Cycling training: How to train properly in high temperatures and what benefits it offers

For most people, the best time to cycle is summer. The days are long, the nights mild. It's actually perfect – if the summer temperatures don't become a challenge during the day. I've been living in Spain for a few years now, and it quickly becomes clear: heat isn't an exceptional condition. It's a training factor. A demanding one. A dangerous one. And – used correctly – a very effective one.

I still remember my first race through Andalusia in southern Spain. Temperatures climbed to over 45 degrees Celsius during the day, and at night the thermometer barely dropped below 30 degrees Celsius. I was prepared—or so I thought. But the reality was tougher than any training plan. My body craved water, my mind craved shade, and after just five minutes, my jersey clung to my skin like a second skin. I learned a lot on that journey—about my limits, about thermoregulation, about the importance of salt and shade.

And that's exactly what we're going to talk about today: What heat training really does, who it's suitable for, and what you should pay attention to if you want to strengthen your body rather than weaken it.

At first glance, it seems counterintuitive: Why would you voluntarily get on your bike when it's over 35 degrees Celsius when you could also ride early in the morning or in an air-conditioned indoor session?

Sports science provides the answer: The goal is what's known as heat adaptation, the body's physiological adaptation to high temperatures. Studies in sports medicine and thermoregulation research show that the body can adapt to heat surprisingly well – and this benefits not only professionals but also ambitious amateur athletes.

Some of the most important adjustment effects:

• Increase in plasma volume: Heat stimuli can increase blood volume, especially the liquid portion (plasma). This can improve circulation, muscle supply, and thermoregulation.

• More efficient sweat production: The body begins to sweat earlier, cooling more effectively. At the same time, it loses fewer salts, reducing the risk of cramps.

• Reduced heart rate during exercise: After successful heat adaptation, the cardiovascular system can react more economically – the heart rate can decrease with the same level of performance.

These adaptations can not only improve performance in hot weather, but can also have a positive effect in moderate temperatures. Once systematically adapted to heat, athletes can benefit from improved blood circulation, increased efficiency, and greater tolerance to climatic stressors.

Heat training is now as much a part of the pre-season build-up for many World Tour teams as altitude training camps. While previously the focus was on altitude and oxygen depletion, today heat is also used in a very targeted manner. With roller sessions in the boiler room, sauna protocols after training, or dehydration strategies under controlled conditions.

Example: Studies examined the effects of two weeks of heat exposure on the performance of professional cyclists. The result: Just five to ten 60-minute sessions in warm environments (35–40 degrees Celsius) were enough to achieve significant improvements – both in maximum oxygen uptake (VO₂max) and anaerobic threshold performance.

Of course, few of us have access to heat chambers or laboratory tests. But the basic principles can be implemented without high-tech:

1. Targeted instead of random

Not every summer day on the bike is automatically heat training. What matters is whether you use it consciously: at what intensity, for how long, and in what form. Important: Heat training is not high-intensity training. The training stimulus lies in the temperature, not the wattage.

2. Indoor without a fan – an underrated classic

I regularly do 45- to 60-minute sessions on the indoor roller, without a fan and instead using a small heater with the window closed. My heart rate is a bit higher, my jersey gets wet faster, but the intensity remains at a basic level. It's easy to integrate into everyday life and is surprisingly effective.

3. Heat afterload – sweating afterward is worth it

Another method is to deliberately delay the cool-down after training. Staying in a warm environment for 20 to 30 minutes after exercise (for example, going to the sauna at the gym after a spin session) prolongs the heat stimulus – without placing additional strain on the cardiovascular system.

4. Sweating has to be learned – and so does drinking

Anyone training in the heat needs to keep their hydration under control. I weigh myself before and after the session and adjust my fluid intake accordingly. As a rule of thumb, you should consume approximately 1.5 liters of fluid with electrolytes for every kilogram of weight lost. Water alone isn't enough for longer sessions.

But be careful: heat training is not a game!

As with any training stimulus, the dose makes the poison. Overdoing it risks heat exhaustion, circulatory problems, or even heatstroke. Particularly dangerous are combinations of intense exercise, high humidity, and insufficient fluid intake. Therefore, my advice: never start on an empty stomach or when you're thirsty. Monitor your heart rate. Take symptoms like dizziness, nausea, or goosebumps seriously. Do not combine heat training with interval training.

I've seen riders who, with the best of intentions, wanted to do everything at once – and ended up having to recover from heat shock for days.

Personally, I value heat training as a smart addition to my training year. It strengthens not only the body but also the mind. Those who learn to stay calm in the heat, avoid getting nervous, drink strategically, and monitor themselves carefully – also have a clear advantage in the race.

For you as a recreational athlete, well-thought-out heat training can be an exciting component – especially if you are planning summer races, Gran Fondos or stage rides.

With that in mind, stay cool, even when it gets hot.

Her

Ulrich Bartholmös

PS: What are your experiences with heat? Have you ever consciously prepared for it—or has it been more of a coincidence that you've been cycling in 35-degree heat? Write to me —I look forward to hearing from you.