Effects of caffeine on neuromuscular fatigue and performance during high-intensity cycling exercise in moderate hypoxia

• Published in: European journal of applied physiology 2017-01, Vol.117 (1), p.27-38
• Main Authors: Smirmaul, Bruno P. C., de Moraes, Antonio Carlos, Angius, Luca, Marcora, Samuele M.
• Format: Article
• Language: English
• Subjects: Adult; Altitude; Athletic Performance; Biomedical and Life Sciences; Biomedicine; Caffeine; Caffeine - administration & dosage; Caffeine - adverse effects; Caffeine - pharmacology; Central Nervous System Stimulants - administration & dosage; Central Nervous System Stimulants - adverse effects; Central Nervous System Stimulants - pharmacology; Endurance; Exercise; Fatigue; Human Physiology; Humans; Hypoxia; Hypoxia - metabolism; Male; Muscle Fatigue - drug effects; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; Nervous system; Occupational Medicine/Industrial Medicine; Original; Original Article; Physical education; Physiology; Sea level; Sports Medicine; Variance analysis
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-016-3496-6

Purpose To investigate the effects of caffeine on performance, neuromuscular fatigue and perception of effort during high-intensity cycling exercise in moderate hypoxia. Methods Seven adult male participants firstly underwent an incremental exercise test on a cycle ergometer in conditions of acute normobaric hypoxia (fraction inspired oxygen = 0.15) to establish peak power output (PPO). In the following two visits, they performed a time to exhaustion test (78 ± 3% PPO) in the same hypoxic conditions after caffeine ingestion (4 mg kg −1 ) and one after placebo ingestion in a double-blind, randomized, counterbalanced cross-over design. Results Caffeine significantly improved time to exhaustion by 12%. A significant decrease in subjective fatigue was found after caffeine consumption. Perception of effort and surface electromyographic signal amplitude of the vastus lateralis were lower and heart rate was higher in the caffeine condition when compared to placebo. However, caffeine did not reduce the peripheral and central fatigue induced by high-intensity cycling exercise in moderate hypoxia. Conclusion The caffeine-induced improvement in time to exhaustion during high-intensity cycling exercise in moderate hypoxia seems to be mediated by a reduction in perception of effort, which occurs despite no reduction in neuromuscular fatigue.