BETHESDA, MD — Good news on the exercise front, including for those who do a little and those who do lot, with a new study showing that any amount of leisure-time physical activity is associated with a significantly lower risk of death when compared with no physical activity at all.
Those who did a little, such as those individuals who did less than the amount outlined in the 2008 Physical Activity Guidelines for Americans, still had a 20% lower mortality risk compared with individuals who did no exercise at all. Those who achieved the minimum recommended physical-activity target—defined as 7.5 to <15 MET hours per week—had a 31% lower risk of dying compared with the physically inactive.
Those who did a lot more, such as those exceeding the weekly recommendations, had an even larger reduction in mortality risk. Compared with those who did no exercise at all, individuals who performed approximately three to five times the recommended minimum had a near 40% reduction in the risk of dying. The benefit peaked at around 22.5 to 40 MET hours per/week, report investigators.
"Individuals should engage in a level of physical activity that meets the recommend minimum," lead investigator Dr Hannah Arem (National Cancer Institute, Bethesda, MD) told heartwire , "but clinicians don't need to caution their highly active patients about a higher mortality risk."
The results of the study are published online April 6, 2015 in JAMA Internal Medicine.
Scary Headlines of Late
In the US, the current guidelines recommend 150 to 300 minutes of moderate-intensity exercise or 75 to 150 minutes of vigorous-intensity exercise each week for health benefits. This translates into an energy expenditure of 7.5 to 15 MET hours per week.
Speaking with heartwire , Arem said there have been studies examining the relationship between physical activity and mortality, and these studies have shown a lower mortality risk with higher amounts of exercise. However, these studies tended to group more active individuals into one homogenous category, such as those who performed two or three times the minimum weekly amount of recommended physical activity.
"Sometimes this top group gets scrunched down into a single risk estimate," said Arem. "We were specifically interested in the dose-response relationship. So what happens to mortality risk with very high levels of exercise? Particularly, in recent years, there have been some studies showing an increased risk with very high levels. Conversely, we didn't really know if there was any plateau in the risk or if there would be a continued decrease [in mortality risk] with more exercise."
In their study, the researchers pooled data from six studies in the National Cancer Institute (NCI) Cohort Consortium. These were population-based prospective cohorts in the US and Europe with self-reported physical-activity data. In total, 661 137 men and women were included in the analysis, and over a median follow-up of 14.2 years there were 116 686 deaths.
For individuals who exercised less than the recommended minimum but who still did something—those who expended 0.1 to <7.5 MET hours per week with moderate to vigorous physical activity—there was a 20% reduction in the risk of all-cause mortality. At the recommended minimum, which translates into 140 to 280 minutes of brisk walking or 45 to 90 minutes of running, there was a 31% reduction in all-cause risk. At two to three times the recommend minimum (15.0 to <22.5 MET hours per week, which is 280 to 420 minutes of walking or 90 to 135 minutes of running), there was a 37% reduction in mortality. Beyond three times the recommended minimum, there was a 39% reduction in mortality, a benefit that appeared to plateau at this volume of exercise.
"There is a slight additional benefit at these higher levels, but it really is quite incremental, suggesting that beyond even the recommend minimum the mortality benefit is probably not the reason one might want to exercise at those levels," Arem told heartwire .
Leisure-Time Physical Activity by Intensity and Mortality (HR [95% CI])
|Intensity of activity||No physical activity||0.1 to <7.5 MET h/wk||7.5 to <15.0 MET h/wk||15.0 to <30.0 MET h/wk||>30.0 MET h/wk|
|Moderate physical activity||1.00||0.80 (0.78–0.83)||0.73 (0.71–0.75)||0.71 (0.68–0.73)||0.72 (0.68–0.76)|
|Vigorous physical activity||1.00||0.80 (0.78–0.83)||0.77 (0.71–0.84)||0.78 (0.73–0.83)||0.79 (0.73–0.85)|
The researchers also stratified exercise by the type of physical activity recommended in the 2008 guidelines. For vigorous-intensity physical activity, any level of activity, even at volumes less than the weekly recommended minimum, there was an approximate 20% reduction in the risk of mortality. For moderate-intensity physical activity, the maximum benefit in terms of mortality reduction occurred at levels around the weekly recommended minimum, with little to be gained by going beyond that amount. To heartwire , Arem said these results suggest it's the volume of activity that makes a difference on mortality rather than the intensity.
Leisure-Time Physical Activity and Cause-Specific Mortality (HR [95% CI])
|Cause of death||No physical activity||0.1 to <7.5 MET h/wk||7.5 to <15.0 MET h/wk||15.0 to <22.5 MET h/wk||22.5 to <40.0 MET h/wk||40.0 to <75.0 MET h/wk||>75.0 MET h/wk|
|Cancer deaths||1.00||0.87 (0.83–0.90)||0.79 (0.75–0.82)||0.75 (0.72–0.79)||0.74 (0.71-0.77)||0.72 (0.66-0.79)||0.69 (0.55-0.87)|
|CVD deaths||1.00||0.80 (0.77–0.84)||0.67 (0.65–0.70)||0.59 (0.57–0.63)||0.58 (0.56–0.61)||0.61 (0.55–0.67)||0.71 (0.56–0.91)|
A second study, led by Dr Klaus Gebel (James Cook University, Townsville City, Australia), also showed there was a dose-response relationship between moderate to vigorous physical activity and mortality. In this study, which included 204 542 Australian adults aged 45 to 75 years old, the risk of all-cause mortality was reduced 34% among those who reported exercising moderately or vigorously for 10 to 149 minutes per week. For those who exercised 150 to 299 and 300 minutes or more per week, all-cause mortality was reduced 47% and 54%, respectively. However, unlike the NCI authors, Gebel and colleagues did observe a larger slightly larger reduction in all-cause mortality in men and women who did more vigorous physical activity (reported as a proportion of total exercise volume).
Nothing Works Quite Like Exercise
In an editorial, Dr Todd Manini (University of Florida, Gainesville) writes that there "is not a single medication treatment that can influence as many organ systems in a positive manner as can physical activity." Most important, the findings support the 2008 Physical Activity Guidelines and provide evidence of a dose-response relationship between exercise and mortality.
Of particular interest to Manini, however, is the reference group group used in the NCI Cohort Consortium analysis, noting that these 52 848 individuals did no exercise at all. This reference sample tended to be younger than 60 years of age, had higher rates of smoking and obesity, and had less than a college level of education. As the analysis suggests, getting these individuals active, even to a threshold less than the recommended minimum, would have a significant impact on mortality risk. "Practitioners have a unique opportunity to influence this reference group, since they are the most likely to receive benefit even with a small amount of physical activity," he writes.
Changing patient behavior is complex, influenced by environmental, social, and personal factors, but there is evidence to show that physicians can influence patient behavior, according to Manini. Still, just one-third of adults receive lifestyle counseling from health professionals, which is disappointing, he adds.
The study authors and editorialist report no relevant financial relationships.
Heartwire from Medscape © 2015
Cite this: Start Moving, Live Longer: Study Shows Physical Activity Lowers Mortality Risk - Medscape - Apr 09, 2015.