Duty Factor Dominates Stride Frequency to Modify Musculoskeletal Peak Loading in Running

Area of Science:

• Biomechanics of running
• Musculoskeletal loading analysis
• Running injury prevention

Background:

• Running style adjustments influence musculoskeletal loading and injury risk.
• Duty factor and stride frequency are linked to peak running loads, but their specific roles are unclear.

Purpose of the Study:

• To investigate the individual and combined effects of duty factor and stride frequency on peak musculoskeletal loading.
• To understand how running pattern modifications impact loading at a constant, individualized speed.

Main Methods:

• Nineteen novice female runners adjusted duty factor and/or stride frequency during treadmill running.
• Ground reaction forces and motion capture data were collected.
• Peak loading was assessed using inverse dynamics, analyzing forces and moments at lower limb joints.

Main Results:

• Increased duty factor consistently decreased most peak loading metrics, except hip moments.
• Stride frequency's impact on loading varied; it reduced knee/hip extensor moments but increased hip flexor moments.
• When duty factor was controlled, stride frequency also influenced vertical ground reaction force and joint reaction forces, sometimes increasing peak loading.

Conclusions:

• Duty factor is the primary determinant of running-related peak musculoskeletal loading.
• Stride frequency's influence on peak loading is secondary and depends on individual factors and specific loading metrics.