deprivation and cognition’, Psychological Bulletin.


    Mah, C.D. et al. (2011) ‘Sleep extension in athletes’, Sleep.


    Milewski, M.D. et al. (2014) ‘Sleep and injury risk’, Journal of Pediatric Orthopaedics.


    Pigeon, W.R. et al. (2010) ‘Tart cherry and sleep’, Journal of Medicinal Food.


    Rasch, B. and Born, J. (2013) ‘Sleep and memory’, Physiological Reviews.


    Res, P. et al. (2012) ‘Pre-sleep protein intake’, Medicine & Science in Sports & Exercise.


    Roehrs, T. and Roth, T. (2001) ‘Alcohol and sleep’, Alcohol Health Research World.


    Samuels, C. (2012) ‘Jet lag in athletes’, Sports Medicine.


    Spiegel, K. et al. (1999) ‘Sleep loss and glucose metabolism’, The Lancet.


    St-Onge, M.P. et al. (2016) ‘Sleep and nutrition’, Sleep Medicine Reviews.


    Taheri, S. et al. (2004) ‘Sleep and appetite regulation’, PLoS Medicine.
    Trommelen, J. and van Loon, L.J.C. (2016) ‘Pre-sleep protein’, Sports Medicine.


    Walker, M.P. and Stickgold, R. (2006) ‘Sleep and learning’, Annual Review of Psychology.


    Walsh, N.P. et al. (2021) ‘Sleep and the athlete consensus’, British Journal of Sports Medicine.


    Waterhouse, J. et al. (2007) ‘Napping and performance’, Chronobiology International.


    Watson, A.M. (2017) ‘Sleep and injury risk’, Sleep Health.


    Weaver, E. et al. (2010) ‘Gaming and sleep disruption’, Journal of Clinical Sleep Medicine.

  • Peptides in the Fitness Industry: Mechanisms, Adaptation, Evidence, Risks and Scientific Limitations.

    Peptides in the Fitness Industry: Mechanisms, Adaptation, Evidence, Risks and Scientific Limitations.

    Peptides have moved rapidly from biomedical research into mainstream fitness culture, marketed as a targeted means of enhancing muscle growth, recovery and overall physiological function. They are often presented as a “precision” alternative to traditional performance-enhancing approaches, promising specific, controllable effects with fewer risks. However, a closer examination of the scientific literature reveals a more complex and far less certain picture. While peptide biology is well understood at a mechanistic level, the evidence supporting meaningful improvements in training adaptation and athletic performance is limited, inconsistent and frequently constrained by methodological weaknesses. The key issue is therefore not whether peptides can influence physiology, but whether they meaningfully improve adaptation to training, which remains the primary determinant of performance outcomes.

    What Are Peptides

    Peptides are short chains of amino acids that function predominantly as signalling molecules within the body. Unlike larger proteins, which primarily serve structural or enzymatic roles, peptides regulate biological processes by binding to receptors and initiating intracellular responses. A number of critical physiological regulators are peptides, including insulin and insulin-like growth factor‑1, which plays a central role in skeletal muscle growth, regeneration and adaptation through its influence on satellite cell activity and protein synthesis pathways (Ahmad et al., 2020). In applied fitness settings, peptides typically refer to synthetic analogues designed to manipulate these signalling systems, often through hormonal or regenerative pathways.

    Mechanisms of Action

    The Growth Hormone–IGF‑1 Axis

    The most extensively discussed mechanism underpinning peptide use in fitness is the growth hormone–IGF‑1 axis. Growth hormone is secreted from the pituitary gland and stimulates the production of IGF‑1 both systemically and within muscle tissue. IGF‑1 then binds to receptors on muscle cells, activating intracellular pathways such as PI3K/Akt and mTOR, which regulate protein synthesis, cell proliferation and survival (Machida and Booth, 2004; Ahmad et al., 2020). Through these mechanisms, IGF‑1 facilitates satellite cell activation, muscle fibre hypertrophy and tissue repair following damage.

    Interaction With Exercise Physiology

    Resistance exercise itself strongly activates the same pathways targeted by peptides. Mechanical loading increases local IGF‑1 expression within muscle tissue and stimulates mTOR signalling, which is central to muscle protein synthesis (Machida and Booth, 2004). This highlights an important limitation: peptides are not introducing new biological mechanisms but attempting to manipulate systems already maximally stimulated through appropriate training and nutrition.

    Tissue Repair and Regeneration Pathways

    Some peptides are proposed to influence recovery through mechanisms such as angiogenesis, enhanced collagen synthesis, modulation of inflammatory pathways and improved fibroblast activity. These mechanisms underpin claims relating to improved healing of connective tissues and reduced injury recovery time. However, the evidence supporting these claims is heavily dominated by preclinical animal research, with limited high-quality human validation.

    Training Adaptation: The Central Issue

    Training adaptation is a multifactorial process driven by the interaction between mechanical, metabolic and biological signals. It depends on progressive overload, motor unit recruitment, neuromuscular adaptation, nutrient availability and recovery processes rather than a single signalling pathway. Peptides influence only a narrow component of this system, primarily intracellular signalling.

    Adaptation follows a sequence whereby a sufficient training stimulus produces intracellular signalling, leading to protein synthesis, structural change and ultimately functional improvement. Peptides act at the signalling stage but do not replace the initial mechanical stimulus. This leads to a critical principle: increasing signalling alone does not produce meaningful adaptation in the absence of appropriate training.

    A consistent finding across the literature is the discrepancy between molecular responses and functional outcomes. Studies often demonstrate increases in IGF‑1, activation of anabolic signalling pathways and changes in gene expression, yet these do not consistently translate into increased strength, improved power output or enhanced performance. For example, collagen peptide studies show increased signalling pathway activation without significant improvements in strength or functional performance (Centner et al., 2022; Balshaw et al., 2022). This highlights that molecular changes are necessary but not sufficient for meaningful adaptation.

