How to ride in hot conditions
Whether you’re enjoying a late summer heatwave, preparing for a warm winter training camp abroad, or simply wondering how to manage your sweaty indoor turbo sessions, cycling in hot conditions serves up some unique challenges.
Hot and humid environments seriously increase the physical strain of cycling, so your body will be under more stress to regulate its core temperature, and your power levels will inevitably drop. That is why many pro cyclists now follow dedicated hot weather strategies so they can perform at a high level when the temperatures soar.
In hot environments, your body responds by sweating, with the fluid evaporating on your skin to deliver a refreshing cooling effect. But on long bike rides in the heat, this process can lead over time to dehydration and a thickening of your blood. These physiological changes force your heart to work harder to pump blood around your body, and mean less blood gets sent to your hard-working muscles.
The result is a much lower power output, and a higher heart rate. Your brain also suffers a drop in fuel and neurotransmitters, which is why you often feel tired and irritated on hot rides, causing you to swear at potholes and make erratic or impulsive decisions in races.
The impact of hot weather on cyclists is huge. One Australian study found that when cyclists exercise in 32°C heat their power output drops by a huge 6.5%. A research paper in Medicine and Science in Sports and Exercise found that when cyclists were asked to ride to exhaustion in 30.5°C heat, their endurance capacity was cut by 42 minutes. And research in the Journal of Applied Physiology showed that dehydration increases a rider’s rate of carb utilisation by 8%.
The good news is that cyclists get to enjoy a cooling breeze when they ride at speed, which aids sweat evaporation. But roads also reflect the heat, so when the temperature in the shade is 32-40°C, that could equate to 50°C or more for a cyclist pedalling along the blistering hot tarmac.
Fortunately, there are plenty of strategies you can adopt to keep cool in hot conditions. Here are seven red-hot strategies to try.
Boost your aerobic fitness
The fitter you are, the more comfortable you will feel when riding in the heat. A 2019 meta-analysis on heat stress, which was published in Frontiers in Physiology, concluded that aerobic fitness was the most effective strategy for heat stress mitigation. If your aerobic fitness is good, you will enjoy an improved sweat response, blood plasma volume and cardiac output to help you survive the hot conditions. So get ready for the heat with plenty of heart-boosting interval sessions and threshold efforts.
If you want to perform well in the heat, you need to acclimatise by riding more regularly in hot conditions. That means deliberately getting out for rides on warm days, or jetting off for a warm weather training camp before hot summer races. Training in hot weather for 60-90 minutes per day over 4-10 days has been shown to elicit a lower resting core temperature, greater blood plasma volume and an increased sweat rate.
Be aware that when you first start riding in the heat, your performance levels will drop, so be prepared to lower your power output and reduce your intensities until your body acclimatises. But the adaptations happen very quickly: most studies find that 9-12 days of heat acclimatisation training is sufficient to see a good improvement.
Acclimation training – as opposed to acclimatisation training – involves the ‘simulation’ of hot conditions instead. This could simply involve riding on your turbo trainer at home with the heating turned up and the windows closed. It’s sweaty and grim – but effective. Research suggests after anywhere from 5–14 one-hour acclimation sessions, riders experience an increased sweat rate, reduced core temperature and improved performance in the heat.
Exciting research by experts at Liverpool John Moores University has revealed that having a hot bath after training in cool conditions can help your body to adapt to the heat. If you have a hot bath after cold rides, over time you will benefit from a reduced resting core temperature of about a third of a degree, which means a lower body temperature during exercise in the heat, a lower heart rate and reduced cardiovascular strain. It’s a really simple way to trigger a winning physiological adaptation, and it is already being adopted by elite rugby players, cyclists and runners.
Get some cooler kit
Wearing a thick jersey and a poorly ventilated helmet will only make the hot weather feel worse. Opt for a light and sweat-wicking jersey, and a helmet which has good ventilation panels. Avoid wearing black, which absorbs the heat, and use reflective colours like white instead. Many garments now have UV filters built in.
Wearing a thin mesh base layer can also help. It may seem strange to wear two layers on a hot day, but a thin base layer can help to wick sweat away from your body and onto the surface of your jersey, where it will evaporate in the breeze to keep you cool. Always remember to loosen your shoe straps slightly too, as your feet can swell in the heat.
Before a hot weather ride, find ways to lower your body temperature before you set out. Many pro riders drink ice slushies, hold handheld fans, or wrap themselves in towels which have been cooled in a freezer before a ride. Some riders soak a thin cap in cold water and wear it under their helmet to keep their head cool. You can now buy insulated bottles which keep your drink cool.
But you can also put your drink in the freezer, and take it out about half an hour before you set out, leaving you with an ice-cool drink to sip during your ride. These techniques can lower your body temperature but also help you to ‘feel’ much cooler, ensuring your hot ride become a bit more bearable.
Cyclists can lose up to 1.5 litres of sweat per hour in hot conditions, which is why you need to drink plenty of fluids. A lot of pro riders now ‘pre-hydrate,’ by drinking an electrolyte solution in the hours before a ride. During the ride itself, aim for around 400-800ml per hour.
It is a good idea to carry one bottle filled with water and another bottle filled with an electrolyte solution which will help to replace the sodium, potassium and magnesium lost through sweat. If the hot weather makes you queasy, try adding tasty pineapple or lemon juice to encourage yourself to sip more often.
Urine colour and thirst are good markers of your hydration levels, so keep an eye on both. But so too is mood: when you start feeling irritable, it is often a sign of dehydration. Cramps and impaired muscle function can also be a warning sign that your electrolyte levels have dipped.
Change your fuel
Hot weather saps your energy, but it also messes with your digestion by reducing blood flow to the gastrointestinal tract. That is why you don’t always feel hungry on hot days. Try to get your energy through drinks and gels instead, which are much more palatable on hot rides.
Taking homemade snacks – like flapjacks, sandwiches or rice cakes – will help too. Homemade food made from natural ingredients boasts a higher moisture content than dry packaged energy bars, making it much easier to digest on hot days.