Methodology, in plain terms.
Where the calculator numbers come from
Every threshold traces to published research, cited on the page where it's used:
- Cold: Søberg et al., Cell Reports Medicine (2021) — winter swimmers averaging ~11 minutes/week of cold exposure across 2–4 sessions; plus standard cold-shock and afterdrop safety guidance.
- Heat: Laukkanen et al., JAMA Internal Medicine (2015) — the Finnish cohort (~2,300 men, 20+ years) associating 4–7 sauna sessions/week (~19 min, ~174°F) with reduced cardiovascular mortality.
- Light: the photobiomodulation dose-response literature (Hamblin and colleagues), using the standard J/cm² = mW/cm² × seconds ÷ 1,000 arithmetic and the commonly cited dose windows by tissue depth.
These are associations and protocols, not prescriptions. Where evidence is thin — and in recovery tech it often is — we say so on the page rather than rounding hype up to fact. The complete study list with PubMed links lives on the sources page.
How gear rankings work
We rank on published, checkable specs: measured irradiance, real temperature ceilings, chiller floor temps, warranty terms, and price-per-performance. We don't claim hands-on lab testing we haven't done. When a placement is sponsored, it's labeled — and sponsorship never buys a ranking position.
Who's behind this
RecoveryCalc is built by Cozy River Studios in Denver, Colorado — the team behind RunBikeCalc (training calculators for endurance athletes) and GlowNoFilter (evidence-based skincare). Small, useful corners of the internet.
Nothing here is medical advice. Cold, heat, and light are real physiological stressors — talk to your doctor before starting, especially with cardiovascular conditions or during pregnancy.