Abstract:

BACKGROUND: Anybody’s musculoskeletal modeling system simulates the relationship between human skeleton, muscle and environment by using mathematical modeling technology. It can study the reverse dynamics of human body and obtain the maximum muscle strength of three lower limb joints.

OBJECTIVE: To study the lower extremity muscle strength values of 24 male college students with different body mass indexes in one cycle of sitting Swiss ball, and to compare the mean root-mean-square of the subjects in sitting Swiss ball and bench. 

METHODS: Twenty-four male college students were divided into normal group, overweight group and obesity group according to body mass index. BTS 3D infrared motion capture system, Kistler 3D dynamometer and BTS surface electromyography system were used to record the dynamic and electromyographic parameters simultaneously. The differences in muscle force and electromyographic parameters between different groups were qualitatively compared by one-way analysis of variance, and the mean differences were compared by quantitative difference analysis.

RESULTS AND CONCLUSION:(1) In terms of muscle strength, from sitting to standing, compared with the obese group, the normal group showed significant differences in rectus femoris, semimememial muscle, biceps femoris longhead, popliteal muscle, soleus muscle and tibial anterior muscle (P < 0.05, 0.47 ≤ QD < 0.80), and the quadratus femoris muscle and pectineus muscle showed significant differences (P < 0.01, QD ≥ 0.80). There was a significant difference in muscle strength of quadratus femoris between the obese group and the overweight group (P < 0.05, 0.47 ≤ QD < 0.80). From standing to sitting, there were significant differences in muscle strength of sartorus, extensor pollicis, and gastrocneum between the normal group and the obese group (P< 0.05, 0.47 ≤ QD < 0.80). (2) In terms of root-mean-square electromyogram value, from sitting to standing, the biceps femoris and gastrocnastus muscles in the normal group were significantly different from those in the obese group (P < 0.05, 0.47 ≤  QD < 0.80); from standing to sitting, rectus femoris muscles in the normal group were significantly different from those in the obese group (P < 0.05,  0.47 ≤ QD < 0.80). In the Swiss ball sitting state, from sitting to standing, the tibial anterior muscle and biceps femoris were significantly different between the normal group and the obese group (P < 0.05, 0.47 ≤ QD < 0.80). From standing to sitting, the electromyogram values of gastrocnemius muscle and right erector spine muscle were significantly different between the normal group and the obese group (P < 0.05, 0.47 ≤ QD < 0.80). These findings indicated that (1) In each group of BMI, the dominant muscle generation from sitting to sitting was gluteus medius muscle, vastus lateralis muscle, biceps longus muscle, rectus femoris muscle, gastrocnemius muscle, tibia anterior muscle and soleus muscle; and from standing to sitting, gluteus medius muscle, vastus lateralis muscle, biceps longus muscle, gastrocnemius muscle, tibia anterior muscle and soleus muscle. (2) Compared with the sitting stool, the subjects had higher root-mean-square of tibial anterior muscle, rectus femoris muscle, biceps femoris muscle and gastrocnemius muscle when sitting Swiss ball.

Key words: simulation, root-mean-square electromyogram, Swiss ball, quantitative difference, college students, male, muscle, body mass index