A new analysis of data from the Women’s Health Initiative (WHI) suggests that older women who do regular physical activity—even just walking—have a lower risk of fracture than their peers who are sedentary. The findings were published in JAMA Network Open.
The prospective WHI cohort included more than 77,000 postmenopausal women aged 50 to 79 who were enrolled at 40 US clinical centers between October 1993 and December 1998. Participants were observed for outcomes through September 2015 and data analysis was performed from June 2017 to August 2019. For the new research, the authors assessed the impact of physical activity and sedentary behavior on fracture incidence in postmenopausal women.
The participants self-reported their activity levels on questionnaires that asked how many days per week they did mild, moderate, and strenuous physical activity and for how long. Mild physical activity was defined as slow dancing, bowling, or golf. Activities considered moderate were biking outdoors, using an exercise machine, calisthenics, easy swimming, or popular or folk dancing. Exercise that resulted in sweating and a fast heartbeat (e.g., aerobics, aerobic dancing, jogging, tennis, or swimming laps) was considered strenuous.
Separate questions were asked about walking, such as “how often do you walk outside the home for more than 10 minutes without stopping. Other specific questions were asked about nonrecreational activities, such as how many hours were spent per week on scrubbing floors and yard work. Participants also self-reported how many hours per day and night they spent doing sedentary activities like sitting, watching television, or lying down.
The authors used standard metabolic equivalent (MET) intensity values to calculate energy expenditures for the participants’ activity levels. Mild activities were considered to be 3.0 METs whereas as moderate activities were 4.5 METs and strenuous activities were 7.0 METs. Walking speeds, heavy chores, and yard work were also assigned METs.