摘要：An increased body mass in children is usually associated with a decrease in athletic performance. Because of the poorer performance, children tend to avoid the participation in sport activities. This leads to the vicious circle resulting in further increase in body weight. The aim of this study was to identify the motor abilities which are most affected by the body mass increase and to investigate the possible differences in the influence of body mass index on motor abilities with regard to sex. The sample comprised 224 children attending 5th, 6th , 7th and 8th grade of the elementary school (mean age 13,07±1,24). Prior to testing, the detailed explanations of the testing procedure as well as the parental consent form were distributed to the parents. The children underwent testing procedure encompassing measurements of morphological characteristics (height, weight, body fat percentage) and motor abilities (various tests for speed, power, reaction time and balance performed on Kistler Quattro jump force platform, balance boards or Newtest Powertimer PC system). For each child the body fat percentage and body mass index were calculated. Each subject was checked on percentile growth chart for children and classified into one of four categories: underweight, normal weight, overweight or obese. The ANOVA/MANOVA analysis showed, in boys, a significant decrease in all tested motor abilities with the increase of body weight except for the balance board performance. On the contrary, the athletic performance in girls was not significantly influenced by the increase of body mass index. The only test in which the decrease in performance in girls was noted was the test measuring the frequency of lower legs repetitive movements. In conclusion, as the overweight boys of that age do not perform in sport activities as good as their leaner counterparts do, we think that a special attention should be paid to the selection of the sport activities offered for boys in school sport clubs. We have seen here that the balance is still well preserved, regardless of the body mass, so it might be a good choice to offer skateboard classes or similar activities.
关键词：body mass index; children; obesity; motor abilities
