Association of body mass index with muscle strength and cardiorespiratory fitness: A cross-sectional study based on Chinese adolescents

BackgroundMuscle strength and cardiorespiratory fitness are important components of physical fitness and are important for the physical and mental health development of university students. However, obesity is also an important factor affecting physical fitness, and there are few studies on how body mass index (BMI), which reflects obesity, is associated with muscle strength and cardiorespiratory fitness among Chinese university students. Therefore, this study analyzed the association between BMI and muscle strength and cardiorespiratory fitness among Chinese university students in order to provide a reference and basis for promoting the development of physical fitness among Chinese university students.MethodsA stratified whole-group sampling method was used to test physical fitness items in 27 973 (15 527 boys, 55.51%) university students in 800 first- to fourth-year university classes in Anhui, Fujian, Xinjiang, Shanghai, and Jiangxi, China. The physical fitness items included height, weight, standing long jump, 1000 m running (boys), and 800 m running (girls) items. Curvilinear regression analysis was used to analyze the correlations that existed between BMI and standing long jump and VO2max.ResultsThe BMI of Chinese 19-22 years old university students was (21.14 +/- 2.92) kg/m2. The mean standing long jump score was (197.31 +/- 34.07) cm. In general, the BMI reached the highest point of 207.92 cm when the BMI was 26.25 kg/m2, and then showed a decreasing trend with the increase of BMI. The overall relationship between BMI and vertical jump showed an inverted "U"-shaped curve. In terms of VO2max, the overall trend of VO2max increased gradually with the increase of BMI, and when BMI reached 40 kg/m2, VO2max was 4.34 L-kg-1-min-1.ConclusionChinese university students showed an inverted "U" curve relationship between BMI and standing long jump in general, while VO2max showed a gradual increase with increasing BMI. Compared with the cardiorespiratory fitness of Chinese university students, the effect of BMI changes on muscle strength was greater.