Introduction

Nationally recommended levels of physical activity (PA) and exercise1,2 are positively associated with better health and well-being in older adults.3–11 Despite strong associations of active aging, involving regular physical activity and avoiding prolonged sitting, with reduced risk of premature mortality and morbidity, physical inactivity and sedentary time remain high among older adults worldwide.11

Structured exercise programs tailored to individual needs and capacities of older adultsare effective strategies to enhance functional independence and increase PA within 6- to 12-months in community-dwelling older adults.1–12 However, few randomized controlled trials (RCTs) have followed older adults for more than two years or demonstrated maintenance of improved PA over time,11,12 defined as six months of sustained regular PA.13 Therefore, no intervention has been shown to prevent or even attenuate the well-established age-related decline in physical activity.

Evidence that increasing PA and reducing sedentary behavior can promote healthy aging at a population level is even more limited, largely because it is challenging to bring about even short-term behavior change at a community or broader population level. Most physical activity intervention studies attract only individuals who believe they are ready to commit to structured exercise sessions with specified PA goals, whether supervised at scheduled times or encouraged through remote strategies, or occurring at well-equipped (climate-controlled) facilities or in home- and neighborhood settings, with or without social support.14–17 Most physical activity RCTs also exclude individuals who are already physically active, despite well-known challenges and barriers to maintaining PA levels over time. Considering the high proportion of older adults who could possibly benefit from increasing current aerobic and multi-component PA levels and decreasing sedentary behavior by any amount, developing low-cost, scalable interventions that attenuate the age-related decline in PA has high public health value.

Motivated by a call from leaders of the National Heart Lung and Blood Institute in 2011–2013 to conduct pragmatic, low-cost trials, including exercise intervention trials, that would be more generalizable to the U.S. population,18–20 the Women’s Health Initiative (WHI) Strong & Healthy (WHISH) RCT deployed a randomized consent design to assign women within the large, well-characterized cohort of the WHI Extension Study,21 to a centralized pragmatic physical activity intervention (PA-I) or “usual activity” Comparison, with major cardiovascular disease (CVD) events as the primary health outcome.22,23

This paper describes the design and implementation of the “light touch,” ie delivered remotely with no individualized customization, WHISH Physical Activity Intervention (PA-I) and key differences in physical activity patterns between women aged 66–99 (mean 79.7) years, who were randomly assigned to the WHISH Intervention versus Comparison arms over a median of 8.7 years. The WHISH PA-I was designed to motivate a large number of older women residing across the United States to move more and sit less and become familiar with current national multi-component physical activity recommendations.1,2 The paper focuses on key differences between the intention-to-treat WHISH Intervention and Comparison arms with respect to self-reported walking, aerobic, and total exercise, measured as MET-hours per week, muscle strengthening sessions per week, and sitting hours per day.