The Science
The research behind
every decision we make
Heat therapy is one of the most well-studied wellness practices on the planet. The peer-reviewed research also reveals tradeoffs worth understanding — and that's where QUOR's design begins.
01
Why Sauna Has Become Non-Negotiable
Regular sauna use is one of the most well-studied wellness practices in the peer-reviewed literature. The landmark Kuopio Ischemic Heart Disease Risk Factor Study followed 2,315 men in Finland over more than 20 years, and the published findings reframed how researchers think about heat therapy.
The figures below reflect findings from that study and related peer-reviewed research. They describe associations observed in study populations — not guaranteed outcomes for any individual.
Even moderate use was associated with measurable benefits in published studies. Two to three sessions per week were associated with a 22% lower risk of sudden cardiac death in the same cohort. Spending 19+ minutes per session was associated with a 52% lower risk. A separate randomized clinical trial reported that a single whole-body hyperthermia session produced antidepressant effects measurable within one week and observed through week six.
A Self-Tracked Case Study
When Heat Therapy Is Taken Seriously
One publicly documented self-tracking protocol reflects what the research suggests at its upper bound: a daily dry Finnish sauna session, 200°F for roughly 20 minutes, sustained over months, paired with extensive lab work. The individual involved is not affiliated with QUOR. We reference the published self-reported data only as one publicly available example of the cumulative effects discussed in the peer-reviewed literature.
What the self-reported data showed, alongside the underlying clinical research, included improvements in cardiovascular markers and reductions in measured environmental toxin levels over the course of dozens of sessions.
The categories of compounds reduced in self-reported sweat-elimination protocols — phthalates, VOCs, and industrial chemicals — are the same categories of compounds the peer-reviewed literature has identified in synthetic apparel materials. The connection is one of the reasons we built QUOR around plant-based fibers at the contact point.
02
What the Research Says About Heat and Sperm
This is the part of the conversation most wellness content skips. The peer-reviewed research suggests that the same heat exposure that benefits cardiovascular and mental health may temporarily affect male reproductive parameters.
The testes sit outside the body for a reason. Healthy spermatogenesis is associated with a scrotal temperature roughly 3.5–5.5°F cooler than core body temperature. During a sauna session, scrotal temperature has been measured to rise from approximately 91°F to approximately 99.5°F within ten minutes — narrowing the thermal differential the body relies on for normal sperm production.
In a small clinical study, healthy men using a Finnish sauna twice per week for three months were observed to have declines in sperm count, motility, and DNA integrity. Researchers also observed activation of heat shock and hypoxia-related genes. Sample sizes in this category of research are typically modest, and the findings have been described by the original authors as transient and reversible after heat exposure stops.
A meta-analysis of nine studies (n=356 men) reported large negative effects across measured sperm parameters — motility, morphology, concentration, count, and volume. As with the underlying studies, the changes were generally described as reversible.
In one study, infertile men who discontinued hot tub use showed a mean increase in total motile sperm count of 491%
Shefi et al., International Brazilian Journal of Urology, 2007
The peer-reviewed literature generally indicates these effects are reversible — sperm parameters in published studies returned toward baseline within roughly 3–6 months after heat exposure stopped. For men actively trying to conceive, or planning to in the near future, the timeline matters in practice. Couples in this position often receive guidance from clinicians to limit heat exposure during that window.
Common clinical guidance is direct: limit heat exposure if you're actively trying to conceive. That guidance creates a practical tension for men who also want the cardiovascular and mental-health benefits of heat therapy. QUOR is designed around that research, not around a promise to override it. Always speak with a qualified clinician about your specific situation.
03
Synthetic Materials in the Research
Most men's underwear — including most pieces guys wear in the sauna — uses synthetic fabrics like polyester, nylon, and conventional elastane. The peer-reviewed research on these materials and male reproductive parameters has prompted ongoing scientific discussion.
In one clinical study, polyester garments were associated with electrostatic charges of 326–395 V/cm² on scrotal skin, while natural fibers in the same comparison generated no measurable charge.
Shafik · Contraception, 1992
In a series of older studies, researchers observed that men wearing polyester garments long-term showed measurable changes in sperm parameters that returned to baseline after the synthetic was removed. In animal studies cited in the same body of work, synthetic-fiber groups showed declines in measured parameters while natural-fiber groups (cotton and wool, in those specific studies) showed no measurable changes. Sample sizes in this body of research are limited, and findings should be understood within that context.
Synthetic Fabrics (in cited research)
- Electrostatic charge measured on scrotal skin in older clinical work
- Microplastics identified in human testicular tissue in recent published research
- Antimony reported to leach from polyester into sweat at elevated temperatures
- PFAS dermal absorption reported to increase substantially with sweat in textile studies
- VOC emissions reported to increase with temperature in materials testing
Natural Cellulose Fibers (in cited research)
- No measurable electrostatic charge in the same cited comparisons
- No microplastic shedding (synthetics, by definition, are the source)
- No reported chemical leaching analogous to the synthetic findings
- No reported endocrine disruption in the cited studies
- Comparable to non-wearing controls in the original cotton and wool studies
A 2024 study reported microplastics in every human testis sample examined (n=23), identifying 12 different polymer types. The authors observed that PVC and PET (polyester) levels were inversely correlated with testis weight and sperm count in the sample. Additional published research has identified antimony (present in much of the world's polyester), PFAS ("forever chemicals") in textile samples, and VOC release at elevated temperatures.
In a sauna environment — extended exposure, continuous sweating, elevated temperatures — the conditions under which the cited research observed changes in synthetic fabrics are concentrated. That is the framing that drove our material decisions.
Section 04
How QUOR Approaches the Research
Integrated CryoInsert Pocket
A purpose-built pocket designed to hold a BPA-free cooling insert during heat exposure. The design is informed by the published research on scrotal temperature; it is a wellness accessory, not a medical device.
Plant-Based Where It Matters
The inner pouch is 100% Tencel Lyocell — pure plant-based fiber against the most important contact point. The body is a 95% Tencel Lyocell / 5% elastane blend designed for fit and movement.
No Synthetics at the Inner Pouch
No polyester or nylon in the inner pouch. No microplastic-shedding synthetics at the most sensitive contact point. Just clean, certified materials engineered for daily wear.
OEKO-TEX Standard 100 Certified
Independently tested against more than 1,000 regulated and harmful substances, including phthalates, BPA, PFAS, formaldehyde, heavy metals, and banned azo dyes. Every material verified.
We're not telling you to skip
the sauna.
We're sharing the research, and the gear we built around it.
Get the Complete KitReferences
All citations are to publicly available peer-reviewed research. Inclusion does not imply that the cited authors endorse QUOR or that the cited findings apply to QUOR products specifically. Where sample sizes were small or findings were preliminary, the page text reflects that context.
Important Notice
The information on this page is provided for educational and informational purposes only and is not intended as, and should not be substituted for, professional medical advice, diagnosis, or treatment. QUOR Wellness Inc. does not diagnose, treat, cure, mitigate, or prevent any disease or medical condition. The cited research reflects findings from third-party peer-reviewed studies in the populations and conditions described in those studies; results in any individual will vary, and the studies do not test QUOR products specifically.
QUOR products are wellness apparel and accessories. They are not FDA-approved, FDA-cleared, or otherwise regulated medical devices. Statements describing the design of QUOR products are statements of design intent informed by the cited research, not claims of clinical efficacy.
Always consult a qualified healthcare professional before making changes to your health routine, particularly regarding fertility, heat exposure, or any medical condition. The cited authors and studies are independent of QUOR; their inclusion does not imply endorsement of QUOR or its products.