Exploring Mechanisms Contributing To Performance Enhancements With Palmar Cooling During Resistance Training

Palmar cooling is a technique that increases fatigue resistance within resistance training modalities by placing the palm of the hand in cool water during resting periods between sets. PURPOSE: To assess proposed neural control and local temperature factors associated with fatigue attenuation when using palmar cooling. METHODS: Four subjects completed a calf raise protocol and were analyzed to date: two males and two females, mean ± 1SD: 20 ± 1.22 years. A repeated measures design was utilized consisting of cooling (C) or non-cooling (NC) sessions. Each session included a warmup followed by four working sets targeting an estimated 10 repetition maximum of loaded calf raises per set. During the C session, subjects placed their hand into a tub of 12-15 °C water during the three-minute rest period between working sets with NC sessions consisting of only quiet rest. H-Reflex was measured after the warmup and following the final working set of repetitions to failure. H-Reflex amplitude was normalized to a percentage of maximum M-wave. Local skin temperature of the calf was measured following each working set. Repetitions to failure and relative H-Reflex amplitude were analyzed using Paired Samples T-tests. Calf skin temperatures were analyzed using a Two-way repeated measures ANOVA. RESULTS: Repetitions to failure for the final working set were not significantly different (p = 0.239); C session (16.67 ± 3.16 reps) vs NC session (14.50 ± 0.577 reps). A large effect was observed for the repetition difference between C and NC sessions (Cohen’s d = 0.953). H-Reflex changes were not different between sessions (p = 0.801) with a small effect (NC 86.95% ± 0.125; C 83.5% ± 0.144; Cohen's d = 0.256). No significant differences were observed in calf temperatures between the C and NC sessions (p = 0.314). A significant main effect of time on temperature was observed, indicating skin temperature increase throughout both exercise sessions over time as expected (p = 0.001). CONCLUSION: Palmar cooling had a large effect on the number of loaded calf raise repetitions to failure but no effect on calf skin temperature. Palmer cooling did not effect the change in H-reflex amplitude compared to no cooling with resistance exercise to failure.