Increase Strength Gains by 100-200% By Keeping Your Hands Cool

When it comes to your muscles performing optimally, its heat is often an underrated component.

An excessively hot muscle has a diminished capacity to produce force.

The body can reduce a muscle’s temperature by circulating blood to it, extracting the heat, and dispersing it around the rest of the body.

However, this cannot continue forever.

As the overall body temperature rises, the circulating blood to the muscle becomes ineffective at heat removal, simply because the circulating blood itself is high in temperature.

Glabrous skin regions, particularly the soles of the feet and palms of the hand, due to having a unique vascular structure, are an effective region to cool down the overall body temperature.

Put simply, cooling the palms of the hand or soles of the feet can decrease the temperature of circulating blood.

Based on all of this information, cooling these glabrous skin regions between your sets on an exercise can cool down the circulating blood, allowing it to be more effective at removing heat from the muscle, thereby potentially facilitating an increase in muscle performance.

The Research on Palm Cooling

An extremely fascinating study by Grahn et al. evaluated how much heat impacts performance, as well as if cooling your palms could improve performance and long-term strength gains.

The study comprised of three protocols, the first evaluated the former question, whereas the last two assessed the latter two questions.

Protocol 1: Heat’s Impact on Muscle Performance

Let’s start with protocol 1.

In one session, subjects ran on a treadmill in a hot environment until their core temperature reached 39°C. 3 minutes after finishing the treadmill run, subjects performed 4 sets of barbell bench press repetitions to failure with a 40% one-rep max load, using 3 minutes of rest between sets.

In this session, across the 4 barbell bench press sets, subjects performed 36 repetitions on average.

In a second session, subjects replicated the amount of work performed on the treadmill in the first session, but they cooled their palms during the run.

Their palms were cooled using a custom-made heat extraction device that circulated cool water (15-16°C) in a vacuum to the hands. Later on, we’ll explore how individuals may cool their palms without special equipment.

As a result, their body temperature was on average 38.4°C after the run.

3 minutes after the run, they again completed 4 sets of bench press repetitions to failure with a 40% one-rep max load and 3 minutes of rest between sets.

In this session, across the 4 barbell bench press sets, subjects performed 42 repetitions on average. 6 more.

In essence, the results of protocol 1 demonstrate how heat can be detrimental to muscle performance. Subjects were able to perform more repetitions with a cooler core temperature.

Now, although protocol 1 depicts how heat can negatively influence muscle performance, it does not demonstrate if palm cooling between sets could enhance performance.

Protocol 2 assesses this.

Protocol 2: Palm Cooling Between Sets

7 men with at least 2 years of pull-up training were recruited.

Subjects performed 10 sets of pull-up repetitions to failure (the point at which the subject cannot bring his chin over the bar), with 3 minutes of rest between sets, two times per week for 6 weeks.

Some subjects, throughout the 3-minute rest interval durations, cooled their palms using the special equipment.

Other subjects passively rested.

The subjects who cooled their palms between sets managed to perform an average of 13 more repetitions across the 10 sets every session.

Contrastingly, the subjects who rested passively managed to perform an average of 6 more repetitions across the 10 sets every session

Put differently, palm cooling in-between pull-up sets just over doubled subjects repetition performance.

Similar findings were also seen with the barbell bench press.

17 men performed the barbell bench press for 6 sets of repetitions to failure with a 50% one-rep max load, using 3 minutes of rest between sets, twice per week for a total of 5 sessions.

I should mention that the load used remained the same throughout the 5 training sessions. That is, the 50% one-rep max load was no adjusted.

Some subjects, throughout the 3-minute rest interval durations, cooled their palms using the special equipment.

Other subjects passively rested.

The subjects that cooled their palms between sets performed 62 repetitions across the 6 sets in the first session on average. By the fifth session, they were performing 86 repetitions across the 6 sets on average.

Opposingly, the subjects that rested passively between sets performed 53 repetitions across the 6 sets in the first session on average. In the 5th session, they only increased up to 60 repetitions across the 6 sets on average.

Again, palm cooling in-between sets resulted in a significantly increased repetition performance over a few sessions.

Now, one would assume this increased repetition performance facilitated by palm cooling between sets should also improve strength gains over the long term. Protocol 3 aimed to verify this.

Protocol 3: Long Term Impacts of Palm Cooling on Strength

10 men who had reportedly plateaued on the bench press trained the barbell bench press twice per week for 10 weeks.

They performed 6 pyramid sets with 3 mins of rest between sets each session. The pyramid sets were as follows:

  • Set 1: 10 reps with a 40% one-rep max load
  • Set 2: 7 reps with a 60% one-rep max load
  • Set 3: 4 reps with an 80% one-rep max load
  • Set 4: 2 reps with a 95% one-rep max load
  • Set 5: 5 reps with a 60% one-rep max load
  • Set 6:10 reps with a 40% one-rep max load

If subjects successfully performed 2 repetitions on the 4th pyramid set, the load was increased by 2.7kg for all pyramid sets in the following training session.

Some subjects, throughout the 3-minute rest interval durations, cooled their palms using the special equipment.

Other subjects rested passively.

The subjects that cooled their palm between sets were initially using an average 97kg load on the 4th pyramid set. By the last session of the study, they were using an average 110kg load on the 4th pyramid set.

The subjects that rested passively between sets appeared to have remained plateaued as no strength gains were observed. They were initially using an average 97kg load on the 4th pyramid set, and by the last session of the study, they were still using an average 97kg load on the 4th pyramid set.

Therefore, the use of palm cooling between sets was effective for increasing bench press strength in plateaued subjects, while passive rest was ineffective.

