APAs 1 Article 1 adult 1 ankle muscles body equilibrium 1 body weight 1 electromyography 1 erector spinae muscle 1 female 1 gait 1 human 1 human experiment 1 leg muscle 1 male 1 motor coordination 1 muscle contraction 1 normal human 1 oblique abdominal muscle 1 postural control 1 prime movers 1 rectus abdominis muscle 1 skeletal muscle 1 soleus muscle 1 tibialis anterior muscle 1 trunk muscles 1 walking speed 1