Precision Versus Endurance Training to Improve Walking After Chronic Incomplete SCI

Spinal Cord Injury Clinical Trial

Official title:

Precision Versus Endurance Training to Improve Walking After Chronic Incomplete SCI

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01765153
• Other study ID #: Pro00003873
• Status: Completed
• Phase: N/A
• First received: November 30, 2012
• Last updated: December 17, 2014
• Start date: March 2008
• Est. completion date: September 2012

Study information

• Verified date: December 2014
• Source: University of Alberta
• Contact: n/a
• Is FDA regulated: No
• Health authority: Canada: Ethics Review CommitteeCanada: Canadian Institutes of Health Research
• Study type: Interventional

Clinical Trial Summary

The objective of the study was to determine the efficacy of two forms of physical therapy training, one emphasizing precise, visually guided walking over obstacles and on targets (Precision Training), the other emphasizing mass practice of walking on a treadmill (Endurance Training). The hypothesis was that visually guided training (Precision) may be especially efficacious because it engages the motor cortex, whose input may facilitate improvements in functional walking. Participants are individuals with a chronic (≥7 months post-injury), motor incomplete spinal cord injury (SCI), with no other problems that would preclude participation in an intensive training program. A randomized, single-blinded, cross-over design was used to randomly allocate participants to start with Precision or Endurance Training, identified as Training Phase I. Training was 5x/wk for 2 months, followed by a 2-month rest period, identified as Rest Period I. Participants then returned for 2-months of training in the other method, identified as Training Phase II, followed by another 2-month rest, Rest Period II. Measures of walking speed, distance, skill, confidence, as well as depression were obtained at least 3 times before any training, then monthly thereafter. Electrophysiological measures were taken before and after each phase of training and period of rest. Change scores were used to determine how each phase of training and rest influenced the scores (see below).

Description:

PARTICIPANTS: Inclusion criteria: 1) SCI from trauma or other stable lesions, 2) injury occurred ≥ 7 mo prior, 3) able to walk independently at least 5 m with a walking aid and/or braces, 4) injury level between C1-L1, 5) able to give informed consent, 6) able to attend training sessions 5x/week. Exclusion criteria: 1) head injury, 2) cognitive or musculoskeletal impairments that preclude participation in walking training, 3) seizures or implants in the head that would preclude participation in experiments using transcranial magnetic stimulation (TMS).

INTERVENTIONS:

Precision Training. Training was performed on a 15 m long track. The track contained obstacles and targets. Obstacles were made of Styrofoam blocks of 3 cm height each, varying in width from 4 cm to 20 cm in divisions of 4 cm increments (which must be cleared without touching), and targets were made of fabric circles, ranging in diameter from 7-10.5 cm (which must be totally obscured by their foot). The difficulty of the track was designed to have the participant achieve ~80% success. The emphasis was on accuracy, not speed.

Endurance Training. The aim of this training was mass practice. Participants walked on the treadmill, with body-weight support (BWS) and manual assistance if needed. The treadmill speed was initially set to be faster than their over ground walking speed as measured by the 10 MWT(ss). Participants were encouraged to walk for as far and as fast as possible with minimal rest periods. Progression involved reducing manual assistance and BWS, increasing walking speed and distance, while reducing rest breaks.

In both phases of training, a research assistant or volunteer recorded training parameters each session. The number of steps executed was measured with a step counter (StepWatch, Orthocare Innovations, USA), which was confirmed to be accurate with simultaneous manual counting prior to its use, and periodically during training sessions. The heart rate before and immediately after each bout of walking was measured with a heart rate monitor (Polar FT7, Polar, Canada). The total time, distance and walking speed for each walking bout was recorded.

MEASURES:

Measures were taken prior to all training at baseline (called Baseline I) and the end of each of the following intervals - one month of Training Phase I, two months of Training Phase I, one month of Rest Period I, two months of Rest Period I, one month of Training Phase II, two months of Training Phase II, one month of Rest Period II, two months of Rest Period II. To measure changes during the second phase of training, the baseline was the average of the one and two month measures of Rest Period I, henceforth called Baseline II.

