It is accepted that exercise lowers your risk of cardiovascular events. The question that is being asked currently is how much exercise gives you the best outcome? Is there a level of physical activity where the benefits drop off? Emerging research is suggesting that there may be a point where high intensity participation in physical activity can increase your risk of a cardiovascular event.
Physical exercise guides such as the 2008 Physical Activity Guidelines for Americans and the Canadian Physical Activity Guideline agree that to achieve health benefits, adults 18-64 years should
- accumulate 150 minutes of moderate to vigorous intensity exercises per week,
- include muscle and bone building activities twice per week, and
- more physical activity provides greater benefits.
One of the leading predictors of a cardiovascular event is the presence of plaque in the arteries, independent of any other risk factor, or type of plaque. In other words, the more plaque you have the bigger a chance of having a heart attack.
The current belief is that regular physical activity lowers the risk of having heart disease or a cardiovascular event. The question is how much exercise is beneficial? Is there an upper limit where too much exercise is detrimental?
The results of new research published in Circulation suggests that there may be a cautionary level where high levels of exercise may increase your risk.
In this study, 284 middle age men (average age 55), who were engaged in competitive or recreational leisure sports were scanned to assess coronary artery calcification (CAC) and plaque characteristics. Participants reported their lifelong exercise history patterns. Participants were categorized as moderate, medium or high levels of activity. For easy comparison, the moderate group accumulated the 150 minutes per week of exercise, while the high group achieved over 300 minutes of exercise per week.
The results were surprising. It was found that the high activity group had about 25% MORE CAC and plaque than the low group! Specifically, the high group had 68% CAC prevalence versus the low group at 43%. The high group showed 77% plaque occurrence compared to the low group at 56%.
These results bring into question the advice that doing more exercise will provide greater benefit. In fact, these data suggest it may increase your cardiac risk because of plaque accumulation. Doing more exercise may not be better. Moderate activity may be providing the optimal benefit.