It’s common knowledge that the more physically fit you are the less likely you are to be affected by some diseases. A study published in The FASEB Journal of November of 2010 applies this concept to animals. It explains the difficulty in testing animals for the risk of getting a disease because, like humans, some are just less likely to get a disease. It is also difficult because this theory can be turned around, you can also say that some people are more susceptible to disease than normal due to no other reason than the fact that they are not as physically fit as the average member of the species.
A study was done to explore this concept further using rats. Very in-shape rats, called high-runners, were bred with high-runners and low-runners, not so in shape rats, were bred with low-runners. This was done until there were eleven generations; it was to hopefully make a distinct gap in the genes between the two groups of runners. It was conluded that the low-runners were at much more of a risk for disease. When analyzed, it became evident that there were seven specific functionally related groups of genes linking running traits with disease risk traits. This model can be applied to other species when determining risk of disease in future studies.