Physical activity and mortality: is the association explained by genetic selection?

Area of Science:

• Epidemiology
• Genetics
• Public Health

Background:

• Public health guidelines advocate physical activity for improved health and longevity.
• Emerging research suggests genetic selection may influence the observed association between physical activity and mortality.

Purpose of the Study:

• To investigate whether genetic factors explain the link between physical activity and mortality.
• To determine if physical activity has an independent effect on reducing all-cause and cardiovascular disease mortality.

Main Methods:

• Utilized data from 13,109 Swedish twin pairs surveyed in 1972.
• Linked questionnaire data with the national Cause of Death Register for mortality follow-up (1975-2004).
• Employed within-pair analyses of monozygotic twins to control for genetic and shared environmental factors.

Main Results:

• High physical activity was associated with a 34% reduced risk of death in men and 25% in women.
• More active monozygotic twins showed a 20% reduced risk of all-cause mortality and a 32% reduced risk of cardiovascular disease mortality compared to their less active co-twins.
• These within-pair findings indicate that genetic selection does not account for the mortality benefits of physical activity.

Conclusions:

• Physical activity is independently associated with a reduced risk of all-cause and cardiovascular disease mortality.
• The findings support a causal relationship between engaging in physical activity and increased longevity.
• Public health recommendations promoting physical activity are strongly supported by these results.