You've seen it at the gym – athletes finishing a session, then heading straight to the cold plunge or sauna. Some do both. Most aren't entirely sure which one is doing what. They just know it feels like recovery.
But temperature-based recovery tools are more than just a ritual. The science behind heat therapy and cold exposure is well-developed, and understanding how each modality works – and when to use them – can meaningfully improve how you recover, how you feel, and ultimately how you perform.
Here's what the research actually shows.
What Happens to Your Body Under Heat Stress
Heat exposure – whether from a traditional sauna, infrared sauna, steam room, or hot bath – triggers a cascade of physiological responses that overlap significantly with the adaptations your body makes to exercise itself.
Cardiovascular output increases. Core temperature rises, your heart rate climbs, and blood is redirected toward the skin to facilitate cooling. This cardiovascular load is real – sustained sauna use can elevate heart rate to levels comparable to moderate aerobic exercise.
Heat shock proteins (HSPs) are activated. These molecular chaperones help protect and repair damaged proteins within cells – including muscle proteins stressed during training. Regular heat exposure has been shown to upregulate HSP expression, which may accelerate cellular repair and reduce the protein degradation that follows intense training sessions.
Growth hormone spikes. Studies have documented significant acute increases in growth hormone (GH) following sauna use. Two 20-minute sauna sessions at 80°C (176°F), separated by a 30-minute cooling period, have been shown to produce GH levels five-fold higher than baseline. GH plays a direct role in tissue repair and muscle protein synthesis.
Plasma volume and red blood cell adaptation. Over time, regular heat exposure can increase plasma volume, improving blood viscosity and oxygen-carrying efficiency – adaptations that also occur with aerobic training.
Sauna Benefits for Athletes: Beyond the Relaxation Narrative
The sauna has long been associated with relaxation and stress relief, and those benefits are real. But framing it purely as a recovery tool for soreness undersells what regular heat exposure can do for athletic performance and long-term adaptation.
Endurance Gains Without Extra Mileage
A landmark study published in the Journal of Science and Medicine in Sport found that post-exercise sauna sessions over three weeks significantly improved run time to exhaustion in distance runners – by approximately 32% compared to a control group. Plasma volume expansion was the primary driver. More blood volume means your heart can pump more oxygen to working muscles before fatigue sets in.
This makes sauna a viable supplemental training tool for endurance athletes, not just a recovery modality.
Muscle Retention During Reduced Training
Heat shock protein activation doesn't just protect muscle during heavy training – it may also slow muscle atrophy during periods of detraining or injury. Research suggests that repeated heat exposure can attenuate the rate of muscle protein breakdown when training volume is reduced, making it a useful tool for athletes managing injury or planned deload periods.
Neurological and Mood Effects
The thermal stress of sauna use triggers release of dynorphins (which paradoxically make you feel cold initially but upregulate opioid receptors) and, in response, a robust release of beta-endorphins. Regular sauna users also show elevated prolactin levels, which has been linked to faster nerve remyelination – relevant for the neurological recovery that supports motor performance.
Practical Sauna Protocol for Athletes
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Timing: Post-training is ideal. Sauna use pre-workout can cause dehydration and reduce performance.
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Duration: 15–20 minutes per session is supported by most research. Extending beyond 30 minutes does not appear to meaningfully increase benefit and increases dehydration risk.
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Temperature: Traditional Finnish saunas (80–100°C / 176–212°F) are most studied. Infrared saunas operate at lower temperatures but produce comparable core temperature increases over longer sessions.
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Frequency: 3–4 sessions per week appear to capture most of the adaptive benefits.
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Hydration: Rehydrate immediately after. Electrolyte losses through sweat are significant.
Cold Exposure: The Case for Deliberate Discomfort
Cold water immersion (CWI), ice baths, and cold showers have become staple recovery tools across endurance sports, team sports, and strength training. The mechanisms are distinct from heat, and the debate around cold's role in training adaptation is more nuanced than popular culture suggests.
