Motor Recruitment Research Articles

Peak Slope Ratio of the Recruitment Curves Compared to Muscle Evoked Potentials to Optimize Standing Configurations with Percutaneous Epidural Stimulation after Spinal Cord Injury.

Background: Percutaneous spinal cord epidural stimulation (pSCES) has effectively restored varying levels of motor control in persons with motor complete spinal cord injury (SCI). Studying and standardizing the pSCES configurations may yield specific motor improvements. Previously, reliance on the amplitude of the SCES-evoked potentials (EPs) was used to determine the correct stimulation configurations. Methods: We, hereby, retrospectively examined the effects of wide and narrow-field configurations on establishing the motor recruitment curves of motor units of three different agonist-antagonist muscle groups. Magnetic resonance imaging was also used to individualize SCI participants (n = 4) according to their lesion characteristics. The slope of the recruitment curves using a six-degree polynomial function was calculated to derive the slope ratio for the agonist-antagonist muscle groups responsible for standing. Results: Axial damage ratios of the spinal cord ranged from 0.80 to 0.92, indicating at least some level of supraspinal connectivity for all participants. Despite the close range of these ratios, standing motor performance was enhanced using different stimulation configurations in the four persons with SCI. A slope ratio of ≥1 was considered for the recommended configurations necessary to achieve standing. The retrospectively identified configurations using the supine slope ratio of the recruitment curves of the motor units agreed with that visually inspected muscle EPs amplitude of the extensor relative to the flexor muscles in two of the four participants. Two participants managed to advance the selected configurations into independent standing performance after using tonic stimulation. The other two participants required different levels of assistance to attain standing performance. Conclusions: The findings suggest that the peak slope ratio of the muscle agonists-antagonists recruitment curves may potentially identify the pSCES configurations necessary to achieve standing in persons with SCI.

Transcranial magnetic stimulation input-output curve slope differences suggest variation in recruitment across muscle representations in primary motor cortex.

Measurement of the input-output (IO) curves of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) can be used to assess corticospinal excitability and motor recruitment. While IO curves have been used to study disease and pharmacology, few studies have compared the IO curves across the body. This study sought to characterize IO curve parameters across the dominant and non-dominant sides of upper and lower limbs in healthy participants. Laterality preferences were assessed in eight healthy participants and IO curves were measured bilaterally for the first dorsal interosseous (FDI), biceps brachii (BB), and tibialis anterior (TA) muscles. Results show that FDI has lower motor threshold than BB which is, in turn, lower than TA. In addition, both BB and TA have markedly shallower logarithmic IO curve slopes from small to large MEP responses than FDI. After normalizing these slopes by their midpoints to account for differences in motor thresholds, which could result from geometric factors such as the target depth, large differences in logarithmic slopes remain present between all three muscles. The differences in slopes between the muscles could not be explained by differences in normalized IO curve spreads, which relate to the extent of the cortical representation and were comparable across the muscles. The IO curve differences therefore suggest muscle-dependent variations in TMS-evoked recruitment across the primary motor cortex, which should be considered when utilizing TMS-evoked MEPs to study disease states and treatment effects.

Physical training and activity in people with diabetic peripheral neuropathy: A case report

