A Wearable Haptic Feedback System for Arm-Swing Amplitude Modulation During Overground Walking in Older Adults.

Arm range of motion increased significantly across all conditions compared to baseline, with the largest increase occurring during feedback conditions.

• Arm ROM increased by +229% during Feedback conditions, +120% during Exaggerated walking, and +64% during Fast walking, all compared to Baseline
• All pairwise comparisons were statistically significant (all p < 0.001)
• Twelve community-dwelling older adults participated (6 males/6 females; 75.8 ± 6.5 years)
• A within-subject repeated-measures design was used across nine total conditions (3 no-feedback, 6 feedback)

Walking speed and stride length increased during feedback conditions relative to baseline.

• Both walking speed and stride length showed statistically significant increases during Feedback relative to Baseline (p < 0.001)
• Gait outcomes were primarily influenced by the Direction factor within feedback conditions
• The feedback conditions varied Direction (Forward, Backward, Combined) and target Magnitude (+100%, +200% of Baseline)

Within feedback conditions, arm ROM showed independent main effects of both Direction and Magnitude, while gait outcomes were primarily influenced by Direction.

• Direction (Forward, Backward, Combined) and Magnitude (+100%, +200%) each had independent main effects on arm ROM
• Gait spatiotemporal outcomes were primarily influenced by Direction rather than Magnitude
• This dissociation suggests that the direction of haptic cueing matters more for gait improvement than the size of the target increment

Arm-swing symmetry was largely preserved across conditions, with the smallest variability observed during feedback conditions.

• Arm-swing symmetry was maintained despite large increases in arm ROM during feedback
• Variability in arm-swing symmetry was smallest during the Feedback conditions compared to other conditions
• Vibrotactile cues were delivered to both arms targeting peak Forward flexion and/or peak Backward extension when the corresponding peak failed to reach the target

The study used a wearable system with upper-arm IMU sensors to estimate arm-swing angle in real time and deliver vibrotactile cues.

• Arm-swing angle was estimated in real time from upper-arm inertial measurement unit (IMU) sensors
• Vibrotactile cues were delivered when peak Forward flexion and/or peak Backward extension failed to reach the target magnitude
• Targets were defined as +100% or +200% of the Baseline arm-swing amplitude
• The system was evaluated during overground walking

Reduced arm swing in older adults is associated with declined gait performance, and experimentally increasing arm swing can improve spatiotemporal gait parameters.

• Experimental studies have demonstrated that restricting arm swing decreases stride length and walking speed
• Deliberately increasing arm swing can improve stride length and walking speed
• Reduced arm swing frequently occurs in older adults
• This background motivated testing whether haptic feedback could enhance arm swing and thereby improve gait outcomes