I tried heat training in winter using the Core body temperature sensor device

According to Puck Alkemade, a Core physiologist and study coordinator, fitness levels do play a part in our ability to handle the heat, which is why it’s good to track.

By maintaining good levels of fitness (for instance, being well-trained in endurance sports or sports with considerable duration and intensity), your core temperature increases, and your body needs to lose heat.

This way, your body starts to adapt (although specific heat training would result in better heat adaptation). Generally speaking, if you are more fit (which doesn’t just mean strength), you’re more likely to be able to handle the heat.

There is currently no evidence to suggest that women have a clear disadvantage compared to men when exercising in the heat based on sex alone.

However, Core did find that smaller individuals (with low body mass, typically females) experienced a large heart rate adaptation, whereas larger individuals (with high body mass, typically males) had a larger sweat adaptation. Both groups adapted, but in different ways.

The menstrual cycle and oral contraceptive use may influence the thermoregulatory system, though the effects on heat susceptibility and performance in the heat require further exploration. Core’s technology can also be used for fertility or ovulation tracking as an alternative to other thermometers, although this feature is not yet integrated into the app.

Some female athletes and teams are experimenting with training optimisation based on the menstrual cycle. For instance, if you feel energetic during a particular phase, you can schedule heavier training blocks. Conversely, if you’re less energetic, struggling with sleep, or dealing with menstrual pain, you can ease off. Tracking the menstrual cycle allows you to align your training with how you’re feeling.

Heat training is incredibly accessible and can deliver impressive results if you stick with it.

The body can adapt to withstand hotter and colder temperatures, but these changes happen gradually over the course of a few weeks.

Using a device like the Core sensor lets you gather personalised data about your heat strain in different conditions (exercise, daily activities, or throughout your menstrual cycle). This can help you predict and adapt your training to match environmental conditions.

According to Core running coach Terrence Mahon, heat training is unique because you don’t need to dedicate hours each day.

Just 40 to 90-minute heat sessions a few times a week can make a difference. Unlike altitude training, which typically requires travelling to the mountains for weeks, heat training is more convenient and cost-effective. Once you’re heat-adapted, you can maintain your gains with occasional top-up sessions.

Another bonus? Heat training can also be achieved passively by hopping into a sauna or steam room, which has the added benefit of supporting recovery.