Therabody’s Palm Cooling Technology Improves Resistance Training Performance, Study Shows

At the baseline visit, athletes completed a 10RM seated overhead press test. That value was used to estimate their one-repetition maximum (1RM), and all experimental sessions were performed at 85% of that estimated 1RM. Repetition performance at high percentages of 1RM typically declines across sets as fatigue accumulates. [12] 

During each experimental session, athletes performed four sets of seated overhead press to failure, with 2.5 minutes of rest between sets.  

Repetitions were defined as full range of motion without assistance. Athletes were instructed to complete as many repetitions as possible but were not cued to move the bar at maximal speed. 

 Table 1. Study protocol

Cooling vs. control condition 

Before the first set and during every rest interval, athletes held a device using cryothermal® technology in both palms for the full 2.5-minute rest period. 

• In the cooling condition, the device was set to 12°C (53.6°F). 
• In the control condition, the device was placed on the palms but not turned on, remaining thermoneutral. 

Earlier palm cooling studies relied on water-based or larger systems that are harder to control and less practical in real training environments. In this study, researchers used a cooling (Peltier-based) device set to 12°C (53.6°F).  

Cooling was applied only during rest periods, not during the lift, and did not extend the workout or alter the prescribed load or rest duration. Practically, this means you can apply cooling during your normal rest period — without adding extra time, changing your weight selection, or altering your workout structure.  

“A key strength of this study is that it evaluated palm cooling within a realistic, high-performance training environment,” says Bailey McLagan, PhD(c), a doctoral student at the University of Southern California and investigator on the study. “Thermoelectric cooling allows for precise, repeatable temperature delivery directly to the palm. That level of control — maintaining a consistent 12°C stimulus during each rest interval — is difficult to achieve with traditional cooling modalities.” 

What researchers measured 

Researchers assessed: 

• Total work volume (load × sets × reps)
• Repetitions performed per set until fatigue
• Rating of perceived exertion (RPE) using the 11-point OMNI scale. [13] 
• Grip strength before and after the session 
• Bar velocity loss using a velocity-based training device 

Velocity loss is commonly used as an indicator of neuromuscular fatigue during resistance training. [14] Movement velocity also reflects relative loading intensity. [15] More recent research supports its sensitivity in detecting acute fatigue during multi-repetition resistance exercise. [16] 

Researchers also checked whether simply repeating the workout influenced performance (learning, order, or carryover effects). They found no evidence that results were affected by learning or by which condition athletes completed first. 

Palm cooling increased total work volume by 28%

Athletes completed 28% more total work during the cooling condition, which was significant compared to control.  

Because the load and number of sets were identical in both conditions for each athlete, the difference was driven by the ability to perform additional repetitions before reaching fatigue. 

“What stood out most was how consistently participants were able to maintain performance across sets when palm cooling was used,” says Jake Heydon, Master’s student at USC and lead investigator. “Rather than seeing the typical decline in repetitions or total work as fatigue accumulated, performance was better sustained throughout the session. This suggests the intervention didn’t just provide a small boost, but meaningfully influenced how fatigue developed during the workout, both in terms of performance outcomes and perceived effort.” 

Key takeaway: Total training volume supports muscle growth. The athletes in this study were able to sustain a higher effort during a session, potentially contributing to the higher-quality work that builds muscle.  

Athletes performed significantly more repetitions — especially in later sets when fatigue typically sets in 

Athletes consistently completed more repetitions per set during the cooling condition compared to control. In fact, the gap between repetitions completed widened in the later sets between the conditions. Compared to thermoneutral control, on average, participants completed: 

• 14% more repetitions in set one
•  24% more repetitions in set two 
• 31% more repetitions in set three 
• 58.3% more repetitions in set four 

The largest difference occurred in the fourth set, when fatigue would normally be highest.  

Key takeaway: Later sets often determine the overall quality of a resistance training session. Delaying fatigue allows athletes to maintain output during repeated high-intensity efforts, supporting training adaptation. 

Palm cooling reduced perceived exertion across successive sets

While there was no significant difference in perceived exertion during the first set (meaning both groups felt similar at the beginning of the workout), athletes in the cooling group reported significantly lower RPE in sets 2-4. 

However, in sets two through four, athletes reported significantly lower RPE during cooling: