The ankle dorsiflexion kinetics demand to increase swing phase foot-ground clearance: implications for assistive device design and energy demands.
Soheil Bajelan, W A Tony Sparrow, Rezaul Begg
PMID 38907255WHAT IT FOUND
To lift the foot higher during walking, the body generates more muscle force and energy, but the ankle joint moment itself does not increase.
Assistive devices should focus on delivering power and energy, not just higher torque, to match this biological demand.
Key findings
01Increasing foot clearance by about 4 cm using only ankle dorsiflexion did not significantly change the ankle joint moment compared to normal walking.
02The Tibialis Anterior muscle force increased throughout the swing phase, supported by EMG data, indicating higher muscular effort despite unchanged joint moment.
03Ankle work and energy demands were significantly higher immediately after toe-off and over the whole swing phase when foot clearance was increased.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only eight healthy, physically active males, excluding females and individuals with gait impairments. Musculoskeletal modeling relies on assumptions about muscle mechanics and optimization criteria, which may not perfectly reflect biological reality. The experimental condition was a voluntary, short-term manipulation of foot clearance in healthy walking, which may not mimic the pathological gait patterns or muscle weaknesses seen in clinical populations. EMG was used only for model validation and does not have a direct linear relationship with muscle force.
Declared interests
The authors declare no competing interests. The study was supported by the Victoria University Human Research Ethics Committee.
The easy way to misread this
Do not assume that assistive devices need to generate higher ankle torque to prevent tripping. This study found that while muscle force and energy demands increased significantly to lift the foot, the net ankle joint moment remained largely unchanged due to antagonist co-activation.