    Adaptation is also constrained by limiting factors such as training stimulus, protein intake, energy availability and recovery. Peptides do not override these constraints, meaning increased signalling cannot compensate for inadequate training or nutrition. Additionally, most peptide studies are conducted in untrained or clinical populations, where adaptive capacity is higher. In trained athletes, physiological systems are already optimised, meaning the marginal benefit of additional signalling is likely to be minimal due to ceiling effects.

    Evidence Base

    Growth Hormone and Related Interventions

    The strongest human evidence comes from research on growth hormone. Randomised controlled trials demonstrate that growth hormone administration can increase lean body mass and reduce fat mass, particularly in ageing or hormone-deficient populations (Hoffman et al., 2004; Fernández‑Garza et al., 2025). However, interpretation of these findings is complex. Growth hormone increases extracellular fluid retention and connective tissue mass, meaning increases in lean mass do not necessarily represent increases in contractile muscle tissue.

    Despite changes in body composition, functional outcomes are inconsistent. Upper-body strength often shows no significant improvement, while lower-body strength gains are modest and variable (Tavares et al., 2013). Performance outcomes are rarely improved, indicating that growth hormone-related hypertrophy is not equivalent to training-induced hypertrophy.

    Growth hormone interventions are also associated with metabolic consequences, including reduced insulin sensitivity and impaired glucose tolerance (Fernández‑Garza et al., 2025). These findings raise concerns regarding long-term health risks and highlight the importance of risk–benefit analysis.

    Collagen Peptides and Resistance Training

    Research on collagen peptides provides additional insight into the disconnect between molecular signalling and functional outcomes. Acute studies demonstrate increased activation of anabolic signalling pathways following collagen supplementation and resistance exercise (Centner et al., 2022). However, longer-term studies show increases in muscle volume without corresponding improvements in strength or performance (Balshaw et al., 2022). This suggests that structural changes at the tissue level do not necessarily translate into functional improvements.

    Protein Versus Peptides

    Comparative studies consistently demonstrate that protein quality and quantity are more important determinants of adaptation than peptide supplementation. Whey protein has been shown to produce greater increases in muscle size than collagen peptides, despite matched leucine content, while strength gains remain similar (Jacinto et al., 2022). This reinforces established principles of sports nutrition, where total protein intake and amino acid availability drive adaptation.

    Recovery Peptides

    Recovery peptides such as BPC‑157 are widely discussed within fitness circles but lack robust human evidence. Systematic reviews indicate that the majority of studies are preclinical, with very few human trials and a lack of randomised controlled evidence (Vasireddi et al., 2025). Narrative reviews further confirm that although animal models demonstrate promising effects, these findings have not been reliably replicated in humans (McGuire et al., 2025). Current claims regarding recovery peptides are therefore not supported by strong clinical data.

    Study Design Limitations

    The peptide evidence base is limited by consistent methodological issues. Many studies involve small sample sizes, reducing statistical power and increasing variability. Research is often conducted in non-athletic populations, limiting applicability to trained individuals. Study durations are typically short, preventing long-term conclusions about adaptation or safety.

    There is a heavy reliance on surrogate outcomes such as lean body mass, hormone concentrations and gene expression, which do not necessarily reflect real-world performance outcomes. Confounding variables such as training programme design, nutritional intake and recovery practices are often not well controlled. Additionally, there is a lack of replication across independent studies and a significant translational gap between animal and human research, particularly in recovery peptide investigations.

    Safety Considerations

    Acute risks include fluid retention, impaired glucose metabolism, reduced insulin sensitivity and injection-related complications. Chronic risks are less well understood but potentially more serious. IGF‑1 promotes cell proliferation and inhibits apoptosis, and chronic elevation is associated with increased cancer risk (Ahmad et al., 2020). Long-term concerns also include cardiovascular strain, endocrine disruption and metabolic dysfunction. A key limitation is the absence of long-term human safety data, meaning the true risk profile remains unclear.

    Practical Implications

    Peptides should not be considered first-line interventions for performance enhancement. Training, nutrition and recovery remain the primary drivers of adaptation. Peptides should be viewed as experimental due to the limited and inconsistent evidence base. The risk–reward profile is currently unfavourable, with modest potential benefits and uncertain long-term risks.

    Practitioners should prioritise evidence-based strategies and educate athletes on the limitations of current knowledge. Any consideration of peptide use should occur within a medically supervised context. Focus should remain on progressive resistance training, adequate protein intake, creatine supplementation and sleep optimisation, all of which are supported by high-quality evidence.

    Final Conclusion

    Peptides are biologically plausible and mechanistically sound, influencing key pathways involved in muscle growth and recovery. However, the current evidence indicates that they do not meaningfully enhance training adaptation or performance beyond what can be achieved through well-structured training and nutrition.

    The literature is constrained by methodological weaknesses, non-athletic populations, reliance on surrogate outcomes and limited long-term data. At the same time, safety concerns remain unresolved.

    From a performance perspective, peptides do not replace training, do not reliably enhance adaptation and should currently be regarded as experimental rather than evidence-based tools. The fundamentals of performance continue to provide the most effective and reliable outcomes.

