Prolonged activity of knee extensors and dorsal flexors is associated with adaptations in gait in diabetes and diabetic polyneuropathy.

BACKGROUND: People with diabetes or diabetic polyneuropathy often experience limitations in mobility and gait. These limitations are believed to be related to disturbed muscle function and sensory information. In previous studies on diabetic gait, results were confounded by a lower, preferred walking speed in people with diabetes or diabetic polyneuropathy. This study aimed to identify gait-velocity independent effects of diabetes and diabetic polyneuropathy on lower extremity kinematics and muscle activation patterns. METHODS: Eight people with diabetic polyneuropathy, 10 diabetic controls without polyneuropathy and ten healthy, age-matched controls walked at their preferred velocity and a standard velocity of 1.4ms(-1). Muscle activation patterns of gluteus maximus, biceps femoris, rectus femoris, vastus medialis, gastrocnemius medialis, soleus, and tibialis anterior, and spatiotemporal and joint angles characteristics were analysed. FINDINGS: Independent of walking speed, muscle activation differed between groups. In diabetic polyneuropathy participants activation of ankle-joint dorsal flexors was prolonged by 5-10% of the stride cycle. Activity of monoarticular knee-joint extensors lasted about 10% longer in both diabetic groups compared to healthy elderly. Initiation of muscle activity did not differ between groups. If gait velocity was controlled, spatiotemporal characteristics were similar between groups. INTERPRETATION: The study showed that independent of the preferred lower gait velocity, people with diabetes or diabetic polyneuropathy adjust the timing of muscle activity. Contrarily, the concurrent changes in spatiotemporal characteristics occurred to be the result of changed velocity only. The delayed cessation of muscle activity suggested a reduced rate of force development underlying the adjusted timing of muscle activation