High but not moderate-intensity endurance training increases pain tolerance: a randomised trial

Area of Science:

• Exercise Physiology
• Sports Science
• Muscle Physiology

Background:

• Endurance training enhances exercise tolerance.
• High-intensity interval training (HIIT) and moderate-intensity continuous training (CONT) are common training modalities.
• The differential effects of HIIT versus CONT on pain tolerance and exercise capacity require further investigation.

Purpose of the Study:

• To compare the effects of 6-week HIIT versus volume-matched CONT on muscle pain tolerance and high-intensity exercise tolerance in healthy adults.
• To determine if improvements in exercise tolerance following HIIT are linked to changes in pain tolerance.

Main Methods:

• Twenty healthy adults underwent 6 weeks of either HIIT or volume-matched CONT on a cycle ergometer.
• Muscle pain tolerance was assessed using a tourniquet test.
• High-intensity exercise tolerance was measured by time to exhaustion (TTE) at absolute and relative intensities.

Main Results:

• Both HIIT and CONT improved aerobic fitness markers similarly.
• HIIT significantly increased TTE at both absolute and relative intensities, whereas CONT showed minimal changes.
• HIIT enhanced muscle pain tolerance by 41%, while CONT had no significant effect.
• Improvements in pain tolerance positively correlated with enhanced TTE at both intensities.

Conclusions:

• Repeated high-intensity training stimulus enhances muscle pain tolerance.
• Increased pain tolerance following HIIT may contribute to improved high-intensity exercise tolerance.
• The benefits of HIIT on pain tolerance appear independent of aerobic fitness improvements.