For years, a persistent belief has shadowed the running community: that pounding the pavement is a surefire way to wreck your knees. But what does the scientific evidence actually say? It turns out, the reality is far more encouraging for runners of all ages.
The Knee Joint: Built for Impact, Not Fragility
Running is undoubtedly a high-impact activity. With each footstrike, the body absorbs a force equivalent to two to three times a person's bodyweight. It's logical to assume this load directly assaults the knee joints. Indeed, research confirms knees absorb three times more load during running than walking.
However, this is not the destructive process many fear. The human body is a dynamic, adaptive system that responds and strengthens under appropriate stress. The cartilage within the knee is a robust, flexible tissue designed precisely to cushion and protect. Studies show that when load is removed—such as during prolonged bed rest—bone and cartilage health actually deteriorates.
Fascinatingly, while running temporarily reduces knee cartilage thickness, it rebounds to normal within a few hours. Scientists theorise this process may help nutrients penetrate the cartilage, promoting adaptation and strength. In support of this, evidence indicates runners typically have thicker knee cartilage and better bone mineral density than their non-running counterparts.
Am I Too Old to Start Running?
A common concern, especially for those considering taking up the sport later in life, is whether age is a barrier. While direct studies on new older runners are limited, related research offers strong, positive indicators.
A 2020 study demonstrated that adults aged 65 and over could safely and effectively begin high-intensity jump training (plyometrics), which places even greater joint loads than running. Participants not only improved in strength and function but also reported enjoying the activity.
The key for any new runner, regardless of age, is a gradual approach. Muscles and joints require time to adapt. Experts recommend beginning with run-walk intervals, alternating short jogs with walking periods. Gradually increasing running distance over time allows the body to build resilience safely.
Managing Risk: Why Injuries Happen and How to Prevent Them
If running is so beneficial, why does its bad reputation endure? The high incidence of injury plays a major role, with nearly half of runners experiencing some issue annually, and knee problems being common.
Crucially, the vast majority of these are overuse injuries, linked to poor load management rather than an inherent flaw in running itself. They often occur when people do too much, too quickly, without allowing adequate adaptation.
To minimise risk, follow these evidence-based strategies:
- Progress slowly: Avoid large spikes in weekly mileage. A good rule is not to increase your total distance by more than a couple of kilometres per week.
- Fuel for recovery: Running expends significant energy. Consuming adequate carbohydrates and protein supports proper recovery and may help prevent issues like stress fractures. Ensuring sufficient calcium and Vitamin D intake is also advised.
- Consider your surface: Some research suggests running on grass generates less impact than harder surfaces like concrete. Incorporating some grass runs, especially when starting out, can help the body adjust.
For the overwhelming majority, the profound benefits of running for cardiovascular, metabolic, and joint health far outweigh the risks. The path to reaping these rewards is straightforward: start gently, build strength progressively, and always listen to your body's signals.
