Palm cooling is a physical technique: palms are held in cool water or on a cool surface during exercise breaks to draw body heat, aiming to improve performance. People reliably feel cooler. Evidence on strength-training volume, endurance in heat and repeated sprints splits; part of the effect appears to come from expectation. Main risks: hand pain from too-cold water; worse performance if cold feels unpleasant. Low-risk, low-cost; benefit uncertain. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Cooling-medium temperature | 10–15 °C | Too cold closes palm vessels and causes pain |
| Resting blood pressure | Below 120/80 mmHg | Cold raises blood pressure |
| Core or ear temperature in heat | No established target; rise per 10 min vs own uncooled baseline | Shows whether cooling reduces heat strain |
| Heart rate at end of rest interval | No established target; vs own uncooled sessions at same load | Marks cardiovascular strain |
| Training volume load | No established target; vs matched uncooled sessions | Main performance outcome |
| Body-mass change across session | Loss below 2% of body mass | Dehydration worsens heat performance |
Cadence: Cooling-medium temperature at every session; cooled and uncooled sessions compared at 2 and 6 weeks, then every 3 months or at each change of season