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G-19 Free Communication/Poster - Genetics: MAY 30, 2009 7:30 AM - 11:00 AM ROOM: Hall 4F

The Heritability Of Consistent Leisure Time Physical Activity And Inactivity In The Finnish Twin Cohort: 2970Board #117 May 30 9:30 AM - 11:00 AM

Aaltonen, Sari; Ortega-Alonso, Alfredo; Kaprio, Jaakko; Kujala, Urho M.

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Medicine & Science in Sports & Exercise: May 2009 - Volume 41 - Issue 5 - p 519-520
doi: 10.1249/01.MSS.0000356134.74694.1e
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Understanding the genetic regulation of physical activity/inactivity is important in tailoring effective ways to promote physical activity. Previous twin studies have shown that genes play an important role in explaining individual differences in exercise participation at a given moment in life. To the present there is little knowledge on possible genetic influences on sustained behaviors over time.

PURPOSE: To examine the role of genetic and environmental factors explaining individual differences in consistent leisure time physical activity and inactivity in both males and females.

METHODS: This investigation is part of the Finnish Twin Cohort study. Data was available from two occasions: years 1975 and 1981. We analyze the total leisure time physical activity in metabolic equivalent units (MET index) utilizing a 2 MET-hours/day threshold. Persons with a MET index ≥2M-hours/day in 1975 and 1981 were categorized as "consistently active" while those persons with a MET index <2M-hours/day were "consistently inactive". The total numbers of twins analyzed were 1840 MZ and 4366 DZ males, 2200 MZ and 4403 DZ females. We analyzed genetic and environmental influences on both consistent activity and inactivity by fitting structural equation models to raw dichotomous data utilizing biometric methods.

RESULTS: 36% of the males and 31% of the females were consistently active, while 30% of the males and 31% of the females were consistently inactive. The results from the model fitting analyses indicated that the heritability for consistent physical activity was 45% (95% CI 39 to 51%) for males and females, while the heritability for consistent inactivity was 53% (44 to 60%) for males and 38% (28 to 40%) for females.

CONCLUSION: The heritability estimates for consistent physical activity were moderate and in the range of those reported earlier for physical activity at a given occasion. Interestingly, estimates of genetic influences for consistent inactivity for males and females differed being higher for males than for females. Environmental influences, such as social factors, seemed to be more important for women to remain sedentary. These findings can be used by public health promoters to understand the gender differences to promote physical activity habits within sedentary populations.

© 2009 American College of Sports Medicine