Collectively, the three protocols in this fascinating study demonstrate how heat negatively impacts muscle performance and how palm cooling can effectively increase work volume and long-term strength gain.

Extra Research

There are other studies also supporting the idea that palm cooling can benefit performance.

Kwon et al. had 16 men with at least 5 years of training experience perform the barbell bench press for 4 sets of repetitions to failure with an 85% one-rep max load and 120 seconds of rest between sets.

Repetition performance across the 4 sets was greater when subjects cooled their palms between sets, using special equipment that subjected the palms to cool water (10°C), compared to palm heating (45°C water temperature) or a neutral temperature condition.

Moreover, the same research group carried out this exact study design in 8 women with at least 5 years of training experience.

The results were the same. That is, palm cooling between sets resulted in greater bench press repetition performance versus palm heating or a neutral temperature condition, except for the last set.

How to Cool Your Palms Without Equipment

Now, in all of the protocols and studies detailed, special equipment was used to cool the palms.

Theoretically, if you can access something that is around 10-15°C, placing your palms on it between sets may itself suffice.

For instance, you could fill and bucket with water at a temperature of 10 to 15°C, and place your hands in it between sets. You would then of course dry your hands before beginning the next set.

Indeed, Caruso et al. found this method to still be beneficial.

They had 35 individuals perform 4 sets of 8 reps on a leg press ergometer with 120 seconds of rest between sets.

Greater average power output across sets 3 and 4 on the leg press ergometer was observed when subjects placed their hands in a 15°C temperature water bath between sets compared to passively resting.

Temperature Is Likely Important

Now, it’s important to mention that you do not want to expose your palms to something excessively cold.

Excessive cold temperatures will likely result in constriction of blood vessels, preventing the cool blood from being circulated throughout the body.

A 10 to 15°C temperature is likely cold enough to reduce circulating blood temperature, but at the same time avoid constriction of blood vessels, successfully enabling the cooler blood to flow throughout the body and extract heat from muscles.

Therefore, excessively cold ice packs will likely not work.

Confirming this, Esteves et al. had 9 men with at least 6 months of training experience perform the biceps curl for 4 sets to failure with an 80% one-rep max load and 1 minute of rest between sets.

Repetition performance was similar when subjects rested passively or applied an ice pack, that was stored at -17°C before its use, to the palms between sets.

Now, if you can get an ice pack to roughly 10 to 15°C, that should probably work

Perhaps you freeze it but leave it at room temperature until it reaches a 10 to 15 temperature. But, I’m unsure how practical this is.

However, another potential method is passing an excessively cold object back and forth between your hands.

Although freezing ice packs may be too cold to make contact with your palms throughout the full duration of your rest interval, you could pass it back and forth between your hands. Doing this might prevent your palms from freezing up to the point of vasoconstriction.

Although, I’m not aware of any data supporting this idea.

Ultimately, if palm cooling between sets interests you, I recommend trying it out with anything you can think of and see if you notice any observable improvement.

Palm Cooling and Muscle Growth?

All the research in this article demonstrates palm cooling can benefit work volume and long-term strength gain.

Unfortunately, I don’t believe there are any studies exploring the impacts of palm cooling between sets on muscle growth.

Theoretically, the increased work volume may translate into greater muscle growth, but, it’s difficult to say without research.

Hopefully, we get future studies exploring the impacts of palm cooling between sets on muscle hypertrophy.

Discussion on Palm Cooling Mechanisms

As we’ve mentioned, an excessively hot muscle has a diminished capacity to produce force.

But, why is this the case, and why can palm cooling improve muscle performance?

There were 3 interesting potential mechanisms put forth in the Grahn et al. study.

1) Central govenor model. This proposes that an increase in core temperature results in decreased nerve signals from the brain to muscles. Therefore, decreasing core temperature (via palm cooling) maintains nerve signals from the brain to muscles, facilitating muscle performance.

2) An increased core temperature reduces cardiac output (blood pumped from the heart), resulting in a decrease in oxygen supply to the muscle, decreasing muscle performance. Therefore, decreasing core temperature (via palm cooling) maintains cardiac output and hence oxygen supply to the muscle, facilitating muscle performance.

3) Pyruvate Kinase. This is an enzyme that plays a crucial role in generating ATP. ATP provides energy for muscle contraction.

There is evidence hot temperatures (40°C) cause this enzyme to transition into an inactive state. Consequently, ATP production, and by extension, muscle contraction are reduced.

As palm cooling decreases a muscle’s temperature, this allows the enzyme to function in its active state, enabling ATP production and hence muscle contraction.

All 3 of these potential mechanisms have their strengths and weaknesses. At this time, I don’t believe any of them are for certain, but it is interesting nonetheless.

Further Question: Can You Just Cool the Muscle Instead of the Palms?

As we discussed, the palms are likely an ideal region to regulate overall body temperature, due to their unique vascular structure.

But, could the application of cold to the trained muscle be sufficient to cool it down and increase performance?

Unfortunately, the two studies I came across exploring this are conflicting.

Interestingly, one paper (Galoza et al.) found that applying an ice pack to the biceps between bicep curl sets did result in an increased repetition performance compared to resting passively.

However, another study (Esteves et al.) found no difference in repetition performance between applying an ice pack to the biceps between sets and passively resting.

In total, it’s unclear if cooling the working muscle directly offers a benefit.

RECEIVE 2 INFOGRAPHICS WEEKLY SUMMARIZING VARIOUS HYPERTROPHY AND STRENGTH RELATED RESEARCH PAPERS ↓

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