Caffeine Affects Time to Exhaustion and Substrate Oxidation during Cycling at Maximal Lactate Steady State.
This study analyzed the effects of caffeine intake on whole-body substrate metabolism and exercise tolerance during cycling by using a more individualized intensity for merging the subjects into homogeneous metabolic responses (the workload associated with the maximal lactate steady state-MLSS). MLSS was firstly determined in eight active males (25 ± 4 years, 176 ± 7 cm, 77 ± 11 kg) using from two to four constant-load tests of 30 min. On two following occasions, participants performed a test until exhaustion at the MLSS workload 1 h after taking either 6 mg/kg of body mass of caffeine or placebo (dextrose), in a randomized, double-blinded manner. Respiratory exchange ratio was calculated from gas exchange measurements. There was an improvement of 22.7% in time to exhaustion at MLSS workload following caffeine ingestion (95% confidence limits of ±10.3%, p = 0.002), which was accompanied by decrease in respiratory exchange ratio (p = 0.001). These results reinforce findings indicating that sparing of the endogenous carbohydrate stores could be one of the several physiological effects of caffeine during submaximal performance around 1 h.
['Cruz|Rogério Santos de Oliveira|RS|', 'de Aguiar|Rafael Alves|RA|', 'Turnes|Tiago|T|', 'Guglielmo|Luiz Guilherme Antonacci|LG|', 'Beneke|Ralph|R|', 'Caputo|Fabrizio|F|']
D000328:Adult D001642:Bicycling D002110:Caffeine D000697:Central Nervous System Stimulants D004311:Double-Blind Method D004734:Energy Metabolism D015444:Exercise D005080:Exercise Test D017079:Exercise Tolerance D005221:Fatigue D006801:Humans D019344:Lactic Acid D008297:Male D010084:Oxidation-Reduction D011659:Pulmonary Gas Exchange D013997:Time Factors D055815:Young Adult
submaximal performance endurance fat metabolism muscle glycogen