Is exercise bad for some people?

Genetic studies show that some people react differently to training than others.

More than 800 genes influence exercise performance. Studies conducted by renowned geneticist Claude Bouchard showed that between 8 and 13 percent of people experienced negative physical changes from exercise, which included increases in blood insulin levels and triglyceride levels, an increase in systolic blood pressure and reduced HDL cholesterol levels (the good cholesterol).

Eric Leifer of the National Heart, Lung and Blood Institute in Bethesda, Maryland, noted that Bouchard and colleagues did not make comparisons with people who did not exercise, so their studies did not have an adequate control group. In a study of 1,200 people and a control group, they found no evidence of subgroups of people who responded negatively to exercise. In addition, everyone has a different metabolism - and this is noticeable for some people when it comes to fat loss . While most people gain fat quickly when they eat excessive amounts of fatty and sugary foods, there are people who only gain weight slowly under similar conditions.

Exercise is healthy for most people, but not everyone reacts in the same way.

(Medicine & Science in Sports & Exercise, 48: 20 - 25, 2016)