Treadmill Oscillation Walking to Improve Weight Transfer During Gait Following Stroke

Fifteen participants with stroke will be enrolled to a longitudinal study that consists of a 6-week (18 sessions) TOW intervention, and gait evaluations at baseline and post-training and 1-month follow up. Kinematic, kinetic, and muscle activation pattern (electromyography, EMG) data will be recorded during pre- and post-training and 1 month follow-up evaluations.

Baseline evaluation:

• The participant will put on tight-fitting shorts and shirt. Hair ties will be donned to maintain clear lines of sight from cameras to markers.
• Overground gait assessment: Participants will walk at their self-selected and maximal walking speeds along an instrumented treadmill. Vertical ground reaction force will be recorded to characterize limb loading. Two familiarization trials will be provided and a safety belt will be worn by all participants. A study team member will walk alongside the participant to provide assistance if needed for safety.
• A study team member will place surface electrodes over the participants' gluteus medius (GM), tensor fasciae latae (TFL), and (Vastus lateralis) VL muscles using a wireless EMG system (Delsys Inc., Natick, MA).
• Participants will then perform the maximal voluntary isometric contraction (MVIC) test: During MVIC, a study team member will assess participants' maximal voluntary isometric knee extension and hip abduction torques with a dynamometer. Testing will begin with the less affected lower limb, followed immediately by the affected lower limb for participants with stroke. During knee extension MVIC, the participant will sit upright (85° from horizontal) with the lower leg strapped to the knee testing apparatus at a 60-degree knee flexion angle. The upper leg and torso will be stabilized with Velcro straps and a safety belt. Participants will be instructed to relax the opposite lower limb and rest their hands in their lap. During hip abduction MVIC, a marker will be placed to approximate the location of the hip center of rotation and the participant will be instructed to align the marker with the axis of motion of the dynamometer during standing. The test limb will be strapped to the Biodex input arm, with the lateral thigh pad just proximal to the knee. Hip abduction MVIC will be performed at a hip angle of 15° of abduction (Johnson et al. 2004). Each participant will be asked to push against the lateral thigh pad as hard and fast as they can. For both knee and Hip MVIC tests, 2 submaximal practice trials will be provided. A tester will stand beside the participant to encourage maximal efforts and to monitor alignment and correct movement execution. Two MVIC trials will be collected for each joint.
• Following the MVIC test, the participant will put on a safety harness with the assistance of the research team. Approximately 39 reflective markers will be attached to target locations on the participant's whole body (the head, arms, wrists, hands, trunk, pelvis, legs and feet) according to the Vicon Full-Body Plug-In Gait Model.
• Treadmill Gait Assessment: the participant will walk with their self-selected comfortable speed (SS) and maximal speed (MS) on a treadmill (Motek Inc., Columbus,OH) located in the Movement and Cognitive Rehabilitation Science core lab (BEL530). SS and MS will be determined by gradually increasing and decreasing the treadmill speed to ensure that each walking speed is identified by the participant. A 1-minute familiarization duration will be provided for each speed. Two 30-second baseline walking trials will be recorded for each walking speed. A handrail with a pressure sensing pad is located on the side of the treadmill. Participants will be instructed to only use the handrail if necessary for safety. Participants will wear a safety harness with no body weight support. Body segment position data will be recorded using a 10-camera motion capture system (Vicon-USA, Denver, CO). The motion capture cameras only record the marker trajectories and therefore this video recording contains no facial recognition information that can be used to identify the participant. Ground reaction forces will be captured by the instrumented split-belt treadmill (Motek Inc., Columbus, OH).

Testing will take approximately 3 hours.

Participants with stroke will then complete a 6-week gait training and a post-training and a 1-month follow up evaluation.

Participants will perform Treadmill and Overground Gait Assessments (described previously in Baseline Evaluation) after training and at 1-month follow-up. Post-training and follow-up testing sessions will be conducted a day and 1-month following the last training session, respectively.

Inclusion criteria

• Hemiparesis as a result of a stroke greater than 6 months previous to the study;
• A single cortical or subcortical stroke
• Able to walk 10 meters with or without a walking aid
• Able to stand unsupported for 5 minutes
• Sufficient cognitive function to follow instruction and communicate with the investigators.
• Reduced paretic limb loading more than 6% compared to the non-paretic limb during overground gait assessment

Exclusion criteria

• Medical condition precluding participant in regular exercise, such as acute cardiac or respiratory conditions limiting activity and other health conditions significantly impacting the ability to walk beyond the effects of the stroke, such as other neurological conditions or peripheral neuropathies;
• Bilateral stroke or a previous stroke in the contralateral hemisphere;
• Had a history of multiple strokes;
• Cerebellar stroke;
• Lower extremity joint replacement;
• Bone or joint problems that limited their ability to walk;
• A resting heart rate outside of the range of 40 to 100 beats per minute;
• A resting blood pressure outside of the range of 90/60 to 170/90 mm Hg;
• Neglect;
• Hemianopia;
• Unexplained dizziness during the past 6 months;
• Chest pain or shortness of breath without exertion;
• Pregnancy by self-report.