Regular participation in sports is associated with enhanced physical fitness and lower fat mass in prepubertal boys

Abstract

OBJECTIVE:To study the effect of physical activity on whole body fat (BF), its regional deposition and the influence of body fatness on physical performance in prepubertal children. DESSIGN: Cross-sectional study. SUBJECTS: A total of 114 boys (9.471.5 y, Tanner I-II), randomly sampled from the population of Gran Canaria (Spain), 63 of them physically active (PA, at least 3 h per week during the previous year) and 51 nonphysically active (non-PA). MEASUREMENTS: Body composition (DXA), anthropometric variables (body circumferences and skinfolds) and physical fitness were determined in all subjects. RESULTS: The PA obtained better results in maximal oxygen uptake, isometric leg extension force, vertical jump (muscular power), and 300 m (anaerobic capacity) and 30 m running tests (speed) than the non-PA. A lower percentage of body fat (% BF) (4 U less, Po0.05), whole BF mass (36% less, Po0.05) and regional fat mass (28, 25, and 30% less in the trunk, legs and arms, respectively, all Po0.05) was observed in the PA compared to the non-PA. The waist and hip circumferences correlated more closely with both the fat mass accumulated in the trunk region and the % BF (r ¼ 0.81-0.95, Po0.001) than the waist-to-hip ratio (WHR). The WHR correlated with the percentage of the whole fat mass accumulated in the trunk (PFT) (r ¼ 0.52-0.53, Po0.001). In both groups, the PFT increased curvilinearly with the % BF, regardless of the level of physical activity. ANCOVA analysis revealed that total and regional fat masses explained less than 40% of the difference in performance between the PA and non-PA group. The mean speed in the 30 m running test (V 30 ), combined with the height and whole body mass, has predictive value for the BF mass (R ¼ 0.98, Po0.001). The % BF may be estimated from the body mass index (BMI) and V 30 (% BF ¼ 8.09 þ 2.44 Á BMI (kg m À2 )-5.8 Á V 30 (m s À1 ), R ¼ 0.94, Po0.001) in prepubertal boys. CONCLUSIONS: Regular participation in at least 3 h per week of sports activities and competitions on top of the compulsory physical education program is associated with increased physical fitness, lower whole body and trunkal fat mass in prepubertal boys.

Physical fitness in childhood and adolescence: a powerful marker of health

“…Data from the Swedish part of the European Youth Heart Study (EYHS), a schoolbased, cross-sectional study of risk factors for future CVD in a random sample of children (9-10 years old) and of adolescents (15-16 years old), 21 indicate that those individuals having a high cardiorespiratory fitness level also have significantly lower total adiposity, as measured by skinfold thicknesses (Figure 2). 22 When total fatness was assessed by a reference method, that is, Dual Energy X-ray Absorptiometry, a similar inverse association was found in Spanish 24 and North American 25 children. Cardiorespiratory fitness has shown a stronger association with total adiposity, as measured by skinfold thicknesses, than other physical fitness components such as muscular fitness, speed/agility, flexibility or motor coordination.…”

Association of objectively assessed physical activity with total and central body fat in Spanish adolescents; The HELENA Study

“…Results from cross-sectional and longitudinal studies also indicated that participation in at least 3 h per week of extracurricular physical activities and sport competitions is associated with less body fat mass (measured by DXA) in prepubertal children compared with children who do not participate in sports regularly. 43 Furthermore, those children who regularly participated in sports activities at least 3 h per week during 3 years were more protected against total and regional, especially central fat mass accumulation. 44 It is important to consider when interpreting the findings from this study that because of the study design (crosssectional) it is not possible to infer a causal relationship between PA and body fatness.…”

The association between low physical fitness and high body mass index or waist circumference is increasing with age in children: the ‘Québec en Forme’ Project

“…[18][19][20][21][22][23][24][25] However, some of these studies were conducted with a small number of subjects, whereas others included children and adolescents in the same analyses. It has also been reported that overweight as well as obese children showed a lower physical fitness than normal children.…”