Essentials: Increase Strength & Endurance with Cooling Protocols | Dr. Craig Heller
Dr. Craig Heller, a Stanford professor, details how cooling glabrous skin (palms, soles, upper face) efficiently releases body heat. This method significantly enhances both aerobic endurance and anaerobic performance, improving short-term output and long-term training adaptation, unlike conventional cooling.
Deep Dive Analysis
13 Topic Outline
Physiological Response to Cold Exposure
Cold Immersion vs. Showers and Aerobic Performance
Anaerobic Exercise, Muscle Overheating, and Failure
Ineffective Cooling Methods for Muscles
Thermoregulation, Brain Cooling, and Hyperthermia Risks
Optimal Body Sites for Heat Loss: Glabrous Skin
Impact of Grip and Apparel on Heat Loss
Direct Brain Cooling via Facial Blood Flow
Brain Cooling for Concussion Protection (Controversial)
Enhancing Anaerobic Performance with Palmar Cooling
Improving Aerobic Endurance with Palmar Cooling
CoolMitt Technology and Optimal Cooling Temperature
Practical Application of Glabrous Skin Cooling
6 Key Concepts
Vasoconstriction
This is the narrowing of blood vessels, which occurs when the body is exposed to cold. It makes it more difficult for the body to get rid of heat, as it shuts off avenues of heat loss to conserve core temperature.
Boundary Layer
In a still cold bath, a layer of water close to the skin comes into equilibrium with the skin temperature, acting as an insulator. Moving around disturbs this layer, re-exposing the skin to the colder water.
Muscle Failure (Heat-Induced)
A primary component of muscle fatigue and failure during intense activity is the local overheating of the muscle. When muscle temperature exceeds 39-39.5 degrees Celsius, an enzyme critical for fuel delivery to mitochondria shuts off, preventing further energy production.
Preoptic Anterior Hypothalamus
This is the brain's thermostat, responsible for physiological temperature regulation. Cooling this area directly (e.g., by putting a cold towel on the neck) can trick the body into feeling cooler than it actually is, potentially masking a dangerously rising core temperature.
Glabrous Skin
Refers to hairless skin, specifically on the palms of the hands, soles of the feet, and the upper face. These areas contain specialized blood vessels that shunt blood directly from arteries to veins, bypassing capillaries, which allows for very efficient and rapid heat loss from the body's core.
Cardiac Drift
This is the phenomenon where heart rate increases as the core body temperature rises, even if the intensity of exercise remains constant. It indicates the heart is working harder to circulate blood and facilitate cooling.
10 Questions Answered
You experience a shock and an adrenaline shot, and your body stimulates vasoconstriction, making it harder to lose heat. While a full cold bath can still cause heat loss due to large surface area, cold showers are less effective for core cooling.
Taking a cold shower or bath before aerobic activity can increase your body's capacity to absorb excess heat, allowing you to sustain activity longer or at a higher intensity before overheating.
Muscle failure during anaerobic exercise is primarily due to the local rise in muscle temperature (above 39-39.5°C), which deactivates a critical enzyme needed to supply fuel to mitochondria, effectively shutting off the muscle's energy production.
The body's surface is a good insulator, preventing rapid heat transfer to muscles. Cooling the body surface or neck can trick the brain's thermostat into thinking the body is cooler than it is, potentially causing vasoconstriction in heat loss portals and leading to dangerous core temperature increases.
The palms of the hands, soles of the feet, and the upper face (glabrous skin areas) are most effective because they contain specialized blood vessels (arteriovenous shunts) that allow high-flow heat transfer directly from arteries to veins, bypassing high-resistance capillaries.
Gripping tightly compresses the blood vessels in the palms, shutting off blood flow and impeding the efficient heat loss that occurs through these specialized glabrous skin surfaces.
While the idea of cooling to decrease swelling and inflammation is plausible, the effectiveness of direct brain cooling for offsetting concussion damage is controversial and requires further investigation.
By efficiently removing heat through the palms, palmar cooling allows muscles to continue working longer without reaching the temperature threshold that causes fatigue and failure, thereby increasing work volume and endurance in both anaerobic and aerobic activities.
Ice cold temperatures cause reflex vasoconstriction in the very blood vessels designed for heat loss in the palms, effectively sealing off the heat within the body rather than releasing it. Optimal cooling should be 'just cool' to maximize heat transfer without constriction.
Yes, the gains are a true conditioning effect. The increased work volume achieved through cooling leads to physiological adaptations, such as an increase in muscle contractile elements, which are retained even when subsequent workouts are performed without cooling.
16 Actionable Insights
1. Leverage Glabrous Skin Cooling
Actively cool the palms of your hands, soles of your feet, and upper face during or between intense exercise to rapidly dissipate heat from the body’s core and muscles, thereby increasing work capacity and endurance. These areas contain specialized blood vessels that efficiently shunt blood for heat loss.
2. Avoid Ice-Cold Glabrous Cooling
Do not use ice-cold temperatures (e.g., ice water) directly on glabrous skin (palms, soles, face) for cooling. This causes reflex vasoconstriction, sealing off the heat loss portals and making cooling less effective.
