Machine-assisted foot stretching in the elderly: a comparison with self-stretching

[Purpose] Self-stretching is the traditional at-home stretching method of choice. We developed an automatic foot-stretching machine to perform effective dorsiflexion stretching safely and easily at home. The effects of automatic stretching using our machine and self-stretching were investigated and compared. [Participants and Methods] Twelve healthy elderly people participated in the study. Automatic dorsiflexion static stretching was performed with the right foot, and self-stretching using a towel was performed with the left foot. Before and after each stretching, passive range of motion in dorsiflexion, maximal voluntary contraction strength in plantarflexion, passive resistive torque during passive dorsiflexion, and displacement of the muscle-tendon junction of the medial gastrocnemius muscle were measured. [Results] The range of motion in dorsiflexion had a significantly greater increase after automatic stretching than after self-stretching. The maximum strength in plantarflexion tended to decrease after automatic stretching but did not decrease after self-stretching. The passive resistive torque in both types of stretches decreased in some of the participants but increased in others. The displacement of the muscle-tendon junction of the medial gastrocnemius tended to shorten during automatic stretching as compared with self-stretching. [Conclusion] Foot stretching using a machine is as effective as self-stretching and tends to affect the tendon rather than the muscle.