Is too much a good thing?
Exercise
Born to Run...but not too far!
What do you mean, don’t run to far?
“Born to Run” by Christopher McDougal is a story about a tribe of native peoples of Mexico who run everywhere. The book highlights an American who had gone to live with the tribes and adopt their long distance running lifestyle. The sequel that should be written is that this American man died suddenly while on a jog in the New Mexico desert and his autopsy showed an enlarged heart with areas of inflammation leading to a fatal abnormal heart rhythm while running.
But running is huge! There’s even magazines dedicated to running.
Running has taken off in the United States thanks to people like Jim Fixx (who interestingly also died while running–though in his defense, he did have bad genes). In 2013, almost 20 million people completed running events. Marathon completions numbered over 500,000 in 2012.
Don’t you run Dr. Lughead?
My apologies to Chris and the editors of Runners World, but I wish I had never jogged so much when I was younger. Two marathons (Best time was 3:05:42 thank you very much) and after thousands of miles, I threw away my running shoes at the age of 25 because my knees would kill me after a run. One of my favorite quotes is from an man named Gordon Hinckley who was asked by Larry King if he attended a lot of funerals at his age. Hinckley quipped, “Yes, all my friends who jog.”
Don’t get me wrong. I’m not opposed to running. I would just love to see more emphasis on bumper stickers that read 2.62 instead of 26.2.
I’m kind of getting excited. You’re going to tell me I shouldn’t exercise at all right?
Not exactly. What I’m hoping you’d ask is does exercise prevent heart disease? If so, how much do I need to do? Can I do too much exercise? The answer starts with the double decker British bus.
In 1958, autopsies on British bus drivers and conductors showed more clogged arteries in drivers
Does exercise really prevent heart disease?
What’s the data on exercise and life expectancy?
Like many things, we really haven’t proven that exercise prevents heart disease or strokes. But the observational evidence that it does is pretty overwhelming. I’ll highlight one of many observational studies. In 1986 the Harvard Alumni Study evaluated the exercise habits of thousands of their graduates. The observation was made that the more activity in a week, the longer the life expectancy by several years.
I love exercise, I could sit and watch it for hours.
What about sitting? Sitting >11 hours a day is associated with a higher incidence of death than those who sit less. It is also estimated that physical inactivity led to the deaths of 5.3 million in 2008.
So how much exercise should I do prevent heart disease?
A phenomenal observational study from Taiwan was done to answer two questions: 1). What effect does exercise have on life expectancy? 2). How much exercise do you need to increase life expectancy? They surveyed 416,175 people and asked them about their exercise habits over a 13 year period.
Exercise intensity was defined as light (walking), moderate (brisk walking), medium vigorous (jogging), or high vigorous (running). Exercise time per week was measured.
So what did they find? Does exercise prevent death?
Before we get to the nitty gritty, they made an important observation. The incidence of death, heart disease, cancer and diabetes were lowest in the groups that exercised the most (most time and highest intensity).
I’m so glad you haven’t shown me a graph yet.
The graph below represents the % reduction in death for vigorous (blue line) and moderate (green line) intensity exercise per number of minutes exercised in a week.
Here’s what the graph says to me: 1). Benefits of exercise are noted at even 15 minutes of moderate activity a day. 2). The more moderate activity one does, the more the benefit. 3). Vigorous exercise reduces death more than moderate exercise, though both intensity of exercise lowers the death rate. This last point is very IMPORTANT: 4). There was no further benefit after about 40 minutes of vigorous activity a day in preventing death–in fact the curve plateaued.
I lost you at “graph,” just tell me what it means.
They concluded from their study that men and women lived 4.2 and 3.6 years longer, respectively, if they averaged 150 minutes of exercise a week.
How much is too much?
Can I exercise too much? Please say that too much is more than 5 minutes a day.
WARNING: This is fairly controversial and I’ve watched smart people argue from both sides. The bottom line to me is that in order to get the most benefit from exercise there is no need to do more than 40 minutes of vigorous activity a day. I’ll highlight a few of the studies.
Forty minutes!!! That’s way more than 5. Is there a “right” amount of activity?
In the Copenhagen City Heart Study, runners had a survival advantage over non-runners by 6.2 years in men and 5.6 years in women. Interestingly, the sweet spot for running at preventing death was 2.5 hours/week, 3 times/week at an “average” pace. A higher death rate was noted in people who ran at a fast pace, >4 hours/week and >3 times/week. Granted there were not many people who did that.
Another study showed the sweet spot for preventing heart disease to be 6-12 miles week, 3 times/week, at a pace of 8 1/2 minute miles. An increase in heart death was seen in those who did >13 miles/week, and >5 times/week.
Any other studies show the “right” amount of exercise?
A third study in the US and UK of over 600,000 people showed the sweet spot of exercise to be walking 6-10 hours/week or jogging 4-6.5 hours/week. A higher death rate again was seen at the extreme. The Million Woman Study showed a higher rate of coronary disease, strokes, and leg blood clots in women who did daily strenuous exercise.
What type of exercises are moderate and vigorous activity?
Moderate activity is brisk walking, bicycling <10 mph, doubles tennis, ballroom dancing, water aerobics, gardening, and housework.
Vigorous activity is jogging, swimming laps, singles tennis, disco dancing, bicycling >10mph, or walking uphill (Disco dancing? Does anybody still do that anymore?).
In the end, most people’s problem is not that they exercise too much, but that they exercise too little. Realize that you don’t have to run marathons to get the benefits of exercise.
In Summary
The ideal amount of exercise is:
3-4 times week
30-40 minutes
vigorous activity
There does not appear to be much more heart protective benefit beyond 40 minutes of daily vigorous exercise to prevent heart disease. Even 15 minutes a day will help.