How exactly does damaging your muscles through exercising make it stronger when it gets rebuilt?

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How exactly does damaging your muscles through exercising make it stronger when it gets rebuilt?

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Basically, your muscles tear ever so slightly. Then your body fills in the tears, resulting in a slightly larger muscle. Do that enough times and you’re swole

After exercising, your muscle fibers are damaged. If you eat enough protein, sleep for 8 hrs and rest enough between your workouts, your body rebuilds and repairs your muscles. The body also adapts to the new workload and builds more muscle fibers, enabling you to lift more weight the next time you work out. The cycle can start again.

Your body tries to adapt to whatever you’re doing. So if you start beating your muscles up, your body will rebuild muscles stronger and bigger to be able to deal with what you previously put it through.

It’s not just your muscles – it’s every part of your body (well, almost every part). The human body is extremely well adapted to get better and more resilient at the things it does time and time again. It does this by repairing small bits that get damaged when used. Bits like muscle fiber especially. Use a muscle hard enough or long enough and very small tears (micro-tears) happen. When tissues are damaged, chemical signals are sent that tell the body to go into repair mode at the site of the damage. Repair mode releases growth factors (hormones, etc.) and increases the blood supply to the tissue (hence, the “pump” after a hard workout), and this increased blood supply brings additional oxygen and nutrients to the area and whisks away waste and muscle breakdown products. So now you have muscle tissue flooding the area with growth/repair chemicals, additional “food” and oxygen, and a stronger waste disposal system. All of this combines to build more (and typically more dense) muscle tissue than existed before the micro-tears from the workout. Repeat this enough times and muscles respond by getting bigger and stronger. Bones in the area will see similar impacts (mostly growing denser) and connective tissue can as well. Tax the heart and lungs hard enough often enough, and they’ll respond in similar fashion with chemical signals and nutrients specific to them.

Very eli5:

You’re weight lifting hard enough to damage your body. Your body goes “damn this is too much for us. We need to get stronger!” So it rebuilds the tears in your muscles and puts some extra to fortify it for the next work out. Keep doing it and eventually your muscles get noticeably bigger and stronger.