In early research on palm cooling, sub-atmospheric pressure (vacuum) was introduced as a way to enhance blood flow to the palms by preventing vasoconstriction. The original application was a clinical context for anesthesiology, in which patients were frequently in a state of hypothermia, where blood vessels are reflexively constricted and peripheral circulation is reduced. The vacuum was intended to mechanically open AVAs (arteriovenous anastomoses) to facilitate warming.

However, this rationale does not apply to exercise-induced heat stress, where vasodilation is the natural default. During hyperthermia and intense physical activity, the body already routes warm blood to glabrous skin surfaces for heat dissipation. This means the very need that vacuum was designed to solve does not exist in typical athletic cooling scenarios.

Literature Review

Kuennen et al. (2010), who compared palm cooling with and without vacuum following exercise in extreme heat (42°C), observed that a vacuum did not influence the effectiveness of palm cooling. Their results showed:

• • Palm cooling alone reduced core temperature (~0.4°C)
  • Adding vacuum provided no additional benefit

Many studies concluding positive performance effect of palm cooling did not utilize a vacuum, further validating that sub-atmospheric pressure is not required for successful heat transfer. The primary contributing variables are based on the thermodynamics of heat transfer:

• • Sufficient contact time
  • High thermal conductivity
  • Adequate surface temperature differential (typically 10–20°C)
  • Targeting glabrous zones (palms, fingers, thenar/hypothenar eminences)

Key Takeaway for Palm Cooling

The inclusion of a vacuum is not necessary for palm cooling to be effective during exercise. There are no negative outcomes associated with the inclusion of the vacuum, making it a neutral variable for efficacy. Proper temperature control, anatomical targeting, and heat sink capacity are more critical variables.

References

• • Kuennen, M. R., Gillum, T. L., Amorim, F. T., Kwon, Y. S., & Schneider, S. M. (2010). Palm cooling to reduce heat strain in subjects during simulated armoured vehicle transport. European journal of applied physiology, 108(6), 1217–1223. https://doi.org/10.1007/s00421-009-1335-8