Abstract-While much is known about the effects of dual tasking on cyclical and continuous motor performance (e.g., locomotion), there is a paucity of information on the effect of dual tasking on the initiation of movement. Therefore, the purpose of this study was to investigate the effect of a concurrent cognitive task on gait initiation in three groups: patients with Parkinson disease, healthy older adults, and healthy young adults. We examined the anticipatory postural adjustment displacements and velocities during single-task gait initiation as well as two dual-task conditions: (1) 0-back + gait initiation and (2) 2-back + gait initiation. The Parkinson disease group exhibited less anticipatory postural adjustment displacement and velocity than their aged-matched healthy peers and young adults during the single-and dual-task gait initiation settings (p < 0.05). Of interest was the finding of no additional effect on anticipatory postural adjustment displacement or velocity of gait initiation during the dual-task conditions in any group, including the Parkinson disease group. More traditionally studied gait/balance dual-task paradigms have demonstrated both motor and cognitive decline. Therefore, our results may suggest a prioritization of more "intentional" movement task (e.g., gait initiation) while dual tasking in Parkinson disease.

Background Coordination between the upper and lower extremities is important to providing dynamic stability during human gait. Though limited, previous research has suggested that interlimb coordination may be impaired in persons with Parkinson’s disease. We extend this previous work using continuous analytical techniques to enhance our understanding of interlimb coordination during gait in persons with Parkinson’s disease. Methods Eighteen adults with Parkinson’s disease and fifteen healthy older adults walked overground while undergoing three-dimensional motion capture. Ipsilateral and contralateral interlimb coordination between the sagittal shoulder and hip angles was assessed using cross-covariance techniques. Independent samples and paired samples t-tests compared measures of interlimb coordination between groups and between sides within the participants with Parkinson’s disease, respectively. Pearson’s correlations were applied to investigate associations between interlimb coordination measures and subscores of gait, posture, and bradykinesia on the Unified Parkinson’s Disease Rating Scale. Findings Ipsilateral and contralateral interlimb coordination was reduced in persons with Parkinson’s disease compared to the healthy older adults. Ipsilateral coordination between the upper and lower extremities more affected by disease was found to be negatively associated with clinical scores of gait and posture. Interlimb coordination was not significantly associated with clinical measures of bradykinesia. Interpretation Persons with Parkinson’s disease exhibit reduced interlimb coordination during gait when compared to healthy older adults. These reductions in coordination are related to clinically-meaningful worsening of gait and posture in persons with PD and coordination of arm and leg movements should be considered in future research on gait therapy in this population.

These new gait assessment techniques successfully captured changes in asymmetry, variability, complexity, and joint coupling patterns. Quantitative gait assessment using these tools can be used to detect various types of gait impairments.

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The only commercially available ankle-foot prosthesis with powered propulsion lacks ruggedization and other capabilities for service members seeking to return to duty and/or other physically demanding activities. Here, we evaluated a ruggedized powered ankle-foot prosthesis with electromyographic control (“Warrior Ankle”; WA) in an experienced male user of the predicate (Empower) prosthesis. The participant (age = 56 years, mass = 86.8 kg, stature = 173 cm) completed a 650 m simulated hike with varying terrain at a fixed, self-selected speed in the WA and predicate prosthesis, with and without a 22.8 kg weighted vest (“loaded” and “unloaded,” respectively). Peak dorsiflexion and plantarflexion angles were extracted from each gait cycle throughout the simulated hike (∼500 prosthetic-side steps). The participant walked faster with the WA (1.15 m/s) compared to predicate (0.80 m/s) prosthesis. On the prosthetic side, peak dorsiflexion angles were larger for the WA (loaded: 27.9°; unloaded: 26.9°) compared to the predicate (loaded: 19.4°; unloaded: 21.3°); peak plantarflexion angles were similar between prostheses and loading conditions [WA (loaded: 15.5°; unloaded: 14.9°), predicate (loaded: 16.9°; unloaded: 14.8°). The WA better accommodated the varying terrain profile, evidenced by greater peak dorsiflexion angles, as well as dorsiflexion and plantarflexion angles that more closely matched or exceeded those of the innate ankle [dorsiflexion (WA: 31.6°, predicate: 27.5°); plantarflexion (WA: 20.7°, predicate: 20.5°)]. Furthermore, the WA facilitated a faster walking speed, suggesting a greater functional capacity with the WA prosthesis. Although further design enhancements are needed, this case study demonstrated feasibility of a proof-of-concept, ruggedized powered ankle-foot prosthesis with electromyographic control.