Caffeine's Ergogenic Effects on Cycling: Neuromuscular and Perceptual Factors.

Abstract

UNLABELLED:

Caffeine improves endurance exercise performance, but its ergogenic mechanism(s) remain unclear.

PURPOSE:

This investigation sought to examine the effects of caffeine on perceptual and physiological responses to endurance exercise.

METHODS:

Two experiments were performed. In study A, 14 participants were tested. Maximal voluntary strength (MVC) and motor-unit recruitment (%ACT) of the knee extensors and elbow flexors were tested before and 60 min after ingestion of a 5-mg·kg⁻¹ dose of caffeine or placebo and after completion of 40 min of exercise (30 min of submaximal leg or arm cycling followed by a 10-min time-trial performance). Muscle pain, RPE, and cardiorespiratory variables were assessed throughout. To determine the effects of caffeine on muscle pain and RPE during high-intensity exercise, a second study (study B) was performed. Twelve participants exercised at 95% of their gas exchange threshold (GET) and at 70% of the difference between their GET and VO(2peak) (70%Δ) after caffeine and placebo ingestion.

RESULTS:

Compared to placebo, caffeine improved MVC (6.3%, P = 0.014) and %ACT (5.5%, P = 0.013) in the knee extensors, but not the elbow flexors, and reduced muscle pain (P < 0.05) and RPE (P < 0.05) during both submaximal cycling modalities. Caffeine ingestion improved time-trial performance during leg cycling (4.9% ± 6.5%, P = 0.03), but not arm crank cycling (2.1% ± 8.2%, P = 0.28), but the effect on pain and RPE was eliminated. Caffeine ingestion had no effect on pain or RPE during cycling at 95% GET and 70%Δ.

CONCLUSIONS:

Our results suggest that augmented strength and motor-unit recruitment, rather than reductions in pain and effort, may underlie caffeine's ergogenic effect on endurance exercise.

• Authors: Christopher D Black, Dwight E Waddell, Alexander R Gonglach
• Journal: Medicine and science in sports and exercise (Med Sci Sports Exerc) Vol. 47 Issue 6 Pg. 1145-58 (Jun 2015) ISSN: 1530-0315 [Electronic] United States
• PMID: 25211364 (Publication Type: Journal Article, Randomized Controlled Trial)

Chemical References

• Central Nervous System Stimulants
• Performance-Enhancing Substances
• Caffeine

Topics

• Bicycling (physiology)
• Caffeine (pharmacology)
• Central Nervous System Stimulants (pharmacology)
• Cross-Over Studies
• Double-Blind Method
• Female
• Humans
• Male
• Muscle Strength (drug effects, physiology)
• Muscle, Skeletal (drug effects, physiology)
• Pain Measurement
• Performance-Enhancing Substances (pharmacology)
• Physical Exertion (drug effects, physiology)
• Pulmonary Gas Exchange
• Young Adult