1,721,027 research outputs found
Spinal Cord Epidural Stimulation for Lower Limb Motor Function Recovery in Individuals with Motor Complete Spinal Cord Injury
No full textSpinal cord epidural stimulation (scES) combined with activity-based training can promote lower limb motor function recovery in chronic, motor complete spinal cord–injured individuals. Task- and individual-specific scES parameters modulate the excitability of human spinal circuitry so that sensory information and residual descending input can serve as sources of control for generating motor patterns appropriate for standing, stepping, and volitionally moving the lower limb. Task-specific activity-based training with scES is crucial for promoting neural plasticity and motor function improvement. Future studies with more individuals and advanced stimulation technology are needed to better understand the recovery potential in this population
Wavelet-derived features as indicators of physiological changes induced by bed rest
No full textObjective: Bed rest studies are employed to simulate microgravity situations as encountered in spaceflight. Current methods of assessing muscle function impairment due to microgravity exposure include techniques such as maximum voluntary contraction assessments using force measurements. Such techniques involve impractical long-feedback loops for applications involving rehabilitation or otherwise detecting physiological changes. Recent studies have made use of the discrete wavelet transform in combination with machine learning methods to classify hand gestures and detect pathologies. In this paper, we demonstrate models capable of discriminating between the before and after bed rest states by extracting features from surface electromyography measurements. Methods: A previously conducted and studied bed rest experiment is examined by discrete wavelet transform for tractable feature sets for the purpose of k-nearest neighbor and Support Vector Machine classification. Forward feature selection is used with k-nearest neighbor or Support Vector Machine selection criteria. Classifiers are evaluated on non-wavelet-derived features for sake of comparison. Results: Wavelet-derived features perform well for both classifiers with classification accuracies as high as 95%. Models without wavelet-derived features do not perform as well overall. Conclusion: These high-accuracy results are promising for future efforts in neuromuscular monitoring and further investigations with larger sample sizes. Significance: Classification algorithms utilizing features derived by wavelet transforms provide a method toward development of short-feedback loop measurements of the physiological effects of prolonged disuse
Energy expenditure and dietary intake of athletes during an ultraendurance event developed by hiking, cycling and mountain climbing
No full textImprovement of voluntary movement following task-specific training with subthreshold lumbosacral epidural stimulation in individuals with severe spinal cord injury
No full textRecovery of voluntary motor function several years after clinical diagnosis of motor complete spinal cord injury (SCI) is rare. Subthreshold network targeted lumbosacral epidural stimulation (scES) has been previously shown to restore voluntary movement in individuals with motor complete SCI (Angeli et al. 2014, Grahn et al. 2017, Darrow et al. 2022). The aim of this study is to determine the effects of task-specific training with scES on voluntary movement ability in individuals with severe SCI.Individuals with chronic motor complete SCI (n=27) were implanted at L1-S1 spinal cord level with an electrode array and neurostimulator. These individuals (age: 35.5 ± 10.6 yrs; time post-injury: 10.1 ± 8.1 yrs; 37% female, 15 AIS A, 11 AIS B, 1 AIS C) were unable to move their legs voluntarily or stand independently. Voluntary movement mapping was performed in all participants while asking individuals to attempt flexion movements of the first toe, ankle and hip. Further changes in parameters were dependent on the observed EMG modulation and joint movements. Individuals were randomized to a voluntary training group (Vol-scES) or a cardiovascular group (CV-scES). Individuals used scES for 6 hours a day practicing voluntary movement (Vol-scES) or for blood pressure regulation (CV-scES). We performed torque and EMG assessments in a dynamometer pre and post training with voluntary specific stimulation.All individuals were able to modulate EMG activity in the presence of scES and were able to move at least one joint. There was no difference between groups prior to the start of the training intervention. Individuals randomized to the Vol-scES group showed an improvement in maximum torque generation and ability to perform multiple consecutive repetitions of hip flexion when compared to their baseline (post-implant, pre-intervention values). While individuals randomized to the CV-scES group showed a slight decrease in both outcomes. When asked to perform ankle dorsiflexion the median RMS value of TA showed a slight increase for the VoL-scES group with a decrease for the CV-scES group. Torque generation during dorsiflexion increased in the VoL-scES post training while there was a decrease in the CV-scES. These results provide evidence that task-specific training with scES results in greater voluntary movement ability. Further, scES modulates network excitability of the injured spinal cord to allow for the integration of afferent and supraspinal descending input to generate movement below the injury after severe SCI
Effects of sitting trunk training and stand training with epidural stimulation on sitting trunk kinematics in individuals with chronic motor complete spinal cord injury
