The aim of this study was to test the hypothesis that individual differences in the response of maximal O2 uptake (V˙o 2 max) 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 V˙o 2 max on a cycle ergometer twice before and twice after the training program. The mean increase inV˙o 2 max 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 theV˙o 2 max response variance. With the use of a model-fitting procedure, the most parsimonious models yielded a maximal heritability estimate of 47% for the V˙o 2 max response, which was adjusted for age and sex with a maternal transmission of 28% in one of the models. We conclude that the trainability ofV˙o 2 max is highly familial and includes a significant genetic component.

  • trainability
  • heritability
  • individuality
  • family lines


  • Address for reprint requests and other correspondence: C. Bouchard, Physical Activity Sciences Laboratory, Division of Kinesiology, Dept. of Social and Preventive Medicine, Faculty of Medicine, PEPS, Laval Univ., Ste-Foy, Québec, Canada G1K 7P4 (E-mail:Claude.Bouchard{at}kin.msp.ulaval.ca).

  • The HERITAGE study is supported by the National Heart, Lung, and Blood Institute through the following grants: HL-45670 (to C. Bouchard, Principal Investigator), HL-47323 (to A. S. Leon, Principal Investigator), HL-47317 (to D. C. Rao, Principal Investigator), HL-47327 (to J. S. Skinner, Principal Investigator), and HL-47321 (to J. H. Wilmore, Principal Investigator). A. S. Leon is partially supported by the Henry L. Taylor Professorship in Exercise Science and Health Enchancement, and C. Bouchard is supported by the Donald B. Brown Research Chair on Obesity funded by the Medical Research Council of Canada and Roche Canada.

  • The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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