A study published in the Journal of Clinical Epidemiology reported overweight persons have a six-times higher chance of developing arthritis in their knees than those with a normal body mass index (BMI), and the clinically obese are eight times more likely to develop arthritis. Researchers from the University of Ulm in Germany found the connection between obesity and osteoarthritis to be the result of the strain of excessive body weight upon the knees through mechanical actions rather than a metabolic link. Researchers studied 809 patients under the age of 75 who had undergone either knee or hip replacement due to osteoarthritis.

High-intensity exercise in which the knees are directly affected also may lead to the development of osteoarthritis, as well as damage to knee cartilage. The study, conducted by Pennsylvania State University, raises questions about heavy-load athletic training but does not discourage any particular activities, as the research was not exercise specific.