What Causes Muscle soreness after working out?

You may have heard the expression, “no pain, no gain” when it comes to embarking on a fitness journey, but have you ever wondered why certain forms of exercise result in pain in the form of muscle soreness?

The technical term for muscle soreness after exercise is DOMS, which stands for delayed-onset muscle soreness. Besides feeling sore, this term also encompasses experiencing reduced range of motion and muscle strength. You will usually experience this 24-48 hours after you try new activities/exercises or increase the intensity of your workout. While DOMS can seem similar to trigger points, trigger points are different in that they are a type of muscle soreness that are the result of an overused muscle and feel more like a “knot” in the muscle.

There is a myth that DOMS is caused by lactic acid build-up. However, lactic acid lasts in your muscles only 1-2 hours after finishing a workout, so that’s not the likely cause. Resistance training causes micro-tears of muscle fibers, which draws increased blood flow and inflammation to the area (you may even notice some mild swelling), which stimulates the pain receptors in the muscle cell and makes them more sensitive to movement. The muscle damage is temporary, and as the muscle rebuilds itself as a response to this process, it gets stronger and can handle heavier lo