The relationship between BMI and physical fitness among 7451 college freshmen: a cross-sectional study in Beijing, China

Abstract

Objective: To identify trends in physical fitness test scores of college freshmen and their physical fitness from 2018 to 2021, and to analyze the relationship between college students' Body Mass Index (BMI) and Physical Fitness Index (PFI).

Methods: This study obtained physical fitness test data from 7,541 freshmen at a university in Beijing, China, from 2018 to 2021. Analysis of variance (ANOVA) was used to compare the physical fitness indicators among different BMI levels by gender. A nonlinear quadratic regression model was used to evaluate the relationship between BMI and each indicator within gender groups.

Results: The BMI of freshmen in China was generally increased over the study period, and BMI levels influenced students' physical fitness indexes to varying degrees. BMI was significantly correlated with the physical fitness indexes and PFI. The increase in BMI had a greater influence on the PFI of males than females.

Conclusion: Students with a normal BMI show better physical fitness. A BMI below or above the normal range may result in poor physical fitness. The relationship between BMI and PFI has an inverted u-shaped curve. Physical education programs should be tailored to students with different fitness levels and fundamentals, including but not limited to the development of strength, speed, and other qualities.

Keywords: BMI levels; college freshmen; physical activity; physical education; physical fitness index.

FIGURE 1

Plot of the effect of different BMI levels in various physical fitness indicators on freshmen of different genders. (A) The effect of different BMI levels on freshmen vital capacity; (B) The effect of different BMI levels on freshmen 50 m sprint; (C) The effect of different BMI levels on freshmen standing long jump; (D) The effect of different BMI levels on freshman sit and reach; (E) The effect of different BMI levels on freshmen endurance running speed; (F) The effect of different BMI levels on freshman coreforce score; (G) The effect of different BMI levels on freshmen PFI. Note: when comparing male and female groups, ** (p < 0.01); A: BMI Low group; B: Normal group; C: Overweight group; D: Obesity group, multiple comparisons in one-way multivariate ANOVA when p < 0.05: A vs. B ω; A vs. C φ; A vs. D λ; B vs. C ε; B vs. D δ; C vs. D γ.

FIGURE 2

Relationship between BMI and Z-scores of various physical fitness tests among students of different genders. (A) Relationship between BMI and Z-Vital capacity in students of different genders; (B) Relationship between BMI and Z-50 m sprint in students of different genders; (C) Relationship between BMI and Z-standing long jump in students of different genders; (D) Rela-tionship between BMI and Z-sit and reach in students of different genders; (E) Relationship between BMI and Z-endurance run in students of different genders; (F) Relationship between BMI and Z-coreforce in students of different genders; (G) Relationship between BMI and PFI in students of different genders.