Wednesday, September 11, 2019

Death by Exercise

Sudden cardiac death – as in the college-age basketball player or the hyper-fit triathlon participant – tends to make the news. As it should. Newsworthy death while exercising provides every non-exerciser with rationale for not exercising. “See” they say, “this person was an avid runner [cyclist, swimmer] and dropped dead at 40.” The contrarian point being that the endurance sports that are supposed to protect against heart disease sometimes appear to do just the opposite.

There is a wisp of truth to this observation. Estimates are that just under one person per 100,000 participating in a marathon, or 1.5/100,000 participating in a triathlon will die during or immediately after the event. Figure a collective three million participants in these types of races and that comes to maybe 30 to 40 deaths per year. There are fuzzier estimates of perhaps one sudden death per every million exercise events for other forms of vigorous exercise. So, the true answer is yes, exercise can kill the physically fit, but no, not a risk factor worth avoiding exercise entirely.

Internet image portraying a man having a heart attack while exercising.
There is more truth in the observation that exertion by the physically unfit can result in fatal cardiovascular events. The classic case is the middle-aged office worker who drops dead shoveling snow while attempting to clear the driveway and get to work. Contributing factors include the fact that blood pressure peaks in the morning a few hours after waking up, and the fact that exertion in cold weather constricts arteries, further adding to heart stress. Snow removal related heart attacks frequently occur in women and men with no known pre-existing heart disease.

Exercise can also result in accidental death. In the U.S., walking, running, bicycling, swimming, boating and winter sports add up to about 10,000 deaths per year. Subtract half who are either children or are adults under the influence of alcohol (as in walking or riding a bike home from a bar, at night), and it’s still a big number. But the total pales compared to the 2,800,000 total deaths per year, of which many are premature cardiovascular deaths brought on by a lifetime of inactivity.

The good news is that benefits from even modest amounts of exercise are becoming clearer. The American Heart Association recommends adults get at least 150 minutes per week of moderate-intensity aerobic activity or 75 minutes per week of vigorous aerobic activity, but notes that even a few minutes per day was better than nothing! Studies have reported the greatest improvement for modest exercise compared to no exercise at all, and diminishing but still cumulative returns for progressively more exercise. A recent article in the Journal of the American Medical Association reported that endurance fitness was a better predictor of good cardiovascular biomarkers (cholesterol, etc.) than strength.

The theory that aside from injuries, over-doing exercise may cause more harm than good has been disproven. A science journal article reviewed studies of longevity of elite athletes. Athletes from endurance sports had 3-6 year longer life spans than the general population. The authors cautioned that elite athletes may by genetically different from the population as a whole, with both their abilities and lifespan being consequences of their genes rather than one causing the other. A review article encompassing 48 published studies confirmed that people doing as much as 7-14 hours per week of moderate to vigorous exercise were had a 15 percent lower mortality risk than those doing only 1-2 hours per week, with no hint that the benefit fades toward the high end.  

There is a non-fatal problem with exercise – it is potentially addictive. As one well-known fitness expert author put it, “…people reduce their lives to fitness routines, training as many as 40 hours a week. That the effort may wreck marriages and compromise immune systems isn’t even relevant. To these people – demographically a diverse lot – exercise is addictive. The more the body gets, the more it wants. In return, the drug of exercise infuses the swimmer, cyclist and runner with two powerful illusions: that he/she is escaping the horrible, and progressing toward the divine.”

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