Whether exercise can damage the knee joint is related to the pressure on the knee joint. Studies have shown that human articular cartilage can withstand the pressure of 25 MPa without obvious damage. When the pressure exceeds 25 MPa, bone cells will die and cartilage cracks will appear. This force is enough to cause a femoral fracture.
Under the condition that the joint is not injured, will the pressure on the joint caused by repeated exercise for a long time lead to the wear of articular cartilage? The results of animal experiments show that moderate exercise can not only protect joints, but also protect joints. For example, let the dog run 4 kilometers a day, 5 days a week and 40 weeks, and find that the articular cartilage is not worn, but the cartilage thickness and proteoglycan content are increased.
However, if the dog runs 20 kilometers a day, 5 days a week and 15 weeks, the cartilage thickness and proteoglycan content will decrease. However, after letting dogs run 40 kilometers a day for a year, these dogs did not develop degenerative joint disease. This shows that long-term high-intensity repetitive exercise may change the composition and properties of articular cartilage, but it may be an adaptation, not necessarily a sign of bone and joint degeneration [4].
Of course, the results of animal experiments may not be applicable to humans. But we can't do this experiment with humans. The usual research method is to follow up the retired athletes to see if they are more prone to osteoarthritis than the average person. This is related to the sports categories that retired athletes used to engage in.
In human research, long-distance running is not a contact sport, but it is the most frequent activity of knee joint. Many people think that frequent activities of the knee joint will lead to wear and tear, and it is easy to suffer from knee arthritis, so there is a saying of "running the knee". Because long-distance runners or amateurs rarely have serious knee injuries, and they often remember the length and frequency of running clearly, long-distance running has become the best case to study the influence of exercise on osteoarthritis. The results of several prospective cohort studies show that long-distance running does not increase the risk of knee osteoarthritis [3].
Some studies even found that long-distance running not only does not increase the risk of knee osteoarthritis, but can reduce its risk.
Next, I want to share three signs of knee degeneration.
1 that kind of knee deformation, our knees are straight when we are young, but as we get older, our knees will gradually bend. Even the kneecaps have become O-legs. This phenomenon is largely caused by knee degeneration.
In fact, when our knees wear over time, the medial meniscus wears faster than the lateral meniscus. Therefore, the inner side will become thinner and flatter, and the outer side will become thicker. In the long run, it will become an O-shape.
In addition, we will also find internal swelling, which is also a manifestation of knee joint degeneration.
This problem is mainly due to the serious inflammation of ligaments and tendons around the knee joint during deformation. So from the appearance, it will be swollen.
Second, the cyst of the knee fossa. Many people often wonder how a big particle swells at the back of the knee. Could it be a tumor? Then, I will go to the oncology department nervously to have a look.
The main reason for this phenomenon is that after the degeneration of your knee joint, the joint capsule is a little broken, and the joint fluid inside will seep out and flow into the joint fossa, so you will feel the back swelling.
If the cyst behind your knee is as swollen as steamed bread, I suggest you go to the hospital to pump out the tissue fluid inside.
The third phenomenon is that the knees can't bend when lying down. Not only can this kind of knee bend itself, but neither can others.
Then rule out your recent accidental injury, such as a fall. There is a good chance that you have arthritis in your knee.
When we talk about bending over here, we don't mean bending over when you stand up straight. But when you lie flat, when your knees bend less than 90 degrees, you can't bend down any more.
It is likely that the joints of your knee are inflamed to a certain extent and can no longer bend to a healthy flexion angle.
The above three symptoms indicate that your knee joint has degenerated.