This study aims (1) to investigate the presence of familial aggregation in physical activity (PA) levels and sedentary behavior (SB) among members of three generations families and (2) to estimate the magnitude of additive genetic influences on PA and SB phenotypes. The sample consisted of 100 extended families covering three generations (n=1034), from the Lisbon area, Portugal. Phenotypes were assessed via the short version of the self-administered International Physical Activity Questionnaire (IPAQ-SF). Measured phenotypes: total physical activity (TPA); vigorous (VPA); moderate (MPA); walking; time spent in sitting time (ST), watching television (WT) and PA levels classification. Body mass index (BMI) was calculated. Exploratory family analysis in all phenotypes was conducted in PEDSTATS software. The genetic component (h²) and shared environmental effect were estimated using maximum likelihood implemented in the SOLAR software package. All graphs were done in HLM software. Sex, age, sex*age, age², sex*age² and BMI were used as covariates. Significant level was set at 0,05. Genetic component estimates (h²) were as follows: TPA h²=0,28±0,06 (p<0.0001); VPA h²=0,35±0,06 (p<0.0001); MPA h²=0,29±0,06 (p<0.0001); walking h²=0,40±0,06 (p<0.0001); ST h²=0,29±0,06 (p<0.0001); WT h²=0,15±0,06 (p<0.003) and determination of the level physical activity h²=0,35±0,14 (p<0.007). Shared environmental effect was not significant. These results showed a low-to-moderate genetic contribution, between 15% to 40% of the total variability, in the PA and SB phenotypes. The genetic factors have low to moderate influence in this sample. Non-shared environmental factors appear to have the major contribution in these phenotypes.
Genetic epidemiology; Physical activity; Heritability
