Using Temperature To Optimize Performance, Brain & Body Health | Dr. Craig Heller
Dr. Craig Heller, Ph.D., Professor of Biology at Stanford, explains how precise temperature regulation, especially via glabrous skin surfaces (palms, soles, upper face), can dramatically enhance athletic and mental performance, and dispels common cooling myths. He details how to leverage these portals for increased endurance, strength, and recovery, even eliminating muscle soreness.
Deep Dive Analysis
27 Topic Outline
Introduction to Dr. Craig Heller and Thermal Regulation
Cold Showers, Ice Baths, and Cryotherapy Effects
Boundary Layers in Water Immersion
Pre-Cooling for Aerobic Performance Enhancement
Local Muscle Heating and Performance Impairment
Heat as a Limiting Factor in Muscular Failure
Counterproductive Cooling Methods (Torso, Neck)
Brain Fog from Exercise and Hyperthermia
Optimal Body Sites for Heat Loss (Glabrous Skin)
Cooling the Brain via the Upper Face
Tripling Anaerobic Performance with Palmer Cooling
Palmer Cooling for Enhanced Recovery and Reduced Soreness
Ameliorating MS Heat Sensitivity with Cooling
Enhancing Endurance with Continuous Cooling
CoolMitt Technology and Optimal Cooling Parameters
Radiation, Convection, and Heat Transfer Principles
Optimal Re-Heating Strategy for Hypothermia
Paw-Cooling for Dog Health and Performance
Warming Up and Varying Body Temperature
Permanence of Cooling-Enhanced Performance Gains
Palmer Cooling vs. Anabolic Steroids for Performance
Female Athletic Performance and Cooling
Shivering, Brown Fat, and Metabolism
Brain Freeze and Vasomotor Changes
Non-Exercise Induced Thermogenesis (NEAT)
Impact of Pre-Workout Drinks and Caffeine on Performance
Temperature and Sleep Hygiene
6 Key Concepts
Boundary Layer
A layer of still water close to the skin during immersion (e.g., in a bath) that comes into thermal equilibrium with the skin, acting as an insulator and reducing the rate of heat transfer to or from the body.
Glabrous Skin
Hairless skin surfaces, primarily found on the palms of the hands, soles of the feet, and the upper part of the face (in primates). These areas contain specialized blood vessels for highly efficient heat exchange.
Arteriovenous Anastomoses (AVAs)
Specialized blood vessels located beneath glabrous skin that directly connect arteries to veins, bypassing the capillaries. This allows for very high blood flow rates and rapid heat transfer, making them efficient heat loss portals.
Thermostat (Brain)
The preoptic anterior hypothalamus in the brain acts as the body's thermostat, integrating thermal information from the overall body surface to regulate core body temperature and initiate responses like shivering or sweating.
Hyperthermia
A condition where the core body temperature rises dangerously high, impairing cognitive and physical performance. It can be deceptively masked by superficial cooling, leading to continued exertion despite internal overheating.
Delayed Onset Muscle Soreness (DOMS)
Muscle soreness that typically appears 24-72 hours after unaccustomed or intense exercise. Proper intra-workout cooling has been shown to eliminate or significantly reduce DOMS, even with increased work volume.
8 Questions Answered
It causes a tremendous shock and a shot of adrenaline. It also stimulates vasoconstriction, making it harder for the body to get rid of heat, though the overall surface area in a true cold bath still leads to heat loss.
The most immediate impairment is the local rise in muscle temperature, which can shut off a critical enzyme (pyruvate kinase) needed to get fuel into mitochondria, thereby stopping energy production.
Cooling the overall body surface, neck, or torso can cause vasoconstriction of the heat loss portals (palms, soles, upper face) and can trick the brain's thermostat into thinking the body is cooler than it actually is, potentially leading to increased core temperature.
The palms of the hands, the soles of the feet, and the upper part of the face are the most effective sites for heat loss due to specialized blood vessels (arteriovenous anastomoses) in their hairless (glabrous) skin.
Yes, studies have shown that athletes who use proper cooling during intense workouts experience significantly less or no delayed onset muscle soreness, despite increasing their work volume.
Yes, the gains in strength and endurance achieved through cooling-enhanced workouts are permanent, representing a true conditioning effect where the body adapts to the increased work volume.
Reputable studies show anabolic steroids increase bench press performance by approximately 1% per week, whereas Palmer cooling has demonstrated increases of 300% (tripling) in total work volume over a month.
Sleeping in a cool environment makes it easier for the body to thermoregulate passively. As the body's thermostat sets downward during sleep, a cool room allows individuals to expose heat loss surfaces (like hands and feet) or cover up as needed, maintaining thermal comfort without active effort.
16 Actionable Insights
1. Leverage Cool Mitt for Training
Utilize Cool Mitt technology (or similar glabrous skin cooling) during rest periods (e.g., 3 minutes) between anaerobic exercise sets to significantly increase work volume (e.g., tripling dips), reduce delayed onset muscle soreness (DOMS), and achieve true conditioning gains that are retained.
