Muscle creatine levels and sprint performance in young adult vegans and vegetarians after 7 days of creatine monohydrate supplementation

Athletes use creatine monohydrate (CM) to enhance high-intensity exercise performance by increasing creatine phosphate availability. While CM supplementation is known to raise muscle creatine levels in vegans and vegetarians, its impact on exercise performance remains uncertain. We examined the effects of CM supplementation on muscle creatine content and exercise performance in vegans and vegetarians. In a randomized, double-blind placebo-controlled design, 15 healthy vegans and vegetarians consumed CM (0.3 g/kg/day, n = 7) or placebo (PLA, 0.3 g maltodextrin/kg/day, n = 8) four times a day for 7 days. Before and after supplementation, repeated sprint capacity was determined. Body mass and fat-free mass (FFM) were assessed by dual-energy x-ray absorptiometry. The CM group increased body mass (1.56 ± 0.57 kg, p < 0.01) and FFM (1.15 ± 0.94 kg, p < 0.05), while the PLA group showed no changes. In the CM group, muscle creatine (Cr) and total muscle creatine (TCr) increased by 18.8 ± 13.1 mmol/kg (p < 0.05) and 30.8 ± 21.2 mmol/kg (p < 0.01), respectively. The PLA group showed no changes in Cr and TCr (−4.6 ± 13.1 mmol/kg and 2.9 ± 11.6 mmol/kg, respectively). Phosphocreatine levels remained consistent within and between groups. There were no observed changes in peak and mean power output during repeated sprints. A seven-day CM supplementation in healthy vegans and vegetarians increased Cr and TCr whereas Phosphocreatine, peak and mean power output during repeated sprints was unchanged.