In a report from the Objectively Measured Physical Activity and Cardiovascular Health (OPACH) study, an ancillary study to the Women’s Health Initiative that began in the early 1990s, LaCroix and colleagues1 provide evidence of the association between light physical activity, as measured by objective wearables (ie, accelerometers), and the outcomes of incident coronary heart disease (CHD) and cardiovascular disease (CVD) among older (mean [SD] age, 78.5 [6.7] years) women who represent a diversity of racial and ethnic groups in the United States. The current study extends to older women the evidence base documenting the independent association of physical activity and incident CHD as initially described among men.2 The strength and uniqueness of the OPACH study include (1) the study participants being older women, examined prospectively from across 3 major race and ethnic groups; (2) the use of an objective method of measuring physical activity (accelerometry); (3) and the examination of the continuum of physical activity with a focus on light physical activity as the primary exposure variable.1
There have been a significant number of studies demonstrating that a dose response of physical activity, even at low doses of moderate physical activity, is associated with a decreased risk of incident CHD.3 However, there is a paucity of studies that have examined the cardioprotective associations of light physical activity. Previous investigations have provided evidence that light doses of physical activity are associated with significant improvements and maintenance of functional health among men and women who are 70 years and older.4,5 Similar findings have been shown among older adults when examining quintiles of cardiorespiratory fitness, where improved functional, CVD, and CHD outcomes are associated with participants whose cardiorespiratory fitness level is just 1 quintile above the lowest quintile.6
The work of LaCroix and colleagues1 aligns remarkably well with the recent scientific report produced by the 2018 Physical Activity Guidelines Advisory Committee,7 which reveals evidence for the association of the accrual of low-dose light physical activity and improved CHD and CVD outcomes, thus recognizing that even light physical activity conveys improved cardiovascular health, especially among older adults.7,8 Hence, the current report further establishes the rationale for the 2018 Physical Activity Guidelines for Americans in recommending specific physical activity guidance for older adults: “Most older adults spend a substantial portion of their day being sedentary, so the key guidelines start in a similar fashion as those for adults—move more and sit less throughout the day. Replacing sitting with light-intensity physical activity or, ideally, moderate-intensity physical activity may provide significant benefits.”9
LaCroix and colleagues1 provide a thorough review of the potential limitations of using accelerometers to measure physical activity and validly discriminate between light, moderate, and vigorous physical activity.1 They support the ability of accelerometry to discriminate among intensities of physical activity by citing the accelerometry calibration studies performed by the OPACH study investigators.1 Indeed it may be possible that accelerometry could misclassify intensity of activity among these older women, erring toward moderate physical activity, since, for some, activities at 2.5 to 2.9 metabolic equivalents could place them at a moderate intensity dose for their age and sex.3 However, LaCroix and colleagues1 acknowledge that it was not feasible for the OPACH investigators to assess aerobic capacity among their study participants and thus enhance the precision of their intensity estimates. Therefore, replication of these findings through additional studies is needed to further strengthen the evidence of the association between light- and low-dose physical activity and CHD and CVD outcomes. Such studies should include not only older women, but also older men and perhaps younger adults and should use both accelerometers and wearable metabolic systems to measure light- and low-dose physical activity.
Among US women 65 years and older, the prevalence of those meeting minimal levels of the Physical Activity Guidelines varies from approximately 25% to 44% depending on the particular national survey instrument.10 Regardless of which estimate is closest to the truth, the current prevalence of physical activity among older women is clearly insufficient and in need of improvement. The findings of LaCroix and colleagues1 should serve as a clarion call to physicians, other health care professionals, health care systems, and public health agencies to embrace, communicate, and promote the 2018 Physical Activity Guidelines to all patients and constituents. To temporize such action is to jeopardize the future health and well-being of older women, leaving most with the consequences of sedentarism and inadequate levels of physical activity with associated premature death and deficits in physical and mental functioning.
Published: March 15, 2019. doi:10.1001/jamanetworkopen.2019.0405
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Heath GW. JAMA Network Open.
Corresponding Author: Gregory W. Heath, DHSc, MPH, Department of Health and Human Performance, University of Tennessee at Chattanooga, 615 McCallie Ave, Department 6606, Chattanooga, TN 37403 (firstname.lastname@example.org).
Conflict of Interest Disclosures: None reported.
et al; Women’s Health Initiative (WHI). Association of light physical activity measured by accelerometry and incidence of coronary heart disease and cardiovascular disease in older women. JAMA Netw Open
. 2019;2(3): e190419. doi:10.1001/jamanetworkopen.2019.0419Google Scholar
US Department of Health and Human Services. 2018 Physical Activity Guidelines Advisory Committee Scientific Report. Washington, DC: Office of Disease Prevention and Health Promotion; 2018.