Gait Symmetry Can Reduce Dependence on the Intact Limb during Walking with Constraint of Unilateral Metatarsophalangeal Joints.

Our previous research showed that healthy subjects exhibited asymmetrical walking gait when their unilateral metatarsophalangeal (MTP) joints were constrained. They relied more on their intact limb for the compensation of missing functions of their constrained limb, which may result in poor balance, increased metabolic cost, and higher risks of falls. We examined how subjects would respond if gait asymmetry in stance time was improved using a split-belt treadmill. Twelve healthy subjects were instructed to walk on a split-belt treadmill at comfortable and fast speeds with their unilateral MTP joints constrained. The walking trials were performed in two conditions, i.e., tied-belt walking (TBW, both belts moved at the same speed), and split-belt walking (SBW, the speed of the belt on the constrained leg was appropriately slower than that of the contralateral leg). The ground reaction forces (GRF) and electromyography (EMG) data during walking were collected. Results showed that the GRF and impulses on the constrained foot at fast speed SBW significantly increased, compared with TBW, and the activation of medial gastrocnemius and soleus of the intact lower limb decreased significantly, which suggest that improved symmetry in stance time may reduce dependence on the intact limb for humans with the constraint of unilateral MTP joints.