Overground Locomotor Training in Spinal Cord Injury: A Performance-Based Framework

Turns while walking among individuals with Parkinson's disease following overground locomotor training: A pilot study

BACKGROUND

Individuals with Parkinson's disease are challenged in making turns while walking, evidenced by reduced intersegmental coordination and reduced dynamic postural stability. Although overground locomotor training previously improved ambulation among people with Parkinson's disease, its effect on walking turns remained unknown. We sought to understand the effects of overground locomotor training on walking turns among individuals with mild-Parkinson's disease.

METHODS

Twelve participants with Parkinson's (7 Males/5 Females; Age: 68.5 ± 6.4 years) completed twenty-four sessions lasting approximately 60 min and over 12-15 weeks. Baseline and follow-up assessments included the ten-minute walk test using wearable sensors. Primary outcomes included changes to intersegmental coordination, measured by peak rotation and normalized peak rotation, and dynamic postural stability, measured by peak turn velocities in the frontal and transverse planes. Statistical analysis included one-tailed paired t-tests and Cohen's d effect sizes with α = 0.05.

FINDINGS

No effects of overground locomotor training on mean peak thoracic rotation (+0.23 ± 4.24°; Cohen's d = 0.05; P = 0.45) or mean normalized peak thoracic rotation (-0.59 ± 5.52 (unitless); Cohen's d = 0.10; P = 0.45) were observed. Moderate and small effects of overground locomotor training were observed on mean peak turn velocities in the frontal (+1.59 ± 2.18°/s; Cohen's d = 0.43; P = 0.01) and transverse planes (+0.88 ± 3.18°/s; Cohen's d = 0.25; P = 0.18).

INTERPRETATION

This pilot study provides preliminary evidence suggesting that individuals with mild-Parkinson's moderately improved frontal plane dynamic postural stability after overground locomotor training, likely attenuating the perturbations experienced while turning.

CLINICAL TRIAL REGISTRATION

NCT03864393.

Walking Endurance and Oxygen Uptake On-Kinetics in Individuals With Parkinson Disease Following Overground Locomotor Training

BACKGROUND AND PURPOSE

Poor walking endurance in Parkinson disease (PD) may be attributable to both bioenergetic and biomechanical factors, but locomotor training methods addressing both these factors simultaneously are understudied. Our objective was to examine the effects of overground locomotor training (OLT) on walking endurance in individuals with mild-to-moderate PD, and to further explore potential cardiorespiratory contributions.

METHODS

A single-arm, longitudinal design was used to examine the effects of 24 biweekly sessions of OLT in people with mild-to-moderate PD (n = 12). Walking endurance was measured as total distance walked during a 10-minute walk test (10minWT). Oxygen uptake (V˙ o2 ) on-kinetic profiles were determined using a monoexponential function. Perceived fatigability was assessed following the 10minWT using a self-report scale. Magnitude of change in primary outcomes was assessed using Cohen's d and adjusted for sample size (Cohen's d(unbiased) ).

RESULTS

Participants executed 3036 (297) steps and maintained 65.5% (8%) age-predicted heart rate maximum in a typical session lasting 56.9 (2.5) minutes. Medium effects in total distance walked-885.9 (157.2) versus 969.5 (140.9); Cohen's d(unbiased) = 0.54-and phase II time constant of the V˙ o2 on-kinetic profile-33.7 (12.3) versus 25.9 (15.3); Cohen's d(unbiased) = 0.54-were observed alongside trivial effects for perceived fatigability-4.7 (1.4) versus 4.8 (1.5); Cohen's d(unbiased) = 0.11-following OLT.

DISCUSSION AND CONCLUSIONS

These preliminary findings may demonstrate the potential for moderate-intensity OLT to improve walking endurance and enhance cardiorespiratory adjustments to walking activity in adults with mild-to-moderate PD.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A407 ).

Walking endurance, muscle oxygen extraction, and perceived fatigability after overground locomotor training in incomplete spinal cord injury: A pilot study

Objective: The purpose of this study was to examine the effects of overground locomotor training (OLT) on walking endurance and gastrocnemius oxygen extraction in people with chronic cervical motor-incomplete spinal cord injury (SCI).Design: Prospective single-arm pre-post pilot study.Setting: Human Performance Research Laboratory.Participants: Adult men with traumatic chronic cervical SCI (n = 6; age = 30.8 ± 12.5).Intervention: Twenty-four sessions of structured OLT.Outcome measures: Walking endurance was determined during a constant work-rate time-to-exhaustion treadmill test. Normalized perceived fatigability was calculated by dividing subjective ratings of tiredness by walking time. Cardiorespiratory outcomes and muscle oxygen extraction were analyzed using breath-by-breath gas-exchange and near-infrared spectroscopy.Results: OLT resulted in large effects on walking endurance (1232 ± 446 s vs 1645 ± 255 s; d = 1.1; P = 0.045) and normalized perceived fatigability (5.3 ± 1.5 a.u. vs 3.6 ± 0.9 a.u.; d = 1.3; P = 0.033). Small-to-medium effects on absolute (2.8 ± 2.5 a.u. vs 4.2 ± 3.5 a.u.; d = 0.42; P = 0.035) and isotime (2.8 ± 2.5 a.u. vs 3.8 ± 3.0 a.u.; d = 0.33; P = 0.023) muscle oxygen extraction were also observed after OLT.Conclusion: These findings provide preliminary data supporting the potential for improved walking endurance, enhanced muscle O2 extraction, and reduced perceived fatigability in people with chronic cervical motor-incomplete SCI following the OLT program described in this study.

