Influence of Creatine Supplementation on the Parameters of the “All-Out Critical Power Test”

We tested the hypotheses that creatine loading would result in no alteration in critical power (CP) or the total work done > CP (W) as estimated from a novel 3-minute all-out cycling protocol. Seven habitually active male subjects completed 3-minute all-out tests against fixed resistance on an electrically-braked cycle ergometer after a 5-day dietary supplementation with 20 g·d−1 of a glucose placebo (PL) and the same dose of creatine monohydrate (CR). The CP was estimated from the mean power output over the final 30 seconds of the test and the W was estimated as the power-time integral above the end-test power output. Creatine supplementation resulted in a significant increase in body mass (from 80.4 ± 9.2 kg to 81.5 ± 9.5 kg; p < 0.05), whereas the body mass was not different after placebo supplementation (80.3 ± 9.3 kg; p > 0.05). There were no differences in the power outputs measured during the 3-minute all-out tests following PL and CR supplementation (CP—PL: 252 ± 30 W vs . CR: 255 ± 28 W, p > 0.05; W—PL: 19.4 ± 3.5 kJ vs . CR: 19.2 ± 3.4 kJ, p > 0.05; total work done—PL: 64.8 ± 4.9 kJ vs . CR: 65.0 ± 4.9 kJ, p > 0.05). Creatine loading had no ergogenic effect on the CP measured using the novel all-out protocol. In contrast to earlier studies which established the power- duration relationship using the conventional protocol, the finite work capacity > CP (W) for all-out exercise was not enhanced by creatine loading.