Muscle soreness (DOMS)

Muscle soreness is caused by tiny tears in the muscle fibres when you put a muscle under unaccustomed strain – especially when braking a movement, for example when walking downhill or lowering yourself into a squat. The body repairs this minor damage, and in the process inflammatory reactions develop that hurt.

The timeline is typical: straight after exercise you usually feel nothing; the pain sets in after 12 to 24 hours, peaks after 24 to 72 hours and has gone after three to seven days. Experts call this DOMS – delayed onset muscle soreness.

One myth is stubbornly persistent: lactic acid (lactate) is not the cause. Lactate is cleared within one to two hours after exercise – long before muscle soreness begins. Stretching before or afterwards doesn't prevent it either; a 2011 Cochrane review found practically no effect.

What helps: gentle movement (a walk, an easy bike ride), warmth (a bath, the sauna), enough sleep, plenty to drink and protein-rich food. Painkillers are usually unnecessary. You can still train, but keep it light and ideally work other muscles – the ache shouldn't get any worse. It's a warning sign if the pain is extreme, your urine turns dark or the muscle swells up a lot: in that case, please get it checked by a doctor.

Very important for anyone just starting out: muscle soreness is not a measure of a good workout. If you repeat the same movement, you'll get much less sore the second time – the muscle has learned. So it's better to start gently and build up slowly than to hobble around for days after your first session.