Abstract
This study shows quantitative muscle loads in the posture and shampooing actions namely, shampoo, rinse, wipe and dry while shampooing hair in the forward-bent- posture sitting position. Five healthy females were chosen as subjects,
We measured the surface electromyogram (EMG) on M. trapezius, M. triceps brachii, M. brachioradialis, M. biceps femoris and M. triceps surae in the sitting posture, the forward-bent-posture sitting position and when shampooing hair in the forward-bent posture sitting position. We examined for physical distress during the forward-bentposture sitting position and shampooing hair in relation to the results of EMG.
The results were as follows,
1) The muscle activity on M. trapezius, M. triceps brachii, M. biceps femoris, M. triceps surae and M. brachioradialis in the forward－bent posture sitting position increased respectively 4.4 times, 21.3 times, 23.3 times, 8.9 times, and 2.4 times as many as that during the sitting posture.
2) The muscle activity on M. trapezius and M. triceps surae during shampoo and rinse was greater than in the forward-bent-posture sitting position. The muscle activity on M. trapezius during wipe and dry was also higher than in the sitting posture.
3) The muscle activity on M. triceps surae during shampoo increased more than rinse. The muscle activity on all muscles measured, particularly M. tapezius during wipe, increased more than for dry.
4) The region of muscle pain and fatigue experienced during the forward-bent-posture sitting position agreed with muscle loads measured by EMG.
Considerable muscle load was produced by the posture during shampooing hair in the forward-bent posture sitting position. The muscle load in each posture was increased further by the shampooing action. Consequently, it was suggested that for a more comfortable shampoo, it is important to do so with due consideration for the muscle loads.
