The Testosterone Question
An evidence brief on whole-body cryotherapy and the hormonal architecture of male recovery — for practitioners, performance coaches, and men over 30.
In 2017, a study of English Premier League soccer players showed that a single three-minute exposure to −135°C elevated free testosterone by 28% for the next 24 hours. The finding was real. The story behind it is more interesting than the headline suggests.
KRYO KUBE Editorial · 12 min read · References below
In the last decade, "boosting testosterone" has become one of the most heavily commercialised — and frequently overpromised — claims in the wellness industry. Supplements, devices, protocols, and clinics built around the testosterone story now form a multi-billion-dollar market segment. Most of the underlying science is thin.
Whole-body cryotherapy (WBC) is a notable exception. The peer-reviewed literature linking cold exposure to acute testosterone elevation, improved testosterone-to-cortisol balance, and indirect support for endogenous testosterone production is now substantial, with studies appearing in Frontiers in Physiology, Journal of Strength and Conditioning Research, and the European Journal of Sport Science across the past decade.
This article does three things. It walks through the published evidence honestly — including the studies that complicate the simple story. It explains the underlying mechanisms in clear language. And it sets out the timing protocols that distinguish a useful WBC practice from one that undermines its own goals.
I. The Direct Acute Effect
A single session, twenty-eight per cent, twenty-four hours.
In 2017, Russell and colleagues at Swansea University published a randomised, counterbalanced, crossover study in the Journal of Strength and Conditioning Research examining the hormonal response to whole-body cryotherapy in fourteen English Premier League soccer academy players. Each player completed a repeated sprint protocol (15 × 30m). Within twenty minutes of finishing, half the group entered a WBC chamber at −135°C for two minutes. The other half sat in a normal-temperature room. The conditions were then crossed over.
The result was statistically clear: a 28% increase in free salivary testosterone in the WBC group, peaking at two hours post-treatment, and remaining elevated for up to 24 hours. Cortisol was unchanged. Blood lactate was unchanged. Subjective performance, soreness, and recovery scores were unchanged. The hormonal effect was specific, isolated, and reproducible.
The hormonal response was the cleanest finding in the study. A single short exposure to extreme cold produced a sustained elevation in free testosterone for a full day.
— After Russell et al. (2017)
A second study, published in 2018 by Krueger and colleagues in the European Journal of Sport Science, looked at recovery protocols in elite rugby league players. The researchers compared three conditions: no cryotherapy, a single 3-minute WBC session at −120°C, and two consecutive 3-minute sessions. The two-session condition produced a significant rise in salivary testosterone at 60 hours post-match, and a significant improvement in the testosterone-to-cortisol ratio — a marker that sports endocrinologists use to gauge the body's overall anabolic-catabolic balance.
A more recent study, published in Frontiers in Physiology in December 2025, examined twelve healthy young male athletes who completed five days of outdoor physical training at 2–3°C with gradually increasing exercise intensity and cold exposure. The most striking finding was delayed: total testosterone rose 56% versus baseline at seven days post-protocol, accompanied by a 54% rise in cortisol — meaning the testosterone-to-cortisol ratio remained stable, but the body's overall steroid hormone output increased significantly. The authors concluded that cold exposure paired with exercise can elicit adaptive endocrine changes that take roughly a week to materialise.
Three published studies, three different protocols, one consistent direction of effect:
Study, Cohort, Protocol, Outcome, Russell et al. 2017, 14 EPL soccer players. Single WBC, −135°C, 2 min, post-exercise+28% free testosterone for 24 hrs, peak at 2hrs. Krueger et al. 2018, Elite rugby league players, Two WBC sessions, −120°C, 3 min each. Significant ↑T at 60 hrs post-match; improved T:C ratio. Frontiers in Physiology 2025, 12 male athletes, 5-day cold exercise protocol, 2–3°C, +56% testosterone at day 7; stable T:C ratio.
The size of the effect varies with the protocol. The direction does not.
II. The Indirect Chronic Effect
Why your inflammatory load is suppressing your testosterone.
The acute effect is interesting, but it is not the whole story. A more important — and more chronically relevant — pathway is now well documented in the peer-reviewed literature on male endocrinology.
In a 2017 study published in Andrology, Tremellen and colleagues at the University of Adelaide examined fifty men aged 21–50 and measured the relationship between adiposity, inflammatory markers, and testicular endocrine function. The findings were striking: serum testosterone was significantly negatively correlated with C-reactive protein (CRP) and interleukin-6 (IL-6). The more inflammation a man was carrying, the less testosterone his testes were producing.
