Exercise and Risk of Hip Fracture in Postmenopausal Women: Feskanich D, Willett W, Colditz G. Walking and leisure-time activity and risk of hip fracture in postmenopausal women. JAMA. 2002;288:2300-2306.

摘要

OBJECTIVE: To assess the association of exercise and leisure-time activity with risk of hip fracture in postmenopausal women. DESIGN: Cohort study. SETTING: The Nurses Health Study (registered nurses in 11 states of the United States) was initiated in 1976. This analysis has a 1986 baseline and follow-up to June 1, 1998. PARTICIPANTS: Registered nurses (age in 1976, 30-55 y; n = 121,700) returned initial questionnaires that included questions on medical history, lifestyle, and other risk factors related to cancer and heart disease. Postmenopausal respondents to the 1986 biannual questionnaire who had not reported a previous hip fracture or a diagnosis of cancer, heart disease, stroke, or osteoporosis and who completed the questions on physical activity were included (n = 61,200). ASSESSMENT OF RISK FACTORS: Participants reported the average amount of time per week during the previous year spent in 7 activities (walking [and walking pace], jogging, running, bicycling, racquet sports, lap swimming, and other aerobic activity) in 1986, 1988, 1992, 1994, and 1996. Additional vigorous activities and lower intensity activities (e.g., yoga) were included on the 1992 to 1996 questionnaires. Metabolic equivalent (MET) hours per week were calculated and cumulatively averaged. Change from 1980 to 1986 was calculated from less detailed activity questions in 1980. Inactivity (hours spent sitting and standing) was also assessed. MAIN OUTCOME MEASURES: The main outcome measure was risk of self-reported hip fracture resulting from low or moderate trauma (e.g., slipping on ice, falling from the height of a chair) during 12 years of follow-up in relation to quintiles of activity (least, <3 MET; most, >/=24 MET h/wk). MAIN RESULTS: The women in the study were fairly sedentary (median activity, 7 MET h/wk; 19% reported <15 min/wk of leisure-time physical activity). In multivariate analysis, the 3 quintiles whose activity level was >/=9 MET h/wk had progressively lower relative risk (RR) of hip fracture in comparison with theleast active quintile (RR [95% CI], 0.67 [0.49-0.92], 0.53 [0.37-0.74], and 0.45 [0.32-0.63], respectively; P for trend through all quintiles, <0.001). Higher body mass index was also independently associated with lower risk of fracture (P for trend, <0.001). In the lowest activity quintile, hormone replacement therapy lowered the risk for hip fracture (RR, 0.45 [0.26-0.78]), but there was little further risk reduction for more active women (P for trend, 0.24). Among women who increased their physical activity between 1980 and 1986 from <1 h/wk to >/=4 h/wk, risk for fracture was lower (P for trend, 0.07), whereas among women whose activity level decreased from >/=4 h/wk, RR doubled for those active <1h/wk in 1986 (2.08 [1.20-3.61]; P for trend through all quintiles, 0.004). Longer duration and faster pace of walking among women who engaged in walking as their only physical activity lowered risk of fracture (RR for >/=4 h/wk vs. <1 h/wk, 0.59 [0.37-0.94], and RR for brisk pace vs. easy pace, 0.35 [0.22-0.55]). CONCLUSIONS: Moderate levels of physical activity and walking were associated with fewer hip fractures among post-menopausal women.