Acute and 2 days delayed effects of exhaustive stretch-shortening cycle exercise on barefoot walking and running patterns

Abstract

This study investigated the acute and 2days delayed influences of exhaustive stretch-shortening cycle exercise (SSC) on barefoot walking and running gait patterns. The SSC exercise was performed on a sledge apparatus, on which the subjects (N=10) repeated until exhaustion intermittent series of 25 bilateral submaximal rebounds. Maximal drop-jumps and submaximal barefoot treadmill walking and running were performed before (PRE) and after (POST) the exhaustive exercise and repeated 48h (D2) later. Electromyographic activity and 3D kinematics of the right lower limb and foot were recorded for 15s at gait initiation (BEG) and at the end (END: at 3min of walk and 5min of run). The exhaustive SSC exercise resulted in 6% reductions in maximal drop jump performance at POST and D2, and affected mostly both gait patterns at D2. The walking pattern presented compensatory neural adjustments within the triceps surae muscle group. This expected pain-induced protective strategy of the soleus muscle was sufficient to preserve the kinematics pattern. The running condition revealed a major knee strategy, which might support the concept of pain protective strategy of knee extensor muscles at the expense of impact cushioning. Regardless the testing session, most parameters showed fatigue-induced changes at gait initiation (BEG), which were opposite to subsequent BEG to END adjustments. This is likely to support anticipatory strategies rather than progressive adjustments during the exercise.