Background: Diabetes mellitus (DM) is the most common endocrine disorder affecting more than 100 million people worldwide, around 6% of the population. This matter characterized by hyperglycemia (high glucose levels in blood) caused by a lack or ineffective production of insulin by the pancreas which results in an increase or decrease in the concentration of glucose in the blood. Diabetic peripheral neuropathy (DPN) or what is called diabetic peripheral neuropathy is the most common complication in cases of diabetes mellitus. DPN is a disease of loss of motor, sensory and autonomic nerve function, which can affect the peripheral nervous system. Sensorimotor training is considered a technique that can improve balance. This emphasizes the function of the sensorimotor system as a unit that works to increase sensory input and motor recruitment patterns in maintaining joint stability and regulating movement through the central nervous system (CNS). Aerobic exercise is a type of physical activity that can prevent and reduce DPN. Aerobic exercise such as treadmill can train balance. Balance training shows a high positive effect on improving motor and sensory symptoms in peripheral neuropathyPurpose: To examine the effects of sensorimotor training and lower limb muscle activity in DPN patients using treadmill.Method: The research uses a case study design, namely a research method that uses various data sources that can be used as research material, describing and explaining comprehensively various aspects of an individual, group, program, organization or event systematically. Participants in this study were patients aged 64 years, female, diagnosed diabetes mellitus type 2 (T2DM) for 10 years by a doctor. This research uses an aspect identification questionnaire instrument. DPN is screened using Michigan Neuropathy Screening Instrument (MNSI). Static balance is determined by romberg test and for dynamic balance it is measured by timed up and go test. Functional lower limb muscle strength is checked using tests Five Time Sit to Stand (5xSST).Results: The data for the respondent is a housewife aged 64 years, last education is junior high school with status as a housewife. The patient suffered from T2DM for 10 years with a hemoglobin 1AC level of 6.8 mg/dl, was overweight as indicated by the patient's BMI of 26 kg/m2. Often feels pain in both legs, when the patient walks and does strenuous activities with a score of 9, and the pain decreases when resting with a score of 3. Apart from that, the patient also has vision problems with a score of 20/40, meaning the patient can only see letters. at a distance of 20 feet. Even though normally letters can be seen clearly, namely 40 feet, this visual disturbance can cause the patient's balance to be disturbed. Providing treatment for 6 weeks can significantly improve the patient's quality of life as seen from the initial WHO QoL score of 58 to 86.Conclusion: Providing treadmill training for 6 weeks carried out 3 times a week showed significant results in reducing hemoglobin levels and DPN scores in T2DM patients.

The Intervention of Physiotherapy in the improvement of facial mimicry in a Peripheral Facial Palsy associated with a Preg-nancy: A Case Report

Peripheral Facial Palsy is a peripheral paralysis of the facial nerve that results in muscle weakness on one side of the face. Patients develop unilateral facial paralysis within one to three days with involvement of the facial musculature associated or not with neurological alterations, the best-known being Bell's Palsy. Symptoms usually peak in the first week and then gradually subside over three weeks to three months. In this context, a female patient with the clinical Diagnosis of Peripheral Facial Paralysis, was subjected to an intervention plan in Physiotherapy lasting 4 months (sessions of 45 minutes at a frequency of 3 times a week), with the particularity of be 28 weeks pregnant at the start of the sessions. After the end of the sessions, there was a considerable improvement in facial movements, translating into considerable functional changes. The patient acquired greater motor recruitment in flaccid muscles, greater facial symmetry, and consequently greater autonomy in eating, chewing, containing liquids and intraoral sensibility.

The Effects of Kinesio Taping® on Muscle Interplay within the Lumbo–Pelvic–Hip Complex: A Randomized Placebo-Controlled Trial

Coordination of muscle activity is determined by the recruitment order of agonists and synergists that results from their onset times. Motor recruitment deficits are possible. This study examined the acute and prolonged effects of three different techniques of the kinesio taping method in optimizing the intermuscular coordination within the lumbo-pelvic-hip complex. The sample consisted of 56 healthy participants of both genders, randomly divided into equal groups by kinesio taping muscle facilitation, muscle inhibition and functional correction technique, and placebo kinesio taping condition. The onsets of the ipsilateral and contralateral erector spinae muscles, in relation to the semitendinosus muscle of the tested leg, were measured using the surface electromyography, during the active performance of the prone hip extension test. Time span was also determined. Measurements were performed at baseline, 60 min, and 48 h post-intervention. For the control group, we did not find statistically significant differences in the onset between the measurement points (p > 0.05), while in the experimental groups, there was a significant delay in the onset of the contralateral erector spinae (p < 0.001) in the second and third measurement points. These results indicate that the kinesio taping method can optimize the intermuscular coordination, with the potential for primary injury prevention.

Rate of change in longitudinal EMG indicates time course of an individual's neuromuscular adaptation in resistance-based muscle training.

