Physical Fitness Across Weight Categories Among Children and Young Adolescents

Background/Purpose: Childhood obesity is a serious national health concern. Although previous research observed a negative relationship between body composition and aerobic fitness among children, whether body composition also plays a role in other physical fitness components such as strength, flexibility, and agility is not clear. The purposes of this study were to determine a) whether there were differences between overweight/obese and healthy weight elementary school students in aerobic fitness, abdominal and upper body strength and endurance, flexibility, and agility, and if so, b) whether such differences changed in middle school students.

Method: The President’s Challenge fitness tests including body mass index (BMI for body composition), endurance run/walk (for aerobic fitness), curl ups (for abdominal strength and endurance), flexed arm hang (for upper-body strength and endurance, sit-and-reach (for flexibility), and shuttle run (for agility), were administered to 256 students who were enrolled in k, 1^st, and 2^nd grade. The same test battery was administered to these students 5 years later when they were in 6^th, 7^th, and 8^th grades. Participants were categorized into overweight/obese (OW) and healthy weight (HW) groups based on the Centers for Disease Control and Preventions’ gender- and age-specific BMI percentile cutoffs (85^th percentile).

Analysis/Results: MANOVA analyses were conducted to examine the differences in multiple dependent fitness variables between two weight categories for elementary school students and middle school students separately. The results indicated that HW elementary students performed significantly better in sit ups (28 ± 8) and flexed arm hang (8.7 ± 8.5 cm) than their OW counterparties (22 ± 11 for sit ups and 3.6 ± 7.7 cm for flexed arm; P=0.003 and p=0.002, respectively). The HW students in their middle school years performed significantly better in mile run (623.9 ± 170.7 vs. 762.5 ± 146.8 sec., p <0.0005), sit ups (37.9 ± 11.8 vs. 27.6 ± 10, p <0.0005), flexed arm hang (34.1 ± 22.3 vs. 8.8 ± 11.2 cm, p < 0.0005), and shuttle run (11.2 ± 1.1 vs. 12.5 ± 1.4 sec., p <0.0005). However, students in the two weight categories exhibited no significant differences in flexibility tests in elementary (p=0.93) and middle school (p=0.42) years.

Conclusions: HW students had better abdominal and upper body strength and endurance in both elementary and middle school years, and they also exhibited higher aerobic capacity and better agility in middle school years. Weight status did not affect flexibility.