Genetic Variation in Physical Performance

In this overview the genetic contributions to physical performance will be outlined with a special focus on strength, power and endurance characteristics. Two basic approaches have been used to study the genetic basis of performance phenotypes and related characteristics: the unmeasured genotype approach (top-down) and the measured genotype approach (bottom up). Assessment of heritability is based on the model that total variation (Vtot) in a phenotype is partitioned into genetic (VG), common environmental (VC) and individual-specific environmental (VE) components (Vtot=VG+VC+VE). Heritability (h 2 ) refers to the proportion of the total variation that can be attributed to genetic effects (VG/Vtot). Estimated heritabilities for strength vary widely between 0.27 and 0.58 in family studies and between 0.14 and 0.83 in twin studies. Heritabilities for dynamic strength of arm and leg muscle groups range from 0.29 to 0.87. For aerobic performance estimated heritabilities vary between 0.40 and 0.94. There is good evidence for genotype*training interaction for strength and aerobic performance. Association and linkage studies have indicated a number of potential interesting regions in the human genome. However few replications have been observed with the exception of associations between strength and ACE, ACTN3 and VDR and ACE for aerobic performance.