Palm Cooling Explained
Palm cooling is a proven method for accelerating recovery during competition, mitigating heat stress, and improving strength gains. It is used to extend time to exhaustion, increase high quality training volume, and cool down when it matters most. It is odd (but awesome!), so let’s explain the physiology at play.
When we exert ourselves, we generate heat, which leads to fatigue.
Heat causes fatigue by:
- Increasing core body temperature which results in an elevated heart rate
- Sending more blood to the skin surface, leaving less available for fueling muscles
- Inhibiting an enzyme (muscle pyruvate kinase) required for our muscles to produce energy
- Intensifying perspiration which causes a loss of electrolytes
Our palms are like radiators for our body.
Our palms, cheeks, and soles of the feet contain vasculature called arterio-venous anastomoses (AVAs), which are responsible for full body temperature control. These special vessels are direct connections between arteries and veins. When we get hot, these areas can experience up to 10X the blood flow compared to other skin areas.
By cooling your palms, you cool your blood, which cools you down systematically.
The trick is to remove as much heat as possible without inducing vasoconstriction of the AVAs. So, it is not as simple as holding ice (that would cause vasoconstriction). To turbo charge this naturally occurring system, follow the 3Cs of palm cooling:
- Cool-not-Cold: Hold something that is cool, not cold. The therapeutic range for effective palm cooling is 50-60°F (10-15°C). Below 50°F, most people’s AVAs will vasoconstrict, preventing the necessary blood flow. Above 60°F, heat transfer is reduced and the effect is diminished substantially.
- Conductive: Your palm should be in contact with a material that has excellent heat transfer capabilities. This requirement is one of the reasons why we use heat pipes which have 100X the thermal conductivity of copper.
- Continuous: Heat flows from hot to cold. A palm cooling device should provide a mechanism for continuous cooling to maintain the temperature gradient between your hand and the device.
Palm cooling protocols for different use cases
Your use case dictates how long you should hold a palm cooling device.
- In-games and practices: 1 to 3 minutes of cooling reduces heart rate and extends a player’s ability to sustain a higher intensity of play longer.
- Heat stress mitigation: 10 minutes of palm cooling has been shown to reduce core body temperature by ½ a degree celsius. Depending on the conditions, 5 to 10 minutes of cooling can reduce occupational or athletic heat stress.
- Resistance training: 2-3 minutes of cooling between working sets of resistance training exercises delays muscular fatigue and enables more sets and reps which contributes to faster strength gains. You will feel a sense of freshness that persists throughout your working sets.
- Pre-race cooling and down regulation: These use cases have been less studied, but elite athletes report benefits from palm cooling after warming up before a race starts, as well as, after intense games and practices to transition back to a calmer state.
A long-lasting palm cooling device that works in the toughest conditions
We designed the Narwhals, our palm cooling device, to maintain a surface temperature of ~55°F (13°F) for several hours even when ambient temperatures are extremely hot. It has no moving parts and nothing to charge.
The “tusks” or handles are made of heat pipes which are a seriously cool technology used to dissipate heat. The heat pipes provide that critical mechanism for continuous cooling and avoiding the formation of a thermal barrier between your palm and the device.
Inside you place our reusable “Cool-not-Cold” packs which have a freezing point above that of ice and a little bit of cool water. Set up takes under a minute and provides you with 2+ hours of palm cooling.
The Narwhals are used by Olympians, Paralympians, D1 athletic programs, and every major professional sport in the U.S. and beyond.
Dive deeper into the science of palm cooling
There is a growing body of peer-reviewed research on palm cooling for heat stress mitigation and athletic performance. Here are some of the studies that have been published:
- Heat loss through the glabrous skin surfaces of heavily insulated, heat-stressed individuals
- Work volume and strength training responses to resistive exercise improve with periodic heat extraction from the palm
- Heat extraction through the palm of one hand improves aerobic exercise endurance in a hot environment
- Use of Gloves to Examine Intermittent Palm Cooling's Impact on Rowing Ergometry
- Active versus passive cooling during work in warm environments while wearing firefighting protective clothing
If you have questions about palm cooling, reach us at hi@apexcoollabs.com or chat with us!
