The claimEvidence A · guideline-tier
Sauna detoxes heavy metals via sweat
The evidence
Sweat heavy-metal concentration is 100× lower than urine; total 'toxin' excretion <1% via sweat.
The mechanism, in brief
Training itself does not make you stronger. It only gives your tissues an order: this needs to be stronger. The actual growth happens during recovery after the session.
Sources (2)
- Schoenfeld, B. J., Grgic, J., Ogborn, D., & Krieger, J. W. (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: A systematic review and meta-analysis. Journal of Strength and Conditioning Research, 31(12), 3508-3523. Despite the id, this is a low- vs high-load meta-analysis, not a training-frequency one (the frequency meta is schoenfeld-2016-frequency-meta): 21 studies comparing low loads (≤ 60% 1RM) with high loads (> 60% 1RM), all sets to momentary failure, at least 6 weeks. Hypertrophy was similar between conditions; 1RM strength gains were greater with heavy loads; isometric strength did not differ (abstract, PMID 28834797).
- Nosaka, K., Newton, M., & Sacco, P. (2002). Delayed-onset muscle soreness does not reflect the magnitude of eccentric exercise-induced muscle damage. Scandinavian Journal of Medicine & Science in Sports, 12(6), 337-346. 110 male students did 12, 24 or 60 maximal eccentric actions of the elbow flexors. The 24- and 60-action bouts caused larger changes in force, joint angles, arm circumference and plasma CK, yet soreness on palpation and flexion did not differ from the 12-action group, and soreness correlated weakly or not at all with the damage markers. Conclusion: DOMS is a poor reflector of eccentric exercise-induced muscle damage and inflammation. The abstract proposes no neural mechanism (abstract, PMID 12453160).