Physical Activity and Sedentary Behaviors Among Lesbian, Bisexual, and Heterosexual Women: Findings from the Nurses' Health Study II.

INTRODUCTION: Lesbian and bisexual (LB) women are at greater risk of obesity than heterosexuals. However, few studies have examined sexual orientation differences in physical activity (PA) and even fewer have examined differences in sedentary behaviors. This study assessed PA more comprehensively than previous research by including aerobic PA, strengthening PA, and sitting time, to explore sexual orientation differences among adult women.

METHODS: Nearly 100,000 women from Nurses' Health Study II were included in multivariable-adjusted repeated measures analyses. PA and sedentary behaviors were assessed in 1989, 1991, 1997, 2001, 2005, and 2009 (age range: 24-64 years). Aerobic PA was converted to metabolic equivalent task (MET)-hours/week, whereas strengthening PA and sedentary behaviors were measured in hours/week. About 1.3% of the sample identified as lesbian (n = 926) or bisexual (n = 415).

RESULTS: On average over repeated measures, LB women reported engaging in 2-3 MET-hours/week more of total aerobic PA (β [95% confidence interval, CI]: lesbian: 2.0 MET-hours/week [0.6-3.4]; bisexual: 2.8 MET-hours/week [0.7-4.7]) than heterosexual women. Bisexual women reported engaging in 0.2 hours/week more of strengthening PA (95% CI: 0.06-0.42) than heterosexuals; there were no differences between lesbians and heterosexuals in strengthening PA. LB women reported sitting an average of 4-5 hours/week more than heterosexuals (lesbian: 4.1 hours/week [3.1-5.2]; bisexual: 5.1 hours/week [3.6-6.7]).

CONCLUSIONS: Interventions promoting less sitting time among LB women may be warranted. Additionally, findings highlight need for more research into other modifiable factors besides PA, such as minority stress or disordered eating behaviors that may contribute to greater obesity among LB women.