Beat HEAT the

Ever overheated in a race? Well you’re not alone, with some of the biggest names in the sport also succumbing to toasty temps. So how can you get the best out of your performance when the mercury rises? Here’s our ultimate guide…

Get the most out of every hot-weather performance with our guide to racing in the heat

You can outrun the opposition, push through the discomfort and reject the negative thoughts, but when your body’s temperature rises too high, no amount of willpower is going to help.

From Jonny Brownlee being famously hauled over the line by brother Alistair at the ITU Worlds in Cozumel in 2016, to Marino Vanhoenacker leading the 2012 Ironman World Championship one minute and plunging his head into a dustbin full of ice the next, it doesn’t matter what’s on the line, when we overheat, the body’s survival mechanisms kick in.

With Tokyo 2020 on the horizon, athletes, coaches and national governing bodies are

doing everything in their power – much of it top secret – to find ways to cope with the predicted heat. From hydration to nutrition to the fabrics worn, testing and retesting is taking place to gain an edge.

But it’s not just elites racing overseas who can benefit. British summers are becoming increasingly balmy – 2018 was the jointhottest on record and the MET office’s latest climate projections study predicts rises of 5.4°C over the next five decades.

It looks like it’s going to become seriously toasty, so if you’re heading out to race, what steps should you take to maximise your performance? We turned to the UK’s top experts in endurance training and racing in the heat to find out...

Acclimation vs acclimatisation

How can we physically prepare for racing in hot conditions? Extended training camps leading into a race are one way, but without limitless supplies of time and disposable income, the bulk of the swim, bike and running still needs to be done at home.

While turning to the turbo in the pain cave and swapping an electric fan for a heater is a tried-and-trusted method, does it really work? Or are there alternative methods that provide similar adaptations and allow us to still enjoy some fresh air?

It’s important to first establish the difference between acclimation and acclimatisation, says Dr Steve Faulkner, a thermal physiologist and expert in human performance from the Sports Engineering and Ergonomic Design Lab (SPEED) at Nottingham Trent University. Faulkner defines acclimation as stimulating the heat adaptation process through simulation. “Acclimation could mean using a heat chamber or cooking yourself in the kitchen with the oven on and little to no airflow,” he says. “But for those not wanting to go stir crazy on a turbo or treadmill, it could also be training outdoors but taking a hot bath directly after exercise for 30-60mins and maintaining the water temperature at 40°C – or as warm as tolerable – to

extend the period above which the body’s temperature is above 38.5 to 39°C.”

In contrast, acclimatisation is your body’s physiology adjusting once you’ve relocated to warmer climes. It’s a chief reason professional athletes often arrive at least a fortnight prior to major races, adapting by both training in the heat and having day-to-day exposure to it.

The good news is that athletes can quickly see positive results from both acclimation and acclimatisation, and although those gains are lost when returning to temperate environments, the body also adjusts faster on the next trip to a hotter venue. “You’ll typically start to see changes such as a reduction in resting core temperature, resting heart rate and heart rate during exercise after three-to-five days or sessions in the heat,” Faulkner adds. “There’s a plethora of other physiological adaptations that take place. Some are obvious, such as sweating more, others less so, such as how blood flow is redistributed during exercise.”

Typically, full adaptation takes around 15 days, but not everyone will respond to heat in the same way. The outlook is more positive for those who are fitter at the start of the process because their sweating mechanics are already superior. The core temperature of larger individuals will also rise faster because they have proportionately less surface area of skin to body mass for moisture to evaporate, the chief

way of cooling down.

Full adaptation takes around 15 days, but not everyone responds the same. If you’re fitter at the start, your sweating mechanics will be superior”

Sweat rates & hydration

How do we find the right balance for drinking in the heat? Consume too little and blood volume decreases and we’re on track for dehydration. Too much and we become uncomfortable and in a worst-case scenario waterlogged, which although rare, can be serious and even deadly.

“Where people get it out of whack is the perception we just need to drink more water – and they go overboard,” Andy Blow, a sports scientist from Precision Hydration, says. “There was a study at Ironman Frankfurt in 2013 that found 10% of finishers were becoming hyponatraemic, indicating a lot were drinking too much.”

Including electrolytes in drinks when racing or undertaking multiple training sessions a day is important because we lose sodium through sweat. But unlike carbohydrates, fluids cannot be easily pre-loaded before a race – we’ll just pee more. However, by taking additional salt beforehand, Blow argues you can expand blood plasma volume slightly, which is useful if going into a long, hot race.

A critical aspect is to test the hydration strategy in hot environments to simulate racing conditions because it’s not a onesize-fits-all solution. “It comes with a bit of trial and error,” he adds. “Some people race fine on a few millilitres of fluid an hour for an entire Ironman, others will go up to 1.4litres per hour.

