The Association between Body Mass Index and Physical Fitness of Normal Weight/Overweight/Obese University Students

Abstract

This study aimed to apply longitudinal data (in four waves) to examine relationships between body mass index (BMI), flexibility, muscular endurance, and explosive power, and employed a random-intercept panel model (RIPM) to divide the variations of different waves into between- and within-person variations. Furthermore, a multi-group model test was conducted to explore whether an interaction effect existed between sex and these relationships. The data were collected from a university in Taiwan between August 2009 and July 2010, and 3863 freshman and junior students were recruited. Results showed that the between- and within-person relationships between BMI and explosive power, and between BMI and muscular endurance, were negative (independent of sex). The negative between- and within-person associations between BMI and muscular endurance were both invariant with respect to sex. The negative between-person associations between BMI and explosive power were not equivalent for both sexes, yet the within-person associations between BMI and explosive power were equivalent for both sexes. The between-person associations between BMI and flexibility were positive for both sexes, but the within-person associations of these two variables were negative for both sexes. The invariance test confirmed that the positive associations of between-person BMI and between-person flexibility were invariant for both sexes, yet the negative associations of within-person BMI and within-person flexibility were not equivalent for both sexes. Between-and within-person correlations among explosive power, muscular endurance, and flexibility were significantly positive. Only the auto-regressions of BMI and muscular endurance were significant and equivalent for both sexes.

The Relationship between Body Mass Index and Physical Fitness among Chinese University Students: Results of a Longitudinal Study

“…In particular, the goodness-of-fit statistics include the comparative fit index (CFI) ≥ 0.95 [ 38 ], root mean square error of approximation (RMSEA) ≤ 0.08 [ 34 ], non-normed fit index (NNFI) > 0.95 [ 39 ], and standardized root mean square residual (SRMR) ≤ 0.08 [ 40 ]. Values of correlation coefficients between BMI, explosive power, flexibility, and cardiorespiratory endurance less than 0.24 were considered as representing low correlation, while values of correlation coefficients exceeding 0.24 indicated a moderate correlation [ 36 ].…”

“…One potential study, though, after testing a sample of Taiwanese students for explosive power, flexibility, and muscular endurance, Kung, Chang, Hwang, and Chi [ 36 ] explored the connections between the participants’ BMI results. The collected data were organized using the random-intercept panel model (RIPM) to display the variations in participant test results for both between- and within-person data sets.…”

“…This observation emphasized the importance of separately considering male and female results in future research. It is believed that studies not separately investigating male and female samples are at risk of arriving at incorrect or incomplete conclusions [ 36 ]. As data were only collected at the start and end of an academic year, the long-term differences between BMI and physical fitness were difficult to determine despite the effective methods of data collection utilized in the research by Kung et al…”

“…To understand the ways normal/overweight/obese weight status in university student populations are related to between-person explosive power, flexibility, and cardiorespiratory endurance, as well as to within-person explosive power, flexibility, and cardiorespiratory endurance, the data analysis method used by Kung et al [ 36 ] was applied in this study. It also utilized the random-intercept panel model (RIPM) as the means to analyze four sets of longitudinal data from a Chinese university.…”

“…This issue is resolved by between-person variations. In contrast, within-person variation exposed the relationships between within-person BMI and within-person flexibility, cardiorespiratory endurance, and explosive power [ 36 ]. The hypothesis is essentially that there are substantial connections across between- and within-level BMI and flexibility, BMI and cardiorespiratory endurance, BMI and explosive power, flexibility and cardiorespiratory endurance, flexibility and explosive power, and cardiorespiratory endurance and explosive power.…”