Chiu C-HChen C-CAli AWu S-LWu C-LNieman DCSchroder H2024-12-042024-12-042024-10-25Chiu C-H, Chen C-C, Ali A, Wu S-L, Wu C-L. (2024). The Effect of Pre-Exercise Caffeine and Glucose Ingestion on Endurance Capacity in Hypoxia: A Double-Blind Crossover Trial.. Nutrients. 16. 21. (pp. 3624-).2072-6643https://mro.massey.ac.nz/handle/10179/72187The impact of caffeine and glucose supplementation in a hypoxic environment on endurance exercise performance remains inconclusive. The current study examined the effect of pre-exercise carbohydrate and caffeine supplementation on endurance exercise performance in an acute hypoxic environment. Eight healthy active young males participated in this double-blind, within-subjects crossover study. Participants ingested the test drink 60 min before exercising at 50% Wmax for 90 min on a cycle ergometer (fatiguing preload); there followed an endurance performance test at 85% Wmax until exhaustion in a hypoxic chamber (~15%O2). Participants completed four experimental trials in a randomized order: caffeine (6 mg·kg-1; Caff), glucose (1 g·kg-1; CHO), caffeine (6 mg·kg-1) + glucose (1 g·kg-1; Caff-CHO), and taste- and color-matched placebo with no caffeine or CHO (PLA). Blood samples were collected during fasting, pre-exercise, every 30 min throughout the exercise, and immediately after exhaustion. The caffeine and glucose trials significantly enhanced endurance capacity in hypoxic conditions by Caff, 44% (68.8-31.5%, 95% confidence interval), CHO, 31% (44.7-15.6%), and Caff-CHO, 46% (79.1-13.2%). Plasma-free fatty-acid and glycerol concentrations were higher in Caff and PLA than in CHO and Caff-CHO (p < 0.05). The estimated rate of fat oxidation was higher in Caff and PLA than in CHO and Caff-CHO (p < 0.05). There were no significant differences in ratings of perceived exertion between trials. In conclusion, the ingestion of caffeine, glucose, or caffeine + glucose one hour before exercising in hypoxic conditions significantly improved 85% Wmax endurance performance after prolonged exercise.(c) 2024 The Author/sCC BY 4.0https://creativecommons.org/licenses/by/4.0/endurance performancefat oxidationglycogenhypoxiaHumansCaffeineMaleCross-Over StudiesDouble-Blind MethodHypoxiaPhysical EnduranceYoung AdultGlucoseAdultExerciseBlood GlucoseDietary SupplementsJournal article10.3390/nu162136242072-6643journal-article3624-https://www.ncbi.nlm.nih.gov/pubmed/395194563624nu16213624