Effects of muscle contraction timing during resistance training on vascular function.

Muscle contractions in normal resistance training are performed by eccentric (ECC, lowering phase) and concentric (CON, lifting phase) muscle contractions. However, the difference in effects of timing of muscle contraction during resistance training on arterial stiffness is unknown. This study investigated the effect of muscle contraction timing during resistance training on vascular function in healthy young adults. Thirty healthy men were randomly assigned to group of resistance training with quick lifting and slow lowering (ERT, n=10), group of resistance training with slow lifting and quick lowering (CRT, n=10) and sedentary groups (SED, n=10). The ERT and CRT groups underwent two supervised resistance-training sessions per week for 10 weeks. The ERT group performed the on set of 8-10 repetitions with 3 s ECC and 1 s CON muscle contractions. In contrast, the CRT group performed the on set of 8-10 repetitions with 1 s ECC and 3 s CON muscle contractions. Brachial-ankle pulse wave velocity (baPWV) after ERT did not change from baseline. In contrast, baPWV after CRT increased from baseline (from 1049+/-37 to 1153+/-30 cm s(-1), P<0.05). No significant changes in flow-mediated dilation were observed in the ERT and CRT groups. These values did not change in the SED group. These findings suggest that although both training does not deteriorate a vascular endothelial function, resistance training with quick lifting and slow lowering (that is, ERT) prevent the stiffening of arterial stiffness.