It is commonly thought that the impact and stress to knee during running motion can wear away at the cartilage, reducing its shock absorption abilities and create pain, however this may not be the case.
When it comes to joint disorders, they are most commonly a progressive degeneration of the joint over time. Continuous levels of inflammation in a joint is what causes it to progress to a degenerative disorder such as osteoarthritis.
Exercise reduces protein levels in the blood indicative of inflammation, while extended periods of sitting can increase the levels of these protein molecules related to inflammation.
The body is always aiming to restore itself to a level of homeostasis through various means. If you maintain a reasonable load on the body, balancing steps and active recovery you will be able to maintain some degree of homeostasis.
There are a number of explanations for knee injuries occurring that are not necessarily a result of running. A genetic predisposition to injury, the biomechanics of an individuals running style and susceptibility from another sport can all result in an injury to the knee that may be blamed on running.
1. Progressive degeneration of the knee joint is a result of continual inflammation
2. This continual inflammation can be caused by increased periods of inactivity
3. Maintaining a reasonable load of activity and active recovery will keep the body in homeostasis
4. Not all knee injuries are caused by running. Appropriate modification of training regime, correction of running technique and adequate recovery strategies may all help to reduce the risk of knee injury.