STATISTICAL ANALYSIS: To determined if one type of training was superior to the other, we compared the change scores (i.e., post-training score minus pre-training score) from each type of training using a standard t-test or a Mann-Whitney U test, as appropriate. Since individuals with high compared to low walking function may respond to the training differently, we divided individuals based on their pretraining walking speed as measured by the 10 MWT(ss) (i.e., > or < 0.5 m/s). The change scores from each of these groups of individuals were then compared for each type of training using a standard t-test or a Mann-Whitney U test, as appropriate. To determine the time course for obtaining a treatment effect, we compared the change scores for the first month (i.e., outcome measure at end of 1 mo minus baseline) versus the second month (outcome measure at end of 2 mo minus at end of 1 mo) of training for each type of training, using a standard t-test or a Mann-Whitney U test, as appropriate. Retention of gains was followed for 2 months after each type of training. The outcome measures at the end of the 2 month rest period were compared to the measures immediately after the training, for individuals that made improvements greater than the standard error of measurement for each measure, using a paired t-test or Wilcoxon signed-rank test, as appropriate.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 21
• Est. completion date: September 2012
• Est. primary completion date: September 2012
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years to 75 Years

Eligibility

Inclusion Criteria:

• spinal cord injury equal or more than 7 months prior

• able to walk at least 5 meters independently (can use walking aids and braces)

• injury level between C1 and L1

• able to give informed consent

• able to attend training sessions 5x/week

Exclusion Criteria:

• head injury

• cognitive of musculoskeletal impairments that preclude participation in walking training

• seizures or implants in the head that would preclude participation in experiments with transcranial magnetic stimulation

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Single Blind (Outcomes Assessor), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Spinal Cord Injuries
• Spinal Cord Injury

Intervention

Behavioral:
• Endurance
Participants are trained daily to walk on a treadmill for as fast and as long as possible. A harness supporting part of their body weight can be used if needed. Assistance from a trainer is used if needed. A physical therapist supervises the training.
• Precision
Participants train daily to walk over ground on 15 m straight hallway with obstacles they must step over, and targets they must step onto.

Locations

Country	Name	City	State
Canada	University of Alberta	Edmonton	Alberta

Sponsors (2)

Lead Sponsor	Collaborator
University of Alberta	Canadian Institutes of Health Research (CIHR)