    References

    Ahmad, S.S. et al. (2020) Implications of insulin-like growth factor‑1 in skeletal muscle and various diseases. Cells, 9(8), 1773

    Balshaw, T.G. et al. (2022) The effect of specific bioactive collagen peptides on function and muscle remodeling during human resistance training. Acta Physiologica

    Centner, C. et al. (2022) Supplementation of specific collagen peptides following high-load resistance exercise upregulates gene expression. Frontiers in Physiology

    Fernández‑Garza, L.E. et al. (2025) Growth hormone and aging: a clinical review. Frontiers in Aging

    Hoffman, A.R. et al. (2004) Growth hormone replacement therapy in adult-onset GH deficiency. Journal of Clinical Endocrinology & Metabolism

    Jacinto, J.L. et al. (2022) Whey protein supplementation is superior to leucine-matched collagen peptides. International Journal of Sport Nutrition and Exercise Metabolism

    Machida, S. and Booth, F.W. (2004) Insulin-like growth factor‑1 and satellite cell proliferation. Proceedings of the Nutrition Society

    McGuire, F.P. et al. (2025) Regeneration or risk? A narrative review of BPC‑157. Current Reviews in Musculoskeletal Medicine

    Tavares, A.B. et al. (2013) Effects of growth hormone administration on muscle strength. International Journal of Endocrinology

    Vasireddi, S. et al. (2025) Systematic review of BPC‑157 for orthopaedic applications. American Journal of Sports Medicine

  • Nutrition for the Menstrual Cycle: Physiology-Based Fueling Strategies for Female Athletes

    Introduction: Why the Menstrual Cycle Matters in Sports Nutrition

    The menstrual cycle is a complex endocrine rhythm governed by the hypothalamic–pituitary–ovarian (HPO) axis. It produces cyclical fluctuations in oestrogen and progesterone that influence nearly every physiological system relevant to sport:

    • Substrate utilisation (fat vs carbohydrate oxidation)
    • Glycogen storage and insulin sensitivity
    • Thermoregulation and heat tolerance
    • Fluid balance and plasma volume
    • Neuromuscular function and connective tissue properties
    • Mood, appetite regulation, and central nervous system drive

    Despite this, the scientific literature consistently highlights that performance effects across the cycle are small, variable, and highly individual, largely due to methodological limitations in cycle tracking and hormone verification (Elliott-Sale et al., 2021).

    Therefore, the most effective approach is not rigid “cycle syncing”, but physiology-led, flexible nutrition periodisation.

    Endocrine Overview: What is Actually Changing?

    The menstrual cycle is typically 21–35 days and is divided into follicular and luteal phases, with ovulation occurring mid-cycle.

    Key hormones and their roles

    Oestrogen (17β-oestradiol)

    • Increases fat oxidation during submaximal exercise
    • Enhances insulin sensitivity
    • Supports endothelial function and blood flow
    • Influences neuromuscular efficiency and central fatigue tolerance

    Progesterone

    • Thermogenic effect (raises core temperature)
    • Increases ventilation (respiratory drive)
    • May increase protein catabolism and glycogen utilisation
    • Can reduce gastrointestinal motility

    (Oosthuyse and Bosch, 2010)

    Menstrual Phase (Day 1–5): Low Hormones, High Inflammatory Activity

    Physiology in detail

    The menstrual phase begins with endometrial shedding, triggered by a sharp decline in both oestrogen and progesterone. This withdrawal leads to:

    Inflammatory cascade

    • Increased prostaglandin production
    • Uterine smooth muscle contraction (cramping)
    • Elevated local inflammatory signalling

    Systemic effects

    • Reduced circulating oestradiol
    • Lower resting core temperature
    • Potential transient reductions in plasma volume
    • Increased perceived fatigue in some individuals

    Importantly, iron loss is the most nutritionally significant factor, especially in athletes with heavy menstrual bleeding or low ferritin status.

    Performance implications

    • No consistent reduction in maximal strength or aerobic capacity in controlled studies
    • Higher inter-individual variability in perceived exertion
    • Pain and fatigue can indirectly reduce training output

    (Elliott-Sale et al., 2021)

    Nutrition strategy (mechanistic focus)

    1. Iron restoration and oxygen transport support

    Menstrual bleeding increases iron turnover, and iron is essential for:

    • Haemoglobin (oxygen transport)
    • Myoglobin (muscle oxygen storage)
    • Mitochondrial electron transport chain enzymes

    Strategy:

    • Heme iron: red meat, liver, poultry
    • Non-heme iron: legumes, spinach, fortified grains
    • Combine with vitamin C to enhance ferric → ferrous conversion

    (Beard and Tobin, 2000)

    Performance rationale:
    Low ferritin reduces VO₂max, increases fatigue, and impairs endurance efficiency.

    2. Prostaglandin and inflammation modulation

    • Omega-3 fatty acids reduce inflammatory eicosanoid production
    • Polyphenols may reduce oxidative stress and perceived pain

    3. Energy stability

    • Maintain carbohydrate intake to support serotonin synthesis
    • Prevent hypoglycaemia-related fatigue amplification

    Follicular Phase (Day 1–13): Rising Oestrogen and Increasing Metabolic Efficiency

    Physiology in detail

    The follicular phase begins with menstruation and continues until ovulation. It is characterised by:

    • Gradual rise in oestradiol
    • Low progesterone
    • Improved insulin sensitivity
    • Increased glucose uptake efficiency in muscle tissue

    Oestrogen also enhances:

    • Lipolysis (fat mobilisation)
    • Glycogen sparing during submaximal exercise
    • Vascular dilation and blood flow

    (Oosthuyse and Bosch, 2010)

    Performance implications

    This phase is often associated (not universally) with:

    • Better tolerance to high-intensity training
    • Improved training adaptation potential
    • Lower perceived exertion in some athletes

    However, meta-analytical evidence shows no consistent performance advantage when hormone confirmation is used (McNulty et al., 2020).

