There have been several studies on the effect of
short-term creatine (Cr) supplementation on exercise
performance, but none have investigated both voluntary
and stimulated muscle contractions in the same
experiment. Fourteen moderately active young men
(19-28 years) were randomly assigned, in a double blind
manner, to either a creatine (Cr) or placebo (P) group. The subjects
supplemented their regular diet 4 times a day for 5 days with either 5 g
Cr + 5 g maltodextrin (Cr group), or 5 g maltodextrin (P group).
Isometric maximal voluntary contraction (MVC), muscle activation, as
assessed using the modified twitch interpolation technique, electrically
stimulated contractile properties, electromyography (EMG), endurance
time and recovery from fatigue were measured in the elbow flexors. The
fatigue protocol involved both voluntary and stimulated contractions.
Following supplementation there was a significant weight gain in the Cr
group (1.0 kg), whereas the P group did not change. For each group,
pre-supplementation measures were not significantly different from
post-supplementation for MVC, twitch and tetanic tensions at rest, time
to peak tension, half-relaxation time and contraction duration. Prior to
Cr supplementation time to fatigue was 10 ± 4 min (mean ± S.E.M.) for
both groups, and following supplementation there was a non-significant
increase of 1 min in each group. MVC force, muscle activation, EMG,
stimulated tensions and durations were similar for the Cr and P groups
over the course of the fatigue protocol and did not change after
supplementation. Furthermore, recovery of MVC, stimulated tensions
and contractile speeds did not differ as a result of Cr supplementation.
These results indicate that short-term Cr supplementation does not
influence isometric elbow flexion force, muscle activation, stimulated
contractile properties, or delay time to fatigue or improve recovery.