Motor programmes for the termination of gait in humans: organisation and velocity-dependent adaptation.

摘要: 1The organisation of the muscular activities responsible for termination gait, their modulation as a function rate progression and associated mechanical effects were investigated in normal adults, using EMG, force plate kinematic recordings. In particular, braking actions reaction to visual cue presented at instant heel-strike analysed quantitatively, with focus on representative leg thigh muscles weight-supporting (stance) oscillating (swing) limb, during walk-and-stop trials performed three different velocities. 2In stance EMG started approximately 150 ms after stop signal and, average, displayed distal-to-proximal activation sequence that primarily involved posterior muscle groups (soleus, SOL, hamstring, HAM). With exception which showed single burst, patterns consisted two or progressively larger components occurring reciprocally antagonistic muscles. Increasing walking speed yielded significant reduction activity distal muscles, simultaneous increment proximal The effect earlier actions, estimated from backward-directed wave horizontal ground force, decreased velocity-dependent manner. 3In swing limb began 330 revealed proximal-to-distal extensor (quadriceps, QUAD, SOL) playing prominent role. They always bursts, largely co-activated antagonist onset latencies individual close correlation, spatio-temporal parameters scaled parallel. Unlike action final contact increased speed. 4The results indicate synergies rapid gait response ground-contact are produced by relatively flexible set motor commands modulated according strategies weight-bearing single, fairly robust programme limb. Mechanical constraints related relative position centre foot pressure body mass time begin affect external forces, may condition difference between sides body.