    Nutrition strategy (performance periodisation model)

    1. Carbohydrate periodisation (key lever)

    Improved insulin sensitivity supports:

    • Higher glycogen synthesis rates
    • More efficient glucose uptake (GLUT-4 activity)

    Application:

    • Higher carbohydrate availability around key training sessions
    • Fuel harder sessions more aggressively

    2. Protein synthesis optimisation

    Muscle protein synthesis is not cycle-dependent in a clinically meaningful way, but adequate intake remains essential:

    • 1.6–2.2 g/kg/day protein
    • 0.3–0.4 g/kg per meal

    (Phillips and Van Loon, 2011)

    3. Training adaptation window

    This phase may be optimal for:

    • Strength development blocks
    • High-intensity interval training
    • Volume progression phases

    Ovulatory Phase (Day ~12–16): Hormonal Peak and Transition Stress Point

    Physiology in detail

    Ovulation is triggered by an LH surge, preceded by peak oestradiol levels. This results in:

    • Follicle rupture and oocyte release
    • Short-term inflammatory response
    • Rapid hormonal transition (oestrogen → progesterone shift begins)
    • Slight thermoregulatory variability

    (Oosthuyse and Bosch, 2010)

    Performance considerations

    Research findings are mixed:

    • Some studies show small improvements in power output
    • Others show no meaningful change
    • Variability is largely due to individual response differences

    (Elliott-Sale et al., 2021)

    Nutrition strategy

    1. Oxidative stress buffering

    Hormonal peaks may increase reactive oxygen species in some contexts:

    • Polyphenols (berries, green tea, cocoa)
    • Omega-3 fatty acids

    2. Hydration and plasma stability

    • Maintain sodium and fluid balance
    • Support cardiovascular stability during training

    3. Energy consistency

    Avoid under-fuelling during hormonal transition phases due to:

    • Increased physiological variability
    • Potential appetite fluctuations

    Luteal Phase (Day 16–28): Elevated Metabolic Demand and Thermoregulatory Stress

    Physiology in detail

    The luteal phase is dominated by progesterone, which drives:

    Metabolic effects

    • Increased resting metabolic rate (~2–10%)
    • Increased oxygen consumption at rest
    • Greater carbohydrate oxidation during exercise

    Thermoregulatory effects

    • Increased core temperature (~0.3–0.5°C)
    • Reduced heat dissipation efficiency
    • Increased sweat rate variability

    Neurometabolic effects

    • Increased ventilation rate
    • Higher perceived exertion
    • Potential serotonin fluctuations influencing appetite

    (Smith and Steege, 2003)

    Performance implications

    • Increased strain in hot environments
    • Higher carbohydrate dependency during exercise
    • Greater perception of effort at same workload

    However, when energy intake is matched, performance decrements are not consistently observed (McNulty et al., 2020).

    Nutrition strategy (key performance phase)

    1. Energy availability adjustment (critical)

    Due to increased metabolic rate:

    • +90–300 kcal/day (individualised)
    • Prioritise energy availability for recovery and adaptation

    2. Carbohydrate emphasis (glycogen reliance increases)

    Progesterone increases glucose utilisation during exercise:

    • Maintain consistent carbohydrate intake
    • Prioritise pre- and post-training fuelling

    3. Micronutrient and neurotransmitter support

    Magnesium

    • Muscle relaxation
    • Sleep quality
    • Neuromuscular regulation

    Vitamin B6

    • Neurotransmitter synthesis (serotonin, dopamine pathways)
    • Mood regulation support

    4. Gastrointestinal management

    Progesterone slows GI transit:

    • Reduce excessive fibre pre-training
    • Choose low-FODMAP carbohydrate sources if needed
    • Avoid large high-fat meals close to exercise

    5. Thermoregulation strategy

    • Increased fluid and sodium intake in hot conditions
    • Cooling strategies for endurance sessions

    Critical Scientific Perspective: What the Evidence Actually Shows

    Despite strong physiological mechanisms, the current consensus is:

    Menstrual cycle phase effects on performance are small, inconsistent, and highly individual when rigorous study designs are used (Elliott-Sale et al., 2021).

    Key limitations in research

    • Lack of hormone confirmation (many studies rely on calendar tracking)
    • Small sample sizes
    • High inter-individual variability
    • Confounding from training status, nutrition, and sleep

    Applied Summary

    Menstrual phase

    Focus: iron + inflammation + energy stability

    Follicular phase

    Focus: carbohydrate availability + training progression

    Ovulation

    Focus: hydration + antioxidant support + consistency

    Luteal phase

    Focus: increased energy intake + carb support + thermoregulation

    Conclusion

    The menstrual cycle is best understood not as a limitation, but as a dynamic physiological framework influencing metabolism and recovery capacity.

    The strongest applied nutrition model is:

    • Maintain energy availability across all phases
    • Adjust carbohydrate intake to metabolic demand
    • Support iron status and micronutrient needs
    • Individualise based on symptoms and training load

    This approach aligns with current sports science consensus and avoids overinterpretation of cycle-based performance claims.

    References

    Beard, J.L. and Tobin, B. (2000) ‘Iron status and exercise’, The American Journal of Clinical Nutrition, 72(2), pp. 594S–597S.

    Elliott-Sale, K.J., McNulty, K.L., Ansdell, P., et al. (2021) ‘Methodological considerations for studies in the menstrual cycle in female athletes’, Sports Medicine, 51(4), pp. 843–861.

    McNulty, K.L., Elliott-Sale, K.J., Dolan, E., et al. (2020) ‘The effects of menstrual cycle phase on exercise performance in eumenorrheic women: a systematic review and meta-analysis’, Sports Medicine, 50, pp. 1813–1827.