An individual's long-term neuromuscular adaptation can be measured through time-domain analyses of surface electromyograms (EMG) in regular resistance-based training. The perceived changes in recruitment, such as those measured during muscle fatigue, can subsequently prolong the recovery time in rehabilitation applications. Thus, by developing quantifiable methods for measuring neuromuscular adaptation, adjuvant treatments applied during neurorehabilitation can be improved to reduce recovery times and to increase patient quality of care. This study demonstrates a novel time-domain analysis of long-term changes in EMG captured neuromuscular activity that we aim to use to develop a quantified performance metric for muscle-based intervention training and optimization of an individual. We measure EMG of endurance and hypertrophy-based resistance exercises of healthy participants over 100 days to identify trends in long-term neuromuscular adaptation. Particularly, we show that the rate of EMG amplitude increase (motor recruitment) is dependent on the training modality of an individual. Particularly, EMG decreases over time with repetitive training - but the rate of decrease is different in hypertrophy, endurance, and control exercises. We found that the EMG peak contraction decreases across all subjects, on average, by 8.23 dB during hypertrophy exercise and 10.09 dB for endurance exercises over 100 days of training, while control participants showed negligible change. This represents approximately 2 dB difference EMG activity when comparing endurance and hypertrophy exercises, and >8 dB change when comparing to our control cases. As such, we show that the slope of the long-term EMG activity is related to the resistance-based exercise. We believe this can be used to identify person-specific performance metrics, and to create optimized interventions using a measured performance baseline of an individual.

Structure of dynein-dynactin on microtubules shows tandem adaptor binding.

Cytoplasmic dynein is a microtubule motor that is activated by its cofactor dynactin and a coiled-coil cargo adaptor1-3. Up to two dynein dimers can be recruited per dynactin, and interactions between them affect their combined motile behaviour4-6. Different coiled-coil adaptors are linked to different cargos7,8, and some share motifs known to contact sites on dynein and dynactin4,9-13. There is limited structural information on how the resulting complex interacts with microtubules and how adaptors are recruited. Here we develop a cryo-electron microscopy processing pipeline to solve the high-resolution structure of dynein-dynactin and the adaptor BICDR1 bound to microtubules. This reveals the asymmetric interactions between neighbouring dynein motor domains and how they relate to motile behaviour. We found that two adaptors occupy the complex. Both adaptors make similar interactions with the dyneins but diverge in their contacts with each other and dynactin. Our structure has implications for the stability and stoichiometry of motor recruitment by cargos.

Mu rhythm and corticospinal excitability capture two different frames of motor resonance: A TMS–EEG co-registration study

Humans are equipped with an extraordinary ability to understand and imitate actions by mapping the observed movement onto their own cortical motor system. Long-established lines of research have identified two correlates of this motor resonance following action observation: the mu rhythm event-related desynchronization (mu-ERD) recorded through electroencephalography (EEG) and the facilitation of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) of the primary motor cortex (M1). Yet, whether mu-ERD and MEP facilitation reflect unique or distinct mechanisms is not conclusive, as prior work did not combine simultaneous TMS–EEG recording with a trial-by-trial analysis of the two markers. To address this issue, here, we used TMS–EEG co-registration while participants observed and executed finger movements. EEG was continuously recorded while single-pulse TMS was administered over the left M1 and MEPs were recorded from the right hand. We found stronger motor cortex recruitment during action execution and observation as shown by mu-ERD. MEPs instead were larger overall during action execution and showed a facilitation specific to the muscles involved in the observed movements. Interestingly, when analyzing these two parameters using a trial-by-trial statistical approach, we did not find any relationship between mu-ERD and MEPs within the action observation condition. Our findings support the notion that EEG and TMS indices of motor resonance reflect distinct neural mechanisms.

Motor recruitment pattern during the prone hip extension test: is hip extension initiated by the hip or the lumbar extensor muscles?

