The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Volker Dietz - One of the best experts on this subject based on the ideXlab platform.
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
Markus Wirz - One of the best experts on this subject based on the ideXlab platform.
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
Lars Lunenburger - One of the best experts on this subject based on the ideXlab platform.
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
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swing phase resistance enhances Flexor muscle activity during treadmill locomotion in incomplete spinal cord injury
Neurorehabilitation and Neural Repair, 2008Co-Authors: Markus Wirz, Lars Lunenburger, Volker DietzAbstract:Background. This study investigated whether loading the legs during the swing phase of walking enhances Flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI). Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee Flexors and sometimes of hip or ankle Flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase Flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through ad...
Rayaz A Malik - One of the best experts on this subject based on the ideXlab platform.
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distal lower limb strength is reduced in subjects with impaired glucose tolerance and is related to elevated intramuscular fat level and vitamin d deficiency
Diabetic Medicine, 2017Co-Authors: M M Almurdhi, Neil D Reeves, Frank L Bowling, Andrew J M Boulton, Maria Jeziorska, Rayaz A MalikAbstract:AIM: To quantify muscle strength and size in subjects with impaired glucose tolerance (IGT) in relation to intramuscular non-contractile tissue, the severity of neuropathy and vitamin D level. METHODS: A total of 20 subjects with impaired glucose tolerance and 20 control subjects underwent assessment of strength and size of knee extensor, Flexor and ankle plantar and dorsi-Flexor muscles, as well as quantification of intramuscular non-contractile tissue and detailed assessment of neuropathy and serum 25-hydroxy vitamin D levels. RESULTS: In subjects with impaired glucose tolerance, proximal knee extensor strength (P=0.17) and volume (P=0.77), and knee Flexor volume (P=0.97) did not differ from those in control subjects. Ankle plantar Flexor strength was significantly lower (P=0.04) in the subjects with impaired glucose tolerance, with no difference in ankle plantar Flexor (P=0.62) or dorsiFlexor volume (P=0.06) between groups. Intramuscular non-contractile tissue level was significantly higher in the ankle plantar Flexors and dorsiFlexors (P=0.03) of subjects with impaired glucose tolerance compared with control subjects, and it correlated with the severity of neuropathy. Ankle plantar Flexor muscle strength correlated significantly with corneal nerve fibre density (r= 0.53; P=0.01), a sensitive measure of small fibre neuropathy, and was significantly lower in subjects with vitamin D deficiency (P=0.02). CONCLUSIONS: People with impaired glucose tolerance have a significant reduction in distal but not proximal leg muscle strength, which is not associated with muscle atrophy, but with increased distal intramuscular non-contractile tissue, small fibre neuropathy and vitamin D deficiency. This article is protected by copyright. All rights reserved.
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reduced lower limb muscle strength and volume in patients with type 2 diabetes in relation to neuropathy intramuscular fat and vitamin d levels
Diabetes Care, 2016Co-Authors: M M Almurdhi, Neil D Reeves, Frank L Bowling, Andrew J M Boulton, Maria Jeziorska, Rayaz A MalikAbstract:OBJECTIVE Muscle weakness and atrophy of the lower limbs may develop in patients with diabetes, increasing their risk of falls. The underlying basis of these abnormalities has not been fully explained. The aim of this study was to objectively quantify muscle strength and size in patients with type 2 diabetes mellitus (T2DM) in relation to the severity of neuropathy, intramuscular noncontractile tissue (IMNCT), and vitamin D deficiency. RESEARCH DESIGN AND METHODS Twenty patients with T2DM and 20 healthy control subjects were matched by age, sex, and BMI. Strength and size of knee extensor, Flexor, and ankle plantar and dorsiFlexor muscles were assessed in relation to the severity of diabetic sensorimotor polyneuropathy (DSPN), amount of IMNCT, and serum 25-hydroxyvitamin D (25OHD) levels. RESULTS Compared with control subjects, patients with T2DM had significantly reduced knee extensor strength ( P = 0.003) and reduced muscle volume of both knee extensors ( P = 0.045) and Flexors ( P = 0.019). Ankle plantar Flexor strength was also significantly reduced ( P = 0.001) but without a reduction in ankle plantar Flexor ( P = 0.23) and dorsiFlexor ( P = 0.45) muscle volumes. IMNCT was significantly increased in the ankle plantar ( P = 0.006) and dorsiFlexors ( P = 0.005). Patients with DSPN had significantly less knee extensor strength than those without ( P = 0.02) but showed no difference in knee extensor volume ( P = 0.38) and ankle plantar Flexor strength ( P = 0.21) or volume ( P = 0.96). In patients with 25 nmol/L 25OHD, no significant differences were found for knee extensor strength and volume ( P = 0.32 vs. 0.18) and ankle plantar Flexors ( P = 0.58 vs. 0.12). CONCLUSIONS Patients with T2DM have a significant reduction in proximal and distal leg muscle strength and a proximal but not distal reduction in muscle volume possibly due to greater intramuscular fat accumulation in distal muscles. Proximal but not distal muscle strength is related to the severity of peripheral neuropathy but not IMNCT or 25OHD level.
