How to beat the heat this summer
As summer temperatures soar, Simon Smythe assesses how best to get acclimatised and discovers some surprising ways your cycling performance stands to benefit
Tony Martin prepared for the 2016 World Time Trial Championship by training on the rollers in his bathroom in front of a fan heater. “Of course, I was using the sauna too,” said the German. Why? Because that year’s Worlds were held in Doha, Qatar, where temperatures were expected to hit 40°C.
“Studies show that you get an adaptation when you simulate the heat this way for a certain amount of time,” added Martin. “You just try everything to gain a few per cent over your rivals.”
On race day, while many riders found themselves unable to produce their usual amounts of power in those searing temperatures, Martin took his fourth world title, demonstrating that the bathroom sessions were much more than just hot air.
Though the TT specialist was left to improvise his own heat acclimation programme in 2016, the benefits of training in high temperatures and high humidities in advance of hot-weather competition are proven.
Much more recently, under the blazing Tuscany sun on the dusty roads of Strade Bianche on 1 August, temperatures soared into the mid-30s, and only onequarter of the peloton made it to the finish. Heat is becoming an ever more prominent factor in bike racing. With Britain increasingly prone to sweltering highs – last July a temperature of 38.7°C in Cambridge broke the record as the hottest-ever day. So should the rest of us be incorporating heat training into our programmes? Does sweating it out on the turbo have hidden benefits?
The most advanced equipment and training strategies are often introduced and developed by national and Olympic federations before they reach amateur or club level via the ‘trickle-down’ effect: in Team GB’S training programme for the 2021 Tokyo Olympics, heat prep will be a crucial part of their training.
Athletes across all the disciplines will spend time in the environmental chamber at the Bisham Abbey National Sports Centre, in Berkshire, a sealed room measuring seven metres by seven metres, where altitude, heat and humidity can be simulated. With temperatures in Tokyo in July and August topping 30°C, with over 70 per cent humidity, the plan is to match and exceed that level in the chamber – so that by the time the athletes arrive in Japan, they will be perfectly acclimated.
“Athletes who are going to be outdoors in the heat competing in longer events such as time trials and road races are obviously most at risk of performance impairment,” explains Luke Gupta, senior project physiologist at the English Institute for Sport.
“It’s that much harder to maintain a steady core body temperature while your muscles are generating heat in what is pretty much a cooker.”
If your core temperature starts to rise above its baseline of between 36.5°C and 37.5°C, your thermoregulatory system takes steps to bring it back down again. According to Heat alleviation strategies for athletic performance: A review and practitioner guidelines, by Oliver Gibson et al, the effects of overheating include increased exercising heart rate, elevated core temperature and skin temperatures, greater perception of effort, thermal strain, thirst and water loss leading to dehydration. This results in fatigue, down-regulation of effort, performance impairment and even heat illness. Heat illness or heatstroke is, according to the NHS, very serious if not treated quickly. A seizure or loss of consciousness can occur when core temperature reaches 40°C – that’s a 999 situation.
Staying hydrated
When sweating heavily in the heat, mild dehydration is practically unavoidable – and is no major problem, as the body is amazingly good at handling it. You can lose up to two per cent of body mass in fluid – that’s 1.4kg for a 70kg cyclist – without a significant effect on your performance. It’s also worth bearing in mind that drinking too much can be not only counterproductive, but even
dangerous, as guzzling wild amounts can put you at risk of lethal hyponatremia.
Some research has shown that deliberately dehydrating by not drinking during heat acclimation sessions may speed up adaptation. Of course, inducing mild dehydration in this way would need to be carried out with caution, rehydrating afterwards with isotonic drinks to fully replace lost volume.
Generally, you should aim for optimum hydration, and certainly to avoid serious dehydration at all costs. Above two per cent fluid loss, your core temperature rises and the reduction in blood volume forces your heart to work harder, meaning your performance begins to suffer. A study by the University of Texas found the optimal rate of fluid ingestion to avoid core temperature rise and cardiovascular drift, is the rate that most closely matches fluid lost through sweating.
The simplest way of working out how much fluid you’ve lost is by weighing yourself after a ride to find out how much you need to replace.
“When you go out training in the heat, you need to know to drink roughly X litres of fluid to maintain a fluid balance,” says Gupta, “but conditions might change; the starting status of your hydration might be different, but it’s something we try to find out beforehand.”
