Supplemental intermittent-day heat training and the lactate threshold

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Sports Science

Background:

• Consecutive-day heat acclimation enhances aerobic performance.
• Heat training may improve performance in temperate environments.
• Athlete training schedules limit consecutive-day heat exposure.

Purpose of the Study:

• To assess the impact of brief, intermittent supplemental heat training on the second lactate threshold (LT2).
• To evaluate LT2 changes in both temperate and hot conditions following heat training.
• To determine if intermittent heat exposure benefits athletes with demanding training loads.

Main Methods:

• Twenty-one participants completed eight intermittent (every 3-4 days) treadmill exercise sessions.
• Training occurred in either hot (30°C; 50% RH) or temperate (18°C; 30% RH) conditions.
• Pre- and post-training incremental exercise tests in both conditions measured LT2.

Main Results:

• The intermittent heat training protocol did not significantly improve LT2 in temperate conditions (ES=0.10±0.16).
• No significant LT2 improvements were observed in hot conditions (ES=0.26±0.26).
• While the intervention group showed a greater change than controls, it was not statistically significant.

Conclusions:

• Brief (30-min) intermittent heat training sessions every 3-4 days are insufficient to enhance LT2.
• The limited duration and infrequent nature of the heat exposure likely explain the lack of performance improvement.
• Further research is needed to optimize intermittent heat training protocols for athletes.