Core temperature is a vital physiological signal that has direct, individual effects on performance. Run too hot, and your power will drop. That's why pro riders focus so much on heat adaptation. In the past, core temperature could not be measured on the road. Lab results could be extrapolated, but the real-time effect of internal body temperature on the bike was a black box. That's changed thanks to CORE's body temperature sensors.

"Historically we've lacked a tool that is easily usable in training and competition to directly quantify the body's response to heat," said EF Pro Cycling performance director Nate Wilson. "Heart rate and power alone tell us something, but they are influenced by too many confounding factors (fatigue, hydration status, altitude, etc.) to give us the full picture. Now that we have access to real-time body temperature data with CORE, we can much better understand how our athletes reacted to the heat in races. This helps us refine in-race cooling protocols, as well as identify riders who need more attention for heat preparation training. In the future, we hope to do even more with the data from CORE to better individualize the amount of heat training needed for a rider to reach a competitive level of heat adaptation. The bottom line is that this data helps us fill in some of the gaps we have in the total performance equation of a rider, both with respect to improving athlete preparation and in analyzing the response to stressors."

If you overheat on the bike, your ability to produce power will fall dramatically. Your body aims to maintain a core temperature between about 36 to 37.5 degrees Celsius by balancing heat production and heat loss. Exercise generates heat. To maintain homeostasis during exercise, the body's cooling functions activate. Sweat cools the skin through evaporation. Blood vessels widen and heart rate rises to increase blood flow to the skin. This reduces blood flow to the muscles. Intense exercise in high temperatures can overwhelm the body's ability to cool itself. Signs of this include increases in core temperature, skin temperature, and heart rate. This is called heat strain. Heat strain results in performance loss.

Before CORE sensors were introduced, it was difficult to isolate the exact effect of heat strain on performance, however.

"For a long time, we've had to infer how riders are coping with heat using indirect markers like heart rate and power," said Nate Wilson. "Those metrics are essential, but they don't directly reflect the athlete's internal thermal state when heat becomes a limiting factor. With real-time core temperature data, we can now observe that internal response directly. It changes how we interpret performance in the heat, and how we respond in real time."

Heat training can dramatically improve your body's ability to perform in hot conditions. Riding in 30-plus degrees Celsius conditions with his core temperature above 38.5 degrees, Ben Healy was able to push 330 watts for almost half an hour longer than his baseline after he had completed a controlled block of heat training.

Heat training reduces core temperature, Heat Strain Index, and heart rate for a given workout in given conditions. It also reduces the amount of sodium lost via sweating, lowers the risk of heat-related illnesses, and improves the body's ability to produce power in hot and humid conditions.

Read more about the heat training protocol that our team uses here.

What CORE allows you to do is track your body's adaptations to heat stimulus outside of a lab setting.

"Before the CORE Sensor, there was no way to continuously, noninvasively, and accurately measure an individual's thermal vitals," said Aline Barre, CORE's endurance performance lead. "Everyone's physiology is completely different and prescribing blanket heat training protocols or cooling strategies fails to address this fact. CORE Sensors provide data at the individual athlete level, allowing for optimized performance in training and racing."

This has been a game changer for our pro racers. Our coaches are now able to monitor our riders' progress in real time and optimize their training for heat, based on each rider's specific thermal response profile.

"Athletes respond very differently to identical environmental conditions," Nate Wilson said. "Heat adaptation is not uniform. This data allows us to better understand those differences and tailor preparation accordingly."

By tracking your core temperature, you can make strategic heat-based decisions. If you have an intense workout planned for an extremely hot day and haven't yet completed a block of heat training, you should adjust the power that you expect to produce on the day accordingly. It may make sense to move that session to a day with a cooler forecast. Heat strain stresses the body and you should account for that stress day over day and week over week when you are developing your training plan.

You should also account for heat strain when you're racing. In hot temperatures, more conservative pacing strategies are more likely to be successful, while cooling strategies, such as pouring water over your head and putting ice down the back of your jersey, become vital.

However, if you know that you are well-adapted to heat and have learned how your body best handles hot temperatures with the information provided by your CORE temperature sensor, you can turn those insights into massive competitive advantages. That's what we're doing at EF Pro Cycling.

"We can refine cooling strategies, adjust hydration approaches, and identify riders under excessive thermal load earlier, before it translates into performance decline," said Nate Wilson.

Thanks to CORE's body temperature sensors, you can now do the same.