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at Completion	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures for all 7 items.	Change from Baseline I to the end of the study (i.e., end of Rest Period II, which was ~8 months after the beginning of the study)	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at 1 month of Training Phase I	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at 2 months of Training Phase I	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at the end of 2 months of Rest Period I	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at 1 month of Training Phase II	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at 2 months of Training Phase II	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Spinal Cord Injury - Functional Ambulation Profile (SCI-FAP) at the end of 2 months of Rest Period II	This is a 7 item, timed walking test. Participants perform each of the walking tasks and the time to complete each task is recorded. In addition, an assistance category is assigned based on the walking aids used. A composite (single) score is obtained by combining the two measures.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in 6 Minute Walk test (6MWT) at 1 month of Training Phase I	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in 6 minute walk test (6MWT) at 2 months of Training Phase I	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in 6 minute walk test (6MWT) at the end of 2 months of Rest Period I	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in 6 minute walk test (6MWT) at 1 month of Training Phase II	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in 6 minute walk test (6MWT) at 2 months of Training Phase II	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in 6 minute walk test (6MWT) at the end of 2 months of Rest Period II	Participants walk for as far as possible in 6 min along a 25m hallway.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in 10 meter walk test at a self-selected speed [10MWT(ss)] at 1 month of Training Phase I	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change score from Baseline I to 1 month of Training Phase I	No
Secondary	Change in 10 metre walk test at a self-selected speed [10MWT(ss)] at 2 months of Training Phase I	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in 10 meter walk test at a self-selected speed [10MWT(ss)] at the end of 2 months of Rest Period I	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in 10 meter walk test at a self-selected speed [10MWT(ss)] at 1 month of Training Phase II	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in 10 meter walk test at a self-selected speed [10MWT(ss)] at 2 months of Training Phase II	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in 10 meter walk test at a self-selected speed [10MWT(ss)] at the end of 2 months of Rest Period II	Participants walk along a 14m path along a smooth floor, in which the middle 10 m is timed.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in 10 meter walk test at fastest safe speed [10MWT(f)] at 1 month Training Phase I	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in 10 meter walk test at a fast speed [10MWT(f)] at 2 months of Training Phase I	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in 10 meter walk test at a fast speed [10MWT(f)] at the end of 2 months of Rest Period I	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in 10 meter walk test at a fast speed [10MWT(f)] at 1 month of Training Phase II	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in 10 meter walk test at a fast speed [10MWT(f)] at 2 months of Training Phase II	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in 10 meter walk test at a fast speed [10MWT(f)] at the end of 2 months of Rest Period II	Participants walk as quickly as they able to safely walk along a 14m path on a smooth floor, in which the middle 10 m is timed.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at 1 month of Training Phase I	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at 2 months of Training Phase I	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at the end of 2 months of Rest Period I	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at 1 month of Training Phase II	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at 2 months of Training Phase II	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II self-selected (WISCI-II ss) at the end of 2 months of Rest Period II	Participants are scored from 0 to 20 based on how they perform a 10m walk in their self-selected way (i.e., with assistance, walking aids, braces ... etc.).	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum (WISCI-II max) at 1 month of Training Phase I	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum [WISCI-II (max)] at 2 months of Training Phase I	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum [WISCI-II (max)] at the end of 2 months of Rest Period I	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum [WISCI-II (max)] at 1 month of Training Phase II	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum [WISCI-II (max)] at 2 months of Training Phase II	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Walking Index for Spinal Cord Injury version II maximum [WISCI-II (max)] at the end of 2 months of Rest Period II	Participants are scored from 0 to 20 based on how they perform a 10m walk when challenged progressively to use less supportive walking aids according to the protocol of the WISCI-II scale.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at 1 month of Training Phase I	A survey with 16 questions participants answer using a pen/paper format.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at 2 months of Training Phase I	A survey with 16 questions participants answer using a pen/paper format.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at the end of 2 months of Rest Period I	A survey with 16 questions participants answer using a pen/paper format.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at 1 month of Training Phase II	A survey with 16 questions participants answer using a pen/paper format.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at 2 months of Training Phase II	A survey with 16 questions participants answer using a pen/paper format.