General Lack of Exercise
The more you use a muscle, the stronger and more durable it gets. The less you use a muscle, the higher the chance for the muscle to eventually suffer from degeneration of muscle and nerve tissue, also known as atrophy. While it might take a monumental amount of inactivity to cause such a thing, it would be wise not push the body’s ability to be more efficient. Those who take the time to exercise don’t have to worry about much, as their bodies are typically much healthier, though they still have to ensure they avoid potential accidents when exercising.
For those on the other side of the spectrum, a general lack of exercise can cause all manner of issues. There is constant pressure on the back as it supports the upper body. If you pair such a thing with inactivity and a lack of exercise, it can cause middle back pain alongside other more debilitating conditions. Muscles that don’t see too much use are not only in danger of degeneration, but are also much easier to injure. Something as simple as going out for a walk daily can help the body in more ways than one.