Why does overstressing your back muscles (bad posture) make them weaker?


Normally, if you overstress a muscle, it gets stronger. But if you have bad posture, causing you to overstress certain back muscle groups, you get back pain. Then the physio gives you exercises to “strengthen” those muscles. How does that work?

In: Biology

If you hunch over you use a different set of muscles than if you use your back muscles to keep your back straight. Not keeping your back straight and depending on the hunched over muscles, will therefore make the muscles straightening your back weaker (by not being used as much as they should)
At least this is my understanding

Over stressing a muscle means that muscle is engaged. If you’re not keeping your back straight, the muscles responsible for that action will not be engaged, making them weaker.

Your muscles get stronger by using them.

Bad posture isn’t caused by overstressing muscles, but by underusing them to the point that they atrophy and become weaker over time.

Muscles have a length/strength relationship. Muscles at the end of the range in which they work are less strong than when they are in the middle of it. So lengthened Muscles due to bad posture can be less strong.
The better answer for posture is lack of use, not over lengthened, as mentioned before.

Being in a weird/unnatural position for a long time can put unhealthy strain on your muscles, unlike when you use good form to intentionally work out those muscles. And when you have bad posture, a lot of your weight is put on types of muscle and supportive tissue that aren’t the core muscle you generally think of when it comes to strength. So extra strain where it shouldn’t be, and less use of the muscles you should be using. It’s advised to strengthen those muscles so that they can more easily support good posture, keep your bones aligned where they should be, and reduce long-term strain especially on other tissues.

(I’m not a fitness/physiology expert tho, so feel free to correct me folks)