Wednesday, July 30, 2014

Running

Cardiovascular

Run for Your Life? Right!

Published: Jul 29, 2014 | Updated: Jul 30, 2014
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Running for even 5 to 10 minutes a day, once or twice a week, or at slow speeds was associated with substantial mortality benefits over 15 years, a prospective study showed.
Runners overall had 30% and 45% lower adjusted risks of all-cause and cardiovascular disease mortality, respectively, over that period and had 3 years longer life expectancy compared with nonrunners, Duck-chul Lee, PhD, of Iowa State University in Ames, and colleagues found.
Running for less than 60 minutes a week -- averaging out to about 8 minutes a day -- was associated with an odds ratios of 0.73 for death from any cause (95% CI 0.61-0.86) and 0.46 for cardiovascular mortality (95% CI 0.33-0.65) compared with nonrunners after adjustment for other factors, including total physical activity from other leisure-time activities.
The associations were also significant at the lowest quintiles of weekly running distance (less than 6 miles), frequency (one to two times), amount (under 506 metabolic equivalent of task or MET-minutes), and speed (less than 6 miles/hour), the group reported in the August 5 issue of theJournal of the American College of Cardiology.
"This study may motivate healthy but sedentary individuals to begin and continue running for substantial and attainable mortality benefits," Lee and colleagues suggested.
Clinical Implications
The effect of “just doing something at slightly higher intensity” was profound, commentedBarry Franklin, PhD, director of preventive cardiology and cardiac rehabilitation in the Beaumont Health System in Royal Oak, Mich.
“A 30% to 40% reduction in mortality -- that’s huge. That’s equivalent to the same mortality reductions we get by taking a cholesterol-lowering statin or going on a beta-blocker or taking a statin,” he told MedPage Today.
The message that some is better than none is important given that 40% to 80% of the global population remains sedentary despite known health benefits of physical activity, Chi Pang Wen, MD, DrPH, of Taiwan's Institute of Population Health Sciences in Zhunan, and colleagues agreed in an accompanying editorial.
Running is clearly better than walking for the same amount of time in terms of mortality, although walking is probably safer and easier to sustain for those starting from zero, they noted.
About a quarter of long-term runners end up with some type of injury that prevents them from continuing, but that risk is much lower for those who do small amounts rather than endurance running, added Paul Thompson, MD, chief of cardiology and The Athletes’ Heart Program at the Hartford Hospital in Hartford, Conn.
“One of the things patients frequently say to me is that I’m too busy to get any exercise. Well, that’s true if you’re going to do something that takes a lot of time, like walking,” he toldMedPage Today. “The most important thing …  is just do it.”
Otherwise healthy patients expect and should get an "exercise prescription" at office visits, Wen's group argued.
"Although devising a customized exercise prescription for each patient may sound complicated, 15 minutes of brisk walking or 5 minutes of running is all it takes for most clinic patients," they wrote.
"A simple message, delivered with sincerity, needs to be repeated every time we encounter our patients. As doctors, we should 'walk the talk,' spending at least 15 min/day in dedicated exercise, while also advocating building a culture of physical activity around us. We do not need to be athletes to exercise -- it should be part of all of our daily routines."
Running Risks
Another study in the same JACC issue suggested that for people who do get involved in long-distance running, heat stroke was more of a serious problem than arrhythmic or other cardiac events during marathons and other foot races.
The retrospective analysis of all long-distance races in Tel Aviv from March 2007 through November 2013 with a total of 137,580 runners turned up only two serious cardiac events -- one heart attack and one hypotensive supraventricular tachyarrhythmia, neither deadly or life threatening.
In the same group, there were 21 serious cases of heat stroke, including two fatalities and 12 that were life threatening.
"Our results put in a different perspective the ongoing debate about the role of pre-participation electrocardiographic screening for the prevention of sudden death in athletes," Sami Viskin, MD, of Tel Aviv Medical Center and colleagues concluded.
The temperatures of Tel Aviv might not generalize broadly to other areas, but the lessons still apply, Brian Olshansky, MD, of the University of Iowa in Iowa City, and David Cannom, MD, of Good Samaritan Hospital in Los Angeles, and colleagues argued in another accompanying editorial in JACC.
