Thigh muscles' responses caused by a single combined aerobic and resistance training session in healthy young men

The aim of this study was to understand the amplitude and localization of neuromuscular response induced by a training session combining an aerobic and a resistance component. Ten healthy men completed a single session of combined (aerobic and resistance) and aerobic only training, in a randomized order. Surface electromyographic activity and torque obtained during maximal voluntary and electrically evoked contractions of the knee extensor muscles were analyzed to distinguish peripheral from central adaptations. The isometric torque developed by the knee extensor muscles during maximal voluntary contraction decreased significantly following a single session of both combined (-9.2%, p=0.043) and aerobic (-9.6%, p=0.005) training. This was accompanied by a decrease in central activation of the knee extensor muscles after each training session (respectively 2.9, p=0.005 and 1.8% p=0.040) as indicated by twitch interpolation technique. After the combined training protocol, the peak torque of the twitch significantly increased by 6.8% (p=0.046), whereas it decreased by 17.3% (p=0.016) after the aerobic training protocol. The present study demonstrates that the decrease in torque production is similar after a single combined training session or after an aerobic training session of the same duration. Both central and peripheral mechanisms could explain the decrease of torque.