“In terms of concentration, the mix could be from zero to 1.5g sodium per litre of fluid. Our free online sweat test is a questionnaire that helps people figure out whether they have a high, medium or low salt requirement.

“The alternative is to have your sweat sodium concentration analysed in a lab. It’s relatively stable so doesn’t have to be done multiple times and it’s also not about hitting a bullseye, but a barn door. The body is good at self-regulating and will work out the finer details.”

Humidity levels also play a role. “The principle method of cooling is when sweat evaporates,” Blow says. “In high humidity, sweats tends to drip off and you just lose more fluid without dissipating heat. The role of pacing becomes incredibly important. Once you overheat by going too hard, the ability of the body to cool down is compromised.”

FUELLING

While our thirst is likely to increase in the heat, our appetite is often suppressed. But – particularly over longer distances – not fuelling optimally will be a mistake.

“You work harder in the heat, so your metabolism is elevated,” Dr Steve Faulkner says. “It’s highly likely you need to increase your nutrition intake – a half bottle or an extra gel to compensate for that additional energy expenditure.”

With solid foods less palatable and harder to digest, opting for more liquid alternatives with some astute planning could pay dividends.

“If feasible, have a cooled drink kept in a bottle chiller, or try getting hold of ice gels, ice lollies or slushies to get the calories in rather than chugging down your 15th sugary gel of the day,” Faulkner suggests. “They probably won’t cool your body temperature, but will make you feel more positive than drinking something that’s been out in the sun and is lukewarm.”

Flavour fatigue, where athletes become weary of the same tasting nutrition during long races, has been shown to have a negative impact on performance, so it’s wise to vary what you’re consuming. The body may also convert a mixture of simple and complex sugars more readily into energy to allow individuals to absorb up to 60g per hour.

“Different types of sugar use different gateways into cells,” Faulkner says. “Simple sugars will result in a fast release of energy, whereas more complex ones will give a slower, longer-lasting supply.

“What type of sugars you ingest at what point should be dependent on the duration of an event. But if you can train yourself to use multiple types of sugar rather than just glucose, you can push the boundaries of how much you can absorb.”

With solid foods less palatable and harder to digest, opting for more liquid alternatives with some astute planning could pay dividends”

CLOTHING

Wicking has entered the athlete’s lexicon in recent years. It’s a term describing how technical fabric moves sweat away from the skin more efficiently to help it evaporate and cool us down – contrasting with more traditional materials that become saturated and inhibit heat loss.

But simply having a wicking tri-suit to maximise heat loss is not enough because it should also be designed with the swim (hydrodynamics) and bike (aerodynamics) in mind.

Dean Jackson, founder of kit manufacturer Huub, says triathletes should look for “polyamide elastane that offers compression, evaporation and comfort” and can be given different coatings to change its properties from mildly to fully hydrophobic – essentially waterproofing the tri-suit to improve its hydrodynamics.

But while hydrophobic material might be of benefit in a non-wetsuit swim, it’s negated if neoprene or a swimskin is worn over the top. In the latter cases, a more breathable mesh might be preferable, perhaps with a release zip on the back as demonstrated frequently in World Triathlon Series races as triathletes leave T2.

There are considerations here too, though, because a more open weave increases the chances of sunburn. Thankfully, there’s no clear evidence to suggest applying sunscreen blocks pores to prevent heat loss. Although even if proven, getting warm is preferable to skin cancer.

To complicate matters further, it’s not all about cooling from the inside out. Another piece of the puzzle to consider is radiative heat and how to deflect the sun’s rays.

“Having lighter colours is generally preferable,” Faulkner says. “Darker colours absorb more radiative heat and contribute to overall levels of heat stress.”

Some manufacturers claim they can give dark fabric a treatment to reduce this radiative effect, but again the danger is that sweat is locked in. “Something coated in material X could reduce the solar heat load, but inhibit the wicking potential of the original fabric,” Faulkner argues. “While there might be benefit in one area, the overall effect could be negative.”

Away from the tri-suit, other heat-defying apparel is recommended. “Kepis, the French foreign legion-style caps, could be beneficial in helping radiate heat away from head and face,” Faulkner adds. “The towel at the back could also have a slight bellows effect with air movement around the head and neck that might improve the athlete’s perception of comfort.” As for trapping heat in with a hat, Faulkner argues the risk is exaggerated. “Our grandmas might tell us to wear a hat when it’s cold,” he says. “But the studies I’ve done on regional heat loss show the head doesn’t account for that much. “If wearing a hat, wear a lightly coloured one with venting, but I’d suggest a visor, allowing for heat exchange to occur and more air to move over the surface of the head.” Sunglasses should stop the eyes straining and a vented lens will help prevent condensation, but perception is also huge. “People rub cold water across their necks and although it won’t cool them down, it might give the impression it is,” Faulkner says. “In theory, the water also increases evaporative cooling which could help maintain hydration as more of the body’s water is retained rather than used for sweat. But that’s not proven.”