Reviewed by John Baur, PT, DPT, OCS, CSCS, FAAOMPT
This article examines whether cooling the palms of the hands or the soles of the feet between sets (“interset distal cooling”) enhances resistance‑training (RT) performance. The authors focus on both mechanistic rationales and experimental evidence, ultimately finding mixed results and notable methodological limitations across the literature.
Proposed mechanisms
Two broad mechanism families are discussed. First are neural/perceptual mechanisms: several experiments report greater EMG amplitude, lower ratings of perceived exertion (RPE), and/or higher perceived arousal with interset cooling; these outcomes have led to the hypothesis that cooling may augment central nervous system (CNS) drive, increase motor‑unit recruitment, reduce sensations of distress, and thereby permit more work to be performed in subsequent sets.
Second are temperature‑related mechanisms, grounded in the high density of arteriovenous anastomoses in glabrous skin (palms/soles) that promote heat exchange. Distal cooling can reduce core temperature during endurance work and might also lower blood temperature delivered to working muscles, benefiting temperature‑sensitive enzymes (e.g., pyruvate kinase) and limiting lactate accumulation, which could help sustain contractile function. The authors note, however, that short, high‑intensity RT bouts (e.g., heavy bench press) in thermoneutral settings rarely produce large core‑temperature rises, making temperature‑centric explanations for RT less clear.
Evidence for palm cooling
Early bench‑press studies by Kwon et al. used 2.5‑min interset palm treatments at 10 °C (cooling), 45 °C (heating), or 22 °C (thermoneutral), finding higher total volume, lower RPE during one set, and greater EMG activation in synergists (e.g., triceps) with cooling (pectoralis major EMG showed no difference). Collectively, these findings suggest interset palm cooling may acutely increase volume capacity and some muscle activation.
In contrast, McMahon et al. used shorter applications—1 minute of 10–15 °C cooling within a 3‑min interset rest—and reported no differences in volume, EMG, or other outcomes versus thermoneutral control. The review highlights duration (1 min vs 2.5 min) as a key methodological difference and notes that despite different application strategies, the mean palm temperatures during rest were similar (~22 °C), muddying the interpretation of why results diverged.
The review also synthesizes physiological indices across five studies (Caruso; Kwon; McMahon & Kennedy): heart rate showed no between‑condition differences with palm cooling. Blood lactate responses are inconsistent—some work showed lower lactate with cooling in a concentric‑only flywheel leg press (Caruso), while others found no differences. These inconsistencies weaken simple global physiological explanations for improved reps to failure.
Longer‑term evidence is scarce but notable. Grahn et al. reported faster pull‑up improvements in both trained and untrained subjects and a 22% bench‑press 1RM increase in plateaued lifters after switching to interset palm cooling. Yet the review flags serious limitations: no random allocation to starting conditions, unclear control of outside training, absent washout periods, and an uncontrolled pre/post 1RM comparison during a multi‑phase design. These concerns limit causal inference.
Evidence for sole (foot) cooling
Cai et al. used 2.5‑min 10 °C foot immersion between sets of heavy leg press and found more repetitions across the final three sets and higher vastus lateralis EMG with cooling, suggesting improved lower‑body volume capacity under these conditions.
Similarly, Wu et al. reported ~7% higher 1RM leg‑press load with interset foot cooling and higher perceived arousal and EMG in final sets. However, the review notes a key limitation: strength testing was built around a predicted 1RM and only three attempts, raising issues about whether a true 1RM was reached and opening the door to day‑to‑day learning effects across separate sessions.
In contrast, Garg & Batra used ice packs (∼10.8 °C) on the soles between sets of back squats and found no differences in total volume or quadriceps EMG vs control, despite ~18% lower RPE with cooling. The article points out that the very low average RPEs cast doubt on whether sets were actually to failure, and that ice packs introduce temperature‑control problems compared with circulating‑water devices or ice‑maintained buckets.
Methodological issues and EMG normalization
A major theme is heterogeneity in cooling modalities (glove devices, water baths, buckets, ice packs), application durations (1–3 min), and EMG normalization strategies. Most studies normalized EMG differently; the review notes MVICs are generally considered superior to DMVCs for normalization because they are more likely to maximally activate the involved musculature, though a recent review found slightly better reliability for DMVCs in weighted tasks. Only McMahon et al. reported reliability statistics and used MVICs; Kwon’s approach—comparing a single early rep vs a single late rep—also raises concerns given high EMG variability under fatigue.
The authors also caution that many trials did not blind participants; with water baths or glove devices, placebo effects are possible unless a sham temperature (e.g., thermoneutral) is used in a blinded fashion for both participants and investigators. Some recent work did blind both groups; the review encourages this approach going forward.
Practical takeaways
Across studies summarized in Table 1 (pp. 719–722), interset distal cooling at 10–15 °C for about 2–3 minutes sometimes improved acute volume capacity and, in limited longitudinal data, maximal strength; however, contradictory findings and design limitations warrant skepticism about consistent ergogenic effects. The authors advise that coaches and athletes may experiment with distal cooling because it appears safe and does not impair dexterity, but they should temper expectations and prioritize well‑designed future research that uses standardized devices, application durations, proper EMG methods, and blinded conditions.
- What has been found in studies that employed interset cooling?
Answer: A. Greater electromyography amplitude. Several studies observed higher EMG amplitude, lower RPE, and/or higher arousal with cooling vs noncooling.
- What is theorized to occur as a result of interset cooling?
Answer: B. Restricted lactate accumulation during resistance exercises. Distal cooling may limit lactate buildup, helping sustain contractile function (though findings are mixed).
- What was the primary difference in methodology between Kwon et al. and McMahon et al.?
Answer: B. McMahon et al. used a shorter duration for the palm cooling group. Kwon: 2.5 min at 10 °C; McMahon: 1 min within a 3‑min rest.
- What effect on heart rate was found between palm cooling and nonpalm cooling across five previous studies?
Answer: A. No difference was found between conditions. Across studies by Caruso, Kwon, and McMahon & Kennedy, HR did not differ between conditions.
- What methodological concern was found in the Grahn et al. pull‑up studies?
Answer: C. There was no random assignment to starting conditions. Additional concerns include absent washout and unclear control of external training.
- What was the effect of sole cooling on leg‑press performance?
Answer: A. More reps were performed across the final three sets in the cooling condition. Cai et al. reported more repetitions and higher VL EMG with foot cooling.
- What cooling method did the Garg and Batra study use?
Answer: C. Ice packs. The study applied ice packs to the soles, which may have introduced temperature‑control issues.
- What limitation was present in the Wu et al. study?
Answer: B. Maximal strength testing was based on predicted 1RM. The design allowed only three attempts, potentially missing a true 1RM and inviting learning effects across days.
- Why are MVICs more generally accepted as superior to DMVCs for EMG normalization?
Answer: A. Greater likelihood of maximally activating the involved musculature. (While some reliability data favor DMVCs, MVICs are broadly accepted in this context.)
- What recommendation is given for future research to rule out placebo confounding?
Answer: B. Blinding of conditions. Use sham/thermoneutral temperatures and blind both participants and investigators when possible.
References:
Burke R, McMahon G, Schoenfeld BJ. Cooling Down to Level Up: Does Interset Palm or Sole Cooling Enhance Resistance Training Performance? Strength Cond J. 2024;46(6):714‑724.