An electromyographic study of human gait both in water and on dry ground.

The purpose of the present study was to define the degree of muscular activation while walking in water in order to aid rehabilitation therapists in their choice of exercises for daily clinical practice in aquatherapy. This study compares the electromyographic (EMG) activity of the rectus femoris, the soleus of the right lower limb and the contra-lateral lumbar erector spinae, during gait in water and on dry ground. The study was carried out on a group of seven healthy female subjects without past rachidian pathology. EMG recordings in water were taken with immersion to the umbilicus at "comfortable" speed. A total of five recordings were made at this speed, in water and on dry ground, with a one-minute rest between recordings. Integrated EMG results, averaged on eight gait cycles, show, for all the subjects, more erector spinae activity in water than on the ground (p<0.01). Soleus activity is greater during gait on dry ground for the whole group (p<0.01). For four subjects, the electromyographic (EMG) activity of the rectus femoris over the entire cycle is greater than that exhibited on dry ground. In the two experimental situations, no differences have been found either on amplitudinal peaks or on the shape of the patterns. The speed and gait cycle length are reduced in water (60% and 25%). Walking in water at an umbilical level increases the activity of the erector spinae and activates the rectus femoris to levels near to or higher than walking on dry ground. These data should be taken into account by the physiotherapist when designing a rehabilitation programme.