Lower Extremity Kinematics During Walking and Elliptical Training in Individuals With and Without Traumatic Brain Injury

Chronic motor performance following different traumatic brain injury severity-A systematic review

Introduction

Traumatic brain injury (TBI) is now known to be a chronic disease, causing ongoing neurodegeneration and linked to increased risk of neurodegenerative motor diseases, such as Parkinson's disease and amyotrophic lateral sclerosis. While the presentation of motor deficits acutely following traumatic brain injury is well-documented, however, less is known about how these evolve in the long-term post-injury, or how the initial severity of injury affects these outcomes. The purpose of this review, therefore, was to examine objective assessment of chronic motor impairment across the spectrum of TBI in both preclinical and clinical models.

Methods

PubMed, Embase, Scopus, and PsycINFO databases were searched with a search strategy containing key search terms for TBI and motor function. Original research articles reporting chronic motor outcomes with a clearly defined TBI severity (mild, repeated mild, moderate, moderate-severe, and severe) in an adult population were included.

Results

A total of 97 studies met the inclusion criteria, incorporating 62 preclinical and 35 clinical studies. Motor domains examined included neuroscore, gait, fine-motor, balance, and locomotion for preclinical studies and neuroscore, fine-motor, posture, and gait for clinical studies. There was little consensus among the articles presented, with extensive differences both in assessment methodology of the tests and parameters reported. In general, an effect of severity was seen, with more severe injury leading to persistent motor deficits, although subtle fine motor deficits were also seen clinically following repeated injury. Only six clinical studies investigated motor outcomes beyond 10 years post-injury and two preclinical studies to 18-24 months post-injury, and, as such, the interaction between a previous TBI and aging on motor performance is yet to be comprehensively examined.

Conclusion

Further research is required to establish standardized motor assessment procedures to fully characterize chronic motor impairment across the spectrum of TBI with comprehensive outcomes and consistent protocols. Longitudinal studies investigating the same cohort over time are also a key for understanding the interaction between TBI and aging. This is particularly critical, given the risk of neurodegenerative motor disease development following TBI.

Individuals with Chronic Mild-to-Moderate Traumatic Brain Injury Exhibit Decreased Neuromuscular Complexity During Gait

BACKGROUND

Synergy analysis provides a means of quantifying the complexity of neuromuscular control during gait. Prior studies have shown evidence of reduced neuromuscular complexity during gait in individuals with neurological disorders associated with stroke, cerebral palsy, and Parkinson's disease.

OBJECTIVE

The purpose of this study was to investigate neuromuscular complexity during gait in individuals who experienced a prior traumatic brain injury (TBI) that resulted in chronic balance deficits.

METHODS

We measured and analyzed lower extremity electromyographic data during treadmill and overground walking for 44 individuals with residual balance deficits from a mild-to-moderate TBI at least 1 year prior. We also tested 20 unimpaired controls as a comparison. Muscle synergies were calculated for each limb using non-negative matrix factorization of the activation patterns for 6 leg muscles. We quantified neuromuscular complexity using Walk-DMC, a normalized metric of the total variance accounted for by a single synergy, in which a Walk-DMC score of 100 represents normal variance accounted for. We compared group average synergy structures and inter-limb similarity using cosine similarity. We also quantified each individual's gait and balance using the Sensory Organization Test, the Dynamic Gait Index, and the Six-Minute Walk Test.

RESULTS

Neuromuscular complexity was diminished for individuals with a prior TBI. Walk-DMC averaged 92.8 ± 12.3 for the TBI group during overground walking, which was significantly less than seen in controls (100.0 ± 10.0). Individuals with a prior TBI exhibited 13% slower overground walking speeds than controls and reduced performance on the Dynamic Gait Index (18.5 ± 4.7 out of 24). However, Walk-DMC measures were insufficient to stratify variations in assessments of gait and balance performance. Group average synergy structures were similar between groups, although there were considerable between-group differences in the inter-limb similarity of the synergy activation vectors.

CONCLUSIONS

Individuals with gait and balance deficits due to a prior TBI exhibit evidence of decreased neuromuscular complexity during gait. Our results suggest that individuals with TBI exhibit similar muscle synergy weightings as controls, but altered control of the temporal activation of these muscle weightings.

Movement direction impacts knee joint kinematics during elliptical exercise at varying incline angles

BACKGROUND

Elliptical trainers are a popular cardiovascular exercise for individuals with injuries or those post-operation. There is currently limited data on the impacts of direction while on elliptical trainers for knee joint kinematic risk factors. This study compared lower extremity kinematics between the forward and reverse direction at varying inclines on an elliptical trainer modified with converging footpath and reduced inter-pedal distance.

