Heat Priming Before Squats Fact or Fiction
Can a quick session in a 90 °C sauna before your heavy squat set really boost your performance? For athletes and coaches, every edge counts, and the idea that “heat priming” your muscles might enhance strength and hypertrophy is intriguing. In this article, we sift through the evidence, consider the practical challenges athletes face, and offer actionable tips for safely integrating heat into your training routine.
Introduction
Imagine you're at the gym, about to start your first set of heavy squats. Instead of jumping straight into dynamic warm-ups, you spend 15 minutes in a cedar-scented sauna, your heart rate rising as you relax into the warmth. The theory behind this approach is simple: that passive heat exposure can prime your muscles for improved performance during your lifts. But can a sauna really do more than provide a comforting ritual? Recent systematic reviews and meta-analyses—examining everything from infrared saunas to hot-water immersions—suggest that while heat may boost your perception of readiness, it might not translate into measurable gains in strength or power [1][2].
The Promise vs. The Data
What Athletes Hope For
- Faster muscle activation
- Immediate improvements in strength numbers
- Enhanced muscle growth over time
What the Research Shows
Seventeen controlled studies suggest that while passive heat exposure makes athletes feel less stiff and often reduces perceived exertion (similar to the boost you might feel from your favorite hype track), it does not consistently result in greater force production or improved neuromuscular activation [1][2]. Think of it as a psychological caffeine boost rather than a miracle pre-workout formula.
Short-Term Effects: Warm Muscles, Unchanged Bar Speed
Muscle Temperature and Comfort
Saunas (around 90–100 °C for 15–20 minutes) and hot baths (40–41 °C for 20–30 minutes) reliably raise deep muscle temperature above the 39 °C threshold. This increase can ease joint stiffness and enhance range of motion, making your body feel more prepared for exercise [1].
Strength & Power
However, measurements like bench press one-repetition maximum (1RM), squat jump height, and isokinetic torque do not show consistent improvements with passive heat priming when compared to an active dynamic warm-up. The take-home message? While heat can make you feel more relaxed and less fatigued, it doesn’t necessarily translate into immediate strength gains [2].
Perceived Exertion
A notable benefit is that athletes often report lower ratings of perceived exertion (RPE)—by about 6–10%—after heat priming. This psychological benefit is real and can be valuable during training, especially on days when the body feels stiff or sluggish [2][3].
Long-Term Adaptations: Heat, Training, and Muscle Growth
Over a period of six to twelve weeks, studies have explored whether regular heat exposure can compound with resistance training to elicit additional gains:
| Population | Heat Protocol | Outcome vs. Training Alone |
|---|---|---|
| Trained lifters | Infrared sauna 3×/week, 15 minutes post-lift | No extra 1RM gain or hypertrophy [2] |
| Recreational gym-goers | Hot-water immersion 4×/week, 25 minutes pre-lift | Small increase in explosive power, but no extra muscle size [3] |
| Clinical/Older adults | Local heat wraps daily, 40 minutes | Slight strength improvements, likely from better session compliance [4] |
Even if the long-term use of heat shows some promise, the protocols that would potentially drive meaningful muscle growth—such as longer or more frequent heat sessions—are often impractical for competitive athletes looking for immediate returns.
Dose–Response: How Much Heat Is Enough?
Research suggests there is a Goldilocks zone when it comes to heat exposure:
- Temperature: The goal is to raise muscle temperature rather than simply heating the skin. Achieving a muscle temperature above 39 °C is key.
- Duration: Systemic methods (like whole-body saunas) generally require 20–30 minutes, while localized heat treatments may need to be doubled.
- Frequency: For chronic adaptations, sessions should be performed at least three times a week for a minimum of four weeks.
- Safety Limits: Pushing beyond—core temperatures above 39.5 °C or sessions lasting over 60 minutes—can increase the risk of dehydration and place extra strain on the cardiovascular system [5].
Think of whole-body heat as a broad brushstroke that benefits your overall sensation of readiness, while localized heat applications are more like a fine-tip pen—useful but slower to produce tangible performance improvements.
Who Can Benefit?
