Introduction
Heat is one of the biggest hidden barriers to athletic performance. Whether in endurance sports, strength training, or high-intensity intervals, the body’s rising core temperature triggers fatigue, reduces power output, and slows recovery. Traditional cooling strategies like ice baths, cold towels, and cooling vests are bulky, slow, and impractical during training or competition.
cryo is a handheld palm-cooling device that targets the palm’s arteriovenous anastomoses (AVAs) to rapidly lower core body temperature. The approach is grounded in peer-reviewed research and built for real-world use.
Why the Palm?
- The palms contain high densities of AVAs, specialized blood vessels that act as the body’s natural radiators.
- When cooled, AVAs transfer heat from the blood to the environment, accelerating core cooling.
- This mechanism is more effective than cooling muscle tissue or skin regions with limited blood flow.
The Science: Palm Cooling Studies
Grahn et al. (2005) – Endurance in the Heat
Summary: Tested whether extracting heat through a single palm could extend aerobic exercise in hot conditions. Endurance increased by about 46% when palm cooling was applied compared with no intervention.
Methodology: Participants walked uphill on a treadmill in a 40°C environment while esophageal temperature and time to exhaustion were measured. A heat sink set to approximately 18–22°C was applied to the palm with mild vacuum to enhance AVA blood flow. Cooling slowed the rise of core temperature and significantly extended exercise duration.
Grahn et al. (2012) – Strength and Work Volume
Summary: Examined whether palm cooling between sets could improve resistance training outcomes. Work volume increased by 40–144% depending on exercise, and 1-rep max strength rose by 22% over 10 weeks when palm cooling was used in training.
Methodology: Participants completed bench press and pull-up programs with palm cooling applied for 3 minutes between sets. By reducing core heat load, cooling delayed fatigue onset and enabled higher training volumes and greater strength gains compared with control conditions.
One Palm vs Two Palms
Some laboratory setups use large, benchtop equipment that can cool one or both palms and may add mild vacuum to maximize blood flow through AVAs. cryo focuses on a single-palm application so athletes can access the benefits without bulky hardware. The endurance study above demonstrated that efficient heat removal and meaningful performance gains are achievable using a single palm. Dual-palm setups can increase total heat exchange surface area, but a single-palm approach already delivers substantial benefits in portable form.
Real-World Applications
- Endurance sports: Runners, cyclists, and triathletes can extend performance in heat without overheating.
- Strength training: Cooling between sets delays fatigue, enabling higher training volumes that drive faster progress.
- Team sports: Faster recovery during breaks helps reduce late-game performance drop-off.
- Field use: Military and tactical users have adopted palm cooling to sustain output in extreme heat.
Why Cryo-1
Cryo-1 translates lab-proven AVA cooling into a portable device:
- Temperature settings: 12°C, 14°C, 16°C
- Time to target: reaches set temperature in under 1 minute (up to 100°F ambient)
- Battery life: about 80 minutes
- Form factor: handheld, approximately the size and weight of a soda can
Conclusion
Heat is an underrated limiter in sport. By targeting the body’s natural heat-release valves in the palm, cryo helps athletes push harder, recover faster, and train smarter. Palm cooling is a practical, science-backed method to manage core temperature and unlock more of your performance potential.