Background/Aims Prone hip extension motion pattern derives from the motor muscle firing pattern, and functional deficits are determined by comparing this pattern with a normal prone hip extension motion muscle recruitment pattern, defined more than 30 years ago by scientifically insufficient methods. The aim of this study was to examine the differences between electromyography recruitment onsets and orders of muscles participating in prone hip extension motion, and to determine whether there is a consistent and dominant motor pattern. Methods The sample consisted of 106 healthy participants. Onset times of semitendinosus, ipsilateral and contralateral erector spinae muscles were determined as 10% of the peak rectified amplitude of the electromyography signal for each of the 18 prone hip extension bilateral repetitions. These values were used to determine the recruitment order for each repetition, as well as to calculate the average ipsilateral and contralatral normalised onset times (ie relative times to firing of the semitendinosus muscle). The main analysis was performed using a one-way analysis of variance. The level of statistical significance was set at P&lt;0.05. Results One-way analysis of variance revealed a significantly delayed onset of prone hip extension of the contralateral erector spinae muscles compared to the other muscles (F=7.02; P&lt;0.001; Cohen's f=0.209). Muscle activation initiated by the semitendinosus and ipsilateral erector spinae muscles was the most common. Conclusions The ipsilateral erector spinae muscle contracts simultaneously with the semitendinosus muscle as a proximal stabiliser, enabling distal hip mobility. The use of the prone hip extension test in recognising dysfunction is limited to when the contralateral erector spinae muscle is initiated first during prone hip extension.

Effect of Rehabilitation Robot Combined with Upper Limb Rehabilitation Training on Hemiplegic Patients in Recovery Stage of Stroke

<bold>Objective:</bold> To observe the effect of upper limb rehabilitation robot combined with upper limb rehabilitation training on motor function of upper extremity of hemiplegic patients in recovery stage of stroke. <bold>Methods</bold> A total of 40 hemiplegic patients in recovery stage of stroke who were treated in the Zhujiang Hospital of Southern Medical University from October 2018 to January 2020, which were randomly divided into the control group and the observation group according to the random number table method, with 20 cases in each group. Both groups received basic medication and conventional rehabilitation therapy (including good limb position, active and passive joint movement, sitting and standing balance training, walking function training, assistive device use training, speech and swallowing therapy, conventional physical therapy, etc.). The control group received upper limb rehabilitation training on the basis of basic medication and conventional rehabilitation therapy, 60 minutes a time, once a day, seven days a week, continuous treatment for two weeks. The observation group received upper limb rehabilitation robot training on the basis of the control group, upper limb rehabilitation training for 30 minutes a time, upper limb robot rehabilitation training for 30 minutes a time, once a day, seven days a week, continuous treatment for two weeks. Before and after treatment, the Fugl-Meyer assessment-upper limb (FMA-UL) was used to evaluate the motor function of upper extremity, including the FMA shoulder and elbow (FMA-SE) score and the FMA wrist and hand (FMA-WH) score; the Barthel index (BI) was used to evaluate activities of daily living; the root mean square (RMS) and integral electromyography (iEMG) values of the biceps, triceps, deltoid of anterior and middle fiber of the affected upper limbs of the subjects during maximal isometric contraction were measured by surface electromyography to assess muscle activation and synchronization of motor recruitment of the upper limbs. <bold>Results</bold> A total of 38 hemiplegia patients in the recovery stage of stroke completed the whole course of treatment. Compared with before treatment, FMA-UL score, FMA-SE score, FMA-WH score, BI score, RMS values of biceps, triceps, deltoid of anterior and middle fiber, and iEMG values of the both groups after treatment were significantly higher, with statistically significant differences (<italic>P</italic>&lt;0.05). Compared with the control group, the FMA-UL score, FMA-SE score, BI scores, triceps RMS value, deltoid of middle fiber RMS value and iEMG value of observation group were significantly higher, with statistically significant differences (<italic>P</italic>&lt;0.05). <bold>Conclusion</bold> Upper limb rehabilitation robot combined with upper limb rehabilitation training can effectively improve motor function of upper limb, muscle activation and motor unit recruitment synchronization of hemiplegic upper limb, and improve the activities of daily living of hemiplegic patients in recovery stage of stroke, which is worthy of clinical promotion.

