How to use CORE temperature data for training and racing

When you get hot, your power output drops.

The more you know about your individual core body temperature behaviour, the better you can train and race. The CORE sensor takes away the guessing so that your training and racing is better suited to you and is more effective.

Our Fast-Start Guide for Sports is a good reference to ensure you are properly set-up. It is essential to pair the CORE sensor with your heart rate monitor for sports activity.

Using CORE sensor data in a nutshell

core body temperature heat training

1. Heat Training - More effective and precise heat adaptation and acclimization to condition your body for better performance.

core body temperature active cooling

2. Active Cooling - Strategic cooling suited to your individual temperature behaviour on race day

core body temperature heat stress

3. Avoiding Overheating - Set your own safe limits to maximise performance while avoiding overheating.

Follow professional medical advice and guidance from an experienced coach so that your heat related training and racing is effective and safe.


In summary, Train hot... race cool!
Read about the science of thermoregulation in sports.

1. Heat Training

Introducing controlled and repeated increases in core body temperature is a highly effective training approach that conditions the body to operate more efficiently when it is hot. Heat training increases the blood volume and improves the physiological efficiency that enables athletes to increase power output and improve performance in both hot and cool conditions.

Heat training is similar to high intensity or altitude training in that it introduces a ‘stress’ and the body adapts to become better under these conditions.

How to use the CORE sensor for Heat Training

The CORE sensor delivers highly accurate core body temperature values in real-time. This eliminates guessing and means you can train with reliable data.

The Heat Ramp Test for cycling and running is a single training workout that is recommended to identify the optimal Heat Training Zone. This is the temperature zone where heat training is effective without being overly fatiguing. Because core body temperature is individual, knowing your exact heat training zone ensures you are not under-training or over-training. There is no performance benefit to over-training (which can impact fatigue and recovery) while under-training means you are not sufficiently conditioned.

During heat training sessions you can monitor your real-time core body temperature and simply adjust intensity and external cooling sources (such as fans) to maintain the core temperature.

There are different approaces to heat training and integrating this into existing training programs. The CORE app calculates the heat load which indicates the time spent within customizable temperature zones and can be used to check that heat training objectives have been achieved.

Within the CORE app and inside FIT files, the core body temperature, skin temperature and metrics provide a precise overview that make it easy to monitor progress and identify irregularities. Learn more about heat training for sporting performance.

2. Active Cooling

While racing, the lower the core body temperature, the more power is available. As the body heats, it diverts more blood away from the power producing muscles to the skin where the body relies on sweat evaporation to cool. In addition to heat training and acclimatization, additional steps that help keep the temperature lower provide a performance advance.

How to use the CORE sensor for Active Cooling

During training, identify the cooling approaches that are the most effective for you:

Pre-cooling ahead of competition involves warming the muscles while keeping the core body temperature low. For example, a predefined core temperature is set and the intensity and external cooling is adjusted during a standard warm-up routine.

Reducing pace or intensity is the most effective way to lower core body temperature, even though it is rarely the prefered solution during races. During training and subsequently while racing, observing the real-time core body temperature enables a balance between pace/intensity and other cooling approaches. For example, pace could be reduced, but perhaps only slightly when combined with increased cooling.

Hydration impacts cooling. Hydration levels are not specifically identified by the CORE sensor though poor hydration leads to rising core body temperature.

Ice slushies and ice on the skin can provide a cooling effect and relief. When ice melts on the skin, this helps evaporative cooling. However consider that there are conflicting scientific viewpoints regarding the perceived positive effects of ice cooling against signals to the brain that may interrupt and slow natural cooling mechanisms of the body.

Wetting the skin (pouring water over the head and body) to externally cool the body and aid the evaporative cooling effect is highly effective, particularly in drier environments. Skin temperature values and the difference between skin temperature and core temperature, (which is calculated as the heat strain score) provide insights into the ability and efficiency of cooling.

Sports wear impacts cooling. Both the clothing textiles themselves and the taking-off of layers play an important role. The discomfort of removing layers of clothing earlier than usual to lower the core body temperature can pay-off with longer sustained power.

Strategic cooling is a natural outcome that follows training and experience monitoring core temperature. For example:
- Clothing layers can be discarded ahead of long inclines (and expected high intensity). When the core temperature is purposely lowered well before a hill, this provides more range against competitors who start warmer
- During descents while cycling, the faster cooling from the wind can be accelerated with extra water over the body to drop the core body temperature further.
- Race reconnaissance can help you plan the cooling strategy

Learn more about strategic approaches for cooling during races.

3. Avoiding Overheating

Racing and training in hot conditions increases the risk of heat-related injury and illnesses and threatens athletes who are unprepared or who overexert themselves.

In some circumstances, overheating may have a small impact such as the loss of energy resulting in under-performance and possible withdrawal from competition. But it can also result in life-threatening heat-releated injuries that require immediate medical attention. Recovery from severe heat stress can take weeks or months.

How to use the CORE sensor to avoid overheating

The CORE sensor can show your real-time core body temperature data on popular sports watches and computers.

It is encouraged to identify a core body temperature limit that you should not exceed. This temperature limit is well below dangerous levels and is intended as a preventative theshold. The intention is that if this limit is reached, you can still take steps to cool down while remaining safe and competitive.

During sports, it is easier to remain cooler and below your own temperature limit than to exceed your limit and then try to cool. The hotter you become, the harder your body needs to work to keep cool.

On some sports devices, you can set specific core body temperature limits to trigger an alert. The Active Cooling section (below) outlines tangible steps that can be taken to lower the core body temperature.

Note: The CORE sensor is not designed to diagnose heat related illnesses. Real-time data can be used to take action to prevent overheating. Learn more about the consequences of overheating.

Would you like to learn more?

In the CORE blog we publish informative articles plus we also have a large resource of internal and external topics for everything about core body temperature.

The CORE sensor can be purchased directly online or from one of our trusted retailers.