Dynamic stability based identification of optimal Tai Chi forms for preventing falls among older adults with knee osteoarthritis

Objective

Knee osteoarthritis increases the risk of falls among older adults. Tai Chi (TC) has been increasingly utilized to prevent falls in older adults. However, findings from previous studies are inconclusive, possibly due to a lack of scientifically sound methodologies to identify targeted TC forms, which likely maximize the training effects in preventing falls. It has been recently indicated that individual TC forms challenge body balance to varying degrees, providing us a foundation to select optimal TC forms. The objective of this preliminary study was to examine whether the challenge to body balance quantified by the range of dynamic stability is different between identified optimal TC forms (OTC) and commonly used TC (CTC) forms among older adults with knee osteoarthritis.

Methods

Eight older adults with knee osteoarthritis learned how to perform 24 ​TC forms correctly. Their full-body kinematics during the performance of 24 ​TC forms was collected. The range of composite dynamic stability was used as the selection criteria to identify eight OTC forms. The range of composite dynamic stability was then compared between the OTC forms and eight CTC forms.

Results

Overall, OTC forms showed a significantly larger range of composite dynamic stability than CTC forms (p ​= ​0.021).

Conclusion

The selected OTC forms could impose a greater challenge on balance control among older adults than CTC forms. The finding in this study is significant as it could furnish a scientific basis for identifying the best TC forms to optimize the effectiveness of TC-based fall prevention interventions.

Treadmill training based on the overload principle promotes locomotor recovery in a mouse model of chronic spinal cord injury

Rehabilitative treatment, including treadmill training, is considered an important strategy for restoring motor function after spinal cord injury (SCI). However, many unexplained problems persist regarding the appropriate rehabilitative method and the mechanism underlying the beneficial effects of rehabilitation. Moreover, only a few preclinical studies have been performed on rehabilitative interventions for chronic SCI, although most patients have chronic injuries. In fact, several preclinical studies reported that rehabilitative training was less effective when applied during the chronic phase than when applied sooner. While numerous studies have examined the effects of treadmill training during the subacute phase, the training conditions vary considerably among preclinical reports. Therefore, establishing a standard training protocol is essential for achieving beneficial rehabilitation effects at the chronic stage. Since the difficulty of applying an appropriate training load hinders training at constant speeds, it is important to adjust the training intensity in accordance with the exercise tolerance of an individual animal to provide further functional recovery benefits. Here, we created a novel quadrupedal treadmill training protocol based on the overload principle for mice with incomplete thoracic SCI. We subjected SCI model mice to rehabilitative training according to the protocol for two consecutive weeks starting at 42 days after injury. We examined the treadmill speeds at which the mice were able to run based on the severity of paresis and investigated the impact of the protocol on functional recovery. Assessment of running speed changes during the treadmill training period revealed faster treadmill speeds for mice with mild paresis than for those with severe paresis. The training parameters, including the speed and distance traveled, were positively correlated with the changes in motor function. These results suggest that the most suitable running speed during treadmill training differs according to the level of motor dysfunction and that running longer distances has a positive impact on motor functional recovery. Based on this established protocol, we compared functional and histological results between the chronic SCI groups with and without rehabilitation. The gait analyses showed significantly better functional improvement in the rehabilitation group than in the nonrehabilitation group. Histological analyses revealed that the BDNF- and VGLUT1-positive areas of lumbar enlargement were significantly increased in the rehabilitation group. These findings implied that rehabilitation promoted not only motor performance but also motor control, including forelimb-hindlimb coordination, even in chronic SCI, resulting in functional improvement by treadmill training alone. Therefore, rehabilitative training based on the overload principle appears to be one of the appropriate treatment options for incomplete thoracic SCI, and evidence of its efficacy exists in actual clinical settings.

Effect of repeated locomotor training on ventilatory measures, perceived exertion and walking endurance in persons with motor incomplete spinal cord injury

STUDY DESIGN

Pre-Post, Repeated Measures.

OBJECTIVES

To determine if a warm-up bout of exercise could elicit a phasic ventilatory response to constant work rate (CWR) exercise in individuals with incomplete spinal cord injury (iSCI) during unsupported CWR treadmill walking. Describe the changes in ventilatory kinetics, ventilatory variability and ratings of perceived exertion (RPE) before and after 12 and 24 weeks of overground locomotor training (OLT). Investigate the relationship among minute ventilation (V_E) variability, RPE, and walking endurance.

SETTING

Laboratory.

