Standardized voluntary force measurement in a lower extremity rehabilitation robot

Bolliger, Marc; Banz, Raphael; Dietz, Volker; Lünenburger, Lars

doi:10.1186/1743-0003-5-23

Cited by 43 publications

(32 citation statements)

References 21 publications

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“…All control subjects walked at a treadmill speed of 0.5 m/s. Subjects then underwent testing of their maximum voluntary contraction (MVC) using isometric strength testing in the Lokomat (Bolliger et al 2008). Three trials were performed to calculate an average hip flexor maximum voluntary force.…”

Section: Subjectsmentioning

confidence: 99%

Locomotor adaptations and aftereffects to resistance during walking in individuals with spinal cord injury

Houldin

Luttin

Lam

2011

Journal of Neurophysiology

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Muscle activity during the swing phase of walking is influenced by proprioceptive feedback pathways. Previous studies have shown that feedback and anticipatory motor commands contribute to locomotor adaptive strategies to prolonged exposure to a resistance against leg movements during walking. The purpose of this study was to determine whether people with motor-incomplete spinal cord injuries (SCI) modulate flexor muscle activity in response to different levels of resistance in a similar way as uninjured controls. A second purpose was to determine whether people with motor-incomplete SCI have the capacity to form anticipatory motor commands following exposure to resistance. Subjects walked on a treadmill with the Lokomat robotic gait orthosis. The Lokomat applied different levels of a velocity-dependent resistance, normalized to each subject's maximum voluntary contraction of the hip flexors. Each condition consisted of 20 steps against resistance followed by 20 steps without. Electromyography and kinematics of the lower limb were recorded. Although both groups responded to the resistance with an overall increase in rectus femoris activity during swing, the SCI group showed weak modulation of muscle activity to different levels of resistance. Following removal of the resistance, both groups showed aftereffects, but they were manifested differently. Controls responded to the removal of resistance with a high step, whereas the SCI subjects exhibited increased step length. The size of the aftereffect was related to the amount of added resistance. In addition, the SCI group showed a negative relationship between the size of the aftereffect and locomotor function.

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Section: Subjectsmentioning

confidence: 99%

Locomotor adaptations and aftereffects to resistance during walking in individuals with spinal cord injury

Houldin

Luttin

Lam

2011

Journal of Neurophysiology

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“…Previously, the Lokomat has been used to assess voluntary muscle force and spasticity in the lower limbs [23,24]. We used 2 different assessments to track lower limb proprioception at the hip and knee joint in able-bodied subjects and in 1 subject with incomplete SCI.…”

Section: Introductionmentioning

confidence: 99%

Quantifying lower limb joint position sense using a robotic exoskeleton: A pilot study

Domingo

Marriott

Grave

et al. 2011

2011 IEEE International Conference on Rehabilitation Robotics

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Clinicians and scientists often focus on tracking the recovery of motor skills after spinal cord injury (SCI), but less attention is paid to the recovery of sensory skills. Measures of sensory function are imperative for evaluating the efficacy of treatments and therapies. Proprioception is one sensory modality that provides information about static position and movement sense. Because of its critical contribution to motor control, proprioception should be measured during the course of recovery after neurological injury. Current clinical methods to test proprioception are limited to crude, manual tests of movement and position sense. The purpose of this study was to develop a quantitative assessment tool to measure joint position sense in the legs. We used the Lokomat, a robotic exoskeleton, and custom software to assess joint position sense in the hip and knee in 9 able-bodied (AB) subjects and 1 person with incomplete SCI. We used two different test paradigms. Both required the subject to move the leg to a target angle, but the presentation of the target was either a remembered or visual target angle. We found that AB subjects had more accurate position sense in the remembered task than in the visual task, and that they tended to have greater accuracy at the hip than at the knee. Position sense of the subject with SCI was comparable to those of the AB subjects. We show that using the Lokomat to assess joint position sense may be an effective clinical measurement tool.

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“…When B is set to zero, no force is applied (null field). The specific resistance level was scaled to 10% of each individual's hip flexor maximum voluntary contraction (MVC), as measured by the Lokomat's force transducers (Bolliger et al 2008) and the average angular velocity during the swing phase of baseline walking.…”

Section: Methodsmentioning

confidence: 99%

Limited interlimb transfer of locomotor adaptations to a velocity-dependent force field during unipedal walking

Houldin

Chua

Carpenter

et al. 2012

Journal of Neurophysiology

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Several studies have demonstrated that motor adaptations to a novel task environment can be transferred between limbs. Such interlimb transfer of motor commands is consistent with the notion of centrally driven strategies that can be generalized across different frames of reference. So far, studies of interlimb transfer of locomotor adaptations have yielded disparate results. Here we sought to determine whether locomotor adaptations in one (trained) leg show transfer to the other (test) leg during a unipedal walking task. We hypothesized that adaptation in the test leg to a velocity-dependent force field previously experienced by the trained leg will be faster, as revealed by faster recovery of kinematic errors and earlier onset of aftereffects. Twenty able-bodied adults walked unipedally in the Lokomat robotic gait orthosis, which applied velocity-dependent resistance to the legs. The amount of resistance was scaled to 10% of each individual's maximum voluntary contraction of the hip flexors. Electromyography and kinematics of the lower limb were recorded. All subjects were right-leg dominant and were tested for transfer of motor adaptations from the right leg to the left leg. Catch trials, consisting of unexpected removal of resistance, were presented after the first step with resistance and after a period of adaptation to test for aftereffects. We found no significant differences in the sizes of the aftereffects between the two legs, except for peak hip flexion during swing, or in the rate at which peak hip flexion adapted during steps against resistance between the two legs. Our results indicate that interlimb transfer of these types of locomotor adaptation is not a robust phenomenon. These findings add to our current understanding of motor adaptations and provide further evidence that generalization of adaptations may be dependent on the movement task.

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Standardized voluntary force measurement in a lower extremity rehabilitation robot

Cited by 43 publications

References 21 publications

Locomotor adaptations and aftereffects to resistance during walking in individuals with spinal cord injury

Locomotor adaptations and aftereffects to resistance during walking in individuals with spinal cord injury

Quantifying lower limb joint position sense using a robotic exoskeleton: A pilot study

Limited interlimb transfer of locomotor adaptations to a velocity-dependent force field during unipedal walking

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