Does Running Harm Your Knees and Is It Safe to Start at Any Age?

Many people believe that running can damage the knees and lead to long-term joint problems. However, current scientific evidence suggests that running, when done correctly, may actually promote knee health rather than harm it. Running is a high-impact activity where each stride causes your body to absorb forces estimated at two to three times your body weight, primarily impacting your knees. Despite this, the impact is not necessarily detrimental. In fact, running stimulates the growth and maintenance of knee cartilage, which is a living tissue that adapts positively to loading.

Our bodies are designed for movement, and the cartilage within the knee joint plays a crucial role in cushioning bones. Proper load-bearing activities like running help keep cartilage and bones strong. When the load on joints is reduced, such as with bed rest or immobilization, deterioration can occur, emphasizing the importance of regular movement.

Research indicates that running induces temporary decreases in knee cartilage thickness, which normalizes within hours post-exercise. This cyclical process may facilitate nutrient exchange within the cartilage, promoting its health and resilience. Runners tend to have thicker knee cartilage and higher bone mineral density than non-runners, which may protect against osteoarthritis—though more research is necessary to confirm this benefit.

Regarding age, starting to run later in life appears to be safe and beneficial. Studies with older adults engaging in high-intensity jump training show improvements in strength and function, implying that initiating running can be safe and effective at older ages if approached gradually. Beginners should start slowly, incorporating walking and short jogging intervals to allow muscles and joints to adapt.

While running is highly beneficial, it does carry a risk of injury. Nearly half of runners experience some injury each year, largely due to overuse. Proper progression, adequate nutrition, and choosing softer surfaces like grass can mitigate these risks. Overall, with mindful progression and listening to your body, running can be a safe and effective activity for people of all ages, contributing to overall health and well-being.