Local exercise based on voluntary contractions produces greater warm-up effects on balance control than...

On the one hand, while general (involving the whole body) warm-up exercises have been extensively used to optimize motor and postural performance, the effect of a local (involving a particular muscular group) warm-up has not yet been addressed. On the other hand, voluntary (VOL) and electro-induced (EI) contractions produce different physiological effects likely to differently affect motor and postural performance. The aim was to analyze and compare the effects of two local warm-up modalities, voluntary and electro-induced (VOL or EI warm-up) on balance control. Balance control was evaluated with a force platform (recording the displacement of the centre of foot pressure - COP) in 27 healthy young subjects before (PRE), immediately after (POST), 5 min after (POST5), and 10 min after (POST10) either warm-up. Each warm-up included 6 sets of 5 contractions at 10% of maximal voluntary contraction of the quadriceps femoris. The results showed that the VOL warm-up improved balance control at POST, POST5 and POST10 while the EI warm-up improved it only at POST10. In addition, balance control was significantly better after the VOL warm-up than after the EI warm-up at POST5 and POST10. A short and local VOL warm-up improved balance control immediately after its completion and for, at least, ten minutes, while the EI warm-up required some minutes of recovery before producing its improving effects.