Effect of dynamic guidance-tubing short foot gait exercise on muscle activity and navicular movement in people with flexible flatfeet.

Abstract

Navicular drop is a common plantar deformity which makes the plantar medial longitudinal arch (MLA) collapse and leads to other deformities in lower extremities. Active structures are from intrinsic and extrinsic foot muscle activities such as abductor hallucis (AbdH), tibialis anterior (TA), tibialis posterior, flexor hallucis brevis, flexor digitorum brevis during dynamic situations. As AbdH plays a role as a dynamic elevator of MLA, the importance of AbdH has been emphasized and the proper recruitment of both intrinsic and extrinsic muscle is crucial for stabilization of MLA during dynamic weight bearing condition. Because the short foot (SF) exercise is difficult to perform and tends to activate the intrinsic muscles concentrically rather than a natural coordination of concentric-isometric-eccentric activation, we have developed the guidance-tubing SF gait (GFG) exercise. We investigated the effect of GFG exercise on muscle activity, AbdH:TA activity ratio, MLA angle, and foot pressure distribution during walking compared to SF gait (SFG) exercise. Thirty-two subjects with flexible flat feet were divided into two groups and performed SFG exercise with (GFG) and without guidance-tubing (SFG) for seven serial days. AbdH muscle activity significantly increased from foot flat to heel rise in the GFG group (p = 0.006). The AbdH:TA activity ratio significantly increased in both the SFG (p = 0.015) group and GFG group (p = 0.006). MLA angles significantly decreased in both the SFG group (p = 0.001) and GFG group (p = 0.000), and the decrement was significantly higher in the GFG group (p = 0.001). The foot pressure distribution did not show any statistically significant change. The result of this study provides a clinical implication for training MLA supporter muscles in individuals with flat feet. The overactive muscle must be inhibited first, then facilitation and strengthening are followed respectively.