    Oosthuyse, T. and Bosch, A.N. (2010) ‘The effect of the menstrual cycle on exercise metabolism: implications for exercise performance in eumenorrheic women’, Sports Medicine, 40(3), pp. 207–227.

    Phillips, S.M. and Van Loon, L.J.C. (2011) ‘Dietary protein for athletes: from requirements to optimum adaptation’, Journal of Sports Sciences, 29(S1), pp. S29–S38.

    Smith, R.L. and Steege, J.F. (2003) ‘The menstrual cycle and exercise performance’, Clinical Sports Medicine, 22(3), pp. 351–372.

  • Behaviour Change and Nutrition: The Key to Consistency

    Whether you’re aiming to build muscle, lose fat, or enhance performance, your nutrition habits are just as important as your training program. But sticking to a diet plan whether it’s a bulking phase, a cutting cycle, or performance nutrition can be harder than hitting a heavy squat. The real challenge isn’t knowing what to eat; it’s changing your behaviour to make it happen consistently.

    This is where behaviour change science comes in. Grounded in psychology, behaviour change strategies can help gym goers, athletes and well honestly, anyone! overcome common barriers like poor planning, low motivation, and decision fatigue turning good intentions into real results.

    Why Motivation Alone Isn’t Enough

    You might start a new meal plan feeling motivated and ready. But motivation fluctuates. To stay consistent long-term, you need more than willpower you need systems and strategies.

    According to the COM-B model, behaviour is driven by three things: Capability, Opportunity, and Motivation (Michie et al., 2011). In a gym context, this might look like:

    Capability: Do you have the cooking skills and nutrition knowledge? Opportunity: Is your environment helping or hindering your eating goals? Motivation: Are you clear on why you’re doing this?

    Addressing all three areas sets you up for long-term adherence not just short-term compliance.

    Habit Formation and Meal Consistency

    For athletes and recreational lifters, habit formation is key. The Health Action Process Approach (HAPA) highlights the difference between intention and action. You might plan to prep meals or hit your macros but without planning, tracking, and adjusting, those intentions often fall flat (Schwarzer, 2008).

    Using tools like MyFitnessPal (or other apps), food scales, and prep routines helps build consistency. Research shows that self-monitoring—tracking what you eat—is one of the most powerful predictors of success in fat loss and muscle gain (Chen et al., 2023).

    Digital Tools for Diet Adherence

    A 2023 meta-analysis confirmed that using nutrition tracking apps significantly improves dietary behaviours and outcomes in people aiming to lose fat or gain lean mass (Chen et al., 2023). These tools don’t just count calories they give real-time feedback, help you spot trends, and reinforce accountability.

    Other behaviour change techniques (BCTs) proven to support gym-related goals include:

    SMART goal-setting (Specific, Measurable, Achievable, Relevant, Time-bound)

    If then planning (e.g., “If I get hungry post-workout, then I’ll have a protein shake”)

    Social support (training partners or online communities)

    Why Most Meal Plans Fail (And How to Fix It)

    Many people fall off their meal plans not because they’re “lazy” or “undisciplined,” but because their approach doesn’t match their lifestyle or values. According to the Theory of Planned Behaviour (TPB), intentions alone aren’t enough people must also believe they have control over their environment and the ability to follow through (Ajzen, 1991).

    That’s why environmental restructuring like prepping meals in advance, keeping snacks out of sight, or having protein options ready post-training is critical. Your environment should make the right choice the easy choice.

    The Bigger Picture: Stress, Sleep, and Social Support

    Behaviour change science also reminds us that diet doesn’t happen in isolation. Poor sleep, stress, or a lack of social support can derail even the best plan. The Science of Behavior Change (SOBC) program by NIH highlights how self-regulation, stress management, and habit loops can be modified to enhance results (NIH, 2023).

    In other words, you don’t need to grind harder you need to train smarter, eat smarter, and structure your environment and mindset for success.

    Conclusion

    If you’ve ever struggled to stay consistent with your nutrition while training hard, you’re not alone and you’re not lacking discipline. You’re just missing the behaviour change strategies that align your habits with your goals.

    By applying science-based models like COM-B, HAPA, and TPB, and using tools like tracking apps, habit systems, and structured planning, you can finally bridge the gap between training and nutrition and unlock your full potential in the gym.

    If you want structured support to improve nutrition behaviour change and long term performance, get in touch

    Contact me

    References

    Ajzen, I., 1991. The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50(2), pp.179–211.

    Chen, J., Cade, J.E. and Allman-Farinelli, M., 2023. The effectiveness of nutrition apps in improving dietary behaviours and health outcomes: a systematic review and meta-analysis. Public Health Nutrition, 26(1), pp.1–12.

    Greaves, C.J., Sheppard, K.E., Abraham, C., Hardeman, W., Roden, M., Evans, P.H. and Schwarz, P., 2011. Systematic review of reviews of intervention components associated with increased effectiveness in dietary and physical activity interventions. BMC Public Health, 11(1), p.119.

    Lee, R.M., Fischer, C., Caballero, P., and Andersson, E., 2022. Behaviour change nutrition interventions and their effectiveness: a systematic review of global public health outcomes. PLOS Global Public Health, 2(9), p.e0000401.

    Michie, S., Atkins, L., and West, R., 2014. The Behaviour Change Wheel: A Guide to Designing Interventions. London: Silverback Publishing.

    Michie, S., van Stralen, M.M. and West, R., 2011. The behaviour change wheel: A new method for characterising and designing behaviour change interventions. Implementation Science, 6(1), p.42.

    NIH Common Fund, 2023. Science of Behavior Change (SOBC). [online] Available at: https://commonfund.nih.gov/science-behavior-change-sobc [Accessed 18 May 2025].

