Fig. 2From: Heritability and genetic etiology of habitual physical activity: a twin study with objective measuresTime spent on high-intensity physical activity (High) as a function of PPARGC1A genotype. Associations obtained using linear regression are shown for twins (a) and unrelated participants (b) assuming an additive model. The number of individuals within a genotype-group is indicated in the bars. Data shown are median and inter-quartile range. *P < 0.05, b P = 0.06Back to article page