Total 71,018 Participants of Women’s Health Initiative Observational Study (N =), aged 50-79 and free of CVD at baseline.
Sitting for more than or equal 10 hours per day compared to less than equal 5 hours per day was associated with increased heart attack risk (HR=1.18, 95% CI 1.09, 1.29). in this study.
Sitting for prolonged hours continued to be harmful in almost every level of activity i.e. high, medium, low, and inactive. Only in women who walked for seven hours per week or jogged or ran for four to five hours week did not have high heart attack risk with prolonged sitting.
Medium level of exercise i.e. two and a half hours a week of moderate activity or 8.4 to 20 MET-hours/weeks was still a risk for heart attack with prolonged sitting.
Women who sat more did less exercise, and prolonged sitting and inactivity were both independent risk factors for heart attack.
More sitting increased heart attack risk in overweight women i.e. BMI more than 25, but not BMI less than 25.
Older age with prolonged sitting increased heart attack risk.
Reducing sitting time positively helped in reducing heart attack risk.