Immediate effects of two types of self-stretching on flexor digitorum longus and tibialis posterior muscle stiffness.

Abstract

We investigated the immediate effects of two types of self-stretching methods to clarify their efficacy on flexor digitorum longue (FDL) and tibialis posterior muscle (TP) stiffness. In 'conventional self-stretching', the subject used the strength of their own hands to dorsiflex the toes and dorsiflex and evert the ankle. In 'weight-bearing stretching', the participants instead weight-bearing to facilitate the dorsiflexion. In this crossover trial, the participants were 13 healthy men. They performed either conventional self-stretching, weight-bearing stretching, or a control trial on different days. Before and then after the intervention, we measured the shear modulus of the FDL and TP using shear wave elastography as an index of muscle stiffness. To compare the changes in the shear modulus following the different stretching methods, we performed a two-way repeated measures analysis of variance with Holm correction with type of intervention and time of measurement as variables. A significant interaction was found for the shear modulus of the FDL. After weight-bearing stretching, the shear modulus was significantly lower than before the intervention and at the same timing in the control trial (p < 0.05). Conversely, no significant differences in the shear modulus of the FDL were observed before or after the control trial and conventional self-stretching (p > 0.05). Neither the main effects nor interactions were observed for the shear modulus of the TP, and no effect was observed by any interventions (p > 0.05). Weight-bearing stretching is suggested by these results to have some efficacy for the stretching of the FDL.