Can Creatine Combat the Mental Fatigue-associated Decrease in Visuomotor Skills?
Level 2 - randomized trial
Double-blind, counterbalanced randomized crossover trial
PubMed 31403610 · doi:10.1249/MSS.0000000000002122
What was done
Fourteen healthy participants (4 females, 10 males; mean age 24 ± 3 years) completed a double-blind, counterbalanced, randomized crossover trial comparing 7 days of creatine supplementation (20 g/day) with a calcium lactate placebo, separated by a 5-week washout. In both conditions, participants completed a 90-minute mentally fatiguing Stroop task. Before and after this task, researchers assessed performance on a 7-minute sport-specific visuomotor task, a dynamic handgrip strength endurance task, a 3-minute Flanker task, and various physiological and perceptual measures.
What was found
Handgrip strength endurance was significantly higher with creatine than placebo (P = 0.022). Mental fatigue impaired visuomotor response time by +4.4% (P = 0.022) and Flanker accuracy by -5.0% (P = 0.009) in both conditions. Creatine improved accuracy during the 90-minute Stroop task by +4.9% compared to placebo (P = 0.026). Among perceptual and physiological measures, self-reported motivation and vigor were significantly lower in the creatine condition compared to placebo (P ≤ 0.027).
Why it matters
These findings suggest that while short-term creatine loading aids physical endurance and sustained cognitive accuracy during prolonged tasks, it does not prevent the degradation of sport-specific visuomotor skills caused by mental fatigue.
Limits
The sample size is very small (n = 14) and predominantly male. The study tested only a short 7-day loading protocol, and brain phosphocreatine concentrations were not directly measured.