Targeted foot muscle strengthening reverses atrophy and reduces plantar peak pressure in diabetic neuropathic feet

INTRODUCTION: Ulcer formation poses a serious clinical problem and has been associated with muscle function and tissue loss in diabetic feet and increased plantar peak pressures during walking. Reduced intrinsic and extrinsic foot muscle strength has been considered to increase the plantar peak pressure at the most affected metatarsal region. We aimed to investigate if a targeted strength training of the toe flexor muscles 1) enhances muscle strength and volume in the diabetic foot, and 2) improves plantar pressure distribution during walking in diabetic patients. RESEARCH DESIGN AND METHODS: Fourteen non-ulcerated diabetic patients performed a monitored toe flexor strength training at 70% of the maximal voluntary isometric contraction on a custom-made dynamometer for eight weeks. The maximal plantarflexion moment at the metatarsophalangeal joints on the dynamometer, the intrinsic foot muscle volume and the plantar pressure distribution during walking were quantified before and after the intervention. RESULTS: Right and left maximal plantarflexion moments increased significantly by 62% (p < 0.001) and 49% (p < 0.001), the intrinsic muscle volume increased by 6.4% (p = 0.018) and the peak pressures decreased at the second (p < 0.001) and lateral (p < 0.01) metatarsal region each by 11% following the training. CONCLUSIONS: Muscle function and tissue loss in diabetic feet can be counteracted by a targeted strength training program. Improved toe flexor muscle strength reduces plantar peak pressure at common ulceration sites.