-
Getting Started 5
-
Athlete App 3
-
Teams Solution 2
-
Sensors, Kits, and Packs 3
-
Accounts and Orders 2
-
Data and Education 8
-
Troubleshooting 2
Understanding Heat Strain
The Heat Strain Index helps you understand how your body is responding to heat and effort in real time—so you can adjust before performance drops.
What Is the Heat Strain Index?
The Heat Strain Index is a real-time score from 0 to 10 that shows how hard your body is working to regulate temperature during exertion. It combines data from core body temperature, skin temperature, and heart rate—captured through your HeatSense thermal sensor and HRM—to give you a single performance-relevant metric.
Why It Matters
As you train or compete, your body works to cool itself through sweat and blood flow. But in high heat or during prolonged intensity, these systems can become overloaded—leading to rising core temp, accelerated heart rate, and reduced power output. That’s heat strain—and understanding it is the key to managing performance under pressure.
More Than Core Temp Alone
Core body temperature is important—but it doesn’t tell the whole story. The HeatSense algorithm calculates mean body temperature by blending core and skin data to reflect total heat load more accurately. This holistic view is what drives the Heat Strain Index score.
How to Read the Score
| Index Score | What It Means | What You Can Do |
|---|---|---|
| 0 – 0.9 | Low strain Your cooling systems are managing the load well. |
Maintain intensity. Use this zone for key performance efforts. |
| 5 – 7 | Elevated strain Heat load is accumulating and performance may begin to suffer. |
Monitor hydration and adjust intensity if the session continues. |
| 10 | Danger zone Core temp likely approaching 103–104°F. |
Reduce intensity or begin cool-down. Use caution. |
How to Train With It
- Game Day Strategy: Stay in lower strain zones to protect performance late in competition.
- Acclimatization: Intentionally expose athletes to higher strain (45–80 min) during training blocks to build heat readiness—always under controlled monitoring.
- Recovery Optimization: Use the Index post-session to evaluate cooling effectiveness and session load.
Your Heat Strain Index is visible in real time through the HeatSense app.
