Muscle work is increased in pre-swing during hemiparetic walking

Area of Science:

• Biomechanics
• Gait Analysis
• Neurology

Background:

• Gait abnormalities in hemiparetic walking affect muscle mechanical work during the paretic pre-swing phase.
• Previous studies may have underestimated paretic work due to not accounting for antagonist muscle co-contraction.
• It remains unknown if the non-paretic leg compensates and how work generation differs at various self-selected speeds.

Purpose of the Study:

• To quantify musculotendon work during the paretic pre-swing phase in hemiparetic walking.
• To compare muscle work between hemiparetic individuals walking at different speeds and a control subject.
• To investigate compensatory work mechanisms in hemiparetic gait.

Main Methods:

• Generated 3D forward dynamics simulations for two hemiparetic subjects (limited community and community walkers) and one control subject.
• Quantified musculotendon (fiber and in-series tendon) work during the paretic pre-swing phase.
• Simulations were based on different self-selected walking speeds (0.45 m/s and 0.9 m/s).

Main Results:

• Total paretic and non-paretic fiber work increased in both hemiparetic groups compared to controls.
• In limited community walkers, increased fiber work was linked to decreased paretic plantar flexor work, necessitating compensatory work by other muscles.
• In community walkers, increased fiber work was primarily due to hip abductor and adductor muscles.

Conclusions:

• Hemiparetic walkers exhibit increased metabolic energy expenditure during pre-swing compared to controls at similar mechanical efficiencies.
• These findings contribute to understanding the elevated metabolic cost observed in hemiparetic gait.
• The study highlights the complex muscle work adaptations in hemiparetic walking.