CORE 2

Frequently asked questions

Here are the answers

Why is core body temperature important for performance?

Muscles generate heat as they work during an activity. If we generate enough heat, our core body temperature rises. The body will try to cool itself by diverting blood away from the muscles to the skin, where it cools through the evaporation of sweat, leading to a decrease in speed and performance. However, there are two ways we can minimize this effect. First, by monitoring our core body temperature, we can make strategic decisions about cooling and pacing during training and racing, which will help us stay cool and maximize our performance. Second, we can use heat training to adapt to higher internal body temperatures on race day. This can lead to radically improved performance – in one study, cyclists improved their time trial speed by 8% after just 10 days of heat training before a race.

What data does CORE 2 measure and display?

The CORE 2 sensor measures both core and skin temperature. These metrics are displayed live in the CORE 2 app and on compatible sports devices (typically a GPS watch or cycling computer). The app and some Garmin devices also display a real-time Heat Stress Index, which shows the amount of heat stress the body is facing.

How to use CORE 2 during training or racing?

During heat training, you can use CORE 2 data to keep your core temperature within your heat training zone. During races, CORE 2 data can tell you when to use cool-down strategies and when to reduce your power or pace to keep your body from overheating.

How much heat training do I need to achieve results?

Maximum benefits are achieved by completing 10-12 training sessions over a 2-6 week period. Most athletes will see the most improvement after 4-5 sessions, and benefits can be maintained throughout the season with as few as 2-3 sessions per week. Each session should include 45-60 minutes of continuous effort within the warm-up training zone. This is the recommended training schedule, although less frequent warm-up training has also been shown to be effective in improving race day performance.

I only race in cold weather. Why should I add warm-up training to my training?

Training in the heat adapts the body to perform more efficiently at elevated core temperatures. It also increases blood plasma volume and hemoglobin, which improves performance (increased lactate threshold and VO₂ max) in both cold and hot conditions.

What is the scientific basis for the benefits of training in the heat?

The effects of heat on human performance have been extensively studied and understood. It has been well documented by sports scientists that training in the heat increases the body's ability to handle higher temperatures, cool itself more efficiently, and perform in both cold and hot conditions. Physiological changes include increased blood plasma volume and hemoglobin, increased sweating rates, and earlier onset of sweating. A list of scientific studies supporting this finding can be found here .

Is the CORE 2 sensor really accurate? How is it tested?

The CORE 2 sensor measures the transfer of thermal energy between the body and the environment. An artificial intelligence algorithm uses this data to calculate core body temperature with medical-grade accuracy. Extensive testing has confirmed the accuracy of CORE 2 data compared to core body temperature data obtained through more invasive methods, such as electronic pills you swallow. This means that athletes can confidently use CORE 2 data to understand what’s going on inside their bodies using a completely non-invasive wearable device that is the first of its kind. Learn more about CORE 2’s accuracy here .

Is the CORE 2 sensor compatible with my watch, bike computer or app?

The CORE 2 app is available on both iOS and Android. The sensor is compatible with COROS watches (native compatibility, watch must have software from January 2022 and later), as well as most watches and cycling computers from Garmin, Suunto, Wahoo and Hammerhead. Functionality with Apple Watch and wearOS is still limited, but improving. Fully compatible training software includes Today's Plan, Intervals.icu and Golden Cheetah. The premium version of Training Peaks is also compatible. A detailed and updated list of all compatible devices can be found here .

Do I need a heart rate monitor (chest) to use the CORE 2 sensor?

For the most accurate readings during sports activities, it is highly recommended to pair the CORE 2 with a heart rate monitor (chest). Heart rate helps the sensor accurately convert the measured heat flow into core body temperature. During normal daily activities (e.g., outside of sports), core temperature readings are accurate with or without a monitor. Consider using the CORE 2 sensor with the COROS Heart Rate Monitor .