Monitor core body temperature in real time

The CORE body temperature sensor gives you a real-time view of your core temperature during training and competition.

With the algorithm in the CORE app, it is highly effective for heat training, heat adaptation, and managing thermal strain.

Connect your CORE device to a Bluetooth heart rate monitor and continuously monitor your heat adaptation score and your personal heat training zones.

Used correctly, heat training can help optimize adaptation for competitions in hot and humid conditions, while also supporting endurance performance and reducing the risk of dehydration, overheating, fatigue, and heat-related injury.

Heat Training Insights

Heat Adaptation Score

The Heat Adaptation Score reflects how well your body is adapted to heat stress over time. As you consistently train in controlled heat conditions, this score improves, indicating better thermoregulation, increased plasma volume, and improved tolerance to elevated core temperatures.

Heat Strain Index

The Heat Strain Index measures the physiological stress your body is under during a session. It combines core temperature and exposure duration to give a clear indication of how demanding the session is.

Heat Zones

Heat Zones guide your training intensity based on core body temperature rather than pace or power. Too low provides little adaptation, while too high increases fatigue and risk. Staying in the right zone improves heat tolerance and performance.

What's in the box?

• CORE Sensor
• USB-C magnetic charging cable
• Clips to secure the sensor to HR monitor strap
• Guide to setting up the CORE iOS / Android app

CORE 2 - What's new?

• Smarter design: a new LED indicator gives instant updates on device status, battery life, and charging progress.
• Improved usability: a detachable and reengineered attachment system with durable, flexible materials keeps CORE 2 secure and simplifies charging.
• More sustainable packaging: more sustainable packaging and a smaller CORE unit mean less material use.
• Future-ready hardware: CORE 2 is designed to support upcoming software innovations.

Why does temperature matter?

• Up to 5% loss of power for every 1°C increase in body temperature
• Up to 8% increase in performance with only a few days of well-structured heat training
• Up to 2.5% increase in hemoglobin mass after long-term heat training

Increased performance in hot and humid climates is an obvious benefit of heat adaptation, but the advantages are broader than that. Heat training can also stimulate blood plasma production and increase hemoglobin mass, supporting performance even outside hot environments. When your core body temperature rises during intense exercise, power and pace decline, and by the time you feel too hot, it is often already too late. CORE helps you train in the right heat zone, as too much heat can have negative effects while too little may provide limited adaptation. With clinically, lab, and field-tested accuracy, CORE enables athletes and coaches to manage heat acclimatization and monitor core temperature during training and racing.