Developmental Differences Between Boys And Girls Result In Sex-Specific Physical Fitness Changes From Fourth To Fifth Grade

Keywords

Anthropometrics; Body composition; Body mass index; Longitudinal study; Physical activity; Pubescence

Abstract

To better understand how developmental differences impact performance on a broad selection of common physical fitness measures, we examined changes in boys and girls from fourth to fifth grade. Subjects included 273 boys (age, 9.5 ± 0.6 years; height, 139.86 ± 7.52 cm; mass, 38.00 6 9.55 kg) and 295 girls (age, 9.6 ± 0.5 years; height, 139.30 ± 7.19 cm; weight, 37.44 ± 9.35 kg). We compared anthropometrics, cardiorespiratory and local muscular endurance, flexibility, power, and strength. A mixedmethod analysis of variance was used to compare boys and girls at the 2 time points. Pearson correlation coefficients were used to examine relationships between anthropometric and fitness measurements. Significance was set at p # 0.05. Weight increased significantly (.10%) in both sexes, and girls became significantly taller than boys after growing 4.9% by fifth grade (vs. 3.5%). Both groups improved cardiorespiratory endurance and power, although boys performed better than girls at both time points. Boys were stronger in fourth grade, but girls improved more, leading to similar fifth-grade values. Girls were more flexible in fourth grade, but their significant decreases (;32.4%) coupled with large improvements in boys (;105%) resulted in similar fifth-grade scores. Body mass index (BMI) was positively correlated with run time regardless of grade or sex. Power was negatively correlated with BMI and run time in fourth grade. In conclusion, sex-specific differences in physical fitness are apparent before pubescence. Furthermore, this selection of measures reveals sexually dimorphic changes, which likely reflect the onset of puberty in girls. Coaches and teachers should account these developmental differences and their effects on anthropometrics and fitness in boys and girls.

Publication Date

1-1-2015

Publication Title

Journal of Strength and Conditioning Research

Volume

29

Issue

1

Number of Pages

175-180

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1519/JSC.0000000000000623

Socpus ID

84927704202 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84927704202

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