Palm cooling and heat extraction through glabrous skin have been studied for decades across academic research and educational platforms. The literature includes both supportive findings and studies that did not replicate the same effects. Below is a curated set of references with the actual results from each study.
Foundational mechanism research
Glabrous skin on the palms carries a dense vessel network built to move heat between the body's core and its surface.
Walløe, L. (2016). Arterio-venous anastomoses in the human skin and their role in temperature control. Temperature, 3(1), 92–103.
Foundational review of arteriovenous anastomoses (AVAs), the dense vessel network in the palms, soles, and face that moves blood between core and surface to regulate temperature. AVA density reaches roughly 600 per cm² in the nail beds and around 100 per cm² in the palm. The thermoneutral zone, where AVA flow alone controls core temperature, sits between 26 and 36°C. Outside that window, the body shifts to sweating or shivering.
Time to exhaustion rose 20 to 40% when palm cooling was applied between efforts in the heat.
Grahn, D. A., Cao, V. H., & Heller, H. C. (2005). Heat extraction through the palm of one hand improves aerobic exercise endurance in a hot environment. Journal of Applied Physiology.
Original Stanford research on palm cooling between bouts of aerobic exercise in hot conditions. Time to exhaustion increased by 20 to 40% when palm cooling was applied between efforts, with a slower rise in core temperature and a lower rate of perceived exertion at equal workloads.
Cooling the glabrous skin of the palms, soles, and cheeks lowered core temperature almost twice as fast as cooling the neck, groin, and armpits.
Lissoway, J. B., et al. (2015). Novel application of chemical cold packs for treatment of exercise-induced hyperthermia: a randomized controlled trial. Wilderness & Environmental Medicine, vol. 26, issue 2, 173–179.
Randomized controlled trial with 10 men walking in 40°C heat until core temperature reached 39.2°C. Cooling applied to glabrous skin lowered core temperature by 0.30°C every 10 minutes, against 0.17°C for cold packs on the traditional neck, groin, and armpit sites, and 0.12°C with no cooling. Direct evidence that the palms and other glabrous surfaces are the body's most effective route for moving heat out of the body.
Palm cooling between sets lifted three-week bench press volume gains to 40%,against 13% without it.
Grahn, D. A., et al. (2012). Work volume and strength training responses to resistive exercise improve with periodic heat extraction from the palm. Journal of Strength and Conditioning Research.
Stanford follow-up on palm cooling between sets of resistance training. Subjects gained 40% more bench press volume over 3 weeks (vs 13% in the control group), 144% more pull-up volume in trained subjects (vs 5% control), and 22% in 1-rep max bench press over 10 weeks of pyramid training.
Palm cooling between efforts lowered core temperature by about 0.5°C and extended exercise capacity.
Grahn, D. A., & Heller, H. C. (2014). Enhancing Thermal Exchange in Humans and Practical Applications. Disruptive Science and Technology.
Follow-up paper from the Stanford lab reviewing the broader applications of glabrous skin cooling during strength and endurance training. Reports approximately 0.5°C reduction in core temperature with palm cooling between efforts, leading to extended exercise capacity and improved recovery between work bouts.
Performance research
Palm cooling produced roughly 20% better performance and faster recovery, and was adopted by Stanford and pro teams.
Stanford University (2012). Stanford researchers' cooling glove 'better than steroids' for athletes. Stanford Report.
Coverage of the Stanford palm cooling research and its adoption by Stanford athletics, the San Francisco 49ers, the Oakland Raiders, and Manchester United. Reports approximately 20% performance improvement during activity using palm cooling, alongside significantly faster recovery between efforts.
Palm cooling between sets sped up blood lactate clearance and held power output into the final set of leg press.
Caruso, J. F., et al. (2015). Intermittent Palm Cooling's Impact on Resistive Exercise Performance. International Journal of Sports Medicine, vol. 36, issue 10, 814–821.
Randomized study on leg press, comparing no palm cooling, palm cooling between sets, and palm cooling both between sets and after exercise. Cooling between sets cleared blood lactate faster and slowed the drop in average power, with the cooled condition holding higher power through the fourth set. Independent support, from the University of Tulsa, for cooling between efforts to limit fatigue.