Different athletes might see varied benefits from integrating heat priming:
| Group | Likely Benefit | Rationale |
|---|---|---|
| Untrained / Rehab Clients | Moderate | Eases stiffness and improves session adherence, which is crucial in rehabilitation [3] |
| Older Adults | Moderate | Provides joint relief and might stimulate anabolic signaling, encouraging consistency [4] |
| Elite Lifters | Minimal | These athletes operate near their performance ceiling and require impractical doses for gains [2][5] |
| Hypertrophy-Focused Bodybuilders | Unclear | While lab models suggest a potential benefit, real-world data are less convincing [3] |
For athletes facing the intense pressures of competition, even small benefits can be attractive—but it’s vital to recognize the limitations and risks involved.
Safety First: Using Heat Responsibly
Before experimenting with heat priming, it’s essential to screen for contraindications such as cardiovascular issues, hypertension, or any conditions that impair thermoregulation. The American College of Sports Medicine (ACSM) recommends gradual acclimation—start with shorter sessions (10–15 minutes at 40–60 °C), stay well-hydrated, and always monitor for signs of dizziness or nausea [5][6].
Practical Playbook for the Weight Room
-
Maintain an Active Warm-Up:
Dynamic mobility exercises remain the most reliable method for neuromuscular activation. Use heat primarily as a supplementary ritual rather than a substitute. -
Leverage Heat for Comfort, Not Performance:
If an athlete enjoys a brief sauna session and experiences reduced stiffness, a 10–15 minute exposure can complement a dynamic warm-up—but avoid promising immediate personal records or explosive gains. -
Reserve Longer Heat Sessions for Recovery:
Consider using 30–40 minute heat treatments post-training. This can be particularly beneficial on recovery days, where the focus is on muscle relaxation and reducing discomfort, especially for beginners. -
Customize According to Individual Needs:
Remember that leaner athletes may heat up faster compared to those with higher body-fat percentages. Adjust the duration and intensity of heat exposure accordingly. -
Monitor Hydration and Core Temperature:
Simple measures such as tracking body weight before and after a session, ensuring urine remains clear, and doing a self-assessment can help mitigate risks.
Conclusion
The allure of the "sauna-then-squat" routine is undeniable, offering a soothing prelude to the rigors of heavy lifting. However, current evidence indicates that while passive heat exposure can enhance your psychological readiness and comfort, it does not directly amplify strength or muscle power. For most healthy, trained athletes, heat priming should be viewed as an optional tool—ideal for recovery and improving session adherence—rather than a substitute for tried-and-true warm-up practices, progressive overload, quality sleep, and balanced nutrition.
Keep your sauna sessions enjoyable, brief, and safely integrated around an active warm-up, and you might just find that extra edge in your training routine.
References
[1] Vrindten, K. L., Lonati, D. P., Mazzocca, J. L., & Matzkin, E. G. (2025). Thermal modalities including hot baths and cold plunges play a unique role in injury prevention and recovery. Arthroscopy, Sports Medicine, and Rehabilitation. Retrieved from https://pubmed.ncbi.nlm.nih.gov/38871373/
[2] Ahokas, E. K., Hanstock, H. G., Kyröläinen, H., & Ihalainen, J. K. (2025). Effects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophy. Frontiers in Sports and Active Living. Retrieved from https://www.frontiersin.org/articles/10.3389/fspor.2025.1382240/full
[3] Normand-Gravier, T., Solsona, R., Dablainville, V., Racinais, S., Borrani, F., Bernardi, H., & Sanchez, A. M. J. (2024). Effects of thermal interventions on skeletal muscle adaptations and regeneration: perspectives on epigenetics. European Journal of Applied Physiology. Retrieved from https://europepmc.org/article/MED/38769714
[4] Kim, J.-S., Cross, J. M., & Bamman, M. M. (2020). Impact of heat application on muscle hypertrophy following resistance training. Journal of Applied Physiology, 129(4), 857-869. Retrieved from https://journals.physiology.org/doi/full/10.1152/japplphysiol.00322.2020
[5] American College of Sports Medicine. (2021). ACSM’s Guidelines for Exercise Testing and Prescription (11th ed.). Wolters Kluwer.
[6] Credeur, D. P., Hollis, B. C., & Black, C. D. (2024). Resistance training in the heat: mechanisms of muscle hypertrophy and practical recommendations. Journal of Strength and Conditioning Research, 38(7), 1416-1424. Retrieved from https://journals.lww.com/nsca-jscr/fulltext/2024/07000/resistance_training_in_the_heat__mechanisms_of.22.aspx