How Cold Exposure Works
- Vasoconstriction and metabolic slowdown. Cold causes peripheral blood vessels to constrict, reducing blood flow to the skin and extremities and driving blood centrally. This reduces the inflammatory mediators that accumulate in muscle tissue post-exercise – edema decreases, metabolite clearance is supported, and perceived soreness often diminishes.
- The "rebound vasodilation" effect. When you exit cold water, vessels dilate rapidly, driving a surge of blood through tissues. This flush effect is thought to accelerate the removal of metabolic waste products.
- Nervous system modulation. Cold exposure activates the sympathetic nervous system acutely, driving norepinephrine release. Over repeated exposures, this may support mood, focus, and stress resilience – effects that extend beyond the training context.
- Brown adipose tissue (BAT) activation. Repeated cold exposure can increase brown fat activity and density. Brown fat burns calories to generate heat (thermogenesis), and emerging research links BAT activation to improved insulin sensitivity and metabolic health.
Cold Exposure vs. Heat for Performance: Key Differences
This is where the nuance matters – because the answer isn't that one is better than the other. They do different things, and the context of your training determines which tool to prioritize.
Where Cold Exposure Excels
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Acute soreness and inflammation management – CWI is consistently effective at reducing delayed-onset muscle soreness (DOMS) and subjective fatigue in the short term.
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Back-to-back performance demands – For athletes competing on consecutive days (team sports, tournaments), cold immersion after day one has been shown to preserve performance on day two more effectively than passive recovery.
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High-volume training blocks – When cumulative fatigue is the primary concern and the immediate training session is complete, cold exposure helps manage the inflammatory load.
Where Cold May Work Against You
Here's the friction point: cold exposure, particularly immediately post-resistance training, can blunt the hypertrophic signaling that strength work generates.
Research published in the Journal of Physiology (Roberts et al., 2015) found that athletes who performed cold water immersion after strength training showed significantly attenuated muscle hypertrophy and strength gains over 12 weeks compared to those who used active recovery. The proposed mechanism: cold suppresses the mTOR signaling pathway and satellite cell activation that drive muscle protein synthesis in response to resistance training.
Practical takeaway: If your primary goal is muscle building, reserve cold exposure for non-training days or use it only sparingly after strength sessions. If your goal is performance maintenance or endurance, cold has a stronger use case in the immediate post-training window.
Where Heat Offers an Edge for Training Adaptation
Heat therapy applied between sessions – rather than immediately post-workout – does not appear to blunt hypertrophic signaling in the same way cold does. In fact, the HSP upregulation and growth hormone response associated with sauna use may complement resistance training adaptation when timed appropriately (i.e., not immediately post-session when your body is in an active anabolic window).
Contrast Therapy: Is Alternating Hot and Cold Worth It?
Contrast therapy – alternating between hot and cold exposure – has gained significant traction in elite sports recovery settings. The proposed mechanism is an "active pump" effect: vasoconstriction from cold alternating with vasodilation from heat accelerates circulatory exchange in peripheral tissues.
The evidence is mixed but generally favorable for acute recovery markers. A 2022 systematic review found that contrast water therapy outperformed passive recovery for reducing DOMS and fatigue in team sport athletes. For competitive athletes with short recovery windows between sessions, it may represent a practical middle ground.
Typical contrast protocol:
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3–4 cycles of alternating hot (38–42°C / 100–108°F, 3 minutes) and cold (10–15°C / 50–59°F, 1 minute)
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Begin with heat, end with cold for acute inflammation management
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Begin with heat, end with heat if the goal is relaxation and sleep quality
Supporting Temperature Recovery With Nutrition and Supplementation
Temperature-based recovery tools work best when your nutritional foundation is solid. Heat and cold exposure both place demands on the body that nutrition can directly support.
Protein and Amino Acids
Whether you're using sauna to amplify GH response or cold to manage inflammation, muscle protein turnover is elevated in the post-training period. Getting adequate high-quality protein in the recovery window ensures your body has the substrates to act on the anabolic signals those recovery modalities generate.