Riding in the heat not only increases your body’s demand for water, but also energy, since your metabolic rate is increased as your body works to thermoregulate itself. Inevitably, you burn slightly more fuel – as well as losing a lot of salt.
“If you’re a particularly salty sweater, add a supplement to your drink to replace electrolytes you’ve lost,” adds Gupta.
Heat’s effect on power
A study published in Medicine and Science in Sports and Exercise measured the actual losses in a 43.4km outdoor cycling time trial at 37°C in Qatar by unacclimated cyclists.
“You can lose up to two per cent of body mass in fluid – that’s 1.4kg for a 70kg cyclist”
The authors found that average power output decreased by around 16 per cent compared to the same distance completed at 8°C in Denmark. However, after a week of acclimatisation, they had halved their power loss, and after two weeks of acclimatisation were around three per cent off their colder-weather power. You can get used to the heat – and quickly. Although you might expect Olympic athletes and pros to be better able to tolerate heat than the average club rider, this is not the case, as Gupta explains: “It’s highly individual. Certain athletes will be more prone to not coping in the heat than others, and there are many factors at play, such as prior experience of being in the heat, body composition, physical fitness – and sometimes, some people just don’t cope in the heat due to an underlying genetic element.”
Acclimation sessions in the heat chamber (versus acclimatisation, which means actually being in the climate) consist of pedalling at moderate intensity for moderate amounts of time.
“Gold-standard protocol is about an
hour-and-a half of low to moderate intensity,” says Gupta, “because if you went hard early you’d overcook yourself pretty quickly. Acclimation is different from a heat tolerance test: the activity might be the same, but with acclimation you’ll make it hotter and more humid, as you want to elicit a heat stress response.”
With acclimation, Gupta uses the principle of “get hot, stay hot” – prolonged periods of heat stress, but while trying to avoid overheating.
“We monitor body temperature to know if we’re hitting the right heat stress response. You want to get them up to around 38.5°C and keep them there for as long as possible. That’s acclimation, and where ‘get hot, stay hot’ comes from.”
The main ways the body adapts, or acclimates, are by sweating freely and by increasing its blood plasma volume.
“Sweating is the main cooling mechanism,” says Gupta. “If your ability to sweat is enhanced, you can tolerate the heat is much better. You also get blood plasma expansion. Think of plasma as like coolant in a car – when you’ve got more of that in your body, you’ve got more fluid to transfer heat away from your core and out to your skin.”
Flaws of perception
There’s also a perceptual side, says Gupta: “People feel better in the heat as they’ve experienced it before. Because your brain is the thermal regulator in the same way that your thermostat works in the house, it is constantly monitoring your body temperature, and there’s research to suggest that if you put people under heat stress, their ability to cognitively function is impaired.”
Initially, thinking about how hot you’re feeling isn’t good for your performance.
“If someone’s in a hot and humid environment and they’re not used to it, thoughts about overheating start to enter your capacity, leaving less space to think about other things – such as focus and pacing – so it does challenge your cognitive ability and athletic ability.” Cooling strategies are a vital part of the plan on event day. Whole-body cold-water immersion is considered the best method of external cooling, according to Gibson et al, but wet towels, ice vests and water sprays may be more practical than having a cold bath before you start your warm-up. Internal cooling directly cools the core organs and circulating blood and can be combined with pre-ride hydration and nutrition strategies, but must be properly trialled before event day. Acclimation can last from five to 14 days, says Gupta. “Then there’s the ability to top up by having smaller doses of heat thrown in throughout the week.” With an extra year to get Team GB’S heat strategies in place, we can look forward to some scorching displays. And who knows... if we’re looking to up our own game, we could soon be jumping on Zwift and turning off the fan.
■ WORD OF WARNING
“If your ability to sweat is enhanced, your ability to tolerate the heat is much better”
Former GB triathlete turned medical doctor Todd Leckie has studied the effects of heat stress: “Heat training is potentially very dangerous, as it’s relatively easy to raise core temperature critically high on a static trainer. That said, heat acclimatisation is arguably sensible if you are intending to ride at a high intensity in very warm conditions. If you want to incorporate heat acclimatisation into your training, my advice is to use heart rate monitoring and exercise below 80 per cent of max HR, effectively using HR as a surrogate marker of heat stress.”