Exercise: If some is good, is more always better?
The benefits of regular exercise are indisputable. Furthermore, something is better than nothing. If you exercise even five minutes a week, it’s better than zero and ten minutes is better than five. Yet, if some exercise is good for our health, is more always better?
Physical Activity Guidelines
Physical activity is key to improving health. Based on the latest science, the current Physical Activity Guidelines for Americans are that adults should engage in a minimum of 150 minutes of moderate- or 75 minutes per week of vigorous-intensity aerobic activity. Additionally, muscle-strengthening exercises at least twice per week are also recommended. For additional benefits, adults should do 300 minutes of moderate- or 150 minutes per week of vigorous-aerobic activity and more is better.
More?
If you’re like me, you are thinking, “Whoa. More? If more is better, does that mean 24 hours per day is best?”
The short answer is no. More exercise is not always better. As with most things, there can be too much of a good thing.
How much is too much?
Since there are individual differences between people, this means that too much exercise for one person may not be too much for another person. So, it is very difficult to say with certainty that “X” amount of exercise is too much. However, recent research presents averages from recreational exercisers and ultra-endurance runners that can be used as a general guide for most people.
Where to Draw the Line
In the last 10 years, there has been a growing number of runners who compete in ultra-endurance events. Ultra-endurance races are longer than a marathon (>26.2 mi) and typically range from 31 to 160 miles, but some continue even farther.
A review published just last year, discussed several recent studies that examined ultra-endurance runners and their relationship with arterial stiffness, a risk factor for cardiovascular disease. Several studies have used a case-control comparison design to compare long-term ultra-marathon runners and an age matched group of recreationally active peers. The results showed an inverted-U relationship between physical activity and risk of arterial stiffness.
The following figure represents the relationship, such that risk for arterial stiffness decreases as a person becomes physically active and endurance-trained. However, when a person does an excessive amount of activity, risk for arterial stiffness is increasingly higher.
How much activity constitutes ultra-endurance training?
The ultra-endurance runners in the reviewed research ran an average of >55 miles per week for more than five years. Furthermore, as participant’s weekly mileage increased above 55 miles their associated risk for arterial stiffness became greater. Physiologists speculate that the increased arterial stiffness is a protective mechanism during training that may be maladaptive to general heart health.
Summary
In this article, I only discussed the harm of excessive exercise on cardiovascular health. It is important to note that excessive exercise can also lead to musculoskeletal injuries and psychological burnout. With that said, over-exercising is generally not a problem for Americans. Most Americans (<23%) don’t engage in even the minimum amount of recommended aerobic and strengthening activities.
This is why the current physical activity guidelines focus primarily on increasing exercise. None-the-less, it is important to take a step back on occasion and remember that just because some exercise is good, doesn’t mean more is always better. Exercise is a part of a healthy life-style, as is keeping a balance between each dimension of our wellness.
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References:
Veiga Sardeli, A., & Traina Chacon-Mikahil, M. P. (2016). Is The Exercise-Induced Increase in Central Arterial Stiffness a Risk Factor for Health? J Arch Mil Med. 4. doi: 10.5812/jamm.36833.
Burr, J.F., Drury, C.T., Phillips, A.A., Ivey, A., Ku, J., Warburton, & D.E. (2014). Long-term ultra-marathon running and arterial compliance. J Sci Med Sport. 7(3):322–5. doi: 10.1016/j.jsams.2013.04.018.
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