METHODS

A 6-min CWR was used as a warm-up preceding a CWR, at the same walking speed, until volitional fatigue or 30 min. Breath-by-breath ventilatory data were examined during the second CWR using a mono-exponential model. V_E variability was calculated as the difference between the observed and predicted values. Data were time-matched before and after 12 and 24 weeks of OLT. A Pearson's correlation was used for V_E variability, RPE, and walking endurance.

RESULTS

A warm-up CWR did elicit a phasic ventilatory response. OLT resulted in faster ventilatory kinetics. Ventilatory variability reduced after 12 weeks of OLT but returned to pre-OLT values after 24 weeks of training. The change in V_E variability was correlated with the change in RPE throughout the study. 12 and 24 weeks of OLT resulted in significant improvements in treadmill walking time.

CONCLUSIONS

SCI patients can achieve a phasic ventilatory response to walking if the exercise bout is preceded by a warm-up. OLT normalizes the ventilatory kinetics and improves walking endurance. The change in V_E variability is correlated to RPE.

EMG median frequency shifts without change in muscle oxygenation following novel locomotor training in individuals with incomplete spinal cord injury

Objectives: To examine the effect of muscle fiber recruitment patterns on muscle oxygen utilization during treadmill walking in a group of individuals who have incomplete spinal cord injury.Methods: 5 participants with motor incomplete spinal cord injury (Age; 42.2 ± 18.8 years, Male; n = 4) completed an over ground locomotor training program. Muscle utilization/oxygenation and activation of the medial gastrocnemius were measured by near infrared spectroscopy and surface electromyography pre- and post-over ground locomotor training during two separate treadmill walking bouts at self-selected speeds. Outcomes were changes in deoxygenation hemoglobin/myoglobin concentrations, and the change in median power of the power spectrum of the electromyography after training.Results: A significant increase in median power of the power spectrum of the electromyography signal was observed during both bouts of treadmill walking, 6-minute walking bout and longer fatiguing bout (49% p = 0.047 and 48% p = 0.035, respectively) post-over ground locomotor training. There was no significant change in muscle utilization/oxygenation post-over ground locomotor training. There was no significant effect of median power of the power spectrum on deoxygenation hemoglobin/myoglobin during either of the walking bouts.Conclusions: The main finding of the current study was that median power of the power spectrum significantly increased following 12 weeks of over ground locomotor training, with no significant change in deoxygenation hemoglobin/myoglobin. The recruitment of more and/or larger motor units was seen in conjunction with no changes in muscle oxygen utilization for the same walking task.Implications for RehabilitationThe reduction of skeletal muscle innervation in Spinal Cord Injury may adversely affect the orderly recruitment of motor units, which could in turn blunt the oxidative metabolic response during physical activity.Over-ground locomotor could be a useful tool in the rehabilitative process following an incomplete spinal cord injury.

Effects of Performance-Based Training on Gait and Balance in Individuals With Incomplete Spinal Cord Injury

OBJECTIVE

To determine changes in balance and gait following a task-specific, performance-based training protocol for overground locomotor training (OLT) in individuals with motor-incomplete spinal cord injury (iSCI).

DESIGN

Convenience sample, prepilot and postpilot study.

SETTING

Human performance research laboratory.

PARTICIPANTS

Adults (N=15; 12 men and 3 women; mean age [y] ± SD, 41.5±16.9), American Spinal Injury Association Impairment Scale C or D, >6 months post-spinal cord injury.

INTERVENTIONS

Two 90-minute OLT sessions per week over 12 to 15 weeks. OLT sessions were built on 3 principles of motor learning: practice variability, task specificity, and progressive overload (movement complexity, resistance, velocity, volume). Training used only voluntary movements without body-weight support, robotics, electrical stimulation, or bracing. Subjects used ambulatory assistive devices as necessary.

MAIN OUTCOME MEASURES

Berg Balance Scale (BBS), Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI) gait parameters, spatiotemporal measures of gait (step length, step width, percent stance, stance:swing ratio) from 7 participants who walked across a pressure-sensitive walkway.

RESULTS

Fourteen participants completed the OLT protocol and 1 participant completed 15 sessions due to scheduled surgery. The BBS scores showed a mean improvement of 4.53±4.09 (P<.001). SCI-FAI scores showed a mean increase of 2.47±3.44 (P=.01). Spatiotemporal measures of gait showed no significant changes.

CONCLUSION

This pilot demonstrated improvements in balance and selected gait characteristics using a task-specific, performance-based OLT for chronic iSCI.

Fatigability during volitional walking in incomplete spinal cord injury: cardiorespiratory and motor performance considerations

Fatigability describes the decline in force production (i.e., performance fatigability) and/or changes in sensations regulating performance (i.e., perceived fatigability) during whole-body activity and poses a major challenge to those living with spinal cord injuries (SCI). After SCI, the inability to overcome disruptions to metabolic homeostasis due to cardiorespiratory limitations and physical deconditioning may contribute to increased fatigability severity. The increased susceptibility to fatigability may have implications for motor control strategies and motor learning. Locomotor training approaches designed to reduce fatigability and enhance aerobic capacity in combination with motor learning may be advantageous for promoting functional recovery after SCI. Future research is required to advance the understanding of the relationship between fatigability, cardiorespiratory function and motor performance following SCI.