Initially developed to improve performance in hot environments, heat training is now widely used by endurance athletes looking to improve performance even when racing in moderate to hot temperatures. But heat training is often misunderstood. More heat is not always better, and poor implementation can compromise training quality or increase fatigue.
This article explains the benefits of heat training, how to implement it effectively, and the most common mistakes to avoid.
What Is Heat Training?
Heat training consists of exposing the body to elevated temperatures repeatedly over a period of days or weeks.
The objective is not simply to feel hot.
The goal is to increase core temperature sufficiently and repeatedly enough to trigger physiological adaptations.
These adaptations can occur through:
- training in a warm environment
- indoor training without a fan
- post-exercise sauna sessions
- overdressing during selected low-intensity sessions
The key is not external temperature itself, but the body's internal temperature response.
Why Can Heat Training Improve Endurance Performance?
Several studies have shown that heat acclimation can improve endurance performance by triggering adaptations that benefit oxygen delivery and cardiovascular efficiency.
The most commonly observed adaptations include:
- increased plasma volume
- improved blood flow distribution
- lower cardiovascular strain during exercise
- improved sweat response
- improved thermoregulation
Some research also suggests an increase in red blood cell production through stimulation of erythropoietin (EPO) and plasma volume expansion.
For endurance athletes, these changes can translate into:
- lower heart rate at a given intensity
- improved cooling capacity
- improved tolerance to prolonged efforts
- potentially improved VO2-related performance
💡 One reason heat training has become popular is that increased plasma volume can create adaptations that partially resemble some of the cardiovascular benefits associated with altitude training.
How to Do Heat Training Properly
The objective is not to make training as uncomfortable as possible.
The objective is to reach and maintain an elevated core temperature long enough to stimulate adaptation.
Most athletes require approximately 30 to 45 minutes before core temperature reaches the desired zone.
For this reason, short sessions are often insufficient.
Practical strategies include:
- indoor training
- avoiding fans
- wearing an additional layer
- using a cap indoors if needed
However, discomfort should remain manageable.
A useful guideline is:
👉 approximately 7/10 perceived heat discomfort.
Beyond that point, additional heat often increases fatigue more than adaptation.
Hotter is not always better. Consistency is more important than extreme exposure.
Heat Training Protocols: Beginner to Advanced
Beginner
2 to 3 sessions per week.
- indoor endurance rides or runs
- no fan
- 45 to 60 minutes
- low intensity
Objective: allow the body to gradually adapt to heat stress.
Intermediate
3 to 5 sessions per week.
- indoor endurance training
- additional clothing layers
- core temperature monitoring
Objective: increase thermal load while maintaining training quality.
Advanced
5 to 7 sessions per week during dedicated heat blocks.
- structured heat sessions
- race-specific preparation
- precise temperature monitoring
Objective: maximize heat adaptation before competition.
Why Core Temperature Matters More Than Air Temperature
One of the biggest mistakes athletes make is measuring heat exposure instead of measuring body response.Two athletes can train in the same room and experience completely different thermal stress.
This is where the CORE 2 Thermal Sensor becomes particularly valuable.
Instead of guessing whether heat exposure is sufficient, athletes can monitor their thermal load directly and make adjustments based on objective data.
Benefits include:
- real-time thermal monitoring
- individualized heat training
- avoidance of under-heating
- avoidance of excessive heat stress
- improved consistency
For athletes serious about heat adaptation, measuring internal thermal response is far more useful than simply monitoring room temperature.
Common Heat Training Mistakes
Several mistakes repeatedly limit the effectiveness of heat training.
1. Doing Heat Training Outdoors on the Bike
Outdoor conditions constantly change.
Wind creates significant cooling, making thermal stress difficult to control.
Indoor sessions generally provide more reliable heat exposure.
2. Wearing Extra Layers During Intensity Sessions
This is one of the most common mistakes.
Adding excessive clothing during intervals or high-intensity training often reduces power output and compromises workout quality.
Heat sessions should generally be separated from key intensity sessions.
3. Thinking More Heat Equals Better Results
Excessive heat exposure can increase fatigue, impair recovery and reduce training quality.
The goal is adaptation, not suffering.
Is Heat Training Worth It for Endurance Athletes?
For endurance athletes, heat training is one of the most effective ways to improve thermal tolerance and cardiovascular efficiency.
The benefits appear to be driven primarily by increased plasma volume and improved thermoregulation, both of which can support endurance performance.
However, successful heat training depends on proper implementation.
The most effective approach is generally:
- progressive exposure
- controlled discomfort
- preservation of training quality
- objective monitoring
This is precisely why tools such as the Core 2 Thermal Sensor are becoming increasingly popular among endurance athletes. By monitoring thermal load directly, athletes can individualize heat training and ensure that sessions are challenging enough to drive adaptation without compromising recovery.