The Relationship of Lower-Extremity Muscle Torque to Locomotor Performance in People With Stroke

Kim, C Maria; Eng, Janice J.

doi:10.1093/ptj/83.1.49

Cited by 245 publications

(116 citation statements)

References 25 publications

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“…Previous work has shown that the plantarflexor muscles are important for generating forward acceleration during the push-off phase of walking [1,2]. Individuals with cerebral palsy, stroke, muscular dystrophy, or Charcot-Marie-Tooth (CMT) disease often exhibit plantarflexor muscle weakness [3][4][5][6][7][8][9] and contracture [3,[9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations

Ong

Geijtenbeek

Hicks

et al. 2019

Preprint

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Deficits in the ankle plantarflexor muscles, such as weakness and contracture, occur commonly in conditions such as cerebral palsy, stroke, muscular dystrophy, and Charcot-Marie-Tooth disease. While these deficits likely contribute to observed gait pathologies, elucidating cause-effect relationships is difficult due to the often co-occurring biomechanical and neural deficits. To elucidate the effects of weakness and contracture, we systematically introduced isolated deficits into a musculoskeletal model and generated simulations of walking to predict gait adaptations due to these deficits. We developed a planar model containing 9 degrees of freedom and 18 musculotendon actuators, and an optimization framework through which we imposed simple objectives, such as minimizing cost of transport while avoiding falling and injury, and maintaining head stability. We first validated that our model could generate gaits that reproduced experimentally observed kinematic, kinetic, and metabolic trends for two cases: 1) walking at prescribed speeds between 0.50 m/s and 2.00 m/s and 2) walking at self-selected speed. We then applied mild, moderate, and severe levels of muscle weakness or contracture to either the soleus (SOL) or gastrocnemius (GAS) or both of these major plantarflexors (PF) and retrained the model to walk at a self-selected speed. The model was robust to all deficits, finding a stable gait in all cases. Severe PF weakness caused the model to adopt a slower, "heel-walking" gait. Severe contracture of only SOL or both PF yielded similar results: the model adopted a "toe-walking" gait with excessive hip and knee flexion during stance. These results highlight how plantarflexor weakness and contracture may contribute to observed gait patterns. Our model, simulation and optimization framework, and results are freely shared so that others can reproduce and build upon our work.Author summaryDeficits in the muscles that extend the ankle are thought to contribute to abnormal walking patterns in conditions such as cerebral palsy, stroke, muscular dystrophy, and Charcot-Marie-Tooth disease. To study how deficits in these muscles contribute to abnormal walking patterns, we used computer simulations to systematically introduce muscle deficits into a biomechanically accurate model. We first showed that our model could discover realistic walking patterns over a wide range of speeds when we posed a simple objective: walking while consuming a minimum amount of energy per distance, maintaining head stability, and avoiding injury. We then used the model to study the effect of two commonly observed problems: muscle weakness and muscle tightness. We found that severe weakness of the ankle extensors caused the model to adopt a slower, “heel-walking” gait, and severe tightness caused the model to adopt a crouched, “toe-walking” gait. These results highlight how deficits in the ankle extensor muscles may contribute to abnormal walking patterns commonly seen in pathological populations.

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Section: Introductionmentioning

confidence: 99%

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations

Ong

Geijtenbeek

Hicks

et al. 2019

Preprint

View full text Add to dashboard Cite

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“…While gait asymmetry is broadly recognized, the best approach to mediate these effects has yet to be established. [14][15][16][17][18][19] Prior work suggests each seemingly subtle decision made in the course of training, including treadmill speed, handrail hold, and harness support, can impact gait symmetry following stroke. 16,[20][21][22] Indeed, both handrail hold and partial body weight support (BWS) are argued to provide stability through added sensory cues, 8 Induced spatiotemporal changes symmetry.…”

Section: Introductionmentioning

confidence: 99%

Direction of gait asymmetry following stroke determines acute response to locomotor task

Little¹,

Perry

Mercado

et al. 2019

Preprint

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limit 250 words) Words: 250 Background Given the prevalence of gait dysfunction following stroke, walking recovery is a primary goal of rehabilitation. However, current gait rehabilitation approaches fail to demonstrate consistent benefits. Furthermore, asymmetry is a prominent feature of gait dysfunction following stroke. Differential patterns of gait asymmetry may respond differently to gait training parameters.Objective The purpose of this study was to determine whether differential responses to locomotor task condition occur on the basis of direction of step length asymmetry (Symmetrical, NP short , P short ) observed during overground walking.Methods Participants first walked overground at their self-selected walking speed.Overground data were compared against three task conditions all tested during treadmill walking: self-selected speed with 0% body weight support (TM); self-selected speed with 30% body weight support (BWS); and fastest comfortable speed with 30% body weight support and nonparetic leg guidance (Guidance NP ). Our primary outcomes were: step length, single limb support duration, and stride length. ResultsWe identified differences in the response to locomotor task conditions for each step length asymmetry subgroup. Guidance NP induced an acute spatial symmetry only in the NP short group and temporal symmetry in the Symmetrical group.Conclusions Task conditions consistent with locomotor training do not produce uniform effects across subpatterns of gait asymmetry. We identified differential responses to locomotor task conditions between groups with distinct asymmetry patterns, suggesting these subgroups may require unique intervention strategies. Despite group differences in asymmetry characteristics, improvements in symmetry noted in the Symmetrical and NP short groups were driven by changes in both the paretic and nonparetic limbs. Induced spatiotemporal changesKey words (6): stroke gait non-paretic training symmetry locomotor training spatiotemporal parameters

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“…Increasing recognition of the importance of muscle strength in stroke recovery is based, in part, on studies that have demonstrated a relationship between muscle strength and function in persons with stroke. Paretic muscle strength is related to a number of activities of daily living in individuals with stroke, including bringing the hand to the mouth, 6 balance, 7 walking speed, [8][9][10] ability to rise from a chair 11 and stair climbing. 8 Muscle strength of the involved side of the body is also inversely related to falls 12 and the inpatient stroke rehabilitation length of stay.…”

Section: Introductionmentioning

confidence: 99%

Strength Training in Individuals with Stroke

Eng¹

2004

Physiother. Can.

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PURPOSE: This paper reviews the mechanisms underlying the inability to generate force in individuals with stroke and summarizes the effects of strength training in these individuals. In addition, a systematic review of studies that have incorporated progressive strengthening interventions in individuals with stroke is presented. SUMMARY OF KEY POINTS: Central (e.g., motor recruitment) and peripheral (e.g., muscle atrophy) sources may alter muscle strength in individuals with stroke and further investigations are needed to partition and quantify their effects. As to the effect of strength training interventions in individuals with stroke, the majority of studies (albeit with small samples) that evaluated muscle strength as an outcome demonstrated improvements. With regard to the effect of strength training on functional outcomes in individuals with stroke, positive outcomes were found in less rigorous pre-test/post-test studies, but more conflicting results with controlled trials. CONCLUSIONS: Although there is some suggestion that strength training alone can improve muscle strength, further research is required to optimize strength training and the transfer of these strength gains to functional tasks in individuals with stroke.

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The Relationship of Lower-Extremity Muscle Torque to Locomotor Performance in People With Stroke

Cited by 245 publications

References 25 publications

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations

Direction of gait asymmetry following stroke determines acute response to locomotor task

Strength Training in Individuals with Stroke

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