For years, runners have been warned that the sport wreaks havoc on their knees. Each foot strike generates forces two to three times bodyweight, and the knee joint absorbs three times more load than it does during walking. Yet scientists say this is not only harmless, but potentially beneficial.
The knee is a dynamic structure that adapts to stress. Cartilage temporarily thins during a run but returns to normal within hours, and research suggests this process helps transport nutrients into the tissue. Runners tend to have thicker knee cartilage and better bone density than non-runners, with some evidence pointing to a lower risk of osteoarthritis.
What about those who take up running later in life? While no strong studies have examined this directly, a 2020 trial found that adults aged 65 and over who began high-impact plyometric training improved their strength and function safely. Since that training imposes greater joint loads than running, it suggests starting to run in later years is likely to be both safe and effective.
The key is gradual progression. Muscles and joints need time to adapt, so experts recommend alternating walking and jogging at first, then building up distance slowly. Most running injuries are overuse injuries, caused by doing too much too quickly rather than by running itself.
To minimise risk, increase weekly mileage by no more than a couple of kilometres. Ensure you eat enough carbohydrates and protein to support recovery, and consider calcium and vitamin D for bone health. Running on grass a couple of times a week can also reduce impact at first.
For the vast majority of people, the health benefits of running far outweigh the risks, especially when you listen to your body and progress sensibly.
