Beat the heat

Jun 18, 2019, 16:56 PM

Over the next couple of months, the world’s finest para-cyclists – whether on a tricycle, handbike or standard bike – face the added competition of heat. They’ll all be following plans to race strong when the mercury rises.

Take the Thailand Para-cycling Cup, 24-28 June. The average temperature is 28°C and regularly tips over 30°C. It’s the same for a number of mainland Europe races such as the Para-cycling Europa Cup in Germany (6-7 July), and national championships in Portugal and even Britain, on the same weekend. And don’t forget the 2020 Tokyo Paralympics, where temperatures exceeding 30° will be the norm. It begs the question: what heat-beating strategies will help the para-cyclists this summer and next?

What happens if the para-cyclist doesn’t adopt an effective hydration strategy? A study undertaken by California State University’s Dr Dan Judelson showed that a sustained state of dehydration impaired strength, power and high-intensity muscular endurance by 2%, 3% and 10%, respectively. Those are significant figures, especially that 10% drop in muscular endurance. 

Yet recent research from Brock University scientist and cyclist Stephen Cheung suggests this figure isn’t set in stone. “My studies showed that a loss of 3% wouldn’t impact as much as you’d think,” writes Cheung. “It might increase heart rate a little bit and increase your core temperature a bit but none of our subjects reached any critical levels.”

Cheung’s comments are supported by a paper in the British Journal of Sports Medicine, entitled ‘Current hydration guidelines are erroneous: dehydration does not impair performance in the heat’, which showed that when cyclists performed a 25km time trial in the heat, while it showed rectal temperature was higher beyond 17km of the time trial, no other differences were observed.

Whether you side with Judelson or Cheung, a well-designed hydration plan is a must, especially for longer events such as the women’s 100km and men’s 120km tandem road race, or the C3-5 men’s 100km and C3-5 women’s 75km races. How can the athlete go about this? Measuring sweat rate is one way. This requires cycling for 60 minutes, ideally in similar hot conditions, and drinking nothing from start to finish. The para-cyclist must weigh before and after and see how much weight has been lost.

Around one litre of sweat loss equates to 1kg of weight loss that, taking into account urination, should be replaced with 1.5l of fluid. Just note that the stomach struggles to absorb more than 1l of fluid per hour; any more is likely to lead to discomfort.

Acclimatisation is another method of preparing the mind and body for the heat of battle.

This is where the para-cyclist trains in the heat to stimulate adaptations conducive to racing in the heat. Research has shown that riders exposed to conditions that elevates their core temperature by 1°C-2°C for 60 to 90mins over a period of up to 14 days will afterwards elicit a lower resting core temperature, greater blood plasma volume and increased sweating rate. These are all favourable physiological changes to riding in the heat. It’s why some athletes will use a heat chamber in the build-up to a race.

Take Dame Sarah Storey, the multiple Paralympic gold-medal winner. The 41-year-old won double gold at the 2018 UCI Para-cycling Road World Championships in the road race and time-trial. To prepare for the hot and humid conditions in Maniago, north-east Italy, the British athlete spent time in Manchester Metropolitan University’s environment chamber. “I’ve been working in the chamber at 32°C and 80% humidity,” Storey said at the university’s graduation ceremony. “It’s been quite spicy and tough!” But clearly it worked. There’s also further evidence that a hot bath (40°C) straight after a cycling session also ultimately lowers core body temperature, resulting in a stronger performance when racing in the heat.

Athletes like Storey also have a fitness-based advantage on their side. As the para-cyclist’s fitness grows, they enjoy a host of adaptations that are conducive to racing fast in the heat. These include an improved sweat response to dissipate heat quickly, which stems from both lower core temperature thresholds for the initiation of sweating and greater sensitivity of sweating response to increasing core temperature.

“Improved aerobic capacity also leads to elevated plasma volume and cardiac output,” writes Cheung. “This minimizes the competition for blood distribution between skeletal muscle and skin.” So while para-cycling stars rack up the miles, their bodies develop a greater capacity for, and a slower rate of, heat storage.

And then, of course, there’s clothing. Light clothing helps to deflect the sun’s rays, while the close-fitting apparel adorned by the majority of para-cyclists helps wicking. This is the process whereby moisture is drawn away from the skin and, in this case, to the surface of the cycling top. Because water conducts heat more than 20 times quickly than air, if sweat is left to pool on the skin, skin temperature rises, which leads to a rise in core temperature and fatigue.

These are some of the methods that the world’s best use to race fast in the heat, and which can also be applied to other cycling disciplines and sports.