Palm cooling during rowing increased distance covered, with lower heart rate and lower blood lactate.
O'Brien, I. T., et al. (2021). Use of Gloves to Examine Intermittent Palm Cooling's Impact on Rowing Ergometry. Journal of Strength and Conditioning Research, vol. 35, issue 4, 931–940.
Study of 34 subjects completing rowing ergometer workouts with and without intermittent palm cooling, applied through gloves. The cooled workouts produced greater distance rowed, alongside lower heart rate and lower blood lactate, which the authors attribute to reduced fatigue. Extends the evidence into an endurance, repeated-effort sport.
Palm cooling between sets raised total bench press volume by about 26%, with lower perceived exertion.
Kwon, Y. S., et al. (2010). Palm cooling delays fatigue during high-intensity bench press exercise. Medicine and Science in Sports and Exercise, vol. 42, issue 8, 1557–1565.
Sixteen resistance-trained men performed four sets of bench press to fatigue, with palm cooling, palm heating, or no treatment during the rest intervals. Total training volume reached 2,480 kg with palm cooling, against 1,972 kg with no cooling, a gain of about 26%. Muscle activation was higher, and core temperature and perceived exertion were lower. An independent replication of the Stanford resistance findings, from a separate lab at the University of New Mexico.
In a randomized trial, palm cooling made the final repeated sprint 2.76% faster, with heart rate about 14 bpm lower.
Khomenok, G., et al. (2025). The Effects of Palmar Cooling on Repeated Sprinting Ability: A Randomized Controlled Clinical Trial. Sensors, 25(6), 1830.
Randomized controlled trial with 15 subjects on repeated 60-meter sprints with directional changes. Subjects using palm cooling completed the final sprint 2.76% faster, with heart rate roughly 14 bpm lower at the end of recovery, and reported significantly less delayed-onset muscle soreness 48 hours after testing.
Cooling the hands and forearms at half-time raised second-half power output, with core temperature down 0.54°C.
Maroni, T., et al. (2023). Cold water immersion of the hand and forearm during half-time improves intermittent exercise performance in the heat. Frontiers in Physiology.
Randomized crossover study with 11 active men cycling in 33°C heat, with hands and forearms immersed in 15 to 17°C water during a 15-minute break. Mean power output in the second half was significantly greater than control. Rectal temperature dropped by 0.54°C, heart rate dropped by 16 bpm, and skin blood flow decreased by approximately 40%.
Mixed and contradictory findings
No significant improvement in running performance from palm cooling.
Hsu, A. R., et al. (2013). Palm cooling does not improve running performance. International Journal of Sports Physiology and Performance.
Study finding no statistically significant improvement in running performance with palm cooling. Included for honest representation of the field. The likely reason, supported by later work, is that palm cooling is most effective in repeated-effort or high-thermal-load contexts rather than continuous running.
No significant effect of palm or sole cooling on resistance training volume.
Adams, W. M., et al. (2024). No Effect of Intermittent Palm or Sole Cooling on Acute Training Volume during Resistance Exercise in Physically Active Adults. Sports, 12(10), 281.
Study finding no statistically significant effect of palm cooling on resistance training volume in active adults. Included for transparency. The authors note that protocol differences (cooling temperature, duration, and timing) compared to earlier Stanford studies may explain the difference in results.
Educational discussions
Episodes covering the glabrous skin cooling mechanism and its use for recovery and performance.
Huberman, A. (2021–present). Huberman Lab Podcast.
Several episodes discuss glabrous skin cooling, the AVA mechanism, and applications for performance and recovery. Notable discussions on how palm cooling can be used to support recovery and training capacity, with references to the Stanford research and practical protocols for athletes.
Our internal testing
In addition to the published literature, we have run our own athlete testing across several sports, including HYROX, CrossFit, hockey, and endurance running. So far it shows up to 50% deeper heart rate recovery between efforts, measured by comparing the same sessions with and without KYLA at a matched pace and workload. An early blood lactate reading points the same way, up to 25% lower at a matched workload, but it is a single result we are now testing at scale. This is our own testing, not independent research. The full methodology and results are updated continuously as more data comes in.