No full textSpinal cord epidural stimulation (scES) as well as activity-based training have the potential to improve seated postural control in individuals with spinal cord injury (SCI). Past evidence also suggests that stand training could lead to improved postural control outcomes. Hence, we compared the effects of sitting trunk-specific training with scES and trunk-specific plus stand training with scES on trunk kinematics in seated tasks. Sixteen individuals with cervical SCI (Age: 37.1 ± 12.1 yrs; time post-injury: 11.2 ± 8.2 yrs) implanted with a scES unit were randomized into: Voluntary - Vol (Group 1); or Vol and Stand (Group 2). Each group performed two 80-session interventions. Vol intervention comprised tasks to improve seated trunk control. Group 1 crossed over to Vol and Stand in the second intervention. Each individual performed tall-sit, sagittal plane leans, and frontal plane leans with Vol-scES at 3 time-points (Post Implant, Post Int1, and Post Int2). Center of mass of pelvis and trunk were obtained from full-body kinematics. Six postural control outcomes were then computed: anterior-posterior (TAPD) and lateral trunk displacement (TLD), and trunk velocity in all four directions (anterior-TAV, posterior-TPV, left-TLV, and right-TRV). Improved outcomes were defined as decreases in all velocities and displacements in all tasks, except for an increase in displacement in the direction of movement in leaning tasks. In tall-sit, both intervention sets tended to decrease postural control for both groups, except Group 2 had TLV and TRV decreases after the second intervention while TAV decreased following Vol and Stand training for both groups. In sagittal plane lean, TAV and TPV tended to decrease for Group 1 after Vol and Stand training suggesting that stand training may have supplemented postural control improvements. For Group 2, TAV tended to decrease after the first intervention and TAPD increased after both intervention sets. In frontal plane lean, all velocities and TAPD tended to decrease for Group 1 after Vol only training while only TAV, and TRV improved after Vol and Stand training, suggesting that added stand training had a limited effect on lateral control. For Group 2, TAV, and TPV tended to decrease after the first intervention, while TLV, and TRV tended to decrease after the second
intervention. The addition of stand training post voluntary training tended to have a greater effect on postural control in sagittal plane lean task, while both groups showed similar improvements in frontal plane lean. These results further our understanding of task-specificity during training interventions and aid in developing better rehabilitation protocols
Changes in Trunk independence following Stand Training with spinal cord epidural stimulation in Cervical SCI: Two Case Studies
No full textMost individuals with motor complete spinal cord injury are unable to stand independently without external assistance. Activity Based Recovery Training (ABRT) promotes reactivation of the neuromuscular system below the level of injury. In addition, spinal cord epidural stimulation (scES) allows for the integration of sensory information leading to the modulation of motor output in the lower extremities. We present a comparison of two case studies proving evidence of the progression of recovery of trunk control during standing with scES and the reliance on upper limb support during standing. One individual (C3 AIS-A) was able to regain independent trunk control and recovered some ability to stand without upper extremity support when assisted at the hips. The second individual (C4 AIS-A) had shorter bouts of trunk independence and always required upper extremity support. Both individuals received 2 hours of stand ABRT with scES for 160 sessions. Participants were assessed prior to the start of training (pre-intervention), after 80 sessions (post intervention 1) and after 160 sessions (post intervention 2). Both participants required trunk assistance in addition to upper limb support to maintain proper trunk kinematics at the pre-intervention time point. This was illustrated by lower forces with a lower coefficient of variation (c.v.) generated through upper extremities compared to periods of independent trunk with upper extremity support. The individual that achieved the greatest level of trunk independence, average of 52 min during intervention 1 and 98 mins during intervention 2, showed a reduction in vertical forces placed through the upper extremities and a reduction in the c.v. when comparing post intervention 2 to post intervention 1. In contrast, the individual with an average of 22 min and 30 min of trunk independence across training sessions during intervention 1 and 2 respectively, showed limited difference in vertical upper extremity
force and c.v. at both time points. Results from this investigation demonstrate the ability to improve trunk control following standing ABRT with scES and decrease the reliance on upper extremity support to maintain proper trunk posture in individuals with a cervical motor complete injury. We show that increased trunk independence time has a tendency to reduce the amount of upper extremity support, hinting towards increased activation of trunk musculature for proper posture. Hereby providing evidence that scES modulates network excitability of the injured spinal cord leading to integration of afferent input to activate trunk and lower extremity muscles and improve independence during stable standing
Effects of NMES-elicited versus voluntary low-level conditioning contractions on explosive knee extensions
