Simple within-stride changes in treadmill speed can drive selective changes in human gait symmetry

Area of Science:

• Biomechanics
• Human locomotion
• Rehabilitation engineering

Background:

• Gait asymmetry affects millions, necessitating adaptable rehabilitation strategies.
• Current methods lack flexibility in targeting diverse gait deviations.
• Understanding gait control mechanisms is crucial for developing new interventions.

Purpose of the Study:

• To investigate if within-stride treadmill speed variations can induce selective gait symmetry changes.
• To explore the effects of closed-loop and open-loop treadmill control on gait patterns.
• To identify potential new techniques for gait rehabilitation.

Main Methods:

• Healthy adults (n=20) walked on an instrumented treadmill.
• Experiment 1: Closed-loop controller adjusted speed based on propulsive leg (1.50 m/s or 0.75 m/s).
• Experiment 2: Open-loop controller altered speed at specific times, guided by a metronome.

Main Results:

• Closed-loop control induced asymmetry: accelerating leg had smaller leading limb angles, larger trailing limb angles, and less propulsive force.
• Open-loop control created different asymmetries based on timing: early speed changes affected step times and limb angles; later changes affected step lengths and propulsion impulses.
• Treadmill speed manipulations selectively altered gait parameters.

Conclusions:

• Simple, within-stride treadmill speed adjustments can effectively drive specific gait asymmetries.
• This technique shows promise for future gait rehabilitation strategies.
• Further research is needed to explore clinical applications for restoring gait symmetry.