METHODS

Twenty-four college age participants exercised on the modified elliptical in both directions at four ramp inclines: 6°, 12°, 25°, and 35°. Three-dimensional kinematics were collected for each direction and ramp incline. A 2 × 4 (direction × incline) repeated measures analysis of variance was run with an alpha of 0.05. Simple effects analysis was run with Bonferroni correction for significant interaction or main effect of ramp incline.

RESULTS

The reverse direction had significantly greater peak knee valgus at 6° incline (mean difference [MD] = 1.35°, p < 0.014, d = 0.31) and 12° (MD = 2.41°, p < 0.001, d = 0.55), peak hip abduction at 6° (MD = 2.86°, p = 0.002, d = 0.49) and 12° (MD = 2.91°, p < 0.001, d = 0.51), but decreased peak knee flexion angles (p = 0.032) at all inclines.

CONCLUSIONS

Individuals with knee pathologies such as knee osteoarthritis or anterior knee pain should exercise in the reverse direction at lower inclines. However, switching to the forward direction and/or increasing incline may increase quadriceps strength during a safe activity such as elliptical trainers.

Variations in plantar pressure variables across elliptical trainers in older adults

BACKGROUND

Ellipticals are used to address walking and cardiorespiratory training goals of older adults, some of whom are at risk for foot injuries. Variations in joint kinematics and muscle demands when using different ellipticals could lead to plantar pressure differences. This study explored plantar pressure variables during gait and use of four ellipticals.

METHODS

Plantar pressures were recorded while 10 adults [68.1 (4.5) years] walked and used the True, Octane, Life Fitness, and SportsArt ellipticals. Repeated-measures ANOVAs (5 × 1) identified forefoot and heel differences across conditions.

FINDINGS

Maximum forefoot forces and peak pressures were significantly lower than walking for each elliptical condition with one exception (Life Fitness peak pressure). However, sustained elliptical pedal contact time contributed to forefoot pressure-time integrals and dosages (i.e., cumulative pressure during one minute of activity) not varying significantly amongst elliptical and walking conditions. Heel maximum forces and peak pressures were significantly lower than walking during all elliptical conditions except SportsArt. Heel contact time on SportsArt and Octane exceeded walking, and SportsArt heel contact time exceeded Life Fitness. Heel pressure-time integral was greater on SportsArt compared to walking, Life Fitness, and True. Sports Art heel dosage exceeded Life Fitness and True.

INTERPRETATION

While elliptical training's sustained double limb support diminished maximal forces and peak pressures under the forefoot and heel compared to walking, each ellipticals' pressure-time integral and dosage were not significantly lower than walking. These findings point to the importance of carefully initiating elliptical training programs to minimize tissue injury, particularly if sensory neuropathy is present.

Effect of motor-assisted elliptical training speed and body weight support on center of pressure movement variability

BACKGROUND

A motor-assisted elliptical trainer is being used clinically to help individuals with physical disabilities regain and/or retain walking ability and cardiorespiratory fitness. Unknown is how the device's training parameters can be used to optimize movement variability and regularity. This study examined the effect of motor-assisted elliptical training speed as well as body weight support (BWS) on center of pressure (CoP) movement variability and regularity during training.

METHODS

CoP was recorded using in-shoe pressure insoles as participants motor-assisted elliptical trained at three speeds (20, 40 and 60 cycles per minute) each performed at four BWS levels (0 %, 20 %, 40 %, and 60 %). Separate two-way repeated measures ANOVAs (3 × 4) evaluated impact of training speed and BWS on linear variability (standard deviation) and non-linear regularity (sample entropy) of CoP excursion (anterior-posterior, medial-lateral) for 10 dominant limb strides.

FINDINGS

Training speed and BWS did not significantly affect the linear variability of CoP in the anterior-posterior or medial-lateral directions. However, sample entropy in both directions revealed the main effect of training speed (p < 0.0001), and a main effect of BWS was observed in the medial-lateral direction (p = 0.004). Faster training speeds and greater levels of BWS resulted in more irregular CoP patterns.

INTERPRETATION

The finding that speed and BWS can be used to manipulate CoP movement variability when using a motor-assisted elliptical has significant clinical implications for promoting/restoring walking capacity. Further research is required to determine the impact of motor-assisted elliptical speed and BWS manipulations on functional recovery of walking in individuals who have experienced a neurologic injury or illness.

