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Adherence to Simple Spring-Mass Mechanics During Submaximal Running in Individuals With Unilateral Transfemoral
Ying Wai Tang1,2, Akihiko Murai2, Hiroaki Hobara3
1Department of Human and Engineered Environmental Studies, University of Tokyo, Kashiwa, Chiba, Japan.
Journal of Applied Biomechanics
|January 22, 2026
Summary
Running prosthetics closely follow spring-loaded inverted pendulum (SLIP) model mechanics, unlike the unaffected limb in amputees. This adherence is maintained across various running speeds, optimizing gait for affected limbs.
Area of Science:
- Biomechanics
- Prosthetics Engineering
- Human Movement Science
Background:
- The spring-loaded inverted pendulum (SLIP) model describes optimized running mechanics.
- Individuals with unilateral transfemoral amputation often use running-specific prostheses.
- Understanding gait mechanics in amputees is crucial for prosthetic design and rehabilitation.
Purpose of the Study:
- To compare experimental vertical ground reaction force (vGRF) with SLIP model predictions in amputees.
- To assess gait adherence to SLIP mechanics in affected vs. unaffected limbs during running.
- To investigate the effect of running speed on SLIP model adherence in this population.
Main Methods:
- Nine participants with unilateral transfemoral amputation ran on an instrumented treadmill at varying speeds (30-80% max speed).
- Vertical ground reaction forces (vGRF) were experimentally measured.
- Experimental vGRF data were compared to SLIP model-predicted vGRF using R2 goodness-of-fit statistics.
Main Results:
- The affected limb's vGRF showed significantly higher adherence to the SLIP model compared to the unaffected limb.
- No significant differences in SLIP model adherence were observed across different running speeds for either limb.
- Running-specific prostheses demonstrated SLIP-consistent mechanics, while the unaffected limb used non-SLIP strategies.
Conclusions:
- Running-specific prostheses effectively replicate SLIP mechanics, suggesting optimized gait for the affected limb.
- The unaffected limb employs compensatory strategies that deviate from SLIP mechanics.
- SLIP-based modeling is applicable to the affected limb in transfemoral amputees, aiding prosthetic development and understanding gait preservation across speeds.
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