Balance ability and foot type characteristics during different postures of standing

Zhu Yaojia; Huo Hongfeng

doi:10.3969/j.issn.2095-4344.1145

Abstract：BACKGROUND: Changes in the center of body weight during standing reflects the structure, function and muscles of the lower limbs and even the whole body. The relationship between standing posture control and foot type, balance ability, and muscle activation is rarely reported. OBJECTIVE: To investigate the effects of natural, lean forward and lean backward standing on foot arch, body balance and muscle activation. METHODS: Fifteen subjects without foot lesions and diseases related to foot function were selected. Three-dimensional foot scanner was used to test and analyze the foot arch in three standing postures. BTS FREEMG 300 surface electromyography tester and balance tester were used to test and analyze the maximum root mean square of muscle and two balance ability indexes (envelope area and average velocity of center of gravity) in three standing postures. RESULTS AND CONCLUSION: (1) For height index of foot arch: there was significant difference between natural standing and forward standing (P ＜ 0.05). There was significant difference between natural standing and backward standing (P ＜ 0.05), but there was no significant difference between forward standing and backward standing (P＞ 0.05). (2) The degree of muscle activation was as follows: when standing naturally, the medial peroneal muscles＞ erector muscles＞ rectus abdominis＞ gluteus medius＞ biceps femoris＞ external oblique femoris＞ anterior tibial muscle＞ rectus femoris muscle＞ gluteus maximus muscle. During forward standing: the medial of the peroneal muscle＞ medius gluteus＞ vertical ridge＞ long head of biceps femoris＞ anterior tibial muscle＞ rectus abdominis muscle＞ gluteus maximus. During backward standing: the obliquus externus femur＞ rectus femoris＞ long head of biceps femoris＞ erector spinae＞ musculus rectus abdominis＞ the medial of the peroneal muscle＞ gluteus medius＞ gluteus maximus. (3) Balance: there was no significant difference between natural standing and forward standing (P＞ 0.05); there was significant difference between natural standing and backward standing (P ＜ 0.05), but there was no significant difference between forward standing and backward standing (P＞ 0.05). (4) In summary, it is easy to maintain body stability at low muscle activation intensity when the human body is standing naturally. During the body backward standing, the muscle activation intensity is highest due to instability. When the center of gravity moves forward and backward, the contralateral muscle is mainly activated. The arch of the foot rises when it leans forward and backward. The slight anterior and posterior movements of the center of gravity in the standing posture can lead to changes in muscle activation degree and balance control.