The effects of a standard elliptical vs. a modified elliptical with a converging footpath on lower limb kinematics and muscle activity

Elliptical trainers that increase the inter-pedal distance may have potential benefits for knee osteoarthritis by decreasing the amount of knee varus. Modifying elliptical trainers with a converging footpath and reduced inter-pedal distance may be beneficial for reducing anterior knee pathology risk by decreasing knee valgus angles. Twenty-one college students participated in a single testing session. Participants exercised on two different elliptical trainers, one modified with a converging footpath and reduced inter-pedal width, and a standard elliptical trainer. Participants exercised for 2 min at three ramps incline at 120 strides per minute and constant work rate. Three-dimensional kinematics and electromyography of the dominant lower limb were recorded. Multiple 2 × 3 (Elliptical x Incline) ANOVAs with Bonferroni corrections were used to compare the two elliptical trainers at each incline for kinematics and muscle activity. The modified elliptical trainer displayed significantly decreased peak knee valgus (p = 0.031, η p 2 = 0.234 ), peak knee flexion (p = 0.006, η p 2 = 0.246 ), and interactions for peak knee flexion (p = 0.001, η p 2 = 0.250 ) and vastus lateralis (p < 0.01, η p 2 = 0.380 ) muscle activity compared to the standard elliptical trainer. The decreased peak knee valgus and flexion angles could be beneficial for reducing long-term injury risk for anterior knee pathologies.

Real-Time Three-Dimensional Knee Moment Estimation in Knee Osteoarthritis: Toward Biodynamic Knee Osteoarthritis Evaluation and Training

We investigated differences in knee kinetic variables (external knee adduction, flexion, internal rotation moments, and impulses) between patients with knee osteoarthritis (KOA) and healthy controls during stepping on a custom elliptical trainer; and searched knee kinetic variable candidates for real-time biofeedback and for complementing diagnosis/evaluation on the elliptical trainer based on the knee kinetic variables' associations with the knee injury and osteoarthritis outcome score (KOOS). Furthermore, we explored potential gait re-training strategies on the elliptical trainer by investigating the knee kinetic variables' associations with 3-D ankle angles. The knee kinetic variables and ankle angles were determined in real-time in a patient group of 10 patients with KOA and an age-and sex-matched control group of 10 healthy subjects. The mean peak external knee adduction moment of the patient group was 47% higher than that of the control group. The KOOS-Sports and Recreational Activities and KOOS-Pain scores were found to be significantly associated with the knee kinetic variables. All the ankle angles were associated with the knee kinetic variables. The findings support the use of the knee kinetic variables on the elliptical trainer to complement KOA diagnosis quantitatively and provide potential real-time KOA gait re-training strategies/guides.

Kinematic and muscle demand similarities between motor-assisted elliptical training and walking: Implications for pediatric gait rehabilitation

Many children with physical disabilities and special health care needs experience barriers to accessing effective therapeutic technologies to improve walking and fitness in healthcare and community environments. The expense of many robotic and exoskeleton technologies hinders widespread use in most clinics, school settings, and fitness facilities. A motor-assisted elliptical trainer that is being used to address walking and fitness deficits in adults was modified to enable children as young as three years of age to access the technology (Pedi-ICARE). We compared children's kinematic and muscle activation patterns during walking and training on the Pedi-ICARE. Eighteen children walked (self-selected comfortable speed), Pedi-ICARE trained with motor-assistance at self-selected comfortable speed (AAC), and trained while over-riding motor-assistance (AAC+). Coefficient of multiple correlations (CMCs) compared lower extremity kinematic profiles during AAC and AAC+ to gait. Repeated measures ANOVAs identified muscle demand differences across conditions. CMCs revealed strong similarities at the hip and knee between each motor-assisted elliptical condition and gait. Ankle CMCs were only moderate. Muscle demands were generally lowest during AAC. Over-riding the motor increased hip and knee muscle demands. The similarity of motion patterns between Pedi-ICARE conditions and walking suggest the device could be used to promote task-specific training to improve walking. The capacity to manipulate muscle demands using different motor-assistance conditions highlights Pedi-ICARE's versatility in addressing a wide range of children's abilities.

Effects of a rapid-resisted elliptical training program on motor, cognitive and neurobehavioral functioning in adults with chronic traumatic brain injury

This small clinical trial utilized a novel rehabilitation strategy, rapid-resisted elliptical training, in an effort to increase motor, and thereby cognitive, processing speed in ambulatory individuals with traumatic brain injury (TBI). As an initial step, multimodal functional abilities were quantified and compared in 12 ambulatory adults with and 12 without TBI. After the baseline assessment, the group with TBI participated in an intensive 8-week daily exercise program using an elliptical trainer and was reassessed after completion and at an 8-week follow-up. The focus of training was on achieving a fast movement speed, and once the target was reached, resistance to motion was increased in small increments to increase intensity of muscle activation. Primary outcomes were: High-Level Mobility Assessment Tool (HiMAT), instrumented balance tests, dual-task (DT) performance and neurobehavioral questionnaires. The group with TBI had poorer movement excursion during balance tests and poorer dual-task (DT) performance. After training, balance reaction times improved and were correlated with gains in the HiMAT and DT. Sleep quality also improved and was correlated with improved depression and learning. This study illustrates how brain injury can affect multiple linked aspects of functioning and provides preliminary evidence that intensive rapid-resisted training has specific positive effects on dynamic balance and more generalized effects on sleep quality in TBI.