Characteristics influencing changes in aerobic performance of children aged 7-9

Interpretation of the actual level of aerobic endurance in a growing child is difficult. Endurance capacity per se is influenced by a number of factors, e.g. by genetic endowment, developmental rate, body composition and habitual physical activity. The respective effects of these factors cannot be distinctly separated from one another, so their particular role is not clearly definable in the various age periods. The aim of our investigation was to define the actual level of aerobic endurance performance in children aged 7-9, and to analyse the relevant factors that may affect this kind of performance according to the different level of sport activities. Two primary school classes (N=42) were selected for the experiment. Both groups had physical education classes every day (five times a week). One group (AG, N=31) consisted of children taking part in regular sport courses at least twice a week (e.g. basket ball, karate, triathlon swimming and gymnastics), as well, the other group (NAG, N=11) served as comparison group. Aerobic performance was estimated by measuring cardiorespiratory response during a Jaeger treadmill run using a "vita maxima" (all-out) testing protocol. The subjects were measured in the Laboratory for Spiroergometry of the Hungarian University of Physical Education twice, in 1997 and 1998. Body composition was assessed by the Drinkwater-Ross [4] body mass fractionation technique. Robustness of the body was described by using the plastic index (PLX) of Conrad's growth type [2], morphological age (MORF AGE) was estimated by using the method of Mészáros and Mohácsi [5]. Exercise performance was studied in the laboratory by using a Jaeger 6000 LE model treadmill and a Jaeger mu-DATASPIR model gas analyser. The functional status of the subjects' cardiopulmonary system was estimated by spiroergometric parameters and total mechanical work (WORK). The AG group had a better endurance performance in 1998 than that of non-athletic group. A factor analytic study (principal component method) of the employed variables revealed that the higher level of endurance fitness in the athletic group was not only affected by growth in size, but also by an increased level of cardiorespiratory performance capacity.