Cycling in summer: Feeling a bit sluggish? Here’s how to get used to the heat quickly

Anyone out and about with a fitness watch on their wrist will have noticed it: everything’s actually showing green, and yet your training session or ride currently feels much more strenuous than usual. This is down to the midsummer temperatures, which have soared well above the 30-degree mark at very short notice over the last few days. But what exactly is actually happening inside the body right now?

Our bodies are currently struggling to perform at their best

To compensate for rising outside temperatures, the heart currently pumps more blood towards the skin, as sweating there now helps to cool the body down. However, this requires the cardiovascular system to expend significantly more energy. The heart beats faster and the core body temperature rises. At the same time, mineral salts (e.g. sodium, potassium, chloride and magnesium) are also lost through sweat. In other words: at 22 degrees and above, a healthy body is busy maintaining its own cooling system – even at rest. It simply lacks the capacity for additional bursts of performance during sport. At first, anyway! Once the body has become accustomed to the higher temperatures, it can once again divert blood – and the oxygen it carries – to the muscles. Hashtag acclimatisation.

Elite athletes need around two weeks to allow their bodies to fully acclimatise to higher temperatures. On the one hand, their cardiovascular system is well-trained and reacts more quickly to changing external conditions. On the other hand, however – particularly when a competition in hotter regions is coming up – they often undergo special ‘heat acclimatisation training’:

​The HWI method: Have a hot bath after your workout!

It sounds tough, and it is: if you want to acclimatise as quickly as possible, you should train despite the heat and, afterwards, rather than plunging into an ice bath to cool down, get into a 40-degree bath (or sauna) – and stay in there for 40 minutes! Soaking in hot water provides an additional heat stimulus without the need for a further training session, and the body accelerates its adaptation mechanisms. This so-called ‘hot water immersion’ method is scientifically proven and is said to show measurable effects within just six days.

If you don’t have a sauna or a bath, you can achieve similar results with ‘heat training’ by wearing clothes that are too warm.

Important: Heat training should only be undertaken at temperatures of up to 30 degrees, provided you have a solid base level of endurance and a stable cardiovascular system. This should be done at a training intensity of 60–70 per cent of your maximum heart rate. The body’s core temperature should be monitored (!) and allowed to rise to a maximum of 39 degrees.

Fluid loss with this training method is massive. It is therefore essential to drink plenty of water before, during and after training. Ideally, the water should contain electrolytes or sodium (one pinch of table salt per litre of water; up to a maximum of three pinches following very heavy sweating).

As soon as temperatures rise above the 30-degree mark – as they have in recent days – or if the humidity is high, please do not train in the heat. The risk of heatstroke is then too high. The first signs of this are: goosebumps, a slight chill, a tingling sensation on the scalp and a red face with a distinct white triangle around the nose and mouth.