Adverse response to exercise

Dr. Claude Bouchard and colleagues from around the US and Finland tell us that people differ in their response to regular exercise.

Sometimes these differences contribute to adverse changes in cardiovascular and diabetes risk factors, according to this study.

First, the details.

• Variations in resting systolic blood pressure and in fasting HDL (good) cholesterol, triglycerides, and insulin were recorded.
• An adverse response to exercise was judged to be an increase of 10 mmHg or more for systolic blood pressure, 0.42 mmol/L or more for triglycerides, or 24 pmol/L or more for fasting insulin levels, or a decrease of 0.12 mmol/L or more for HDL-cholesterol.
• The findings come from those who completed: the HERITAGE Family Study; DREW, INFLAME, STRRIDE, a University of Maryland group, and from a University of Jyvaskyla study for a total of 1,687 men and women.

And, the results.

• Adverse responders included…
• 8% for insulin levels
• 12% for systolic blood pressure
• 10% for triglycerides
• 13% for HDL-cholesterol
• About 7% of participants experienced adverse responses in at least 2 risk factors.
• There was no evidence of differences between blacks and whites, or between men and women.

The bottom line?

The authors concluded, “Adverse responses to regular exercise in cardiovascular and diabetes risk factors occur. Identifying the predictors of such unwarranted responses and how to prevent them will provide the foundation for personalized exercise prescription.”

Some pundits are concerned that people will use these results as an excuse not to exercise. That’s probably a minor concern since people who don’t want to exercise don’t need much of an excuse.

Considering the widespread coverage this study has garnered, it’s main contribution for the “average Joe” is to raise awareness that differences in genetics play a role in these findings.

Earlier this year, Dr. Bouchard reported that differences in just 9 genes account for the inherited tendency to achieve a submaximal heart rate training response.

Dr. Bouchard has studied families, especially families with twins and reported that heredity (genotypes) affects different fitness components (phenotypes) in different ways. For example, two people of the same age and gender with similar lifestyles could vary in health-related fitness just because of the genes they inherited.

But heritability only accounts for differences when comparing 2 people who have not trained.

We knew, thanks to other research by Dr. Bouchard and colleagues, that people of different genetic backgrounds respond differently to training. In other words, 2 people of different genetic background could do the exact same exercise program and get quite different benefits. In fact, some people get as much as 10 times as much benefit from activity as others who do the same program.

6/1/12 20:35 JR