Neuromuscular electrical stimulation restores upper limb sensory-motor functions and body representations in chronic stroke survivors

A conventional treatment outcome is suboptimal for sensory impairments in stroke patients. Novel approaches based on electrical stimulation or robotics are proposed as an adjuvant for rehabilitation, though their efficacy for motor, sensory, and body representation recovery have not been tested. Sixty chronic stroke patients with unilateral motor deficits were included in a pseudo-randomized open-label multi-arm control trial (ClinicalTrials.gov: NCT03349138). We tested the effects of a robotic glove (GloReha [GR]) and a new neuromuscular electrical stimulation system (Helping Hand [HH]) and compared them with conventional treatment (CT) in restoring motor and sensory functions and the affected limb perception. HH was designed to concurrently deliver peripheral motor activation and enhanced cutaneous sensation. Patients were split in four dose-matched groups: CT, GR, HH, and GRHH (receiving 50% GR and 50% HH). Assessments were performed at inclusion, halfway, end of treatment (week 9), and follow-up (week 13). HH provided an earlier benefit, quantified by the Motricity Index (MI), than GR. At the end of the treatment, the amelioration was higher in groups GRHH and HH and extended to somatosensory functions. These benefits persisted at the follow-up. GRHH and HH also improved the perceived dimensions and altered feeling toward the affected limb. Interestingly, the reduction of altered feelings correlated with MI improvements and depended on the amount of HH. We suggest that HH concurrently stimulates sensory and motor systems by generating an enhanced cutaneous sensation, coherent in location with the elicited motor recruitment, leading to ameliorated sensorimotor functions and bodily perceptions in stroke patients. This work was supported by a Foundation advised by CARIGEST, by Fondazione CARIPLO, by the SNSF NCCR Robotics, and by the Bertarelli Foundation.

Wireless microelectrode arrays for selective and chronically stable peripheral nerve stimulation for hindlimb movement

Objective. Maximizing the stability of implanted neural interfaces will be critical to developing effective treatments for neurological and neuromuscular disorders. Our research aims to develop a stable neural interface using wireless communication and intrafascicular microelectrodes to provide highly selective stimulation of neural tissue. Approach. We implanted a wireless floating microelectrode array into the left sciatic nerve of six rats. Over a 38 week implantation period, we recorded stimulation thresholds and movements evoked at each implanted electrode. We also tracked each animal’s response to sensory stimuli and performance on two different walking tasks. Main results. Presence of the microelectrode array inside the sciatic nerve did not cause any obvious motor or sensory deficits in the hindlimb. Visible movement in the hindlimb was evoked by stimulating the sciatic nerve with currents as low as 4.1 µA. Thresholds for most of the 96 electrodes we implanted were below 20 µA, and predictable recruitment of plantar flexion and dorsiflexion was achieved by stimulating rat sciatic nerve with the intrafascicular microelectrode array. Further, motor recruitment patterns for each electrode did not change significantly throughout the study. Significance. Incorporating wireless communication and a low-profile neural interface facilitated highly stable motor recruitment thresholds and fine motor control in the hindlimb throughout an extensive 9.5 month assessment in rodent peripheral nerve. Results of this study indicate that use of the wireless device tested here could be extended to other applications requiring selective neural stimulation and chronic implantation.

Effects of dry needling on mechanical and contractile properties of the upper trapezius with latent myofascial trigger points: A randomized controlled trial