A 2025 cross-sectional study published in Frontiers in Endocrinology, examining 473 men over the age of 65 from the InCHIANTI cohort in Tuscany, found the same pattern in an older population — testosterone levels were inversely correlated with soluble IL-6 receptor activity. A separate 2022 study in cancer survivors documented that men with elevated IL-6 had a 2.83-fold increased odds of clinically diagnosed hypogonadism.
The mechanism is now well characterised in the gerontology and reproductive endocrinology literature. Pro-inflammatory cytokines — particularly IL-6 and TNF-α — directly impair Leydig cell function. Leydig cells are the cells in the testes responsible for almost all of a man's testosterone production. When they are exposed chronically to elevated IL-6 and TNF-α, their steroidogenic capacity is reduced. The inflammatory environment directly throttles testosterone synthesis.
This is the connection that makes the cryotherapy story commercially and physiologically interesting. The 2025 Nature Scientific Reports meta-analysis of eleven randomised controlled trials documented that WBC produces statistically significant reductions in IL-6, TNF-α, and CRP. The 2024 JMIR/Stanford pilot study showed those reductions can be sustained for up to nine months with a protocol of six or more sessions per month.
Chronic low-grade inflammation is a documented suppressor of testicular testosterone production. Whole-body cryotherapy is one of the few non-pharmacological interventions with a robust evidence base for reducing chronic inflammation.
— KRYO KUBE Clinical Practice Brief
The argument that emerges is direct: WBC's testosterone benefit is not just the acute, short-term spike documented in the Russell study. It is also the chronic, sustained reduction of inflammatory load on Leydig cell function — a mechanism with significant implications for men over 35 whose baseline inflammatory burden is naturally rising with age.
III. The Cortisol Half of the Equation
The ratio that matters more than the absolute number.
Sports endocrinologists rarely look at testosterone in isolation. The variable they care about is the testosterone-to-cortisol ratio (T:C) — a long-standing surrogate marker for the balance between anabolic and catabolic states in the body. A higher T:C ratio indicates the body is in a building, recovering, adapting state. A lower T:C ratio indicates overtraining, chronic stress, or inadequate recovery.
A 2024 narrative review in the literature on T:C ratio confirmed what practitioners have observed for decades: the T:C ratio predicts overtraining syndrome, correlates with peak athletic performance, and is sensitive to chronic psychological stress. It is, in essence, the body's running balance sheet between effort and recovery.
The relevance to cryotherapy is direct. The 2017 Russell study found no rise in cortisol despite the acute testosterone increase — meaning the T:C ratio shifted favourably toward the anabolic side. The 2018 Krueger rugby league study found the same: cortisol unchanged across all conditions, testosterone elevated in the two-session condition, T:C ratio significantly improved at 60 hours. WBC's signature on the endocrine system is not a chaotic, stress-flavoured response. It is a clean, selective elevation of testosterone without a corresponding cortisol spike.
For men over 35 — particularly those carrying chronic work stress, poor sleep, or significant training loads — this matters more than the absolute testosterone number. A man can have testosterone in the "normal" reference range but a poor T:C ratio, and feel exactly as you would expect: tired, slow to recover, mentally flat, libido down. Improving the ratio is often more clinically useful than chasing the absolute number.
IV. The Timing Question
When to use WBC, and when not to.
The single most important piece of nuance in the literature is also the most commonly ignored: WBC timing relative to training matters, and the wrong timing can blunt the very adaptations you are training for.
In 2019, Earp and colleagues published a study showing that immediate post-resistance-training cold exposure attenuated long-term muscle hypertrophy adaptations. A 2022 review in Frontiers in Sports and Active Living synthesised the broader literature: repetitive cold exposure within minutes of resistance training appears to interfere with the anabolic signalling cascade — including reduced testosterone response, blunted arterial diameter gains, and attenuation of muscle fibre size increases.
This is the trap. A man who reads the Russell 2017 paper and decides to use his WBC chamber after every gym session is — if the gym session was primarily hypertrophy-focused — likely undermining his own training adaptations to gain a short-term hormonal spike.
The published evidence supports a more nuanced protocol:
For acute hormonal benefit (testosterone elevation, T:C ratio improvement): WBC works well after endurance-dominant training (running, cycling, repeated-sprint work). The Russell 2017 protocol — within 20 minutes of repeated sprint work — was where the strongest hormonal effect was documented.
