Objective: To compare gait parameters in Parkinson's disease (PD) during the on-phase of medication cycle with those of healthy elderly control subjects.Design: A group-comparison study. Setting: Gait analysis laboratory of a university hospital. Participants: Fifteen patients with PD and 9 healthy elderly controls.Interventions: Not applicable. Main Outcome Measures: Spatiotemporal, kinematic, and kinetic gait parameters.Results: The PD spatiotemporal results showed a significant reduction in step length and walking velocity compared with controls. In the kinematics, the major feature of the PD group was a markedly reduced ankle plantarflexion excursion (at 50%-60% of the gait cycle). Most important, the kinetics showed reduced ankle push-off power and hip pull-off power. Unlike the control subjects, the patients with PD did not show any correlation between ankle generation (push-off) power and stride length (rϭ.19) or with gait speed (rϭ.29). Correction for walking velocity did not result in significant changes in the kinetics between the groups.Conclusions: Reduced ankle (push-off) power generation and reduced hip flexion (pull-off) power persisted in PD gait despite being tested in the on-phase of the medication cycle. Lack of a correlation between ankle and hip power generation and walking velocity suggests that peripheral and central factors contribute to lack of forward progression. Patients with PD may benefit from intervention strategies that correct the kinematic and the kinetic gait components.

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The impact of dual tasks on gait in Parkinson's disease (PD) reveals lack of automaticity and increased cognitive demands. We explored which characteristics explained walking speed with and without dual task interference and if they reflected the cognitive demands of the task. In 130 people with PD, gait performance was quantified in the home using accelerometers allowing estimates of single and dual task walking speed and interference (difference between dual and single task). Multiple regression analysis was used to explore the effect of 12 characteristics representing four domains (personal, motor symptoms, cognitive, affective) on gait outcomes. Thirty-seven percent of variance in single task speed was explained by increased fear of falling, sex, age, disease severity, and depression; 34% of variance in dual task speed was explained by increased fear of falling, disease severity, medication, and depression; 12% of variance in interference scores was explained by greater disease severity and impaired executive function. Personal, motor, affective, and cognitive characteristics contribute to walking speed and interference, highlighting the multifactorial nature of gait. Different patterns of characteristics for each outcome indicates the impact of cognitive demand and task complexity, providing cautious support for dual task speed and interference as valid proxy measures of cognitive demand in PD gait.

Rhythmical cueing yielded faster performance of a functional turn in both freezers and nonfreezers. This may be explained by enhancing attentional mechanisms during turning. Although no harmful effects were recorded, the safety of cueing for turning as a therapeutic strategy needs further study.

Summary Changes in gait performance in 153 subjects with PD using three rhythmical cues (auditory, visual and somatosensory) were measured during a simple walking task and a dual walking task in the home. Subjects were 'on' medication and were cued at preferred step frequency. Accelerometers recorded gait and walking speed, step amplitude and step frequency were determined from raw data. Data were analysed with SAS using linear regression models. Gait performance during a single task reduced with cues in contrast to a dual task where PD subjects appeared to benefit from rhythmical cues (increased speed and step length). Effects were dependent on cue modality with significant improvements for auditory cues compared to others. A significant short-term carry-over effect of cues reduced 3 weeks later. Cues may reduce attentional demands by facilitating attentional allocation, accounting for differences of cue seen during single and dual task. Furthermore cue modality may influence attentional demand which is an important consideration for rehabilitation.