    Schwarzer, R., 2008. Modeling health behavior change: How to predict and modify the adoption and maintenance of health behaviors. Applied Psychology, 57(1), pp.1–29.

  • Understand HMB, Benefits, Mechanisms and Safety

    A former athlete I worked with popped up the other day asking if he should start taking HMB to increase muscle mass. I wish I could have given him a straight yes or no but generally if your aim is to lose body fat then HMB may help with preserving lean tissue. However, research is far from definitive in support of its efficacy.

    Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite of the essential amino acid leucine, recognized for its potential to enhance muscle health and performance. I will attempt to delve into the current scientific understanding of HMB, exploring its benefits, mechanisms of action, and safety profile.

    Benefits of HMB Supplementation

    1. Muscle Mass and Strength Enhancement

    Research indicates that HMB supplementation can lead to significant improvements in muscle mass and strength. An umbrella review of meta-analyses by Bideshki et al. (2025) found that HMB supplementation resulted in increases in fat-free mass and muscle strength index. These findings suggest that HMB can be particularly beneficial for individuals experiencing muscle atrophy due to various physiological conditions. 

    2. Attenuation of Muscle Loss in Clinical Conditions

    Loss of skeletal muscle mass and muscle weakness are common in various clinical conditions, leading to impaired physical function. A systematic review and meta-analysis by Rowlands et al. (2019) involving 2,137 patients demonstrated that HMB supplementation increased muscle mass and strength, although the effect sizes were small. This suggests that HMB could be a valuable nutritional intervention for preserving muscle health in clinical populations and athletic populations.

    3. Reduction of Exercise-Induced Muscle Damage

    HMB has been shown to reduce muscle damage associated with intense physical activity, thereby accelerating recovery. The International Society of Sports Nutrition’s position stand, as outlined by Wilson et al. (2013), highlights that HMB supplementation decreases post-exercise muscle damage and enhances recovery, making it beneficial across various sports disciplines, regardless of age or sex.  

    Mechanisms of Action

    The anabolic effects of HMB are primarily attributed to its role in protein metabolism. HMB stimulates protein synthesis while attenuating protein degradation in skeletal muscle, potentially leading to muscle hypertrophy and improved strength. Additionally, HMB supplementation has been associated with reductions in total cholesterol, LDL cholesterol, and systolic blood pressure, suggesting potential cardiovascular benefits

    Safety and Dosage

    HMB supplementation is generally considered safe for consumption. The International Society of Sports Nutrition’s position stand by Wilson et al. (2013) reports that a daily intake of 3g per day is well-tolerated without adverse effects on tissue health and function. However, individuals may experience mild gastrointestinal issues, and it is advisable to consult an SENr/AfN registered Nutritionist before starting any new supplement regimen. The combination of HMB with other supplements, such as vitamin D, creatine has also been explored for potential synergistic effects on muscle health, highlighting some positive results.

    Before you decide if HMB is worth adding to your nutrition strategy ask yourself, am I getting the fundamentals right? I.e consuming enough high quality protein, fuelling your training correctly, recovering efficiently? If you answer no to any one of those then HMB may not be for you until you address the fundamental gaps.

    Conclusion

    HMB emerges as a promising supplement for enhancing muscle mass, strength, and recovery, particularly in populations susceptible to muscle loss, such as older adults and those undergoing intense physical training. Its safety profile and potential additional benefits, including cardiovascular improvements, make it a valuable consideration for individuals aiming to optimize muscle health providing the fundamentals (Timing, Type, Total Amount) are maximised. As with any supplement, it is essential to consult with a SENr/AfN registered nutritionist to tailor interventions to individual health needs, conditions and trained status.

    References

    1. Bideshki, A., Bagheri, R., Rashidlamir, A., Motevalli, M. S., & Wong, A. (2025). Ergogenic Benefits of β-Hydroxy-β-Methyl Butyrate (HMB) Supplementation on Body Composition and Muscle Strength: An Umbrella Review of Meta-Analyses. Journal of Cachexia, Sarcopenia and Muscle, 16(2), 123-135. 

    2. Rowlands, D. S., Thomson, J. S., Timmons, B. W., Raymond, F., Fuerholz, A., Mansourian, R., Zwahlen, R., Metairon, S., Glover, E., & Tarnopolsky, M. A. (2019). β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis. The American Journal of Clinical Nutrition, 109(4), 1119-1132. 

    3. Wilson, J. M., Lowery, R. P., Joy, J. M., Andersen, J. C., Wilson, S. M., Stout, J. R., & Duncan, N. (2013). International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). Journal of the International Society of Sports Nutrition, 10(1), 6. 

    4. Nissen, S. L., & Sharp, R. L. (2000). β-Hydroxy-β-methylbutyrate (HMB) supplementation in humans is safe and may decrease cardiovascular risk factors. The Journal of Nutrition, 130(8), 1937-1945.

  • Multi-Ingredient Pre-Workout Supplements: What Does the Science Actually Say?

    Introduction

    Multi-ingredient pre-workout supplements (MIPS) have become one of the most popular categories within the sports nutrition industry. Marketed as products that can increase energy, improve focus, enhance muscular endurance, boost strength, and deliver a superior training session, they are widely used by recreational gym-goers and elite athletes alike.

    However, despite their popularity, the scientific evidence supporting pre-workout supplements is often misunderstood. While some ingredients have substantial research demonstrating improvements in exercise performance, others possess limited evidence or are frequently included at doses below those shown to be effective in the literature.

    Furthermore, many products utilise proprietary blends, preventing consumers from knowing whether they are receiving evidence-based dosages of key ingredients.

    This article critically evaluates the most common ingredients found within multi-ingredient pre-workout supplements and examines whether they work according to current peer-reviewed scientific evidence.

