How to Train and Race in the Heat

5 strategies to improve your performance when it’s roasting outside

You can control your training, your bike maintenance and your nutrition, but you can’t control the weather — and heat can make a big impact on your performance. Luckily, we have science- and experience-backed solutions to help you beat the heat through adaptation, nutrition and planning. Give our latest podcast a listen and read our 5 strategies below.

Got a target event coming up that might be hot? Here’s how you can set yourself up for success.

1. Give yourself two weeks to acclimate 

The Science: Your body is always trying to maintain equilibrium, and heat can significantly disrupt that. Heat comes from metabolism and needs to be dissipated through the skin or breath. When the ambient temperature is too hot, it limits the body’s cooling and can raise core body temperature. Core body temperature is the central governor of exertion in the human body; get too hot and the brain exerts protective measures to slow the body down. 

The Performance: The optimum ambient temperature for cycling is around 50-65 degrees. The further you get from this range, the more your performance suffers. High heat affects metabolic efficiency and stresses the body’s cooling processes (such as sweat rate, vasodilation/constriction of non-active muscle, and cardiac efficiency via stroke volume changes) that indirectly impact power output. Similarly to the effects of altitude, there is a curvilinear decline in power as temperatures exceed about 80 degrees. That can be lessened with acclimatization but never completely mitigated. 

The Practical: It takes your body 10-14 days to adapt to high heat. During this time your body is increasing blood plasma volume and altering its sweat sodium concentration, diluting your sweat so that you can take better advantage of evaporative cooling. During this acclimatization phase it’s important to hydrate consistently throughout the day and with cool drinks on rides, plus hyper hydrate before and after sleep.  

How to Acclimate: Very few of us — even top professionals — can afford to spend two weeks at a race location to acclimatize, but there are other effective solutions. Overstressing the body to adapt to heat is something lots of cyclists and multisport athletes do. Sauna protocols, hot baths, and over-dressing are common practices to send heat acclimatization into overdrive. These practices, when done well-supervised and in small doses can be very effective. They do add stress to your training week, so adding these in comes at a cost of recovery. 

2. Use a sauna (or hot bath) to acclimate and ice to moderate

The Science: Your body cools itself by sweating, which is why hydration and adequate plasma volume are so important. If you don’t have enough fluid for your body to use for the cellular processes that exercise demands of it in addition to the water required to sweat, your training session will come to an end much sooner than expected. 

The Performance: If you hydrate and fuel well, you should be able to get through a relatively short to moderate duration training session, but as the intensity increases, your performance will decline more quickly.

The Practical: Plan ahead! This goes for event day as well as training. For event day, prepare some ice socks. If you’re doing a triathlon, leave frozen gel flasks in transition. If you run with it, you get a cooling effect as you hold it in your hand, and it’s a much more appealing fuel source than a warm drink or gel. Bring a soft cooler or lunch box with you to events so you have a way to keep your pre-race and during event drinks cold before the start. 

How to Acclimate: Follow this two-week sauna protocol. (No access to a sauna? Use a hot bath.) Use the sauna after training every day for a week, then allow a week for recovery and adaptation before your target event. Sitting in the sauna for 30 minutes after your training session when you’re dehydrated stresses the cardiovascular and renal systems. This drops the partial pressure of oxygen to the kidney and stimulates EPO and plasma volume production. It’s important to go into it a little dehydrated and rehydrate very slowly afterwards over the course of 2-3 hours. If you drink a lot of fluid immediately afterwards, you stop the stimulus to the renal system. If you don’t train on one of your seven days in the week that you’re doing the protocol, then just do your sauna time in the afternoon when you’re a little naturally dehydrated, and follow the same guidelines otherwise. It’s important to decrease intensity by 15% and volume by 20-25% during the week that you’re performing the sauna protocol.

3. Don’t avoid the heat

The Science: When it’s hot, your body sends more red blood cells to your skin to help lose the excess heat as opposed to the muscles, which gives you a higher heart rate. You can see this through cardiac drift in your heart rate.  

The Performance: Typically in hot conditions, power will decrease and heart rate will increase along with perceived exertion. As coaches we often see peak heart rate numbers come in June when it gets hot but we often won’t see power numbers near their peak. 

The Practical: Don’t avoid the heat! Instead, adapt to it. This can either be through active or passive ways. Active is exercising in the heat or through passive ways like a sauna. 

How to Acclimate: Instead of training early or late, try riding in the midday heat to adapt. Not hot outside? Then ride the trainer without a fan or wear extra clothes outside. Fortunately, heat adaptation does not take long and once you are adapted you do not have to do it as often. 

You can test how your endurance and heat adaptation is progressing with zone 2 rides at a steady power. The more you’re adapted, the less your heart rate will increase at a steady power over time. For instance, test yourself with a few 3-hour rides at a steady zone 2 and see how your heart rate responds and at what point if any it starts to drift. You can also look at your power-to-heart ratio in TrainingPeaks.

4. Mind your electrolyte consumption

The Science: Electrolytes are distributed through body fluids to conduct the electrical activity needed for many bodily functions, including: controlling fluid balance, muscle contractions, transmission of nerve impulses, maintaining the correct acidity (pH) of your blood, and regulating blood pressure. Because electrolytes are central to so many basic daily functions, they must be present in consistent and adequate concentrations to maintain optimal athletic performance. 

The Performance: One deleterious effect of the heat is cramps. Cramps are often associated with hot weather and although it’s debated can be attributed to electrolyte imbalance. Fluids and electrolytes consumed by athletes are recommended for a number of reasons before, during and after exercise. The reasons are generally to sustain total body water, as deficits (dehydration) will increase cardiovascular and thermal strain, and degrade aerobic performance.

The Practical: Adjust your nutrition based on what works well for you. You may need to take on more calories from liquids. Beware of hypernatremia, and don’t just slam a ton of water without electrolytes. Reduce warmup time and intensity. A good rule of thumb is to warm up until sweating becomes profuse, then spin easy for the remainder of your time or find somewhere shady/cool.

How to Acclimate: The latest science points to a balance of four electrolytes for best performance: sodium, potassium, magnesium and calcium. The best times to replenish electrolytes are before a workout (if you’re a salty sweater), during a workout (look for drinks lower in sugar to avoid stomach issues), and after a workout.

5. Remember that it’s hot for everyone

Whatever the conditions are on race day, they are going to be the same for everyone. If it’s really hot, know when to pull the plug by knowing the signs of heat stroke: dizziness, headache, chills, and nausea. The flipside of this is that dwelling on the heat can have a meaningfully negative effect on your perceived exertion and your performance.  Keep yourself as cool as possible before, during, and after the event. Pour water on yourself, use ice socks, and measure your effort accordingly with pacing or number of attacks. 

Lastly, when acclimating to the heat, it’s not beneficial to be hot all the time. So there’s no need to make yourself miserable by trying to sleep in a hot room. 

As with other types of training, by setting and following a plan to deal with the heat beforehand, you’ll have less to worry about on race day and will be better prepared than by simply hoping for cool temperatures. As always, train hard, ride fast, and have fun! 

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