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Activities-specific Balance Confidence Scale (ABC) at the end of 2 months of Rest Period II	A survey with 16 questions participants answer using a pen/paper format.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at 1 month of Training Phase I	A survey filled out by participants using a pen/paper format.	Change from Baseline I to 1 month of Training Phase I	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at 2 months of Training Phase I	A survey filled out by participants using a pen/paper format.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at the end of 2 months of Rest Period I	A survey filled out by participants using a pen/paper format.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at 1 month of Training Phase II	A survey filled out by participants using a pen/paper format.	Change from Baseline II to 1 month of Training Phase II	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at 2 months of Training Phase II	A survey filled out by participants using a pen/paper format.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Center for Epidemiologic Studies - Depression Scale (CES-D) at the end of 2 months of Rest Period II	A survey filled out by participants using a pen/paper format.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Manual muscle test (MMT) at 2 months of Training Phase I	The strength of major muscle groups in the lower extremities, bilaterally (8 groups/side), is tested manually using the standard manual muscle test used in clinics, and a composite single score is calculated.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Manual muscle test (MMT) at the end of 2 months of Rest Period I	The strength of major muscle groups in the lower extremities, bilaterally (8 groups/side), is tested manually using the standard manual muscle test used in clinics, and a composite single score is calculated.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Manual muscle test (MMT) at 2 months of Training Phase II	The strength of major muscle groups in the lower extremities, bilaterally (8 groups/side), is tested manually using the standard manual muscle test used in clinics, and a composite single score is calculated.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Manual muscle test (MMT) at the end of 2 months of Rest Period II	The strength of major muscle groups in the lower extremities, bilaterally (8 groups/side), is tested manually using the standard manual muscle test used in clinics, and a composite single score is calculated.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in cutaneomuscular reflexes at 2 months of Training Phase I	Reflexes are elicited with electrical stimulation (3 pulses) of the tibial nerve at the ankle using surface electrodes. Responses are recorded with surface electromyography (EMG). Responses are recorded in standing.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in cutaneomuscular reflexes at the end of 2 months of Rest Period I	Reflexes are elicited with electrical stimulation (3 pulses) of the tibial nerve at the ankle using surface electrodes. Responses are recorded with surface electromyography (EMG). Responses are typically recorded in standing.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in cutaneomuscular reflexes at 2 months of Training Phase II	Reflexes are elicited with electrical stimulation (3 pulses) of the tibial nerve at the ankle using surface electrodes. Responses are recorded with surface electromyography (EMG). Responses are typically recorded in standing.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in cutaneomuscular reflexes at the end of 2 months of Rest Period II	Reflexes are elicited with electrical stimulation (3 pulses) of the tibial nerve at the ankle using surface electrodes. Responses are recorded with surface electromyography (EMG). Responses are typically recorded in standing.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No
Secondary	Change in Transcranial magnetic stimulation (TMS) at 2 months of Training Phase I	Single-pulse TMS is applied over the motor cortex, and electromyographic responses are recorded in the tibialis anterior muscles on both legs.	Change from Baseline I to 2 months of Training Phase I	Yes
Secondary	Change in Transcranial magnetic stimulation (TMS) at the end of 2 months of Rest Period I	Single-pulse TMS is applied over the motor cortex, and electromyographic responses are recorded in the tibialis anterior muscles on both legs.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	Yes
Secondary	Change in Transcranial magnetic stimulation (TMS) at 2 months of Training Phase II	Single-pulse TMS is applied over the motor cortex, and electromyographic responses are recorded in the tibialis anterior muscles on both legs.	Change from Baseline II to 2 months of Training Phase II	Yes
Secondary	Change in Transcranial magnetic stimulation (TMS) at the end of 2 months of Rest Period II	2 months of Training Phase 2	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	Yes
Secondary	Change in Electromyography during treadmill walking at 2 months of Training Phase I	Participants walk on a treadmill at a variety of speeds while we record surface electromyography from leg muscles and motion data from electrogoniometers place on the knees.	Change from Baseline I to 2 months of Training Phase I	No
Secondary	Change in Electromyography during treadmill walking at the end of 2 months of Rest Period I	Participants walk on a treadmill at a variety of speeds while we record surface electromyography from leg muscles and motion data from electrogoniometers place on the knees.	Change from the end of Phase I training (measured at 2 months of Training Phase I) to 2 months of Rest Period I	No
Secondary	Change in Electromyography during treadmill walking at 2 months of Training Phase II	Participants walk on a treadmill at a variety of speeds while we record surface electromyography from leg muscles and motion data from electrogoniometers place on the knees.	Change from Baseline II to 2 months of Training Phase II	No
Secondary	Change in Electromyography during treadmill walking at the end of 2 months of Rest Period II	Participants walk on a treadmill at a variety of speeds while we record surface electromyography from leg muscles and motion data from electrogoniometers place on the knees.	Change from the end of Phase II training (measured at 2 months of Training Phase II) to 2 months of Rest Period II	No