BOUCHARD, C, R. LESAGE, G. LORTIE, J.-A. SIMONEAU, P. HAMEL, M. R. BOULAY, L. PEARUSSE, G. THEARIAULT, and C. LEBLANC. Aerobic performance in brothers, dizygotic and monozygotic twins. Med. Sci. Sports Exerc., Vol. 18, No. 6, pp. 639-646, 1986. Forty-two brothers, 66 dizygotic twins of both sexes and 106 monozygotic twins of both sexes, 16 to 34 yr of age, took part in this study that was designed to investigate the effect of heredity in aerobic performance. Maximal oxygen uptake (VO2max), maximal heart rate (HRmax), maximal ventilation, and maximal oxygen pulse were obtained from a progressive ergocycle test to exhaustion. Total work output in a 90-min maximal ergocycle test was also determined in the twins. Fat-free weight was estimated from body density measurements obtained through underwater weighing. Aerobic performance scores were adjusted for age (brothers), and age and sex (dizygotic and monozygotic twins) by regression procedures. Dizygotic twins and brothers of same sibship exhibited about the same level of resemblance for all variables or were only slightly different, with the exception of HRmax. Monozygotic pairs were generally more alike than the other sibs, as suggested by the intra-class coefficients. Twin data were used to compute the genetic effects. The within-pair estimate of genetic variance revealed that it was significant (P < 0.05) for all variables except VO2ma-kg-1 fat-free weight.min-1. In the case of HRmax the among-pairs component estimate had to be used, and it also proved significant (P < 0.01). The size of the genetic effect was computed from three different methods, and it reached about 40% for VO2max-kg-1-min-1, 50% for HRmax 60% for maximal oxygen pulse and maximal ventilation, and 70% for 90-min work output-kg-1. Estimates for aerobic performances decreased when reported per kilogram of fat-free weight, i.e., to about 10% for VO2max and 60% for 90-min work output. These data indicate that a significant genetic effect is present in the population for endurance performance but that a much lower heritability exists for VO2max.
(C)1986The American College of Sports Medicine