Why do some people get more fit than others? I have always wondered why some people get more fit than others while doing the same workout. Studies indicate that genetics must be involved because a high or low response to exercise tends to run in families. There are not enough answers to which genes might be involved, and how those genes increase or decrease the body’s response. There are studies being performed on rats. In the study, rats with a certain set of genes had a strong response to exercise, becoming much more fit after a few weeks of running. The rats born with other genes had a weaker response and had little cardiovascular benefit from the same workout. For the new rodent study, which was published in The Journal of the American College of Cardiology, scientists created two strains of rats that would or would not respond well to working out. The scientists had rats run for several weeks and they recorded how long it took the rats to get tired and whether they were adapting to the workouts. The males and females that had the most mileage were bred together and the rats who ran less were mated to one another. Seven generations of rats completed the same workout that were the same in speed and intensity for two months on tiny treadmills. The rats that responded well to running had increased the distance that they could run by about forty percent before getting tired. The rats that did not respond well to running lost about two percent of their endurance during the exercise.
Scientists then studied the hearts of rats and discovered that some rats strongly responded to exercises because the cells from their left ventricles showed structural changes associated with growth and strength. The rats that did not respond well to workouts had no increase in cardiovascular health and their left ventricles looked like animals that did not run. If hearts do not adapt to exercise, then workouts will not strengthen the bodies. When the scientists carefully evaluated gene expression in the rat’s heart cells, they found more than 360 genes that were functioning differently in the two groups of rats. Many of these genes are known to affect cell growth. Humans have the same genes in their heart cells, but scientists are not exactly sure if human genes respond in the same way as the genes of rats during exercise.
From this research, I learned that humans should closely monitor their body’s response to exercise. Not everyone will have the same degree or percentage of improvement. If an individual has been working out for months and does not see an improvement, then they should attempt a different workout routine such as weight training.