Abstract des Autors

The present paper reviews the literature concerning the effects of aerobic training on maximal aerobic power VO2max in youth. The influences of three major factors on the VO2max are discussed (a) heredity, (b) growth and development and (c) training. From heritability studies it is concluded that 50-70% of the variability in VO2max can be explained by genetic differences (Malina and Bouchard, 1991). Absolute VO2max/min increases with growth and development between age 4 and 14 in boys and girls. However VO2max per kg body mass (VO2max/BM) is in boys relatively constant over that age period: between 50 and 55 ml/kg/min. In girls, there is a gradual decrease from 50 to 40 ml/kg/min (Kemper, 1986). The changes in VO2max/BM during growth and development are more clear in longitudinal data than in cross-sectional data. The latter include more confounding factors such as differences in birth cohorts and maturation (Krahenbuhl et al, 1985). This paper reviewed 27 longitudinal training studies in wich control groups (ie no training) were used. Training effects were measured as the percentage change (delta-%) of VO2max/BM in the training group with respect to the delta-% in the control group. The short term studies (less than 6 months, n=18) show a mean delta-% of -7.6% (range +20.7 to -2.3). The long term studies (6 months or more, n=9) have a mean delta-% of -1.8% (range +10.3 to -11.3). Although it seems that the training effects over shorter periods of time are more effective than the studies with training effects over longer periods, the negative relationship (r=-0.31) is not significant due to the wide range of both positive and negative training effects. The training effects found in children with training programs that are sufficient in intensity, frequency and duration (ACSM, 1990) appear to be similar across the two different maturation levels: In the nine studies with prepubertal children the mean delta-% in VO2max/BM is 8.4% and in the fibe-studies with circum pubertal children the mean delta-% is 6.6% and this difference is not significant. On the other hand it appeared that the nine prepubertal training studies are significantly more effective (8.4%) than the 16 studies that have inadequate or poorly documented training regimen (0.9%). Only one child study has reported VO2max/BM values exceeding 70 ml/kg/min (Kobayashi et al, 1978) after aerobic training. Since in adult top endurance athletes values exceeding 80 ml/kg/min are not unusual, it is unlikely that intensive aerobic training before or during puberty will lead to the high values seen at adult age. Verf.-Referat