Introduction

Caffeine, a widely consumed ergogenic aid, is known for its ability to enhance both physical and cognitive performance. Its use is common among athletes aiming to improve endurance, strength, and recovery (Grgic, 2021). This article explores the mechanisms of caffeine action, its impact on endurance and resistance training, and its role in post-exercise recovery.

Mechanisms of Action

Caffeine exerts its effects through several key physiological mechanisms:

Adenosine Receptor Antagonism:

Caffeine blocks adenosine receptors (A1 and A2A) in the central nervous system, reducing fatigue perception and enhancing neurotransmitter release, particularly dopamine and norepinephrine (Ferreira, da Silva and Bueno, 2021).

Calcium Mobilization:

Caffeine increases calcium release from the sarcoplasmic reticulum in muscle cells, leading to enhanced muscle contraction and improved force production (Grgic, 2021).

Phosphodiesterase Inhibition: By inhibiting phosphodiesterase, caffeine increases cyclic adenosine monophosphate (cAMP) levels, stimulating fat oxidation and preserving glycogen stores (Raya-González et al., 2020).

Impact on Endurance Performance

Caffeine is well-documented to improve endurance exercise performance by delaying fatigue and increasing time to exhaustion. Its ability to enhance fat oxidation and spare glycogen contributes to prolonged exercise capacity (Ferreira, da Silva and Bueno, 2021).

Impact on Resistance Training

Caffeine also has notable effects on resistance training:

Muscular Strength:

Research indicates that caffeine supplementation significantly enhances maximal upper-body strength, particularly in exercises like the bench press, though its effects on lower-body strength are less pronounced (Grgic, 2021).

Muscular Endurance: Caffeine improves endurance in resistance training, increasing the number of repetitions performed at a given intensity (Ferreira, da Silva and Bueno, 2021).

Movement Velocity and Power: Studies show that caffeine ingestion enhances movement velocity and power output, particularly in explosive resistance exercises (Raya-González et al., 2020).

Impact on Recovery

Caffeine’s influence on recovery is multifaceted:

Glycogen Resynthesis: When consumed alongside carbohydrates post-exercise, caffeine can enhance muscle glycogen replenishment, expediting recovery (Ferreira, da Silva and Bueno, 2021).

Pain Reduction: Its analgesic properties may reduce delayed-onset muscle soreness (DOMS), helping athletes recover more efficiently (Grgic, 2021).

Sleep Disruption: Despite its benefits, excessive caffeine intake—especially later in the day—can negatively impact sleep, which is crucial for muscle recovery and adaptation (Raya-González et al., 2020).

Conclusion

Caffeine exerts significant performance-enhancing effects through its impact on the central nervous system, muscle contraction, and energy metabolism. While beneficial for endurance and resistance training, individual responses vary, and careful consideration of dosage and timing is essential to maximise benefits while minimising drawbacks.

References

Ferreira, T.T., da Silva, J.V.F. and Bueno, N.B. (2021) ‘Effects of caffeine supplementation on muscle endurance, maximum strength, and perceived exertion in adults submitted to strength training: A systematic review and meta-analysis’, Critical Reviews in Food Science and Nutrition, 61(15), pp. 2587–2600. https://doi.org/10.1080/10408398.2020.1781051. Grgic, J. (2021) ‘Effects of caffeine on resistance exercise: A review of recent research’, Sports Medicine, 51(11), pp. 2281–2298. https://doi.org/10.1007/s40279-021-01493-9. Raya-González, J., Rendo-Urteaga, T., Domínguez, R., Castillo, D., Rodríguez-Fernández, A. and Grgic, J. (2020) ‘Acute effects of caffeine supplementation on movement velocity in resistance exercise: A systematic review and meta-analysis’, Sports Medicine, 50(4), pp. 717–729. https://doi.org/10.1007/s40279-019-01211-9.