Changes in Running Mechanics During a 6-Hour Running Race

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Ultraendurance running races present unique physiological and biomechanical challenges.
• Understanding how running mechanics evolve during prolonged exercise is crucial for optimizing performance and preventing injury.

Purpose of the Study:

• To investigate the changes in key running mechanical parameters during a 6-hour self-paced running race.
• To identify potential time thresholds at which significant biomechanical alterations occur.

Main Methods:

• Twelve male ultraendurance runners completed a 6-hour race on a 874-m loop course.
• Running speed, ground-reaction forces, and temporal parameters (contact and aerial times) were measured throughout the race.
• Biomechanical variables including stride length and stiffness were calculated.

Main Results:

• Running speed decreased significantly after 4.5 hours of running.
• Contact time increased, while vertical stiffness, aerial time, and peak vertical ground-reaction force decreased after 4.5 hours.
• Stride length showed a significant reduction in the final hour of the race.

Conclusions:

• Significant changes in running mechanics emerge after approximately 4 to 4.5 hours of continuous running.
• These findings suggest a critical time threshold that influences running economy and performance, irrespective of absolute speed.
• Further research could explore interventions to mitigate fatigue-related biomechanical decline.