JACC：久坐增绝经后女性心血管疾病危险

　　美国学者的一项研究表明，在无心血管疾病（CVD）病史的绝经后女性中，久坐与CVD危险增加相关，该因素独立于休闲时间的体力活动；同时存在低体力活动和久坐可增加CVD风险。相关论文2013年4月在线发表于《美国心脏病学会杂志》（J Am Coll Cardiol）。

　　该研究纳入“妇女健康初始观察前瞻性研究”的71018名受试者，她们在基线水平的年龄为50-79岁，无CVD病史，并提供久坐行为的信息（每天的坐位时间以及基线和随访时的常规体力活动）。

　　多变量模型结果显示，与久坐时间≤ 5 h的受试者相比，久坐时间≥10 h与CVD风险增加相关【HR=1.18，95% 可信区间（CI）1.09, 1.29】。低体力活动也与CVD风险增加相关。通过久坐时间和体力活动进行交叉分类后发现，久坐时间≥10 h/d的不活动女性发生CVD风险最高。分别测试冠心病（CHD）和卒中其结果也相似。与体重正常和年轻的受试者相比，久坐与CVD风险的相关性在超重和年龄≥70岁的受试者中相关性更强。

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The Relationship of Sedentary Behavior and Physical Activity to Incident Cardiovascular Disease: Results from the Women’s Health Initiative
Objectives 
The aim was to examine the independent and joint associations of sitting time and physical activity with risk of incident cardiovascular disease (CVD).
Background 
Sedentary behavior is recognized as a distinct construct beyond lack of leisure-time physical activity, but limited data exists on the interrelationship between these two components of energy balance.
Methods 
Participants in the prospective Women’s Health Initiative Observational Study (N = 71,018), aged 50-79 and free of CVD at baseline (1993-1998), provided information on sedentary behavior, defined as hours of sitting per day, and usual physical activity at baseline and during follow-up through September 2010. First CVD (coronary heart disease or stroke) events were centrally adjudicated.
Results 
Sitting ≥ 10 hours/day compared to ≤ 5 hours/day was associated with increased CVD risk (HR=1.18, 95% CI 1.09, 1.29) in multivariable models including physical activity. Low physical activity was also associated with higher CVD risk (P,trend <0.001). When women were cross-classified by sitting time and physical activity (P,interaction = 0.94), CVD risk was highest in inactive women (≤1.7 MET-hrs/week) who also reported ≥10 hrs/day of sitting. Results were similar for CHD and stroke when examined separately. Associations between prolonged sitting and risk of CVD were stronger in overweight versus normal weight women and women aged 70 years and older compared to younger women.
Conclusions 
Prolonged sitting time was associated with increased CVD risk, independent of leisure-time physical activity, in postmenopausal women without a history of CVD. A combination of low physical activity and prolonged sitting augments CVD risk.