Arthritis (especially osteoarthritis) is often thought to be caused by the overstraining of the joints. For example, knee arthritis occurs from being overweight.
But the opposite may actually be true, according to a new study in the journal npj Microgravity.
Inside your knees, there is tissue called meniscus. This tissue is responsible for distributing your body’s weight evenly across your knee joint.
It consists of cartilage and gets broken down if you have arthritis.
A team of researchers noticed that astronauts who spent a lot of time in space had an increased risk of osteoarthritis. Interestingly, in space there is no gravity and therefore no strain on their joints.
The researchers placed meniscus cells in a bioreactor built by NASA that simulated space conditions.
After just three weeks, they observed genetic changes in the cells that normally occur when arthritis begins to take hold.
From this, they concluded that microgravity caused genes responsible for healthy meniscus tissue to switch off while simultaneously causing genes that led to the breakdown of this tissue to switch on.
The harmful effects of microgravity on weight-bearing joints might result from the fact that they are precisely engineered to withstand tension and large biomechanical forces.
When this tension and force in the form of body weight is removed in space, the joints cannot perform the functions for which they exist, thus triggering their degradation.
This is similar to what happens to the cartilage of people who don’t exercise at all. Their bodies seem to realize that their joints aren’t being used, and consequently starts breaking their cartilage down.
So, the key to fight arthritis is not to take all strain off the joint but to exercise it moderately, along with ensuring you make the right movements.