Is the physical fitness of schoolchildren dependent on their physical activity levels and nutritional status? The experience from Serbia.

Introduction: based on the presumed relationship between physical activity and physical fitness, it seems reasonable to expect that being active would result in sufficient fitness levels. However, the relationship between physical activity and fitness is not so plausible and needs deeper exploration. Objectives: we conducted a study aimed at exploring: a) the potential variation in physical activity level by gender and school grade; and b) the effect of physical activity level, gender, and nutritional status on physical fitness test results. Methods: a total of 2795 males and 2614 females participated in the study (11-14 years). Their physical fitness was assessed by measuring anthropometric status, muscular fitness, endurance, flexibility, agility, and cardiorespiratory fitness, while their physical activity was assessed using the Physical Activity Questionnaire (PAQ-A). Results: a higher percentage of boys were highly active, while a higher percentage of girls were scarcely active (χ2 [2, n = 5017] = 151.4, p < 0.01). Decline in physical activity with age was higher in girls than in boys (χ2 [6, n = 5409] = 90.4, p < 0.01). MANOVA revealed a significant effect of gender (V = 0.009, F [6, 3669] = 5.29, p < 0.01), nutritional status (V = 0.193, F [12, 7340] = 65.16, p < 0.01) and physical activity levels (V = 0.043, F [12, 7340] = 13.60, p < 0.01) on tests outcomes. Conclusions: our study has shown that activity level in Serbian schoolchildren declines with age and is affected by nutritional status. Nutritional status represents a significant factor confounding physical fitness scores, regardless of activity levels.