Introduction: Resulting from the interaction between environmental and genetic factors differences in somatic potentials that manifest in different body size and body proportions may decide of children's motor skills and predispositions. Determination of morphological conditioning of physical fitness facilitates a more rational control of physical education processes.
Aim of the study: Somatic characteristics of 9-year-old boys with different levels of physical fitness:
Material and methods: Somatic traits and physical fitness were assessed in 9-year-old boys (n=308) attending to public elementary schools in Warsaw. Based on the results of the International Test of Physical Fitness (ITPF), groups of boys with low (lowest quartile; n=77) or high (highest quartile; n=76) levels of physical fitness were distinguished. Anthropometric measurements comprised of assessment of body height, body mass, sitting height, arm span, waist and hip circumferences, shoulder and hip widths and thickness of 5 skinfolds. Based on the biceps and subscapular skinfolds body fat content was determined. Additionally, ponderal index, waist-to-hip ratio, sitting height to body height ratio and shoulders-to-hip ratio were calculated. Based on body mass index (BMI) values, underweight, overweight and normal body mass subjects were distinguished among the boys within both, low and high physical fitness categories.
Results: No significant differences between the groups were found for body height, trunk length and arm span. However, boys with low physical fitness were less slim, had a significantly higher body mass (by about 18%), almost two-fold higher body fat content (24.0 vs. 13.7%), significantly greater waist-to-hip circumference, lesser shoulder-to-hip ratio (p <0.001) and relatively shorter legs (p <0.05) compared to boys exhibiting higher levels of physical fitness. Among boys with higher levels of physical fitness, subjects classified as having normal body mass predominated (87%), while in boys with low physical fitness the percentages of normal and overweight subjects were equal and amounted to 47%.
Conclusions: Body height and longitudinal dimensions seem to contribute to physical fitness of 9-year-old boys to a considerably lesser degree than body mass and other body-size related features. Since the prevalence of overweight subjects among less fit boys is alarmingly high some preventive steps should be made, one of them being arranging additional forms of physical activity that would reduce body fat and consequently diminish deficiencies in physical fitness.