Despite what you may have heard, exercise is good for the knees, concluded a study published this month in the scientific journal of the American College of Sports Medicine.
There have been studies -- with conflicting conclusions -- on the impact of exercise on the knee as a whole. But the study conducted by researchers at Monash University in Melbourne, Australia, is the first to examine the effects of physical activity on individual parts of the knee.
"As it turns out, exercise affects each part of the knee differently, which helps explain why there have been conflicting reports for so long," said Flavia Cicuttini, head of the musculoskeletal unit in the School of Public Health and Preventive Medicine at Monash University.
The study led by Donna Urquhart and Ms. Cicuttini examined data from 28 studies representing 9,737 participants from all over the world. The study found that while exercise is linked to osteophytes (bony spurs), exercise caused no harm to joint space (where cartilage is housed), and there were beneficial effects on cartilage integrity.
"These findings ... suggest that osteophytes, in the absence of cartilage damage, may be just a functional adaptation to mechanical stimuli," Ms. Urquhart said.
"There is really no evidence that exercise accelerates the development of osteoarthritis [a degenerative disease that attacks cartilage and affects nearly 27 million Americans]," said Dennis Phillips, an orthopedic surgeon at Allegheny General Hospital. "Exercise is good for the knees unless there is a previous injury to the knee."
Constance Chu, director of the cartilage restoration program in the Department of Orthopaedic Surgery at the University of Pittsburgh's School of Medicine, said she was delighted with the study because "with our population suffering from the effects of inactivity, these types of messages are critically important."
While exercise overall has positive effects on knees, your exercise program should be tailored to your individual condition, both your fitness level and the condition of your joints, she cautioned.
People who have suffered injuries to their joints, or who are overweight, need to be careful about the degree of loading they place on their knees, she said.
"The message would be to start slow but increase as the overall fitness level increases," Dr. Chu said.
People who are susceptible to twisting and stretching injuries of the knee would benefit from exercises and stretches that focus on the glutes, hips, quadriceps, hamstrings and calves, said Reggie Dulaney, a personal trainer at Panthro Fitness in Monroeville.
If you don't exercise, you could put your joints at greater risk of injury because the muscles supporting them will be weaker, Mr. Dulaney said.
Jack Kelly: firstname.lastname@example.org or 412-263-1476.