Currently, progressive resistance exercise training, high intensity treadmill training, balanced-based perturbation, and standard physical exercises are utilized to treat mobility deficits associated with PD; however, the effectiveness of these therapies is limited. This study proposes to investigate the utility of a portable exoskeleton for people with PD. The goal is to establish the safety of a lightweight portable exoskeleton, the Keeogo, for gait training and to preliminarily assess its potential efficacy for gait mobility and fall reduction. As the vast majority of PD patients eventually require assistive mobility devices, portable exoskeletons represents an avenue for increased, mobility, quality of life, and independence. Robotic-assist gait training (RAGT) has been extensively applied as a remarkable therapeutic modality, such that it is enabling highly motivated people with devastating neurologic injuries to regain independent ambulation. Despite the potential for this technology to transform the lives of people with PD, these devices are not being adequately investigated in people with movement disorders.

To establish preliminary safety and efficiency of the Keeogo exoskeleton for PD patients at various disease stages, the investigators will examine representative subjects in Hohen \& Yahr stages II, III, IV, and V. Inclusion criteria are: 1) PD confirmed by a PADRECC movement disorder specialist using UK Brain Bank Criteria, 2) Modified H\&Y stage II-V. Exclusion criteria are: 1) neurological, musculoskeletal, or other disorders unrelated to PD contributing to impairment of stance, gait, balance or coordination, 2) severe CHF, COPD, or those requiring nasal canula O2, 3) history of implantable cardiac device or ablative surgery, 4) moderate to severe cognitive impairment / dementia (Montreal Cognitive Assessment \< 17/30), 5) symptomatic orthostatic hypotension with exertion, 6) feeding tube or associated port placement (PEG/J-PEG), 7) body height less than 5'1" or greater than 6'3" 8) body weight greater than 250 pounds, and 9) amputation of any portion of the lower limbs. Subjects will participate in a total of 30 minutes RAGT ambulation with the Keeogo twice per week for 6 weeks (12 sessions). Subjects may opt to utilize a platform rolling walker, rolling walker, bilateral Lofstrand crutches or a unilateral device, such as a cane or Lofstrand crutch, and will be maintained throughout the intervention.

To establish safety, the number and severity of AEs, such as falls, discomfort, skin or musculoskeletal injury, and orthostatic hypotensive episodes will be documented. Intervention efficacy will be measured pre- and post-donning of the Keeogo exoskeleton at bi-weekly intervention visits, and at a 6-week post-study visit. Walking capacity, including benefits on FoG, will be assessed with the Six Minute Walk Test (6MWT), balance and postural stability with the Berg Balance Scale (BBS), and disease severity with the Examination, Part III, of the Unified Parkinson's Disease Rating Scale (UPDRS). Additional assessments will include Berg Balance Scale (BBS), ascending and descending stair climb, PDQ39, The University of Alabama at Birmingham (UAB) Study of Aging Life-Space Assessment (LSA), and PD-Carer. As a primary end point for establishing efficacy, the 6MWT will be compared between end of training and baseline (with and without the exoskeleton), as well as at 6 and 12 weeks post-study as a durability assessment towards establishing a need for future assessment of in-home usage. These pilot investigations are expected to lay the groundwork for a large multi-center clinical study to establish ground exoskeletons as modern, standard of care devices to aid Veterans and other people with PD and other disabling movement disorders to maintain a more normal and productive life.