Exercise is generally beneficial to long term health in many ways - though it's somewhat cruel that it's so beneficial for the suffers of conditions that make it hard to exercise: "physical activity improves arthritis symptoms even among obese mice that continue to chow down on a high-fat diet. The insight suggests that excess weight alone isn't what causes the aches and pains of osteoarthritis, despite the long-held notion that carrying extra pounds strains the joints and leads to the inflammatory condition. ... Many cases of arthritis are associated with obesity and inactivity, so [the] researchers set out to determine whether a high fat diet induces knee osteoarthritis, and then whether exercise provides a protective effect. Using two sets of male mice - half fed a high-fat diet and the other fed regular chow - the researchers noted significant differences among the two groups. The mice on the high-fat food gained weight rapidly, processed glucose poorly and had much higher blood levels of molecules that trigger the chronic inflammation associated with osteoarthritis. But when these animals got regular running wheel workouts, many of the harmful effects diminished - even though the mice ate the same high-fat food and shed no weight. Glucose tolerance improved, while the inflammatory response was disrupted among key signaling molecules called cytokines, easing the development of arthritis. If the extra weight on the joints had been the cause of the arthritis, the researchers noted, exercise would have exacerbated the problem. Instead, it helped. ... I don't want to say exercise is turning off that inflammatory signal, it just impairs it." The fat tissue accumulated by the obese is a trigger for inflammation via chemical signaling; weight on joints may not be aggravating arthritis, but the increase to levels of chronic inflammation will do just that. Better to be both exercising and shedding the excess fat than just one or the other.