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Published on: April 18, 2011
Muscle force redistributes segmental power for body progression during walking
R R Neptune1, F E Zajac, S A Kautz
1Department of Mechanical Engineering, University of Texas at Austin, Austin, TX 78712-1063, USA. rneptune@mail.utexas.edu
Gait & Posture
|March 12, 2004
Summary
Uniarticular knee and hip extensors provide crucial body support during early stance. Muscle-generated segmental power redistribution is key for forward progression throughout the gait cycle.
Area of Science:
- Biomechanics
- Human locomotion
- Musculoskeletal dynamics
Background:
- Ankle plantar flexors (soleus and gastrocnemius) were previously understood to support the body in single-leg stance for forward progression.
- Their net effect on trunk and leg acceleration is negligible mid-stance but accelerates forward in late stance, suggesting active push-off.
Purpose of the Study:
- To investigate the role of other muscles, beyond ankle plantar flexors, in supporting the body and redistributing segmental power during walking.
- To quantify the contributions of specific muscles to ground reaction forces and segmental accelerations and power.
Main Methods:
- Muscle-actuated forward dynamical simulations were used to emulate walking kinematics and kinetics.
- Simulations analyzed muscle contributions to vertical and horizontal ground reaction forces.
- Quantified muscle contributions to leg and trunk acceleration and mechanical power.
Main Results:
- Eccentric vasti (knee extensors) and concentric gluteus maximus (hip extensors) critically supported the body in early stance before plantar flexor activation.
- Vasti decelerated trunk and leg forward motion and redistributed power to the trunk in mid-stance.
- Rectus femoris and hamstrings showed varied roles in late stance, swing, and early stance, influencing leg and trunk motion and power redistribution.
Conclusions:
- Uniarticular knee and hip extensors are critical for body support at the beginning of stance.
- Redistribution of segmental power by muscles throughout the gait cycle is essential for forward progression of the trunk and legs.
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