Should we be Cooling down during Warm-ups?

warning Misunderstanding about Warm-Ups

We have spent decades thinking warming up is literally about warming up the body and muscles. Specifically increasing muscle temperature, initiating metabolic and circulatory adjustments, as well as preparing psychologically for the upcoming task. There is an assumption that warm muscles and warm core temp will optimise performance. This comes from lab studies showing that an increase in muscle temperature increases the rate of force development and relaxation without modifying the peak tension (figure).

So far so good, but there are some problems with this observation. An increase in torque has not been consistently observed in vivo, i.e. outside the lab. Second, the effect is also not really seen at normal ambient temperatures (15–25°C). Further, the effect is likely to be reversed in hot temperatures… i.e. warming up above 25°C may actually be detrimental!

Why so? Muscle temp is only one variable determining performance. Also important are CORE temp, skin temp, and even brain temperature. For example, when warming-up in hot and/or humid ambient conditions, a classical warm-up risks an increase in thermal and circulatory strain.

In hot conditions, fatigue has been shown to be less reliant on high absolute core temperature, but more dependent on hot skin temperature (> 35°C) (or perhaps it’s 50:50); because fatigue can occur at relatively low core temperatures of approximately 38.5°C linkLatzka, 1998.

Performance impairment can of course occur in both cold and hot environments and is partly related to a modification in neural drive. The amount of voluntary neural drive is reduced with hyperthermia as a protection mechanism whereas in cold temperatures there is also a decline in coactivation and coordination.

So, today I am asking should we be undertaking efforts at cooling (not warming) during warm-ups? In a more sophisticated model, I am asking should we be warming muscles, but keeping core temp and skin temp cool?

Time to look at the evidence…

ac_unit What is Pre-Cooling?

In hot conditions, it is likely gains can be made from pre-cooling during warm ups. This effect can be achieved from:

• Wind (fans)
• Cool drinks (or ice)
• Menthol mouth wash (mainly tested during event)
• Head cooling
• Cool jackets

Clearly, the degree and duration of effect will vary, and it is also possible to combine cooling strategies. But the most basic question is how do these compare to each other, and to no-precooling (but with warm up)… in fact we could have these comparisons…

Also the usual question is…

Usual warm up 🆚 warm up with pre-cooling in hot conditions

but I would also like to know

Usual warm up 🆚 warm up with pre-cooling in normal conditions

I suspect there are gains to be made there, but so far I can only find the first type of studies (i.e. hot conditions… although each study does vary the temp quite a bit).

science Some Individual Studies

linkLevels et al. asked 10 athletes to do four 15-km time trials (@30°C) either using warm-up or warm-up with cooling (30m scalp cooling) or just cooling (ice ingestion + scalp cooling). This is what they found:

Pre-cooling had a modest but a significant effect on event skin temp and core temp… and Power output was lower for WARM-UP alone than for cooling alone with warm up+cooling in the middle. So in this case, a normal warm-up alone was the worst option.

A similar result was found by linkAl-Horani et al., 2018. In this study, 9 athletes completed three 16.1-km time trials @33°C after: precooling (ice slurry and ice vest) alone; warm-up alone. Results over 16km were as follows:

• Cooling alone = 31.9 min
• COMBO = 32.6 min
• Warm-up alone = 33.1 min

And again, the same story comes from this study from linkFaulkner et al. who asked 10 cyclists to do a time trial on three occasions in hot (35°C) with a pre-event cooling jacket vs warm-up alone.

So these three studies all say warming up is detrimental and somewhat rescued by pre-cooling.

But 😲 shock, horror cooling 😲 alone without a warm-up at all might be best!!

However, I note that the benefits of pre-cooling are less effective in short sprints; even in repeated-sprints the effect may be a wash.

severe_cold I am Too Cool? 😎

Just as you can go too hot (core >40°C, skin >35°C) you can risk going too cool. Core and muscle temperatures below 37.5°C and 38°C, respectively, are associated with reduced aerobic performance and peak oxygen uptake (VO2max) linkBerg et al., 1979.

So cooling can get excessive. An example where cooling during warm-ups might be going too far includes cold water immersion. For example, 30 mins at water temperatures between 22−30°C (or just legs at 10−18°C). Such low temps are likely to have deleterious effects on nerve conduction rate and muscle contraction velocities.

analytics Meta-Analyses of Pre-Cooling

Although a large number of studies have been conducted, I have to admit they are small sized, relatively low quality in the most part. However this is where a meta-analysis will help. That’s when we bring all the studies together… but we still need a large study for sure.

In one meta-analysis linkRodriguez, 2020 found 26 studies of pre-cooling techniques (exposure to ice water, cold packs, or cooling clothes, intake of cold water or ice). Cooling prior to exercise concluded increases in distance covered (1.5–13.1%), mean power output (0.9–6.9%), time to exhaustion (19–31.9%), work (0.1–8.5%), and mean peak torque (10.4–22.6%), as well as reductions in completion time (0.6–6.5%). Mixed strategies seemed to be the most effective techniques, being directly related with the duration of cooling and showing the major effects in prolonged exercise protocols.

Next, linkRoriz, 2022 found 43 studies BUT including during event cooling (aka per-cooling)… 472 participants exercising between 22°C (106) to 38°C (131). 7 exclusively included a menthol solution mouth rinse, 30 exclusively involved ice slurry/ice slush/crushed ice/cold beverages intake, and 6 examined both the effect of thermal and non-thermal internal techniques in the same protocol.

Rinsing a menthol solution (0.01%) improved physical performance during continuous endurance exercise in the heat but mainly when taken during exercise.

Conversely, the pre-event ingestion of ice or cold beverages did not seem to consistently increase performance but co-administration of menthol with or within ice beverages seems to exert a synergistic effect by improving physical performance.

device_thermostat What About Acclimatisation?

These results apply to athletes exercising in hot environments who are not acclimatised to the heat. If you are acclimatised then skin temperature increases more slowly, as you sweat earlier than less-trained individuals and have other internal “cooling” adaptations.

Indeed no beneficial effects of pre-cooling were observed in terms of performance in acclimatised amateur trained runners linkJames et al., 2018. Two weeks of acclimatisation offered similar results compared with cool conditions in terms of time when trained cyclists were subjected to a prolonged time trial. Crushed ice ingestion prior to exercise offered identical improvements in endurance cycling performance compared with a 12 day acclimatisation training programme linkZimmermann, 2018.

summarize Summary

• If you warm up in hot conditions you will likely run the risk of overheating.
• In hot conditions (e.g. over 25°C) you should try and cool down as a warm-up and forget the warm up totally!
• If it is possible, acclimatise to hot conditions (for 2 weeks+) but if not, use cooling strategies.
• You can test whether your race conditions will be a problem in our heat calculator here: https://fft.tips/heat

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