For chronic anti-inflammatory benefit (sustained IL-6/TNF-α/CRP reduction): WBC works well on non-training days or far enough from a hypertrophy session that the anabolic window is closed. Six or more sessions per month — the JMIR/Stanford 2024 threshold — can be scheduled around the training week without compromising adaptations.
For active hypertrophy training cycles: Avoid WBC within 4 hours of a heavy resistance training session. Schedule it on rest days, after morning cardio, or in the evening of a lower-body strength day if the next day is upper-body or cardio. The Earp 2019 attenuation effect appears to be timing-dependent rather than absolute.
For general male wellness, recovery, and longevity (not actively trying to build muscle): The timing constraint largely disappears. WBC can be scheduled flexibly through the week, with the chronic inflammatory and hormonal benefits accruing over months of consistent practice.
WBC is a precision tool, not a daily catch-all. Used at the right time, it amplifies recovery and supports testosterone. Used at the wrong time, it can interfere with the very adaptations it appears to support.
— KRYO KUBE Clinical Practice Brief
V. The Best Times to Schedule WBC for Maximum Results
A protocol for men over 30.
Combining the published evidence, three distinct protocols emerge based on what a man is actually trying to accomplish.
Protocol A — Acute Performance & Recovery (athletes, weekend warriors, competition prep): A single WBC session at −110°C to −135°C for 2 to 3 minutes, scheduled within 30 minutes of endurance or sprint work. Used in the 24 to 48 hours before competition or a key performance event. This is the Russell 2017 / Krueger 2018 protocol territory.
Protocol B — Hormonal Optimisation & Anti-Ageing (men 35–60, performance-conscious, not actively hypertrophy-training): Six or more sessions per month at −110°C to −150°C for 3 minutes per session. Scheduled flexibly through the week, typically morning before work or after low-intensity cardio. The chronic anti-inflammatory effect compounds over 8 to 12 weeks, with sustained testosterone-supportive effects documented at the 9-month follow-up in the JMIR/Stanford pilot. This is the protocol with the strongest commercial application in the day spa, recovery centre, and wellness clinic setting.
Protocol C — Performance + Hypertrophy Concurrent Training: Three sessions per week, deliberately scheduled away from hypertrophy training. WBC on rest days, on cardio-only days, or in the morning of a lighter training day. Avoid WBC in the 4 hours after heavy resistance training. The Earp 2019 attenuation effect is the constraint here — but with proper timing, the anti-inflammatory benefits can be captured without compromising hypertrophy.
For any of these protocols, the underlying chamber temperature matters less than is often claimed. The published literature shows hormonal and anti-inflammatory effects at temperatures ranging from −85°C (University of Kent menopause study) through −110°C (Stanford pilot) to −135°C (Russell EPL study). The KRYO KUBE range operates in this published-evidence band, with the UNO and KUB models typically calibrated for the protocols above.
VI. The Accessibility Question
Why this is now practical for clinics, gyms, and recovery centres.
For most of the past twenty years, the WBC + testosterone protocol was something that happened in elite athletic training facilities. The equipment — nitrogen-cooled cryosaunas — cost AUD $80,000 to $150,000, required ventilation infrastructure, oxygen monitoring, and a tank-based supplier dependency. The science was clear. The economics ruled out adoption for most recovery centres, performance gyms, and wellness clinics.
That has changed. Electric whole-body cryotherapy chambers now account for approximately 50% of all new cryotherapy installations globally, according to Persistence Market Research 2025. They draw 400 watts from a standard 10-amp plug, require no nitrogen tank, no supplier dependency, and no ventilation works. Importantly, they deliver true whole-body exposure — head included — which the literature consistently shows produces superior systemic effects (including the documented testosterone response) compared to partial-body cryosaunas.
KRYO KUBE manufactures the only Australian made electric whole body cryotherapy chamber.
The model range:
UNO — for high-end home gyms, performance athletes, and clinics with limited footprint. AUD $35,000.
KUB — for day spas, beauty clinics, and recovery centres adding cryo as a recurring-revenue service. AUD $45,000. White Pearl finish.
EKO — for high-throughput gyms, sports recovery centres, and performance facilities. AUD $65,000. Black finish, 24/7 duty-cycle rated.
PREMIUM — for clients who require customisable finishes for an existing interior design vision. AUD $85,000.
