Fitness Genetics: All Pain, No Gain?
by Nitin KapaiDo you really think that getting up each morning at 5’o clock and going for that strenuous morning run and a nice workout at the gym is gonna give you that great look you’ve always wanted? You do, don’t you? Well here’s something to burst your bubble: researcher Claude Bouchard of Laval University in Quebec, Canada, proved that everyone’s fitness is largely dependent on the genes that they possess. So even though you may exercise loads and loads, unless your family has a history of producing fit people, chances are that your fitness will be hampered and not develop in proportion to your work out.
Researcher Bouchard and his colleagues started their work by focusing on maximum amount of oxygen absorbed by the body from a lungful of air- a standard measure of aerobic fitness. They found that most people could get more oxygen out of each breath after exercise and training but that the minority was no better off, regardless of how efficient their lungs were at the start. Because the variation was much less extreme than was expected, research concluded that genes largely dictated the effect.
Mr. Bouchard later extended this work in 1992 by helping to set up a multicentre research effort called HERITAGE family study, which is still running today. It is now based, together with Mr. Bouchard, at the Pennington Biomedical Research Centre at Louisiana. The study’s main data comes from some 740 adults who were subjected to an intense exercise regime in the lab. The study’s main aim was to determine how exercise reduces risk factors for cardiovascular disease and diabetes, but the researchers also took blood samples for genetic analysis. The results so far confirm Mr. Bouchard’s earlier studies. The average increase in aerobic fitness after training programme was 19%. But 5% of the subjects had virtually no change and another 5% had improved by more than twice the average amount. Similarly, most people had lower exercising heart rates and blood pressure after training programme - an indication of improved fitness - but the extent of reduction was extremely variable. Much of the variability seems to be attributable to genes. The research concluded that at least a portion of a person’s ability to benefit from exercise is inherited.
Conventionally it is believed that regular exercise reduces risk of heart diseases by raising blood levels of high density lipoprotein (HDL) cholesterol, a complex that helps prevent from forming fatty deposits on blood vessel walls. But HERITAGE data shows that the training does not inevitably increase levels of HDL cholesterol. In fact, in about one third of exercisers, the level of complex fell.
Does this mean that exercise could actually harm us and be bad for those of us with the ‘wrong genes’? No. The researchers believe that everybody improves on some score. Even those who could not raise their aerobic fitness through exercise were still getting some benefits such as higher HDL cholesterol levels.
Scientists at HERITAGE are scanning the genomes of participants for gene variants that occur more frequently in association with different fitness responses. Although some metabolism genes have been identified that may play a role, the most strongly linked gene is “Titin”. This produces protein fibres that contribute to the elasticity of heart muscle cells. It may be that some forms of the gene allow heart to pump larger volumes of blood than others.
Could ‘Fitness Genetics’ become the new excuse for couch potatoes? Well, that is yet to be seen but for those of us who believe in exercise, there is still some hope as for everyone, it seems, there is at least some benefit.
April 2006, Jeev
http://www.dce.edu/jeev
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