Muscular strength and power are important components of fitness essential for the execution of a variety of daily and sporting activities. Static or isometric strength, explosive strength or power, and dynamic (sometimes called functional) strength are generally considered in epidemiological studies.

Analyses of the genetic determinants of strength provide information concerning the contribution of both genes and environmental factors. Interaction effects between genes and environment (the dependence of weight training response on genes) and the identification of genes or coding variants in relation to strength characteristics are also of interest.

METHODOLOGICAL CONSIDERATIONS

Power and strength show normal variation in the general population, as is typical for quantitative, multifactorial phenotypes that are influenced by both multiple genes (polygenic) and environmental factors. The search for the genetic basis of muscular strength and power is based on two approaches: the unmeasured genotype approach (top down) and the measured genotype approach (bottom up).

When the measured genotype is not available, inferences concerning genetic influences on a phenotype are based on statistical analyses of the distributions of strength measures in related individuals and families based on the theoretical framework of biometrical genetics. Twin and family studies are the two major strategies used to identify genetic and environmental contributions to muscular strength. The heritability coefficient derived thereof is specific for the studied population and can be estimated using ANOVA or genetic modelling techniques.

Two major complementary strategies are available in humans to identify genes using the measured genotype approach. The first method is localisation and identification by quantitative …