The aim of this study was to test the hypothesis that individual differences in the response of maximal O2 uptake (V̇O(2max)) to a standardized training program are characterized by familial aggregation. A total of 481 sedentary adult Caucasians from 98 two-generation families was exercise trained for 20 wk and was tested for V̇O(2max) on a cycle ergometer twice before and twice after the training program. The mean increase in V̇O(2max) reached ~400 ml/min, but there was considerable heterogeneity in responsiveness, with some individuals experiencing little or no gain, whereas others gained >1.0 l/min. An ANOVA revealed that there was 2.5 times more variance between families than within families in the V̇O(2max) response variance. With the use of a model-fitting procedure, the most parsimonious models yielded a maximal heritability estimate of 47% for the V̇O(2max) response, which was adjusted for age and sex with a maternal transmission of 28% in one of the models. We conclude that the trainability of V̇O(2max) is highly familial and includes a significant genetic component.
- Family lines