Richard R. Neptune - One of the best experts on this subject based on the ideXlab platform.
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The neuromuscular demands of toe walking: a forward dynamics simulation analysis.
Journal of biomechanics, 2006Co-Authors: Richard R. Neptune, Judith M. Burnfield, Sara J. MulroyAbstract:Toe walking is a gait deviation with multiple etiologies and often associated with premature and prolonged ankle plantar Flexor electromyographic activity. The goal of this study was to use a detailed musculoskeletal model and forward dynamical simulations that emulate able-bodied toe and heel-toe walking to understand why, despite an increase in muscle activity in the ankle plantar Flexors during toe walking, the internal ankle joint moment decreases relative to heel-toe walking. The simulations were analyzed to assess the force generating capacity of the plantar Flexors by examining each muscle's contractile state (i.e., the muscle fiber length, velocity and activation). Consistent with experimental measurements, the simulation data showed that despite a 122% increase in soleus muscle activity and a 76% increase in gastrocnemius activity, the peak internal ankle moment in late stance decreased. The decrease was attributed to non-optimal contractile conditions for the plantar Flexors (primarily the force-length relationship) that reduced their ability to generate force. As a result, greater muscle activity is needed during toe walking to produce a given muscle force level. In addition, toe walking requires greater sustained plantar Flexor force and moment generation during stance. Thus, even though toe walking requires lower peak plantar Flexor forces that might suggest a compensatory advantage for those with plantar Flexor weakness, greater neuromuscular demand is placed on those muscles. Therefore, medical decisions concerning whether to reduce equinus should consider not only the impact on the ankle moment, but also the expected change to the plantar Flexor's force generating capacity.
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ankle plantar Flexor force production is an important determinant of the preferred walk to run transition speed
The Journal of Experimental Biology, 2005Co-Authors: Richard R. Neptune, Kotaro SasakiAbstract:The mechanisms that govern the voluntary transition from walking to running as walking speed increases in human gait are not well understood. The objective of this study was to examine the hypothesis that plantar Flexor muscle force production is greatly impaired at the preferred transition speed (PTS) due to intrinsic muscle properties and, thus, serves as a determinant for the walk-to-run transition. The plantar Flexors have been shown to be important contributors to satisfying the mechanical energetic demands of walking and are the primary contributors to the observed ground reaction forces (GRFs) during the propulsion phase. Thus, if the plantar Flexor force production begins to diminish near the PTS despite an increase in muscle activation, then a corresponding decrease in the GRFs during the propulsion phase would be expected. This expectation was supported. Both the peak anterior/posterior and vertical GRFs decreased during the propulsion phase at walking speeds near the PTS. A similar decrease was not observed during the braking phase. Further analysis using forward dynamics simulations of walking at increasing speeds and running at the PTS revealed that all lower extremity muscle forces increased with walking speed, except the ankle plantar Flexors. Despite an increase in muscle activation with walking speed, the gastrocnemius muscle force decreased with increasing speed, and the soleus force decreased for walking speeds exceeding 80% PTS. These decreases in force production were attributed to the intrinsic force-length-velocity properties of muscle. In addition, the running simulation analysis revealed that the plantar Flexor forces nearly doubled for similar activation levels when the gait switched to a run at the PTS due to improved contractile conditions. These results suggest the plantar Flexors may serve as an important determinant for the walk-to-run transition and highlight the important role intrinsic muscle properties play in determining the specific neuromotor strategies used in human locomotion.
