The aim of the present study was to investigate the effects of unilateral shoulder bag weight and heel heights on trunk muscle activities. This study recruited 40 healthy women in their twenties. Electromyography activities of rectus abdominis muscle, external abdominal oblique muscle, internal abdominal oblique muscle and erector spinae muscle during standing position were measured using a surface electromyography system. The overall muscle activities of the trunk muscles were significantly increased in the contralateral trunk muscles (p<.05). Inaddition, the trunk muscles overall activities on the contralateral side without the shoulder bag was positive correlation with the heel height and unilateral shoulder bag weight (p<.05). Both high-heeled wear and unilateral shoulder bags are fashion items that cause asymmetry in the trunk muscles of women in their twenties. These findings suggest that the increase in the weight and heel height of the unilateral shoulder bag in women cause asymmetry of trunk muscle activities.

This study was conducted to identify the effects of high-heel shoes on EMG activities of rectus femoris and biceps femoris in 28 healthy women. Subjects were composed of experimental group (wearing high-heel shoes) and control group (wearing low-heel shoes). Two groups participated in three conditions standing (bare foot wearing athletic shoes and 7.5 cm height shoes). In high-heel shoes condition, EMG activities of rectus femoris of control group were significantly lower than that of biceps femoris of experimental group, but EMG activities of both muscles of experimental group did not should significant difference. In bare foot standing condition, EMG activities of rectus femoris of experimental group were significantly lower than that of biceps femoris but EMG activities of both muscles of control group had no significant difference. These results showed that hamstring lengthening effects was produced when wearing high-heel shoes because the external knee extension moment was increased. In the short term, high-heel shoes effect on the increase of the biceps femoris activities by spindle reflex, but in the long term, the normal amplitude of the same muscle activities by Golgi tendon organ reflex.