"The first is that heat stroke is common in warm climates during long-distance running races, and the second is that heat stroke can be successfully treated if it is suspected in a runner who collapses," they wrote.
Heat stroke isn't like potentially fatal cardiac arrhythmias where there's a predictive clinical profile that screening could potentially uncover, the editorialists noted.
In Tel Aviv, race physicians and technicians were trained to diagnose and care for heat stroke and were prepared to take a rectal temperature in the field when a runner collapsed to determine cause.
"The emphasis on training the medical team to look for this problem seems to account for the high number of diagnosed cases and the high recovery rate," Olshansky and Cannom suggested. "Without an early, accurate diagnosis, the necessary aggressive treatment may not be delivered."
Running and Mortality
Lee's study looking for health benefits of running regardless of distance included 55,137 adults, ages 18 to 100 (mean 44), in the prospective, observational Aerobics Center Longitudinal Study who had been self-, employer-, or physician-referred for periodic preventive medical examinations at the Cooper Clinic in Dallas.
Among them, 24% reported running during the 3 months prior to the baseline questionnaire. About a third of the cohort had follow-up questionnaire responses available on running behaviors.
"Not running was almost as important as hypertension, accounting for 16% of all-cause and 25% of cardiovascular disease mortality," the researchers noted.
The dose-response analyses suggested that more running wasn't that much better than a little each week in terms of mortality risk.
"In fact, among runners (after nonrunners were excluded in the analyses), there were no significant differences in hazard ratios of all-cause and cardiovascular mortality across quintiles of weekly running time (all P values >0.10)," they pointed out.
Adjusted hazard ratios across those groups compared with nonrunners were:
  • For less than 60 min per week: 0.73 for all-cause mortality (95% CI 0.61-0.86) and 0.46 for cardiovascular mortality (95% CI 0.33-0.65)
  • For 60 to 119 min per week: 0.65 (95% CI 0.56-0.75) and 0.56 (95% CI 0.43-0.73)
  • For 120 to 179 min per week: 0.71 (95% CI 0.59-0.86) and 0.54 (95% CI 0.38-0.77)
  • For 180 min or more per week: 0.76 (95% CI 0.63-0.92) and 0.65 (95% CI 0.46-0.92)
Some studies have suggested somewhat less or no mortality benefit at high doses of vigorous intensity physical activity, the researchers pointed out.
"Thus, future studies are needed on this dose-response issue about whether there is an optimum upper limit of vigorous-intensity activities, beyond which additional activity provides no further mortality benefits," Lee's group cautioned.
Excluding the 39% of runners who also reported other physical activities left all the associations significant, as did adjustment for possible mediating variables, such as body mass index and medical conditions.
The 13% of runners who stuck with it over an average 5.9 years appeared to have gained the most, with a 29% reduced all-cause mortality risk and 50% lower cardiovascular mortality.
One limitation was that the Cooper Clinic cohort was largely a white, upper to upper-middle class population, Franklin cautioned.
“I’m not sure that these data can be generalized to the population at large,” he told MedPage Today.
Thompson also questioned the ability of the study to entirely adjust for the differences in characteristics between runners and nonrunners.
While the study couldn't draw causal association, the editorialists noted the consistent results across sensitivity analyses, and consistency with findings from prospective randomized trials in secondary cardiovascular prevention.
"The reality is that a virtuous cycle exists for an iterative process of incremental exercise promoting incremental health, and the healthier individuals in turn being more likely to exercise, blurring the simple cause-and-effect relationship," Wen's group wrote.
UPDATE: This article, originally published July 29, 2014, at 2 p.m., was updated with new material (July 29, 2014, at 4:40 p.m.).
The study by Lee's group was supported by the NIH and an unrestricted research grant from the Coca-Cola Company.
Lee disclosed no relevant relationships with industry.
Viskin disclosed no relevant relationships with industry.
The editorial by Wen's group was supported in part by the Taiwan Department of Health Clinical Trial and Research Center of Excellence and by the MJ Health Management Institution.
The editorialists disclosed no relevant relationships with industry.
Olshanksy disclosed relationships with Medtronic, Boston Scientific, Amarin, Boehringer Ingelheim, Daiichi Sankyo, sanofi-aventis, and BioControl.
Cannom disclosed no relevant relationships with industry.
Franklin and Thompson disclosed no relevant relationships with industry.
From the American Heart Association:

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