Exercise Needn't Be Strenuous to Reduce Heart Risk

Doug Brunk

March 06, 2020

PHOENIX – The level of physical activity people engage in during their golden years doesn't have to be strenuous in order to be effective, results from two studies presented at the Epidemiology and Prevention/Lifestyle and Cardiometabolic Health meeting showed.

In one study, women who walked 2,100-4,500 steps each day reduced their risk of dying from cardiovascular disease by up to 38%, compared with those who walked fewer than 2,100 steps each day. In addition, women who walked more than 4,500 steps each day reduced their risk of cardiovascular disease (CVD) mortality risk by 48%.

The findings come from an ancillary analysis of the Women's Health Study known as the Objective Physical Activity and Cardiovascular Health (OPACH) Study.

"Our work shows that both light-intensity and moderate-/vigorous-intensity steps are associated with reduced risk of cardiovascular disease death," lead author Andrea Z. LaCroix, PhD, said in an interview. "And our previous studies show that all movement while standing, stepping, or just moving about at whatever intensity you choose, appears to have cardiovascular benefits, whereas long hours spent sedentary, especially prolonged sitting bouts are associated with increased risk of cardiovascular disease.

"These new findings on steps are best interpreted as showing that moving instead of sitting is good for your heart and blood vessels as we get older. Find the things you love to do and get moving."

For OPACH, 6,379 women with an average age of 79 years wore ActiGraph GT3X+ triaxial accelerometers on their wrist for 7 days during 2012-2014, as a way to ascertain the number of steps they took. The researchers followed the study participants to March 1, 2019, and used Cox proportional hazard models to estimate CVD mortality across four quartiles of steps per day, adjusted for age, race/ethnicity, education, smoking, alcohol consumption, self-reported health, comorbidities, and physical function.

The lowest quartile reference category was less than 2,108 steps per day. The second, third and fourth quartiles were: 2,108 to fewer than 3,136 steps, 3,136 to fewer than 4,499, and 4,500 and above.

Dr. LaCroix, distinguished professor and chief of epidemiology at the University of California, San Diego, reported that women who walked 2,100-4,500 steps daily reduced their risk of dying from CVD by up to up to 38%, compared with women who walked fewer than 2,100 daily steps. The women who walked more than 4,500 steps per day reduced their risk by 48%.

She noted that, for many years, common wisdom was that 10,000 steps per day should be used as a general fitness target, that goal "was never evidence based, and so far, emerging evidence using accelerometers to measure steps shows benefit way below the level of 10,000 steps." Dr. LaCroix added that, in this study, "we were able separate steps taken at a light intensity of energy expenditure versus a moderate or vigorous level of energy expenditure. This is like comparing slower versus faster steps. Both influenced the risk of CVD death and we found no evidence that faster steps were more beneficial for reducing risk of CVD death than slower steps. So, the main message I want my demographic [women aged over 60] to understand is that all movement appears to be good for your heart."

Barry A. Franklin, PhD, director of preventive cardiology and cardiac rehabilitation at Beaumont Health in Royal Oak, Mich., characterized the study findings as "good news" but not entirely surprising. "It goes along with other research showing that the biggest bang from the buck is going from the least fit, least active cohort, which we call the bottom 20%, to the next lowest level," he said in an interview. "So, by simply doing some steps, certainly less than 10,000, there were significant benefits for this older age group."

Dr. LaCroix acknowledged certain limitations of the OPACH study, including the fact that it did not include men or women aged younger than 60 years. In addition, the accelerometer used in this and other studies may measure fewer steps than women are actually taking. "Devices vary in their accuracy," she said. "If you are tracking steps, try to aim for 4,500 or a little more, but know that every step counts."

In a separate study, researchers found that an increase of 30 minutes per day of low-intensity physical activity (LIPA) may lower the risk of death among older adults, regardless of the amount of moderate to vigorous physical activity (MVPA) participants are involved in or whether they have impaired physical function. In addition, an increase of 30 minutes of sedentary time per day may increase the risk of death regardless of the amount of MVPA or whether participants have impaired physical function.

Those are key findings from an analysis of 1,262 participants in the Framingham Offspring Study.

"Given that MVPA tends to decline with age, particularly during the mid- to late-life transition, promoting LIPA and reducing sedentary time may be a more practical alternative among older adults for reducing the risk of mortality," lead author Joowon Lee, PhD, said in an interview at the meeting sponsored by the American Heart Association.

According to Dr. Lee, a postdoctoral fellow at Boston University, prior studies found that the inverse association between MVPA and cardiovascular and all-cause mortality among older adults. "However, we focused on sedentary and light-intensity physical activity, which is prevalent in older adult population," he said. "Additionally, we looked at the association between physical activity and mortality after excluding participants with frailty as a sensitivity analysis."

The researchers drew from accelerometry-derived physical activity data from 1,262 Framingham Offspring Study participants at their ninth examination (2011-2014). The mean age of the subjects was 69 years, 54% were women, and they had worn the accelerometers at least 10 hours per day for at least 4 days prior to the exam visit. The researchers used multivariable Cox proportional hazards regression models to relate physician activity and sedentary time with all-cause mortality adjusting for potential confounders.

During a median follow-up of 4.8 years, 67 study participants died. Dr. Lee and colleagues observed that higher total physical activity, LIPA, adherence to physical activity guidelines (at least 150 minutes of activity each week), and lower sedentary time were associated with a lower risk of all-cause mortality. Specifically, they were 67% less likely to die of any cause if they spent at least 150 minutes per week in moderate to vigorous physical activity, compared with those who did not. In addition, the researchers found that each 30-minute interval of LIPA, such as doing household chores or casual walking, was associated with a 20% lower risk of dying from any cause. On the other hand, every additional 30 minutes of being sedentary was related to a 32% higher risk of dying from any cause. The results remained statistically significant even after excluding those with frailty.

"In the present analysis, an increase of 10 minutes in MVPA was not associated with the risk of all-cause mortality although meeting physical activity guidelines [MVPA of at least 150 minutes per week] was the strongest factor associated with the risk of all-cause mortality," Dr. Lee said.

He acknowledged certain limitations of the analysis, including the fact that the study participants were white individuals with European ancestry. "Additionally, a small number of mortality events were observed in the current investigation," he said. "So, an additional study of larger multiethnic samples of older adults is warranted to confirm our findings."

"We tell people: 'You need 30 minutes of moderate intensity exercise most days of the week,'" Dr. Franklin said. "That's true, but a classic study in Lancet showed that if you do 12 or 15 minutes of moderate exercise, not 30 minutes, you also get a 14% reduction in mortality. Some exercise is better than none, and for older adults, they don't even have to do moderate intensity exercise to get benefits."

Dr. LaCroix's study was funded by the National Heart, Lung, and Blood Institute; Dr. LaCroix reported having no financial disclosures. Dr. Lee's study was supported by the National Heart, Lung, and Blood Institute; Dr. Lee reported having no disclosures.

Epi/Lifestyle 2020, Abstract 30, Abstract 31. Presented March 5, 2020.

This article first appeared on MDedge.com.

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