    What Are Multi-Ingredient Pre-Workout Supplements?

    Multi-ingredient pre-workout supplements are formulations designed to be consumed before exercise and typically contain a combination of:

    • Stimulants
    • Amino acids
    • Ergogenic aids
    • Nootropics
    • Vitamins and minerals

    The rationale behind these products is that combining multiple ingredients may produce synergistic effects that enhance both physical and cognitive performance.

    Research suggests that some MIPS can improve training volume, muscular endurance, anaerobic performance and subjective feelings of energy (Jagim et al., 2019). However, many of these benefits appear to be driven primarily by a small number of evidence-based ingredients.

    Caffeine

    What is it?

    Caffeine is a naturally occurring stimulant found in coffee, tea, cocoa and numerous sports supplements.

    Does it work?

    Yes.

    Caffeine is arguably the most effective acute ergogenic aid available to athletes. Numerous systematic reviews and meta-analyses have demonstrated improvements in:

    • Strength
    • Power output
    • Muscular endurance
    • Sprint performance
    • Endurance performance
    • Cognitive function
    • Alertness and reaction time

    Caffeine acts primarily through antagonism of adenosine receptors within the central nervous system, reducing perceptions of fatigue and increasing alertness (Guest et al., 2021).

    A meta-analysis by Grgic et al. (2020) concluded that caffeine supplementation significantly improves maximal strength and muscular power across a range of exercise modalities.

    Effective Dose

    Current recommendations suggest:

    3–6 mg·kg⁻¹ body mass

    Consumed approximately 30–60 minutes before exercise (Guest et al., 2021).

    For a 75 kg athlete this equates to approximately 225–450 mg of caffeine.

    Verdict

    ★★★★★

    Strong evidence.

    If a pre-workout supplement improves performance acutely, caffeine is often the primary reason.

    Beta-Alanine

    What is it?

    Beta-alanine is a non-essential amino acid that increases intramuscular carnosine concentrations.

    Carnosine acts as an intracellular buffer, helping to reduce the accumulation of hydrogen ions during intense exercise.

    Does it work?

    Yes, but not immediately.

    Unlike caffeine, beta-alanine does not provide an acute performance benefit following a single serving. Instead, benefits occur following chronic supplementation over several weeks.

    Research suggests improvements in exercise lasting approximately 60–240 seconds, where metabolic acidosis contributes to fatigue (Saunders et al., 2017).

    The tingling sensation commonly associated with beta-alanine supplementation (paresthesia) is harmless but unrelated to performance enhancement.

    Effective Dose

    3.2–6.4 g per day

    For at least 4–8 weeks (Trexler et al., 2015).

    Verdict

    ★★★★☆

    Strong evidence for chronic use.

    Less relevant as an acute pre-workout ingredient.

    Citrulline Malate

    What is it?

    Citrulline is a non-essential amino acid involved in nitric oxide production.

    Nitric oxide promotes vasodilation, potentially increasing blood flow and nutrient delivery to working muscles.

    Does it work?

    Current evidence suggests that citrulline supplementation can:

    • Increase training volume
    • Reduce perceived fatigue
    • Improve muscular endurance
    • Enhance recovery between repeated efforts

    A systematic review by Trexler et al. (2019) reported that citrulline may improve resistance training performance, particularly during higher-volume sessions.

    Effective Dose

    6–8 g citrulline malate

    or

    6 g L-citrulline

    Consumed approximately 60 minutes before exercise.

    Common Problem

    Many commercial pre-workout products contain substantially less than the recommended dosage, limiting the likelihood of meaningful physiological benefits.

    Verdict

    ★★★★☆

    Good evidence when adequately dosed.

    Creatine Monohydrate

    What is it?

    Creatine is a naturally occurring compound stored within skeletal muscle as phosphocreatine.

    Its primary role is to facilitate rapid ATP regeneration during high-intensity exercise.

    Does it work?

    Absolutely.

    Creatine is one of the most extensively researched sports supplements available and consistently demonstrates improvements in:

    • Strength
    • Power
    • Sprint performance
    • Lean mass gains
    • Training adaptations

    A comprehensive review by Kreider et al. (2022) concluded that creatine remains one of the safest and most effective nutritional supplements for improving exercise capacity and increasing lean tissue mass.

    Effective Dose

    3–5 g daily

    Timing is considerably less important than consistent daily consumption.

    Verdict

    ★★★★★

    Exceptional evidence.

    One of the few supplements that consistently improves training adaptations.

    Betaine

    What is it?

    Betaine (trimethylglycine) is a naturally occurring compound found in foods such as beetroot and spinach.

    It functions as an osmolyte and methyl donor within the body.

    Does it work?

    Research remains mixed.

    Some studies have demonstrated improvements in:

    • Muscular endurance
    • Power production
    • Training volume

    However, evidence remains less consistent than that supporting caffeine or creatine.

    Effective Dose

    Approximately 2.5 g daily.

    Verdict

    ★★★☆☆

    Promising but requires further investigation.

    Taurine

    What is it?

    Taurine is an amino acid involved in numerous physiological processes including:

    • Muscle contraction
    • Calcium regulation
    • Cellular hydration
    • Antioxidant defence

    Does it work?

    Evidence suggests taurine may improve endurance performance and reduce fatigue under certain conditions.

    However, findings remain inconsistent and effects appear relatively modest compared with caffeine or creatine.

    Effective Dose

    1–3 g prior to exercise.

    Verdict

    ★★★☆☆

    Potentially beneficial but not a primary performance enhancer.

    L-Tyrosine

    What is it?

    Tyrosine is a precursor for dopamine, adrenaline and noradrenaline.

