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To determine the effects of creatine supplementation on blood lactate during incremental cycling exercise.
Thirteen male subjects (M ± SD 23 ± 2 yr, 178.0 ± 8.1 cm, 86.3 ± 16.0 kg, 24% ± 9% body fat) performed a maximal, incremental cycling test to exhaustion before (Pre) and after (Post) 6 d of creatine supplementation (4 doses/d of 5 g creatine + 15 g glucose). Blood lactate was measured at the end of each exercise stage during the protocol, and the lactate threshold was determined as the stage before achieving 4 mmol/L. Lactate concentrations during the incremental test were analyzed using a 2 (condition) × 6 (exercise stage) repeated-measures ANOVA. Differences in power at lactate threshold, power at exhaustion, and total exercise time were determined by paired t tests and are presented as M ± SD.
Lactate concentrations were reduced during exercise after supplementation, demonstrating a significant condition effect (p = .041). There was a tendency for increased power at the lactate threshold (Pre 128 ± 45 W, Post 143 ± 26 W; p = .11). Total time to fatigue approached significant increases (Pre 22.6 ± 3.2 min, Post 23.3 ± 3.3 min; p = .056), as did maximal power output (Pre 212.5 ± 32.5 W, Post 220 ± 34.6 W; p = .082).
Our findings demonstrate that creatine supplementation decreases lactate during incremental cycling exercise and tends to raise lactate threshold. Therefore, creatine supplementation could potentially benefit endurance athletes.
Oliver is with the Dept. of Kinesiology, Texas Christian University, Fort Worth, TX. Joubert, Martin, and Crouse are with the Applied Exercise Science Laboratory, Texas A&M University, College Station, TX.