Genetic Factors Associated With Human Physical Activity: Are Your Genes Too Tight To Prevent You Exercising?

The benefits of physical activity (PA) on health and fitness are well known. Recently, it has become apparent from studies of heritability that there is a considerable genetic component to PA. However, PA is such complex phenotype that the measurement and quantification of it provide a challenge to a clearer understanding of its genetic basis. In this review we assessed available evidence from family and twin studies that have estimated the heritability of PA. Heritability is greater when evaluated by accelerometry compared to questionnaires, and for questionnaires higher in twin studies. Accelerometry studies suggest heritability of PA is around 51-56%. There have been many genome-wide linkage studies, candidate gene studies and four genome wide association studies (GWAS) to highlight specific genetic factors linked to different PA levels. These studies have generally failed to replicate identified loci with the exception of the melanocortin 4 receptor (MC4R) and this may be because of the variability in the measurement techniques used to characterise the behaviour. Future work should aim to standardise the procedures used to measure PA in the context of trying to identify genetic causes. The link of genetics to physical exercise is not so tight that it prevents voluntary interventions.