Running has long been established as a physical activity with substantial health benefits. The World Health Organization and the U.S. government recently released the evidence-based Physical Activity Guidelines, recommending at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week, but it has remained unclear whether there are health benefits to leisure-time running, clocking in less than 75 minutes per week.

A study published July 28 in the Journal of the American College of Cardiology (JACC) led by Duck–chul Lee, PhD, Department of Kinesiology, Iowa State University, sought to learn if leisure-time running could be associated with all-cause mortality and cardiovascular risks, if there is a dose-response relation between running and mortality, and if different patterns of change in running behaviors are associated with mortality. The authors found that running for only a few minutes a day or at slow speeds may significantly reduce a person’s risk of mortality from cardiovascular disease compared to someone who does not run.

Drawing from 55,136 adults aged 18-100 (mean age, 44; 26 percent women) from the Aerobics Center Longitudinal Study, baseline running or jogging activity was assessed through a questionnaire featuring questions on duration, distance, frequency and speed. At a follow-up of 15 years, results showed that 3,413 all-cause and 1,217 cardiovascular deaths occurred within the population. In comparison with non-runners, runners had 30 percent and 45 percent lower risks of all-cause and cardiovascular mortality, respectively, after adjusting for potential confounders, with a three-year advantage in life-expectancy.

In dose-response analyses, runners across all quintiles of weekly running time had lower risks of all-cause and cardiovascular mortality compared with non-runners. Even running less than 51 minutes per week less (or under six miles, one to two times, under six mph) proved to be sufficient enough to reduce the risk of mortality compared with not running. Persistent runners over an approximately length of six years demonstrated the most significant mortality benefit with 29 percent and 50 percent lower risk of all-cause and cardiovascular mortality, respectively compared with non-runners.

"Since time is one of the strongest barriers to participate in physical activity, the study may motivate more people to start running and continue to run as an attainable health goal for mortality benefits," said Lee. "Running may be a better exercise option than more moderate intensity exercises for healthy but sedentary people since it produces similar, if not greater, mortality benefits in five to 10 minutes compared to the 15 to 20 minutes per day of moderate intensity activity that many find too time consuming."

Meanwhile, a separate study also published July 28 in JACC looked into the prevailing risk of heat stroke against the more widely debated and discussed arrhythmic death on long-distance endurance runners. Defined as having a core body temperature exceeding 104 to 105° Fahrenheit, heat stroke is associated with multi-organ dysfunction, and its initial symptoms often go unrecognized.

The retrospective study—led by Lior Yankelson, MD, PhD, Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Israel – looked at all long-distances races that took place in Tel Aviv between March 2007 and November 2012 and prospectively collected data for the 2013 races. Yankelson and his colleagues found that out of the 137,580 participant runners, there were only two serious cardiac events (one myocardial infarction and one hypotensive supraventricular tachyarrhythmia), neither of which were fatal or life threatening. Incidences of heat stroke however were much more significant, with 21 serious cases, including 12 that were life threatening and two that were fatal. Of the two fatalities one presented cardiac arrest without previous warning.

While the temperature of Tel Aviv may be warmer than in other locations, in a commenting editorial Brian Olshansky, MD, FACC, and David S. Cannom, MD, FACC, write that the study "highlights two distinct threats to participants in long-distance races: one of which is cardiac and the other is an emerging recognition of heat stroke as a cause of multi-organ failure and subsequent death. The best methodology to screen athletes for cardiac disease has been debated over 30 years since we realized that marathons do not secure cardiac immortality. On the other hand, heart stroke has no predictive clinical profile that a screening examination might uncover and can only be diagnosed at the onset of the episode." They note that having trained medical personnel available during the race and initiating treatment in the field can help eliminate any "potentially catastrophic events." They add that "by emphasizing the importance of recognizing heat stroke when it presents and outlining a plan of care, Yankelson and colleagues have made a valuable contribution to making long-distance running safer."

Keywords: Athletes, Myocardial Infarction, Stroke, Follow-Up Studies, Risk Factors, Running, Heart Arrest, Surveys and Questionnaires, Jogging, Tachycardia