EFFECT OF DIFFERENT FREQUENCIES OF CREATINE SUPPLEMENTATION ON MUSCLE SIZE AND STRENGTH IN YOUNG ADULTS

Candow, DG, Chilibeck, PD, Burke, DG, Mueller, KD, and Lewis, JD. Effect of different frequencies of creatine supplementation on muscle size and strength in young adults. J Strength Cond Res 25(7): 1831-1838, 2011-The purpose was to determine if creatine supplementation, consumed immediately before and immediately after exercise, with different dosing frequency (i.e., 2 or 3 d wk(-1)) could enhance the gains in muscle size and strength from resistance training (RT) in young adults. A group of 38 physically active, nonresistance trained university students (21-28 years) was randomly allocated to 1 of 4 groups: CR2 (0.15 g.kg(-1) creatine during 2 d wk(-1) of RT; 3 sets of 10 repetitions; n = 11, 6 men, 5 women), CR3 (0.10 g.kg(-1) creatine during 3 d wk(-1) of RT; 2 sets of 10 repetitions; n = 11, 6 men, 5 women;), PLA2 (placebo during 2 d wk(-1) of RT; n = 8, 5 men, 3 women), and PLA3 (placebo during 3 d wk(-1) of RT; n = 8, 4 men, 4 women) for 6 weeks. Before and after training, measurements were taken for muscle thickness of the elbow and knee flexor and extensor muscle groups (ultrasound), 1-repetition maximumleg press and chest press strength, and kidney function (urinary microalbumin). Repeated-measures analysis of variance showed that strength and muscle thickness increased in all groups with training (p < 0.05). The CR2 (0.6 +/- 0.9 cm or 20%; p < 0.05) and CR3 groups (0.4 +/- 0.6 cm or 16.4%; p < 0.05) experienced greater change in muscle thickness of the elbow flexors compared to the PLA2 (0.05 +/- 0.5 cm or 2.3%) and PLA3 groups (0.13 +/- 0.7 cm or 6.3%). Men supplementing with creatine experienced a greater increase in leg press strength (77.3 +/- 51.2 kg or 62%) compared to women on creatine (21.3 +/- 10 kg or 34%, p < 0.05). We conclude that creatine supplementation during RT has a small beneficial effect on regional muscle thickness in young adults but that giving the creatine over 3 d wk(-1) did not differ from giving the same dose over 2 d wk(-1).