Painelli, V. de S., Alves, V. T., Silva, V. E., Riani, L. A., Ugrinowitsch, C, Tricoli, V. A., & Braga, F. (2014). Creatine counteracts the acute interference effect of aerobic exercise on strength performance. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 1794.

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"Concurrent exercise (C.E., i.e., the combination of aerobic and strength exercises within a training session/period) is alleged to induce an impairment in the adaptive response to muscle strength and mass gains. The acute interference hypothesis suggests that an acute fatigue after the aerobic exercise could compromise the subsequent force production and, therefore, the chronic adaptation. It is hypothesized that this acute interference is related to energetic substrate depletion, in particular, the intramuscular concentrations of creatine and phosphocreatine."

This study investigated the effect of creatine supplementation on acute interference induced by aerobic exercise on maximum strength (1 RM) and strength endurance (SE, total number of repetitions completed in four 80% 1 RM sets to failure). Recreational strength-trained men (N = 32) underwent a graded exercise test to determine VO2max and anaerobic threshold velocity, and baseline assessments of maximum strength and strength-endurance (the control condition). After the control tests, Ss were randomly assigned to either a creatine supplementation (20 g/d for seven days followed by 5 g/d throughout the rest of the study) or a placebo (dextrose) group. Ss then completed four experimental sessions (72 hours apart) consisting of a 5-km run on a treadmill either continuously (90% anaerobic threshold velocity) or intermittently (1:1 minutes at vVO2max) followed by either a leg- or bench-press strength test.

Creatine supplementation significantly increased strength after either continuous (bench press and leg press) or intermittent (bench press) aerobic exercise, while the placebo group only maintained their strength. Additionally, creatine supplementation was able to maintain the leg-press strength-endurance after the intermittent aerobic exercise in relation to the control session. On the other hand, the placebo group showed a significant decrease in leg-press strength. No difference was observed in leg-press strength after the continuous aerobic exercise in both groups. As expected, bench-press strength was not affected by either mode of aerobic exercise in the placebo group. Importantly, creatine supplementation significantly increased bench-press strength after both aerobic exercises.

Implication. The acute interference effect observed in concurrent exercise may be counteracted by creatine supplementation.

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