How Much, How Hard, How Often: Exercise Study Shows Weekend Warriors Also See Cuts in CVD Death
The best intensity, duration, and frequency of physical activity for preventing cardiovascular and other diseases may embrace multiple options.
Doing a certain amount of physical exercise at a certain level is associated with reduced risk of dying of cardiovascular disease, but does it matter what you do and when you do it? Not so much, according to a large observational study investigating the link between physical activity and subsequent death based on whether subjects were active multiple days per week or were so-called weekend warriors who cram their requisite exercise into just one or two intense sessions.
In fact, all of the levels of exercise duration, frequency, and intensity that were studied conferred benefits in terms of reduced all-cause, cardiovascular, and cancer mortality.
“I would say to those who are already weekend warriors to keep up the good work,” lead author on the study, Gary O’Donovan, MD (National Centre for Sport and Exercise Medicine–East Midlands, Loughborough, England), told TCTMD. “And I would say to those who have read our study and are inspired to become more active, that they should start. If they are middle-aged or older individuals they should start with moderate activity like brisk walking, that they should set themselves realistic goals that provide motivation and build confidence and that they should add or consider some vigorous activity after about 12 weeks to gain additional health benefits.”
The study was published earlier this week in JAMA Internal Medicine.
Recommendations from both the World Health Organization and the American Heart Association specify that adults between the ages of 18 and 64 do at least 150 minutes of moderate-intensity activity or at least 75 minutes of vigorous activity per week. But as O’Donovan and colleagues point out in their paper, there is little research clarifying whether frequency, duration, and intensity have different effects on health. Weekend warriors, they point out, tend to get all of their recommended exercise in just one or two high intensity work outs per week, while others try to keep active but fall short of the recommended minutes or intensity.
The study drew on health survey data gathered in England and Scotland over a 12-year period, with an additional 8 years of follow-up. In all, more than 63,500 people participated in the survey. Levels of self-reported physical activity were grouped in four categories:
- Inactive (no moderate or vigorous activity; 62.8% of the cohort)
- Insufficiently active (less than the recommended moderate or vigorous minutes per week; 22.4%)
- Regularly active (performing at least the minimum recommended minutes/level of activity per week across three or more sessions; 11.7%)
- Weekend warrior (performing at least the minimum recommended minutes/level of activity per week in just one or two sessions; 3.7%)
Using outcomes in the inactive group as the comparator, O’Donovan and colleagues found that the hazard ratios for all-cause mortality, cardiovascular disease mortality, and cancer mortality were surprisingly similar in the insufficiently active, regularly active, and weekend warrior groups. For cardiovascular mortality specifically, all three categories of physical activity were associated with a significant 40% reduction in death for all groups over the follow-up period.
One of the “most striking findings” the group writes, “is that just one or two sessions per week of moderate- or vigorous-intensity leisure time physical activity was sufficient to reduce all-cause, CVD, and cancer mortality risks regardless of adherence to prevailing physical activity guidelines.”
Guidelines, Take Note
To TCTMD, O’Donovan pointed out that existing physical activity guidelines are evidence based, but added that other recent studies—this one included—have started to show that less than the recommended levels of physical activity may also be beneficial. Also, frequency or duration may be more flexible than originally thought.
“There’s good reason to think it would be advantageous to be active more often,” O’Donovan observed. “Every sustained bout of aerobic activity is going to improve your cholesterol metabolism, lower your blood pressure, and improve your glucose metabolism for a day or two. So it is quite surprising what we found in terms of mortality benefits [for less regular activity].”
Insights from the current paper and others should be incorporated into subsequent guidelines, O’Donovan said, with the caveat that as with so many other areas of medicine, it appears exercise recommendations may need to be tailored to individuals and their circumstances in order to yield the most benefit.
“Not so long ago—10, 15 years ago—we did have the one-size-fits-all approach across the world,” he continued. “The idea that everyone should do 30 minutes of brisk walking 5 days week. That was it. Which left some people . . . completely disillusioned and wondering if they weren’t actually doing enough.”
On the contrary, O’Donovan said his message to weekend warriors would be that they are doing just as well if not better than the regular moderate exercisers, because they are typically doing more vigorous levels of activity and therefore likely have better cardiorespiratory fitness. “And as your readers will know, cardiorespiratory fitness is one of the strongest predictors of mortality,” with a number of studies suggesting it is an even stronger predictor than physical activity, he noted.
More Realistic Targets
Commenting on the study for TCTMD, Cara Hendry, MD (Manchester Heart Centre, England), pointed out that the data offer new insight into “exercise groups which have been formerly thought not to benefit from a mortality viewpoint,” namely the insufficiently active and weekend warriors, both of whom, along with the regularly active, saw reduced mortality from cardiovascular causes and from cancer in this study.
“This could potentially represent confounding from other complex social or economic reasons, but the authors have tried to correct for this, and nonetheless all grades of exercise seem to benefit in terms of mortality,” she told TCTMD. “More work is needed to explore this relationship, but for now, the conscience of the weekend warriors can take comfort from the fact that some exercise is better than none from a mortality viewpoint. Potentially this may lead to softening of exercise recommendations, which many feel are not achievable.”
A final point, said Hendry, is that a full two-thirds of the people in O’Donovan et al’s study described themselves as inactive—none would enjoy the mortality benefit seen in the other three groups. “Perhaps giving these people more realistic targets would encourage them to do something from a physical viewpoint and enable them to benefit,” she said.
- O’Donovan G, Lee IM, Hamer M, et al. Association of “weekend warrior” and other leisure time physical activity patterns with risks for all-cause, cardiovascular disease, and cancer mortality. JAMA Int Med. 2017;Epub ahead of print.
- O’Donovan et al as well as Hendry report having no relevant conflicts of interest.