OBJECTIVE: The objective of this study was to verify if creatine supplementation exerts an ergogenic effect during concurrent exercise. METHODS: Sixteen female university students were divided into two groups: placebo (P) and creatine supplemented (CRE). The participants received 20 g of placebo or creatine for five days and 3 g for the following seven days in a double-blind design. Before supplementation, the participants were submitted to a 1-RM test in the leg press followed by maximum repetition test (three sets of repetitions-to-fatigue, performed at 80% of the 1-RM and separated from 150 seconds of recovery - P 1st set: 9.0 ± 2.4; 2nd set: 8.9 ± 2.9 and 3rd set: 8.3 ± 3.3 and CRE 1st set: 10.2 ± 2.2; 2nd set: 9.8 ± 2.9 e 3rd set: 9.7 ± 3.5 reps). After 12 days of supplementation, the participants were submitted to aerobic test in which they were instructed to cover the maximal distance as possible in 20 min. Subsequently, the participants were submitted to 1-RM test once again followed by the maximum repetition test. RESULTS: No differences were observed in the aerobic task performance and in the 1-RM test. After the aerobic test, a decline on the repetition maximum capacity was observed during the last two sets in P (Reps - P: 1st set: 7.6 ± 2.6; 2nd set: 4.3 ± 2.9*; p < 0.01 and 3rd set: 4.6 ± 2.3*; p < 0.01). This reduction was not observed in CRE (Reps - CRE: 1st set: 10.9 ± 2.9; 2nd set: 9.5 ± 2.7 and 3rd set: 9.0 ± 3.0). CONCLUSIONS: There is a hypothesis that the performance of resistance exercise is reduced by a residual fatigue from the previous aerobic exercise bout. One of the peripheral causes of acute fatigue during resistance exercise is related to creatine-phosphate depletion. Probably, the supplementation-induced greater muscle creatine-phosphate content accelerates the recovery and the ATP re-phosphorylation, serving as an additional energetic substrate during concurrent exercise.
Creatine; Supplementation; Concurrent exercise; Interference
