Differences in physiological test results and cross country skiing race performance of a pair of identical twins

Studies of identical and non identical twins, especially when there have been differences in the intensity and duration of sports training and competition experience between the twins. have contributed substantially to knowledge of the effects of training on sports perfonnance. Holmer and Astrand (1972) studied one pair of identical twins. only one of whom had extensive training and com'petitive experience in Swimming. When tested for maximal oxygen uptake [V02max) while running there was little difference between the twins (3.61 v 3.56 Lomin-1j (swim trained v non swim trained twin respectively). However as the mode oftesting became more speCific to swimming. differences between the twins became more pronounced [3.36 v 2.71 Lomin-1 for front crawl and 2.74 v 1.84 L°min- 1 for arm only Swimming). Significant genetic effects have been identified in perfonnance characteristics related to maximal enpurance effqrts. including maximal heart rate [HRmax). maximal ventilation (VE",ax) and V02max [Bouchard et al. 1986. Fagard et al. 1991); and in indicators of anaerobic perfonnance capacity. including blood lactate accumulation ([La)) and muscle enzyme responses to intense interval training (Rodas et al. 1998, Simoneau et al. 1986). Howeyer, physiological responses to submaximal exercise such as oxygen uptake [V02). or economy, are less related to heritability [Fagard et al. 1991) and more to training status(Rodas et al. 1998).