3. Test Glabrous Cooling Efficacy
To ensure effective cooling of glabrous skin, check if the cooled area (e.g., palm) feels warm to the touch after cooling. If it feels cold, it indicates vasoconstriction, meaning the heat loss portals are shut down and the cooling is not optimal.
4. Prioritize Glabrous Areas for Cooling
When attempting to cool the body, focus on applying cooling to the palms of the hands, soles of the feet, and the upper face. These areas cool the body twice as fast as applying cold packs to the armpits, groin, or back of the neck.
5. Consistent Cooling Builds Gains
Engaging in consistent cooling protocols during workouts leads to true conditioning effects and lasting performance gains. The body adapts to the increased work volume, leading to benefits like increased muscle contractile elements and muscle size.
6. Use Coolmit Technology
Utilize the Coolmit device by placing your hand into it and holding onto the cooling surface for approximately 2-3 minutes between sets or during endurance activities. This effectively cools the body and enhances performance, with the biggest benefit occurring in the first few minutes.
7. Crude Glabrous Cooling Method
For a crude cooling method, use a package of frozen peas or blueberries and pass it back and forth between your hands. Ensure your hands do not become too cold to avoid vasoconstriction.
8. Pre-Cool Before Aerobic Activity
Take a cool bath or shower before engaging in long-duration aerobic activity, especially on warm days. This increases your body’s capacity to absorb excess heat, delays the onset of sweating, and can potentially improve speed or distance.
9. Loosen Grip During Exercise
When cycling or using similar exercise equipment, avoid gripping handlebars too tightly, especially in warm conditions. This can impede heat loss from the palms and limit performance; periodically loosen your grip or expose your hands.
10. Wear Thin Hand/Foot Coverings
To maximize heat loss from hands and feet during exercise, opt for the thinnest possible coverings (e.g., gloves, socks) or go without them if safe and practical. Thicker materials impede heat dissipation.
11. Maintain Loose Hands While Running
When running, keep your hands loose, as if holding crackers lightly, rather than gripping them tightly or holding a phone. This posture can be more beneficial for performance by allowing better heat dissipation from the palms.
12. Cool Brain by Pouring Water
Pouring water on the head and upper face can have a cooling effect on the brain. Cooled blood from these facial regions can reverse flow into the brain’s venous circulation, acting as a cooling source.
13. Beware Subjective Cooling vs. Core
Avoid cooling the torso, neck, or head with cold stimuli (e.g., ice vests, cold towels) when overheated. This can trick the brain’s thermostat into feeling cooler than you are, potentially causing vasoconstriction of heat loss portals and allowing core body temperature to continue rising dangerously.
14. Recognize Hyperthermia Symptoms
Be aware of symptoms of hyperthermia, which include feeling exhausted, miserable, and having a very high heart rate (cardiac drift). These indicate a dangerously high core body temperature.
15. Cold Showers/Ice Baths Caution
While cold showers or ice baths provide a ’tremendous shock’ and a ‘shot of adrenaline,’ they may not offer significant physiological benefits for performance or heat loss. They can even stimulate vasoconstriction, making it harder for the body to get rid of heat.
16. Cooling for Brain Injury
Cooling the brain, such as by applying cold to the neck or head, is theorized to help decrease swelling, inflammation, and blood flow after brain injury. However, this idea is considered controversial and requires further investigation.
5 Key Quotes
The most immediate, the most immediate impairment of muscle activity, muscle fatigue, in other words, is the rise in the temperature of the muscle.
Dr. Craig Heller
So you literally have the capacity to cook your muscles.
Dr. Craig Heller
So you're saying that if somebody's hyperthermic, they could trick themselves into subjectively thinking that they are cooling off by putting a cold towel and that they can go further, but their brain could cook.
Andrew Huberman
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
3 Protocols
Pre-Aerobic Activity Cooling Protocol
Dr. Craig Heller- Take a cool shower before engaging in long-duration aerobic activity, especially on warm days.
- Allow this pre-cooling to increase your body's capacity to absorb excess heat, delaying the onset of sweating and overheating.
- Leverage this benefit to either go farther at the same pace or go faster for the same distance, depending on your goal.
Anaerobic Performance Enhancement with Palmar Cooling
Dr. Craig Heller- During rest periods between sets of anaerobic exercise (e.g., dips, bench press), place your hands into a cooling device that cools the palms.
- Ensure the cooling device provides a 'just cool' temperature, avoiding 'ice cold' to prevent reflex vasoconstriction.
- Maintain cooling for approximately 2-3 minutes during each rest period to maximize heat loss.
- This protocol allows for increased work volume (more reps, more sets) and leads to conditioning adaptations and strength gains.
Crude Palmar Cooling for Performance (Experimental)
Dr. Craig Heller and Andrew Huberman- Obtain a cold pack, such as a package of frozen peas or blueberries.
- Hold the cold pack in one hand, then switch it to the other hand during rest periods or when feeling overheated.
- Periodically assess if your palms feel cool to the touch by someone else. If it feels cold, it indicates vasoconstriction, which is counterproductive.
- If the palm feels warm, it means hot blood is still flowing, allowing for heat transfer. Aim for a 'cool' sensation without the hand becoming 'cold' to the touch to indicate optimal heat transfer without constriction.