BackgroundLatent trigger point (LTrP) can cause motor dysfunction and disturb normal patterns of motor recruitment. ObjectiveTo analyze the effects of DN in the upper trapezius (UT) LTrP on pain and the mechanical and contractile properties of the muscle. DesignA randomized, double-blinded, parallel-group-trial. MethodsFifty healthy volunteers with LTrPs in the UT were randomly divided into a DN-group (n = 26) and a Sham-DN-group (n = 24) and received one session of DN or placebo treatment. Mechanical and contractile properties of the muscle and pressure pain perception (PPP) were evaluated before treatment and in a 30min, 24 h and 72 h follow-up after treatment. ResultsIn the mechanical properties, the DN-group showed lower values than the Sham-DN-group for dynamic stiffness at 72 h (p = 0.04). The DN-group showed lower values for dynamic stiffness at 72 h from baseline (278.74 ± 38.40 to 261.54 ± 33.64 N/m; p = 0.01) and for tone at 72 h from 30min (16.62 ± 1.27 to 15.88 ± 1.31 Hz; p = 0.01). In the contractile properties, the DN-group showed higher values for maximal radial displacement (Dm) of the muscle belly at 72 h from baseline (5.38 ± 1.67 to 6.13 ± 1.70 mm; p = 0.04), higher values for contraction time at 30min (28.53 ± 8.80 s; p = 0.03) and lower ones at 72 h (24.74 ± 4.36 s; p = 0.04) from baseline (26.97 ± 6.63 s). The DN-group showed a decrease of PPP from baseline to 72 h after treatment (5.16 ± 1.33 to 4.02 ± 0.97 mm; p < 0.01). ConclusionThe application of DN in healthy volunteers over LTrPs in the UT decreased dynamic stiffness, tone and contraction time and increased Dm at 72 h after treatment. Additionally, the PPP showed a decrease at 72 h after needling. ClinicalTrials.govNCT04466813

Age-related differences in calf muscle recruitment strategies in the time-frequency domain during walking as a function of task demand.

Activation of the plantar flexors is critical in governing ankle push-off power during walking, which decreases due to age. However, electromyographic (EMG) signal amplitude alone is unable to fully characterize motor unit recruitment during functional activity. Although not yet studied in walking, EMG frequency content may also vary due to age-related differences in muscle morphology and neural signaling. Our purpose was to quantify plantar flexor activation differences in the time-frequency domain between young and older adults during walking across a range of speeds and with and without horizontal aiding and impeding forces. Ten healthy young (24.0 ± 3.4 yr) and older adults (73.7 ± 3.9 yr) walked at three speeds and walked with horizontal aiding and impeding force while muscle activations of soleus (SOL) and gastrocnemius (GAS) were recorded. The EMG signals were decomposed in the time-frequency domain with wavelet transformation. Principal component analyses extracted principal components (PCs) and PC scores. Compared with young adults, we observed that GAS activation in older adults: 1) was lower across all frequency ranges during midstance and in slow to middle frequency ranges during push-off, independent of walking speed and 2) shifted to slower frequencies with earlier timing as walking speed increased. Our results implicate GAS time-frequency content, and its morphological and neural origins, as a potential determinant of hallmark ankle push-off deficits due to aging, particularly at faster walking speeds. Rehabilitation specialists may attempt to restore GAS intensity across all frequency ranges during mid-to-late stance while avoiding disproportionate increases in slower frequencies during early stance.NEW & NOTEWORTHY We use time-frequency analyses of calf muscle activation to quantify age-related differences in motor recruitment in walking. Gastrocnemius activation in older versus young adults was lower across all frequencies during midstance and in slow-to-middle frequencies during push-off, independent of speed, and shifted to slower frequencies with earlier timing as speed increased. Our results implicate gastrocnemius time-frequency content as a potential determinant of hallmark ankle push-off deficits due to aging, particularly at faster speeds.

Development and Test of a Serious Game for Dorsiflexion and Plantarflexion Exercises of the Feet

Congenital clubfoot is the most common disease of the musculoskeletal system, causing deformities in the musculature of the foot and requiring long-term motor rehabilitation. This article shows the design and development of a serious game to support the process of motor rehabilitation of clubfoot through dorsiflexion and plantarflexion exercises. The game is controlled by a wearable device (Papeteshoes), where the accelerometers are responsible for detecting the movement of the foot. A pilot test was carried out withtwo children with and without clubfoot (Congenital Talipes Equi-novarus-CTE) to examine the feasibility of the game as a therapy instrument. Usability and applicability questionnaires were applied after using the game. The results show that both children reacted in the same way to the proposals, performing the necessary movements for the motor recruitment of the muscles related to the leg and foot and maintaining the range of motion of the ankle joint.