2. Cool Glabrous Skin for Core
To cool the body most effectively, apply cold packs or cooling devices to the glabrous skin surfaces: the palms of your hands, soles of your feet, and upper part of your face, as this cools twice as fast as other areas.
3. Control Core Body Temperature
Leverage thermal regulation to optimize mental and physical performance, as controlling core body temperature is a powerful tool regardless of the environment.
4. Pre-Cool for Aerobic Performance
Take a cold bath or shower for a couple of minutes before aerobic activity to increase your body’s capacity to absorb excess heat, delaying the sweat point and potentially increasing speed or distance.
5. Practice Good Sleep Hygiene
Establish a regular bedtime and wake-up time, avoid screens for a couple of hours before bed due to blue light affecting circadian rhythms, and engage in relaxing activities before sleep instead of working.
6. Sleep in a Cool Environment
Sleep in a cool environment to facilitate easier thermal regulation, allowing you to passively adjust body temperature by exposing or covering glabrous skin surfaces like hands and feet.
7. Avoid Head/Neck Cold Packs
Do not place cold packs on your head or neck to cool down quickly, as this can be counterproductive and lead to hyperthermia by tricking the body’s thermostat.
8. Warm Glabrous Skin for Hypothermia
To warm a hypothermic person, apply warm pads or hot water bottles to the glabrous skin surfaces like the hands and feet, as these specialized blood vessels are most effective for heat transfer into the body.
9. Loosen Grip to Maximize Cooling
During exercise, especially in heat, loosen your grip on handlebars or other equipment, or periodically expose your hands, to maximize heat loss from the palms and prevent performance limitation.
10. Thin Hand/Foot Coverings
To maximize heat loss, wear the thinnest possible coverings on your hands and feet, or remove them if safe and practical, as gloves and socks impede heat loss from these critical portals.
11. Crude Home Cooling Test
For a crude home cooling protocol, hold a cold pack (like frozen peas) in your hand, ensuring your palm remains warm to the touch by another person, indicating vasodilation and effective heat transfer, rather than vasoconstriction. Experiment with timing to find what works best.
12. Supplement Vitamin D3K2
Supplement with Vitamin D3K2, as D3 is essential for brain and body health (many are deficient even with sunshine), and K2 regulates cardiovascular function and calcium.
13. Ventilate Helmets for Cooling
Use ventilated helmets with sufficient space and holes for air circulation to prevent thermal insulation of the scalp and decrease heat loss, especially during activity.
14. Wear Knit Cap in Cold
Wear a knit cap in cold weather to reduce constant heat loss from the head, helping to stay warmer.
15. Take a Warm Bath for Sleep
Take a warm bath before bed, as it can be conducive to good sleep.
16. Wear Socks for Cold Feet
If your toes are sensitive to cold, wearing socks during sleep can promote thermal comfort by insulating this area.
5 Key Quotes
Learning to control your core body temperature is one of the most, if not the most powerful thing that you can do to optimize mental and physical performance regardless of the environment that you're in.
Andrew Huberman
The most immediate impairment of muscle activity, muscle fatigue, in other words, is the rise in temperature of the muscle.
Dr. Craig Heller
You can feel great and have a dangerously hyperthermic temperature.
Dr. Craig Heller
Ice cold is too cold. What that does is that causes reflex vasoconstriction of the very portals that you're trying to maximize the heat loss from.
Dr. Craig Heller
You keep your gains. It's a true conditioning effect. You respond to the increased work volume by all of those mechanisms you mentioned.
Dr. Craig Heller
4 Protocols
Cooling Before Aerobic Activity
Dr. Craig Heller- Take a cool shower or bath for a few minutes before starting aerobic activity.
- This increases the body's capacity to absorb excess heat, delaying the onset of sweating and performance impairment.
Intra-Workout Palmer Cooling for Anaerobic Performance
Dr. Craig Heller- During rest periods between sets, cool the palms of the hands using a device like the CoolMitt or a crude cold pack (e.g., frozen peas).
- Ensure the palms remain warm to the touch (not cold or vasoconstricted) while cooling, indicating active blood flow.
- Cool for approximately 3 minutes per rest interval, as this duration provides the most significant benefit.
Re-Heating a Hypothermic Person
Dr. Craig Heller- Apply warm pads (e.g., circulating water-perfused pads, hot water bottles) to the feet.
- This targets the glabrous skin surfaces to efficiently transfer heat into the core body.
Sleep Hygiene for Better Sleep
Dr. Craig Heller- Maintain a regular bedtime and wake-up time consistently.
- Avoid using screens (rich in blue light) for a couple of hours before bedtime to prevent disruption of the circadian system.
- Engage in relaxing activities before bed, avoiding work or intense mental stimulation.
- Sleep in a cool environment, which allows for passive thermoregulation by exposing or covering glabrous skin surfaces (hands, feet, face) as needed for thermal comfort.