'Adaptation to exercise' is a familiar phenomenon, even if the phrase is not: A sedentary person takes up jogging and can barely make it around the block.
After jogging regularly for a few weeks, the person can jog a mile, then two, then three. With regular exercise, the body adapts, becoming fitter and more efficient. The heart can pump more blood, delivering more oxygen to the muscles. The muscles get stronger, and so on.
There are individual differences in the ability to adapt to exercise. Some sedentary individuals who take up jogging will be able to run three miles after a short training period, while others will take much longer to get to the same level. What accounts for this difference in a person's ability to adapt to exercise? One important factor is our genes.
Research into the role genes play in exercise has been gaining steam over the past few decades and is the topic of a symposium at the Experimental Biology conference in New Orleans on April 20. Mark Olfert of the University of California at San Diego and Claude Bouchard of the Pennington Biomedical Research Center have organized the symposium, the Genetics of the Adaptation to Exercise. The American Physiological Society is sponsoring the symposium.
Speakers at the symposium will include Eric Hoffman of the Children's National Medical Center, Washington, D.C. and Tuomo Rankinen of the Pennington Biomedical Research Center. Dr. Hoffman will discuss Genetics and skeletal muscle adaptation to exercise, while Dr. Rankinen will talk on Genetics and the response to exercise in human populations. The symposium will also include presentation of selected abstracts.
Focus on individual genes
So far, scientists have identified about 200 genes that play a role in the body's ability to adapt to exercise. Although the research includes the term 'exercise' this work extends well beyond athletic performance. For example, it will lead to greater knowledge of how the muscles work, and to understanding muscle diseases such as muscular dystrophy.
Some of the research into the genetics of exercise has focused on individual genes. Dr. Olfert has looked at thrombospondin, a gene that limits the growth of small blood vessels, known as capillaries, in the muscles. Removing the gene allows greater capillary growth. The more capillaries in the muscle, the more oxygen the muscle will have available during exercise.
In one study, Olfert compared sedentary mice that did not have the thrombospondin gene in their skeletal muscle to mice that did have the gene. He found the mice without the thrombospondin, as expected, could exercise at a much greater capacity compared to the normal sedentary mice with the gene. What's more, the mice without thrombospondin could exercise at almost the same level as the mice with thrombospondin that exercised regularly.
Multi-gene approach
While this research is exciting, it has its limitations, Dr. Olfert said. Many genes play a role in exercise adaptation, most of these genes probably have a minor effect, and the way these genes work and interact with each other is quite complicated.