Comparison of Effectiveness of Cryotherapy and Neuromuscular Electrical Stimulation (NMES) on Pain, Range of Motion and Gait Speed in Early Post-Operative Phase in Subjects with Unilateral Total Knee Arthroplasty

Introduction: In acute phase after Total Knee Arthroplasty (TKA), physiotherapy, aims at reducing pain, local edema and muscle weakness. Among treatment techniques, cryotherapy increases pain tolerance, helping in uninhibited motor recruitment of quadriceps. Intermittent muscle fiber contraction with Neuromuscular Electrical Stimulation (NMES) improves blood flow, reduces pain and decreases quadriceps arthrogenic muscle inhibition. Exercise therapy causes muscle strengthening. Effects of perioperative cold therapy have conflicting evidences. Early NMES use, post TKA for pain and swelling reduction has shown paucity of literature. Hence, this study aims to compare the effectiveness of these techniques in improving function. Method: Interventional study was conducted with 30 subjects randomly allocated into two groups (Group A- cryotherapy and Group B- NMES). Both received standardized exercise therapy. On 2nd postoperative day- pain (using Visual Analog Scale), Range Of Motion (using universal goniometer) and gait speed (using 4 metre walk test) was measured. Treatment was given for 5 days according to allocated group. Post-treatment outcome measures were taken. Results: Out of 30 participants, both groups showed statistically significant (p&lt;0.05) improvement in all outcomes. Comparing effectiveness between the groups, NMES showed statistically significant improvement for knee flexion ROM. Other outcome measures showed no statistically significant difference. Conclusion: Rehabilitation in acute phase is essential for improving patient’s strength in long term. Along with exercise therapy, both cryotherapy and NMES showed improved function. On comparison, NMES showed better results for improvement in knee flexion ROM. Keywords: Total Knee Arthroplasty, cryotherapy, neuromuscular electrical stimulation, exercise therapy, visual analog scale, range of motion, gait speed.

Age Differences in Motor Recruitment Patterns of the Shoulder in Dynamic and Isometric Contractions. A Cross-Sectional Study.

Aging processes in the musculoskeletal system lead to functional impairments that restrict participation. Purpose: To assess differences in the force and motor recruitment patterns of shoulder muscles between age groups to understand functional disorders. A cross-sectional study comparing 30 adults (20–64) and 30 older adults (>65). Surface electromyography (sEMG) of the middle deltoid, upper and lower trapezius, infraspinatus, and serratus anterior muscles was recorded. Maximum isometric voluntary contraction (MIVC) was determined at 45° glenohumeral abduction. For the sEMG signal registration, concentric and eccentric contraction with and without 1 kg and isometric contraction were requested. Participants abducted the arm from 0° up to an abduction angle of 135° for concentric and eccentric contraction, and from 0° to 45°, and remained there at 80% of the MIVC level while isometrically pushing against a handheld dynamometer. Differences in sEMG amplitudes (root mean square, RMS) of all contractions, but also onset latencies during concentric contraction of each muscle between age groups, were analyzed. Statistical differences in strength (Adults > Older adults; 0.05) existed between groups. No significant differences in RMS values of dynamic contractions were detected, except for the serratus anterior, but there were for isometric contractions of all muscles analyzed (Adults > Older adults; 0.05). The recruitment order varied between age groups, showing a general tendency towards delayed onset times in older adults, except for the upper trapezius muscle. Age differences in muscle recruitment patterns were found, which underscores the importance of developing musculoskeletal data to prevent and guide geriatric shoulder pathologies.

Effect of muscle stimulation intensity on the heterogeneous function of regions within an architecturally complex muscle.