    It is often included in pre-workout supplements to improve focus and cognitive performance.

    Does it work?

    Tyrosine appears most effective during situations involving:

    • Mental fatigue
    • Sleep deprivation
    • Psychological stress

    Evidence supporting direct improvements in physical performance is limited.

    Effective Dose

    500–2000 mg pre-exercise.

    Verdict

    ★★★☆☆

    May support cognitive performance rather than physical performance.

    B Vitamins

    What are they?

    Many pre-workout supplements contain large doses of:

    • Vitamin B6
    • Vitamin B12
    • Niacin
    • Riboflavin

    Manufacturers often market these ingredients as “energy boosters.”

    Do they work?

    Not in individuals who are already meeting nutritional requirements.

    B vitamins play essential roles in energy metabolism, but supplementation beyond physiological requirements does not appear to enhance exercise performance in healthy individuals.

    Verdict

    ★★☆☆☆

    Important for health but unlikely to improve performance unless a deficiency exists.

    The Problem with Proprietary Blends

    One of the greatest concerns surrounding many commercial pre-workout supplements is the use of proprietary blends.

    These blends allow manufacturers to disclose the total weight of a mixture without revealing individual ingredient quantities.

    Consequently, consumers cannot determine whether evidence-based dosages are present.

    Research analysing commercially available pre-workout supplements found that many ingredients are under-dosed relative to scientifically supported recommendations (Jagim et al., 2019).

    When selecting a pre-workout supplement, transparency is often a positive indicator of product quality.

    Should Athletes Use Pre-Workout Supplements?

    For athletes, context is critical.

    Before Strength Training

    A caffeine-containing pre-workout may improve:

    • Training quality
    • Power output
    • Resistance training performance

    Before Technical Training

    Benefits may be smaller, particularly if training intensity is moderate.

    Before Matches

    Caffeine can enhance performance, but individual tolerance must be assessed carefully.

    Potential drawbacks include:

    • Gastrointestinal discomfort
    • Increased anxiety
    • Sleep disruption following evening fixtures

    For many players, targeted caffeine supplementation may be more appropriate than a highly stimulant-based pre-workout product.

    Practical Recommendations

    When evaluating a pre-workout supplement, look for:

    Ingredient

    Evidence-Based Dose

    Caffeine

    3–6 mg·kg⁻¹

    Creatine Monohydrate

    3–5 g daily

    Beta-Alanine

    3.2–6.4 g daily

    Citrulline Malate

    6–8 g

    Betaine

    2.5 g

    Taurine

    1–3 g

    Be cautious if:

    • Ingredient amounts are hidden
    • Proprietary blends dominate the label
    • Marketing claims exceed the available scientific evidence

    Conclusion

    Multi-ingredient pre-workout supplements can improve exercise performance, but their effectiveness depends largely on the ingredients and dosages they contain.

    The strongest evidence supports caffeine, creatine monohydrate, beta-alanine and citrulline. These ingredients have consistently demonstrated meaningful performance benefits within peer-reviewed research.

    Many other ingredients commonly found in pre-workout supplements show promise, but currently possess weaker evidence bases.

    Rather than selecting a product based on marketing claims, athletes should evaluate supplements according to transparent labelling and evidence-based dosing strategies.

    Ultimately, no pre-workout supplement can compensate for poor nutrition, inadequate sleep, or suboptimal training. Supplements should enhance an already robust performance programme rather than serve as its foundation.

    References

    Grgic, J., Trexler, E.T., Lazinica, B. and Pedisic, Z. (2020) ‘Effects of caffeine intake on muscle strength and power: A systematic review and meta-analysis’, Journal of the International Society of Sports Nutrition, 17(1), pp. 1–10.

    Guest, N.S., VanDusseldorp, T.A., Nelson, M.T., Grgic, J., Schoenfeld, B.J., Jenkins, N.D.M., Arent, S.M., Antonio, J., Stout, J.R., Trexler, E.T. and Smith-Ryan, A.E. (2021) ‘International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance’, Journal of the International Society of Sports Nutrition, 18(1), pp. 1–37.

    Jagim, A.R., Harty, P.S., Camic, C.L. and Kerksick, C.M. (2019) ‘Common ingredient profiles of multi-ingredient pre-workout supplements’, Nutrients, 11(2), pp. 254–266.

    Kreider, R.B., Kalman, D.S., Antonio, J., Ziegenfuss, T.N., Wildman, R., Collins, R., Candow, D.G., Kleiner, S.M., Almada, A.L. and Lopez, H.L. (2022) ‘International Society of Sports Nutrition Position Stand: Safety and efficacy of creatine supplementation in exercise, sport and medicine’, Journal of the International Society of Sports Nutrition, 19(1), pp. 1–46.

    Saunders, B., Elliott-Sale, K., Artioli, G.G., Swinton, P.A., Dolan, E., Roschel, H., Sale, C. and Gualano, B. (2017) ‘β-Alanine supplementation to improve exercise capacity and performance: A systematic review and meta-analysis’, British Journal of Sports Medicine, 51(8), pp. 658–669.

    Trexler, E.T., Smith-Ryan, A.E., Stout, J.R., Hoffman, J.R., Wilborn, C.D., Sale, C., Kreider, R.B., Jäger, R., Earnest, C.P., Bannock, L. and Campbell, B.I. (2015) ‘International Society of Sports Nutrition Position Stand: Beta-Alanine’, Journal of the International Society of Sports Nutrition, 12(30), pp. 1–14.

    Trexler, E.T., Keith, D.S. and Smith-Ryan, A.E. (2019) ‘Citrulline supplementation and exercise performance: A systematic review and meta-analysis’, Journal of Strength and Conditioning Research, 33(12), pp. 3574–3586.