Prostar 100% Whey Protein provides fast-digesting complete protein to support muscle repair in the acute post-training window – relevant whether you're heading to a sauna or ice bath after your session.
For overnight recovery – especially relevant when heat exposure before bed is part of your protocol – a slower-releasing protein like Prostar 100% Casein Protein sustains amino acid availability across the hours when growth hormone is naturally elevated during sleep.
BCAAs and Glutamine
Branched-chain amino acids support muscle protein synthesis directly and may help offset the protein degradation associated with high training volume and thermal stress. BCAA 12,000 delivers leucine, isoleucine, and valine in a clinically relevant ratio.
GlutaPure (L-Glutamine) supports gut integrity and immune function – both of which can be stressed during periods of high training volume combined with regular sauna use, where core temperature and immune demand are chronically elevated.
Creatine
Creatine Monohydrate is one of the most researched supplements in sport and supports ATP regeneration, muscle hydration, and recovery from high-intensity efforts. Its role in supporting cellular energy availability complements the recovery demands of regular heat and cold exposure protocols.
Electrolytes and Hydration
Sauna use results in significant sweat-based electrolyte loss – sodium, potassium, and magnesium in particular. Athletes using frequent sauna sessions should monitor electrolyte status and rehydrate deliberately, not just with water.
Sleep Support
Regular sauna use in the evening has been associated with improved sleep onset and slow-wave sleep – partly due to the core temperature drop that follows heat exposure, which the body interprets as a sleep signal. If you're using evening heat as part of a sleep optimization strategy, REM Zone supports natural melatonin production and deeper sleep architecture. ZMA® – zinc, magnesium, and vitamin B6 – supports both sleep quality and testosterone recovery, which aligns with the hormonal benefits heat therapy is already working to support.
Who Should Prioritize Heat vs. Cold
Prioritize heat therapy if you are:
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An endurance athlete building aerobic base
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In a deload or injury recovery phase
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Focused on sleep quality and hormonal recovery
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Training for performance over a longer competitive season
Prioritize cold exposure if you are:
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In a high-volume training block with back-to-back session demands
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Competing in multi-day events or tournaments
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Managing acute DOMS or joint inflammation
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Using it as a mental toughness and stress resilience practice
Use both (contrast therapy) if you are:
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A team sport athlete with frequent competition windows
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Looking for comprehensive recovery modality without choosing one extreme
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Already well-hydrated and have time for a structured protocol post-session
Common Mistakes With Temperature-Based Recovery
Doing cold immediately after strength training on muscle-building programs. As noted above, this can directly interfere with hypertrophic adaptation. Time it better or skip it on heavy lifting days.
Neglecting hydration before and after sauna. Entering a sauna already mildly dehydrated – common after a hard training session – compounds fluid loss and can impair rather than support recovery.
Using temperature therapy as a substitute for sleep. Sauna and cold exposure are recovery complements, not replacements. Sleep is where the majority of tissue repair, hormonal resetting, and neural recovery occurs. No modality replaces it.
Staying too long in cold water. Extended cold immersion (beyond 10–15 minutes) can suppress immune function and increase injury risk during the post-exposure period. More time is not more benefit.
Inconsistency. Like most training adaptations, the benefits of regular heat exposure (plasma volume, HSP upregulation, cardiovascular adaptation) accumulate over weeks of consistent practice. Occasional use captures some of the acute benefits but not the adaptive ones.
The Bottom Line
Heat and cold exposure are legitimate performance and recovery tools — when you understand what each one does and when to use it. Sauna builds adaptation. Cold manages acute damage. Used strategically alongside solid nutrition, quality sleep, and progressive training, temperature therapy can be the edge that separates average recovery from exceptional one.
Expose yourself to the extremes. Recover with intention.
The information provided in our articles is meant for informational and educational purposes exclusively and should not be considered as medical advice. It is essential to consult a healthcare professional before starting a new nutritional product and/or making significant changes to your diet and exercise routine. These products are not intended to diagnose, treat, cure, or prevent any disease.
