The claimWhat Laird actually said
Speaking to a writer from The Inertia who took part in his pool training session, Hamilton described the sauna and ice bath portion. He said thermoregulation is the body's most energy-intensive process, compared it to a muscle that heat and ice can train, and said the routine makes people better in the cold and in the heat.
- theinertia.com: Laird Hamilton in their own words
- Laukkanen T et al., JAMA Internal Medicine, 2015: more frequent sauna bathing was associated with lower risk of fatal cardiovascular events and all-cause mortality in Finnish men
- Kunutsor SK et al., Annals of Medicine, 2018: combined high fitness and frequent sauna use was associated with the lowest cardiovascular and all-cause mortality risk
- Esperland D et al., International Journal of Circumpolar Health, 2022: review finds evidence on the health effects of voluntary cold-water exposure limited and still debated
- Moore E et al., Sports Medicine, 2023: systematic review and meta-analysis of cold-water immersion versus other recovery methods after strenuous exercise, with outcome-dependent effects
Why it mattersWhy this matters for longevity
Contrast therapy is spreading from elite athletes into home saunas and backyard cold tubs, often sold with longevity promises.
Sudden cold immersion puts real strain on the heart, which matters more for older adults and people with cardiovascular disease.
The evidenceWhat the science says
In a cohort of more than 2,000 middle-aged Finnish men, sauna bathing four to seven times a week was associated with lower fatal cardiovascular and all-cause mortality than once a week, and a follow-up analysis found the lowest risk in men who combined frequent sauna use with high fitness. Meta-analyses of cold-water immersion after hard exercise find some benefit for perceived soreness and recovery, but the effects are small and vary by outcome and timing.
The honest caveat: the sauna data are observational, mostly from Finnish men, and cannot rule out that healthier people simply sauna more. Reviews of voluntary cold-water exposure call the evidence inconclusive and note risks, including cold shock. Calling thermoregulation a trainable muscle is a coaching metaphor, and no study shows that alternating heat and ice extends life.
TakeawayThe honest takeaway
The practical lesson
If you enjoy the sauna and your doctor agrees, it is a reasonable habit, but treat cold plunges as optional and start gradually, especially if you have heart concerns.
Planning for a parent, or for yourself?
Good habits matter, and so does knowing what help exists. AIOSeniors asks a few questions and gives you a free, personalized list of what applies: government programs, nonprofits and community resources included, whether or not anyone earns anything from them. Where the answer is not known, it says so.
RelatedRelated habits
Each of these is a habit you can build on its own. Explore them through the Topics index.
SupplementsThe supplement angle: Fluids and electrolytes
Support a habit, do not replace one
Heat sessions increase sweat loss, so replacing fluids matters more than any supplement. No supplement has been shown to reproduce the effects of heat or cold exposure.
Supplements can support good habits. They do not replace sleep, movement, nutrition, or medical care. Talk with your healthcare provider before starting anything new.
This is educational commentary, not medical advice, and does not imply that Laird Hamilton endorses, is affiliated with, or uses Winning Longevity or any product. We critique the claim and the evidence, not the person. Any direct quote is a placeholder until sourced. Talk with a qualified healthcare provider before changing your routine. See our health disclaimer.
