Cold showers don't reduce muscle soreness — they reduce gains

A common recovery myth is that cold-water immersion after training reduces delayed-onset muscle soreness (DOMS) and helps you recover faster. A 2015 study in the Journal of Physiology found it did blunt soreness, but by suppressing the inflammatory signals required for muscle protein synthesis. Athletes using cold baths regularly showed significantly less muscle and strength growth than those who warmed down normally. Save the ice bath for competition recovery, not training days.

Source: Roberts, L.A. et al., 'Post-exercise cold water immersion attenuates acute anabolic signalling', Journal of Physiology (2015)