Skeletal muscle has fiber architectures ranging from simple to complex, alongside variations in fiber-type and neuro-anatomical compartmentalization. However, the functional implications of muscle subdivision into discrete functional units remain poorly understood. The rat medial gastrocnemius has well-characterized regions with distinct architectures and fiber type composition. Here, force-length and force-velocity contractions were performed for two stimulation intensities (supramaximal and submaximal) and for three structural units (whole muscle belly, proximal region, and distal region) to assess the effect of muscle compartmentalization on contractile force-length-velocity relationships and optimal speed for power production. Additionally, fiber strain, fiber rotation, pennation, and architectural gearing were quantified. Our results suggest that the proximal and distal muscle regions have fundamentally different physiological function. During supramaximal activation, the proximal region has shorter (8.4 ± 0.8 mm versus 10.9 ± 0.7 mm) fibers and steeper (28.7 ± 11.0° versus 19.6 ± 6.3°) fiber angles at optimum length, and operates over a larger (17.9 ± 3.8% versus 12.6 ± 2.7%) range of its force-length curve. The proximal region also exhibits larger changes in pennation angle (5.6 ± 2.2°/mm versus 2.4 ± 1.5°/mm muscle shortening) and architectural gearing (1.82 ± 0.53 versus 1.25 ± 0.24), whereas the distal region exhibits greater peak shortening speed (96.0 mm/s versus 81.3 mm/s) and 18-27% greater optimal speed. Overall, similar patterns were observed during submaximal activation. These regional differences in physiological function with respect to the whole muscle highlight how variation in motor recruitment could fundamentally shift regional functional patterns within a single muscle, which likely has important implications for whole muscle force and work output in vivo.NEW & NOTEWORTHY We show that muscle compartmentalization can influence whole muscle contractile properties, with slower-fibered proximal rat medial gastrocnemius undergoing larger changes in pennation angle and architectural gearing, whereas the faster-fibered distal region achieves greater peak and optimal shortening velocity, and power output. Consequently, regional variation in motor recruitment can fundamentally influence functional patterns within a single muscle.

Spinal motor mapping by epidural stimulation of lumbosacral posterior roots in humans.

SummaryEpidural electrical stimulation of the spinal cord is an emergent strategy for the neurological recovery of lower-extremity motor function. Motoneuron pools are thought to be recruited by stimulation of posterior roots. Here, we linked electromyographic data of epidurally evoked lower-extremity responses of 34 individuals with upper motoneuron disorders to a population model of the spinal cord constructed using anatomical parameters of thousands of individuals. We identified a relationship between segmental stimulation sites and activated spinal cord segments, which made spinal motor mapping from epidural space possible despite the complex anatomical interface imposed by the posterior roots. Our statistical approach provided evidence for low-threshold sites of posterior roots and effects of monopolar and bipolar stimulation previously predicted by computer modeling and allowed us to test the impact of different upper motoneuron disorders on the evoked responses. Finally, we revealed a statistical association between intraoperative and postoperative mapping of the spinal cord.

Selective Wireless Stimulation of Rat Sciatic Nerve.

Chronic stability of functional performance is a significant challenge to the success of implantable devices for neural stimulation and recording. Integrating wireless technology with typical microelectrode array designs is one approach that may reduce instances of mechanical failure and improve the long-term performance of neural devices. We have investigated the long-term stability of Wireless Floating Microelectrode Arrays (WMFAs) implanted in rat sciatic nerve, and their ability to selectively recruit muscles in the hind limb via neural stimulation. Thresholds as low as 4.1 μA were able to generate visible motion of the rear paw. Each implanted device (n=6) was able to selectively recruit plantar flexion and dorsiflexion of the rear paw, and selective stimulation of both movements was achieved throughout the study period. The evoked limb motion was electrode specific and was dependent on location within the fascicular structure of the nerve. Motor thresholds and movement patterns remained stable for more than 8 weeks after device implantation. No major changes in limb function were observed between the implanted and contralateral limb, or between implanted animals and control group animals. The results of this study show that WFMAs with intrafascicular electrodes implanted in a healthy peripheral nerve can provide stable and selective motor recruitment, without altering overall limb function.