This is the one narrow, modern, cited kernel of truth behind the broader Kneipp cold-water tradition, though it comes from trials of generic post-exercise cold-water immersion (cryotherapy), not the Kneipp-branded regimen itself: a Cochrane systematic review of 17 small trials (n=366) found some evidence that cold-water immersion reduces self-reported muscle soreness in the days after exercise, versus rest or no intervention (Bleakley et al., Cochrane Database Syst Rev, 2012, CD008262). The review rates overall study quality as low and evidence on other outcomes (fatigue, strength recovery) as limited. Muscle-soreness reduction is a surrogate, symptom-level endpoint measured over days, not a hard endpoint and not evidence for disease prevention, immune benefit, or longevity — the claims Kneipp’s own broader system made (see kneipp-broad-disease-claim-1886).