Muscle soreness: should you train through it

Soreness — scientists call it delayed-onset muscle soreness — comes from micro-damage to muscle fibers, caused mainly by movements where the muscle lengthens under tension (the lowering phase). It is not lactic acid, contrary to a stubborn belief.

It typically appears 12 to 48 hours after effort, peaks, then fades within a few days. It is more pronounced after a new exercise, a comeback, or a sudden jump in volume.

Many judge a session by the intensity of next day's soreness. That is a mistake: the absence of soreness does not mean the session was useless, and heavy soreness does not guarantee good results. Over time, a muscle used to an exercise progresses very well while rarely getting sore.

What builds muscle is progressive overload and adequate volume, not pain. Judge your progress by your loads, your reps and your physique in the mirror — not by the severity of your soreness.

Mild to moderate soreness does not prevent training: moving the muscle even increases circulation and can ease the feeling somewhat. You can train another muscle group entirely, or repeat the exact same one with a slightly reduced load and range of motion if the discomfort is genuinely minor.

However, if the pain is sharp, limits range or strength, or affects a joint rather than the muscle, give yourself rest. Always distinguish diffuse, bearable soreness from genuine sharp, localized pain, which should alert you.

No miracle cure removes soreness entirely, but a few levers speed recovery: quality sleep, enough protein, good hydration, and light activity (walking, mobility work) that boosts circulation without fatiguing the sore muscle further.

Massage, foam rolling and gentle stretching can ease the feeling in the moment, without necessarily speeding healing. The best tool remains gradual progression: raise your volume in small steps, and your body will adapt without laying you flat.

Hamstrings, calves and glutes are notorious for particularly intense soreness, especially after a Romanian deadlift or an intense lunge session. This is no coincidence: these muscles do a lot of work while lengthening under tension (the eccentric phase), the exact mechanism behind the micro-damage.

Conversely, muscles like the forearms or traps, used almost daily in everyday life (carrying, gripping), adapt quickly and rarely get very sore, even after high volume. How new the stimulus is matters as much as the muscle itself: a movement you have never done will cause marked soreness even in a muscle 'used to' other exercises.

This is why introducing a new exercise — even a light one — deserves the same caution as a comeback: start with a moderate volume, and increase it the following session once you know how your body reacts.

Sleep is when most muscle repair happens, driven in particular by growth hormone release during deep sleep. Sleeping less than six to seven hours clearly slows this repair, which prolongs the soreness and raises injury risk in the following sessions.

Conversely, intense soreness can itself disrupt sleep by making certain positions uncomfortable. In that case, a warm shower before bed and gentle stretching can help you fall asleep, without necessarily speeding up the muscle healing itself.

If you are stacking short nights during a period of high training volume, prioritize sleep above every other recovery lever: no nutrition or mobility strategy durably compensates for chronic sleep debt.