While, further research is required, a new study by radiologists says middle-aged men and women who indulge in excessive exercising, most particularly in high impact activities like running and jumping, are without knowing it are damaging their knees and raising the risk of developing osteoarthritis. This means, the study findings imply low impact activities like swimming and cycling are far better, since they may protect damaged or healthy joints.

According to US Centres for Disease Control and Prevention (CDC) estimates, over 27-million Americans suffer from osteoarthritis, the most common form of arthritis. A degenerative disease, it affects the joints, causing pain, swelling and stiffness in them.

There are three features to it, such as, damage to the strong, smooth lining that enables joints to move without friction i.e. the cartilage, or bony growths around joint edges, or mild inflammation (synovitis) of tissue surrounding the affected joint.

For the study, researchers analysed the data of normal weight 100-men and 136-women aged 45 to 55, none of whom had reported experiencing knee pain before enrolling in the National Institutes of Health Osteoarthritis Initiative (OAI incidence cohort). Study participants were categorized as low, middle and high activity, based on their responses to a questionnaire for assessing their physical activity.

A middle-aged person who spent several hours walking every week, or played sport including doing other exercises, yard work, heavy gardening and household chores was rated as a high activity individual.

MRI images of the participants were analysed for assessing severity of damage to any cartilage, meniscal or ligaments, as well as, for other abnormalities in the right knee.

The results indicated:
• 47% had meniscal lesions.
• 74.6% participants had cartilage lesions.
• 40.3% had bone marrow edema.
• 17% ligament lesions.
• Abnormality incidences went up in line with activity level i.e. low, medium, high.
• Grading of cartilage lesions also went up with activity level.
• Other knee abnormalities were also significantly linked to cartilage defects.
• Abnormalities were linked solely with activity levels and not age or gender.

In conclusion, the researchers said, some activities carry a greater risk of knee damage over time, with high-impact, weight-bearing physical activity like running and jumping extremely harmful for cartilage health. In implication, what the researchers are saying is that low-impact activities, such as, swimming and cycling protect diseased cartilage, including preventing healthy cartilage from becoming diseased.