Knee osteoarthritis (OA) is a prevalent condition, especially among aging populations. It causes joint pain, swelling, and reduced mobility, often leading to knee replacement surgery. With around 790,000 knee replacements performed annually in the United States, addressing the root causes of knee OA is essential. New research now highlights the role of lower-limb muscle strength in preventing or slowing the progression of this condition.

Understanding Knee Osteoarthritis

Osteoarthritis is a degenerative joint disease marked by the breakdown of cartilage. According to an August 2023 study in Experimental and Therapeutic Medicine, knee OA has a high impact on morbidity and disability rates. Risk factors include:

• Age and Gender: Older adults, particularly women, are more prone to OA.
• Weight: Excess weight puts additional stress on knee joints.
• Sports Participation: High-impact activities like soccer, tennis, and long-distance running can increase the risk.
• Genetics and Past Injuries: Family history and previous knee injuries also contribute.

The Role of Muscle Mass in Knee Health

A groundbreaking study published in April in JAMA Network Open found that muscle mass plays a protective role against knee OA. Researchers performed a meta-analysis involving over 5,000 participants in the Netherlands. They discovered a key distinction:

• Weight-Bearing Activities and OA Risk: Activities like walking and running increased OA risk in individuals with lower muscle mass.
• Muscle Mass as a Protector: Participants with stronger lower-limb muscles were shielded from the increased OA risk associated with weight-bearing activities.

“Larger muscle mass cushions the knee joint from mechanical stress,” explained Dr. Joyce van Meurs, a study coauthor and professor at Erasmus Medical Center. This finding reinforces the long-held belief that muscle mass supports joint health.

Implications for Exercise and Sports Participation

The study’s findings offer new insights but also raise questions:

• Weight’s Impact on OA Risk: High body mass index (BMI) is a major risk factor for knee OA. Since the study participants had an average BMI of 26 (slightly overweight but lower than the U.S. average), further research is needed to understand if these findings apply to individuals with higher BMIs.
• Personalized Recommendations: Ongoing research at Erasmus Medical Center aims to tailor exercise and lifestyle recommendations based on individual factors like weight, muscle mass, and joint movement.

How to Build Stronger Knees Safely

To protect your knees and reduce the risk of OA, follow these expert tips:

1. Strengthen Your Leg Muscles
   Before engaging in weight-bearing activities, focus on strength training. Exercises like squats, lunges, or leg presses can help build muscle mass around your knees.
2. Start Slowly with New Activities
   Ease into high-impact sports like running. Allow your muscles, tendons, and joints time to adapt to the new stresses.
3. Maintain a Healthy Weight
   Excess weight increases joint stress. Losing even a small amount of weight can reduce knee strain and improve joint health.
4. Keep Moving
   Avoid a sedentary lifestyle, as inactivity weakens muscles and joints. Low-impact exercises like swimming, cycling, or walking can be excellent options.
5. Manage Pain Wisely
   Listen to your body. Mild discomfort during activity is normal, but persistent or worsening pain suggests you may need to modify your routine.

The Bottom Line

Strengthening lower-limb muscles isn’t just about improving physical fitness—it’s about protecting your knees and enhancing overall joint health. Whether you’re trying to prevent knee osteoarthritis or manage its symptoms, regular exercise, weight management, and gradual progression in physical activities can make a significant difference.

So, lace up your shoes, hit the gym, or simply take a walk. Stronger legs lead to healthier knees, keeping you active and mobile for years to come.