Introduction: In obese children the aerobic capacity (maximal oxygen intake) is lower than in non-obese children, but lower ability to perform long-term efforts can also result from higher physiological cost (in comparison to normal weight children) during locomotion efforts.
Aim of the study: was to determine developmental changes in physiological cost of walks in boys with excessive level of body fat (F%) during puberty.
Material and methods: The study was conducted on 11 boys with excessive level of body fat (%F=26.82±2.89 % - GROUP O) and 14 with normal level of body fat (%F=12.51±2.35% - GROUP P). The boys performed the graded test and a few days later two submaximal walks (6 min each with a 4 min pause for rest between walks) on mechanical treadmill with different speed (3.6 km×h(-1) and 4.8 km×h(-1)) every two years (three series) beginning at the age about 10 years and finishing at the age of 13-14 years.
Results: The level of pulmonary ventilation (VE) and tidal volume (TV) were significantly higher in overweight boys, but breathing frequency (BF) was similar in both groups. With age, the economy of breathing was improved in both groups: pulmonary ventilation and tidal volume were increasing but BF was decreasing. The work intensity during walking, expressed as %VO2max and %HRmax, was higher in boys with excessive level of body fat and decreased with age. Total values of VO2 (l×min(-1)) were higher in the group of overweight boys, but relatively to body mass the values of VO2 were significantly lower in this group and with age the difference between groups was constant.
Conclusions: The physiological cost of walking was higher in boys with excessive level of body fat in each test in comparison with non-obese boys. The difference between groups in level of physiological parameters increased with speed of walking. The physiological cost of walking decreased with age in both groups.