Exercise has been shown to activate hundreds of genes, and differences in their activation may partly explain differences in athletic ability.

James Timmons and Carl Sundberg of the Karolinska Institutet in Stockholm have shown that regular cycle training affects about 500 genes in thigh muscles.

Their findings suggest that differences in training responses are due to differences in people’s ability to activate genes more forcefully.

The study, which involved healthy young men in regular cycle training for six weeks, showed that participants who improved their performance most also had markedly greater activation of several genes in muscles.

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