Train Hot. Race Cool.

The CORE 2 Thermal Sensor monitors your real-time thermal data for better performance. Safely and effectively facilitate heat training to boost your hemoglobin mass and VO2 max or monitor your data on race-day so you can cool and pace your effort accordingly.

CORE allows you to safely facilitate heat training, which over time produces advantageous physiological transformations that allow your body to adapt to performing at higher temperatures. Heat adaptations allow you to stay cooler for longer, increasing your performance on race day regardless of the temperatures. CORE also allows you to monitor your thermal vitals in real-time so you can pace and cool accordingly.

CORE 2 isn't just a smaller sensor—it's a smarter tool for real-time thermal monitoring:

• More Compact: 48% smaller and 30% lighter than CORE 1
• Smarter Design: New red LED light for clearer battery charging status indication
• Modular Usability: Detachable strap clip for easier securing and charging
• Future-Ready Hardware: Designed to support upcoming software innovations

Bring the Heat

Heat strain describes the physiological processes that cool the body. The harder the body works to cool itself, the greater the strain, and the greater the impact on performance. CORE's Heat Strain Index (HSI) quantifies this strain in real time using an algorithmic combination of core and skin temperatures.

Your Heat Strain Index can fall into 1 of 4 Heat Zones. The heat training zone (Zone 3) is the one that causes physiological adaptations that improve performance. Time spent in each zone is tracked on the CORE app.

Your Heat Training Load is the daily value (on a scale of 0-10) of the amount of time spent in the heat training zone (Zone 3). Optimal heat training involves 2–3 sessions per week, with 45–60 minutes per session in the heat training zone. Sequential days with high Heat Training Load will increase your Heat Adaptation Score.

The Heat Adaptation Score uses an evidence-backed formula to calculate how adapted you are to heat on a scale of 0-100%. Use Heat Zones to guide your training towards high daily Heat Training Loads, which ultimately boost your Heat Adaptation Score over time.

Features:

• Compact size: 41.9 x 29.4 x 7.1mm (no clip) | 45.1 x 32.6 x 9.6mm (with clip)
• Weight: 8.6g (no clip) | 11.4g (with clip)
• Battery: 6 days; up to 30 days with standby mode enabled
• Power supply: USB-C magnetic adapter cable (included)
• Connectivity: Bluetooth low energy (BLE), ANT+ (2.4 GHz band)
• Waterproof: up to 1.5m (IPX7 rating)
• Research-backed accuracy: mean difference range of -0.01°C to +0.23°C
• Includes CORE 2 Thermal Sensor, CORE 2 HRM Strap Clip, Magnetic USB-C Charging Cable, and Product Information Guide in fully recyclable packaging.