Enhancing Corticospinal Activation for Improved Walking Function

Walking speed was the primary outcome measure for walking function, as speed has been the standard measure used in the literature and allowed us to assess outcomes relative to other published studies. Walking speed was determined using the 10-Meter Walk Test. Participants completed 3 walk trials at each time point, separated by 2 minutes of seated rest. The average walking speed of 3 walks was calculated and used in the analyses. Data reported were obtained at baseline at Day 1 (D1) and at follow-up on Day 5 (D5), 24-hours post-intervention.

Gait quality was quantified by spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] and step length [cm] of the weaker and stronger limbs) collected via instrumented walkway (GAITRite, CIR Systems Inc., NJ, USA) as participants completed three, 10-Meter Walk Test trials at each time point. Cadence for each walk trial was computed using the GAITRite system, and the average cadence across three walks was used in the analyses. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Gait quality was quantified by spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] and step length [cm] of the weaker and stronger limbs) collected via instrumented walkway (GAITRite, CIR Systems Inc., NJ, USA) as participants completed three, 10-Meter Walk Test trials at each time point. Average stride length of the weaker limb for each walk trial was computed from data obtained from the GAITRite system, and the average stride length across three walks was used in the analyses. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Gait quality was quantified by spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] and step length [cm] of the weaker and stronger limbs) collected via instrumented walkway (GAITRite, CIR Systems Inc., NJ, USA) as participants completed three, 10-Meter Walk Test trials at each time point. Average stride length of the stronger limb for each walk trial was computed from data obtained from the GAITRite system, and the average stride length across three walks was used in the analyses. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Step length [cm] of the weaker and stronger limbs were collected via instrumented walkway (GAITRite, CIR Systems Inc., NJ, USA) as participants completed three, 10-Meter Walk Test trials at each time point. Average step length of each lower limb for each walk trial was computed from data obtained from the GAITRite system. Lower limbs were classified as stronger or weaker according to manual muscle test scores collected at baseline (D1). The average step length for the stronger and weaker limbs was used to calculate the step symmetry index (SI) using the following formula: SI = ((SLs - SLw)/0.5(SLs + SLw)) x 100; where SLs = stronger limb stride length and SLw = weaker limb stride length. Final values are reported as the absolute % of the ratio difference in step length between the stronger and weaker limbs. A SI value of 0% indicates perfect interlimb step symmetry. Higher SI values indicate greater interlimb step length asymmetry.

Ankle dorsiflexion (tibialis anterior) strength was measured with the subject seated and with the test foot strapped to a handheld dynamometer. An ankle dorsiflexion test was selected based on evidence indicating that the tibialis anterior is under the greatest corticospinal control. Maximum dorsiflexion force was calculated based on the highest force measured over three attempts. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Balance was measured using the Berg Balance Scale (BBS), which has been found to be valid for use in persons with SCI. The BBS total score was calculated for each participant at each time point, and the median score for each group was calculated. The total range of scores for the BBS equals 0-56, with higher scores from baseline indicating greater balance performance and lower scores from baseline indicating worsened balance performance. Data reported were obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

The fear of falling may be a major concern for persons with mobility impairments and may limit one's confidence or ability to perform activities of daily living. Fear of falling may also limit an individual's performance of specific overground motor tasks irrespective of functional ability to perform that task. Therefore, the fear of falling was an important factor to consider relative to the mobility interventions employed in the present study. The FES-I total score was calculated for each participant at each time point, and the median for each group was recorded. The total range of scores possible for the FES-I is equal to 16-64, with lower total scores indicating decreased fear of falling. Data reported were obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

The Spinal Cord Assessment Tool for Spastic Reflexes (SCATS) was used to assess the impact of motor skill training + sham stimulation and motor training + tDCS on spasticity. SCATS is well correlated with electrophysiological measures of spasticity and is better correlated with self-reported measures of spasm frequency than the Ashworth test. Total SCATS scores for each limb were summed and median values were obtained for each group. The total range of scores possible for the SCATS is 0-18, with a total score of 0 indicating no lower limb spasticity and higher total scores indicating greater spasticity severity. Data reported were obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

The modified 5-times sit-to-stand test was used as a measure of functional lower extremity strength. In this test, the participant was seated on a mat table with height adjusted to 80% of lower extremity length. The time required to complete 5 repetitions of standing up and sitting down (without using the upper extremities for assistance) was recorded. The average time to complete the test was calculated at each time point for each group. Lower sit-to-stand times indicate greater functional lower extremity strength. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Knee extensor (quadriceps) strength was measured with participants seated, with the test leg strapped to a handheld dynamometer. Prior studies have shown that a single session of tDCS improves quadriceps strength in persons with stroke. Maximum knee extensor force was analyzed based on the maximum force produced over three attempts. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.

Functional walking capacity was measured based on 2-minute walk test distance. The use of the 2-minute rather than the 6-minute walk test allowed us to include individuals whose impairments result in inability to walk for 6 minutes. Total distance walked in 2-minutes was recorded for each participant at each time point, and the average distance was calculated for each group. Results are reported for data obtained at baseline Day-1 (D1) and at follow-up on Day-5, 24-hours post-intervention.