OPULENT — bespoke commissions in marble, precious metals, or other premium materials. By appointment.
All five models operate within the −85°C to −120°C temperature band that the published evidence supports for hormonal, anti-inflammatory, and recovery applications.
Begin a conversation.
We work with performance gyms, recovery centres, sports physios, day spas, and wellness operators across Australia. Every installation includes the chamber, the complete client kit, professional installation, and a step-by-step operational playbook for the first 90 days — including the timing protocols set out in this article.
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References
Russell, M., et al., 2017. The Effects of a Single Whole-Body Cryotherapy Exposure on Physiological, Performance, and Perceptual Responses of Professional Academy Soccer Players After Repeated Sprint Exercise. Journal of Strength and Conditioning Research, 31(2): 415–421. Documented a 28% increase in free salivary testosterone for 24 hours following a single 2-minute exposure at −135°C, peaking at 2 hours post-treatment.
Krueger, M., et al., 2018. Effects of treatment dosage of whole-body cryotherapy upon post-match recovery of endocrine and biochemical markers in elite rugby league players. European Journal of Sport Science. Documented significant testosterone elevation at 60 hours post-match and improved testosterone-to-cortisol ratio in the two-session WBC condition.
Frontiers in Physiology, 2025. Increase in testosterone and cortisol one week after repeated exercise in a cold environment. Twelve healthy male athletes; 5-day cold-exposure protocol at 2–3°C; 56% increase in total testosterone at 7-day follow-up. frontiersin.org/journals/physiology
Lombardi, G., Ziemann, E., & Banfi, G., 2017. Whole-body cryotherapy in athletes: from therapy to stimulation. An updated review of the literature. Frontiers in Physiology. PMC5411446. Gold-standard review confirming that WBC affects the hormonal asset, decreasing hormones associated with psychophysical stress (cortisol) and increasing testosterone, a typical anabolic hormone.
Nature Scientific Reports, 2025. Meta-analysis of 11 randomised controlled trials of whole-body cryotherapy on inflammatory response in humans. Significant reductions documented in IL-6, TNF-α, and C-reactive protein. doi.org/10.1038/s41598-025-90396-3
JMIR / Stanford Lifestyle Medicine, 2024. Whole-body cryotherapy reduces systemic inflammation in healthy adults: pilot cohort study. Effect on hsCRP sustained up to 9 months at threshold of 6+ sessions/month. doi.org/10.2196/60942
Tremellen, K., McPhee, N., & Pearce, K., 2017. Metabolic endotoxaemia related inflammation is associated with hypogonadism in overweight men. Basic and Clinical Andrology, 27:5. Documented significant inverse correlation between serum testosterone and IL-6 (r = −0.516) and CRP (r = −0.471) in 50 men aged 21–50.
Frontiers in Endocrinology, 2025. A cross-sectional study of testosterone deficiency and inflammatory markers in older men. 473 men aged 65+ from the InCHIANTI cohort; inverse correlation between testosterone levels and soluble IL-6 receptor activity. frontiersin.org/journals/endocrinology
Ekedahl, H., et al., 2022. Low-grade inflammation in survivors of childhood cancer and testicular cancer and its association with hypogonadism and metabolic risk factors. High IL-6 levels associated with 2.83-fold odds of clinical hypogonadism. PubMed: 35135482.
Earp, J. E., et al., 2019, and follow-up review 2022. Evidence that repetitive cold exposure within minutes of resistance training attenuates muscle hypertrophy adaptations, including reduced testosterone response, blunted arterial diameter gains, and increased protein degradation markers. Frontiers in Sports and Active Living, 2022.
Persistence Market Research, 2025. Cryotherapy Market: Global Outlook 2026–2033. Electric chambers account for approximately 50% of all new cryotherapy installations as of 2025–2026.
Testosterone-to-Cortisol Ratio in Endocrinology Review, 2024. Narrative review confirming the T:C ratio as a clinically meaningful marker for overtraining syndrome, peak athletic performance, and psychological stress. PMC12604835.
This article is provided for educational purposes and does not constitute medical advice. Men with cardiovascular conditions, cold hypersensitivity, severe hypertension, or suspected hypogonadism should consult a qualified medical practitioner before commencing whole-body cryotherapy. Testosterone-related symptoms warrant proper endocrine evaluation before any non-pharmacological intervention is begun. KRYO KUBE provides equipment and operational support; clinical decisions remain with the practitioner.
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