OBJECTIVE: The goal of this study was to evaluate the effects of creatine (Cr) 
supplementation on oxidative stress and inflammation markers after acute 
repeated-sprint exercise in humans.
METHODS: Twenty-five players under age 20 y were randomly assigned to two 
groups: Cr supplemented and placebo. Double-blind controlled supplementation was 
performed using Cr (0.3 g/kg) or placebo tablets for 7 d. Before and after 7 d 
of supplementation, the athletes performed two consecutive Running-based 
Anaerobic Sprint Tests (RAST). RAST consisted of six 35-m sprint runs at maximum 
speed with 10 sec rest between them. Blood samples were collected just prior to 
start of test (pre), just after the completion (0 h), and 1 h after completion.
RESULTS: Average, maximum, and minimum power values were greater in the 
Cr-supplemented group compared with placebo (P < 0.05). There were significant 
increases (P < 0.05) in plasma tumor necrosis factor alpha (TNF-α) and 
C-reactive protein (CRP) up to 1 h after acute sprint exercise in the 
placebo-supplemented group. Malondialdehyde, lactate dehydrogenase (LDH), 
catalase, and superoxide dismutase enzymes also were increased after exercise in 
both groups. Red blood cell glutathione was lower after exercise in both groups. 
Cr supplementation reversed the increase in TNF-α and CRP as well as LDH induced 
by acute exercise. Controversially, Cr supplementation did not inhibit the rise 
in oxidative stress markers. Also, antioxidant enzyme activity was not different 
between placebo and Cr-supplemented groups.
CONCLUSION: Cr supplementation inhibited the increase of inflammation markers 
TNF-α and CRP, but not oxidative stress markers, due to acute exercise.