No full textObjectives: Electrically-induced or voluntary conditioning-contractions (CC) can be used to affect contractile properties of a subsequent explosive contraction (EC). Here, we aimed at comparing the effect of neuromuscular-electrical-stimulation (NMES) vs voluntary CC performed prior to explosive contractions of the knee extensors. Methods: A 10 sec NMES CC (100Hz, 1000μs, 10% MVC), or a voluntary contraction (VOL CC) mimicking the NMES CC, preceded an isometric EC of the knee extensors. Explosive contraction was performed with the goal to reach the target (70% MVC) as quickly as possible. Results: All the parameters related with the explosive contractions’ muscle-output were similar between protocols (difference ranging from 0.23%, Mean Torque; to 5.8%, Time to Target), except for the Time to Peak Torque, which was lower when preceded by NMES (11.1%, p=0.019). Interestingly, the RTD 0–50 ms_EC was 37.3% higher after the NMES compared with the VOL CC protocol. Conclusion: Explosive contraction was potentiated by an NMES CC as compared with a voluntary CC. This may be due to a reduction in descending drive following VOL CC, which has been shown to occur even with low-level voluntary efforts. These findings could be used to improve rehabilitation or training protocols that include conditioning contractions
Sensory Information Modulates Voluntary Movement in an Individual with a Clinically Motor- and Sensory-Complete Spinal Cord Injury: A Case Report
Full text linkMotor recovery following a complete spinal cord injury is not likely. This is partially due to insurance limitations. Rehabilitation strategies for individuals with this type of severe injury focus on the compensation for the activities of daily living in the home and community and not on the restoration of function. With limited time in therapies, the initial goals must focus on getting the patient home safely without the expectation of recovery of voluntary movement below the level of injury. In this study, we report a case of an individual with a chronic, cervical (C3)-level clinically motor- and sensory-complete injury who was able to perform voluntary movements with both upper and lower extremities when positioned in a sensory-rich environment conducive to the specific motor task. We show how he is able to intentionally perform push-ups, trunk extensions and leg presses only when appropriate sensory information is available to the spinal circuitry. These data show that the human spinal circuitry, even in the absence of clinically detectable supraspinal input, can generate motor patterns effective for the execution of various upper and lower extremity tasks, only when appropriate sensory information is present. Neurorehabilitation in the right sensory–motor environment that can promote partial recovery of voluntary movements below the level of injury, even in individuals diagnosed with a clinically motor-complete spinal cord injury
Motor recovery after activity-based training with spinal cord epidural stimulation in a chronic motor complete paraplegic
No full textThe prognosis for recovery of motor function in motor complete spinal cord injured (SCI) individuals is poor. Our research team has demonstrated that lumbosacral spinal cord epidural stimulation (scES) and activity-based training can progressively promote the recovery of volitional leg movements and standing in individuals with chronic clinically complete SCI. However, scES was required to perform these motor tasks. Herein, we show the progressive recovery of voluntary leg movement and standing without scES in an individual with chronic, motor complete SCI throughout 3.7 years of activity-based interventions utilizing scES configurations customized for the different motor tasks that were specifically trained (standing, stepping, volitional leg movement). In particular, this report details the ongoing neural adaptations that allowed a functional progression from no volitional muscle activation to a refined, task-specific activation pattern and movement generation during volitional attempts without scES. Similarly, we observed the re-emergence of muscle activation patterns sufficient for standing with independent knee and hip extension. These findings highlight the recovery potential of the human nervous system after chronic clinically motor complete SCI
Effects of gravitational versus iso-inertial resistance training on leg muscle force and metabolic cost of walking in healthy older adults
No full textBACKGROUND: The purpose was to compare the effects of 8-week resistance training programs (flywheel iso-inertial [FW] versus traditional gravity-dependent resistance training [GD]) performed twice a week at the same rate of perceived exertion (RPE), on muscle force and power capacities and physical performance in healthy older participants. METHODS: Twenty-four participants were randomly assigned to either FW (male/female ratio: 7/5, age: 67.1±3.8 years) or GD (male/female ratio: 6/6, age 68.3±3.0 years) group. Knee extension maximal isometric voluntary contractions (MVC), lower limb maximal explosive power (MEP), Six-Minute Walking Test (6MWT), Timed Up-and-Go Test (TUG), metabolic cost of walking (CW) and agonist-antagonist co-contraction time (CCT) during walking were evaluated before and after training. RESULTS: absolute MEP and MEP normalized for body mass increased only in FW than GD group (+10.8% vs. +0.31%, P=0.056, respectively; +14.8% vs. +13.9%, P<0.001, respectively). Both training modalities improved MVC to a similar extent (+11.1% in FW vs. +13.4% in GD, P<0.001). Analogously, 6MWT distance increased in FW and GD (+5.2 and +5.5%, P<0.041, respectively). No effects of time and training modality were observed on the other parameters. CONCLUSIONS: The results of this study suggest that when FW and GD are administered at the same RPE with FW performed at higher movement speed in the concentric phase, both the trainings generate similar improvements in muscle strength but only the former can promote greater muscle power enhancements than GDin healthy older adults
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