Paul Saladino· MD
when you exercise the reason why your endurance and your endurance improves when you run often or the reason why you get stronger when you lift weights or the reason why your flexibility improves when you stretch is because your body sees this activity as a stress right it identifies it as a stress when you exercise it's hard you're you're causing inflammation in the body the body's expending energy and so your body's goal is to get better at that particular activity so that the same insult next time doesn't cause the same stress it's really no different than your skin's ability to tan in the sun like i go on the sun uv rays hit my skin a little bit of damage happens my body tries to adapt by darkening so that the same exposure no longer causes a sunburn