Figure 1

The experimental setup. A. The subjects were required to step over an obstacle of 15% body height from quiet stance in a self-paced way. B. In the control trials, the subjects were required to hold a load (5.3 Kg) in front of the body or behind the body for 5 s, they held a handle which was connected to the load through a pulley system. Location of some of the EMG electrodes is also shown in panel A (GL lateral head of gastrocnemius, GM medial head of gastrocnemius, SOL soleus, ST semi-tendinosus, BF biceps femoris, GMED gluteus medius, ES erector spinae, TA tibialis anterior, VL vastus lateralis, RF rectus femoris, TF tensor fasciae latae, RA rectus abdominis).