Dynamic Muscle Research Articles

Treinamento muscular inspiratório na qualidade de vida e capacidade funcional na cardiotoxicidade: relato de caso

ABSTRACT Cancer patients develop frequent cardiac problems due to chemotherapy toxicity, which impacts functional capacity (FC) and quality of life (QoL). Inspiratory Muscle Training (IMT) may be a viable therapeutic resource since cause-effect studies have shown improvement in FC and QoL in other populations. However, its effect was not evaluated in cardio-oncology patients. The study aimed to describe the effect of an IMT program on the FC and QoL of a patient with cardiotoxicity, LDM, aged 41 years, female and, sedentary that developed heart failure after chemotherapy. The QoL was evaluated by the Minnesota test. Dynamic Inspiratory Muscle Strength (S-Index) and Glycemic Threshold (GT) of the inspiratory muscles were also evaluated. The GT was determined by capillary glycemia with a digital glucometer (Accu-Chek - Roche), at the lowest value of glycemia of the load corresponding to the Incremental Inspiratory Muscle Test (IIMT). The load progression was performed every two weeks. After two months, all tests were reapplied. In the Minnesota test, the values related to FC, pre and post IMT, were 36 v. 8 (78% improvement); the clinical and psychological aspects 32 v. 7 (78% improvement); S-Index was 41 v. 51cmH2O (24% improvement). IMT improved the FC and QoL of a cardio-oncology patient, configuring itself as a possible and viable therapeutic resource for this population.

Peak counting in surface electromyography signals for quantification of muscle fatigue during dynamic contractions

This study aimed to assess the utility of peak counting in dynamic muscle contractions. Surface electromyography (sEMG) data were collected from three quadriceps femoris muscles of twelve healthy individuals during 50 repeated isokinetic knee extensions. The level of muscle fatigue was quantified by applying peak counting, mean frequency (MNF), and median frequency (MDF) to sEMG signals, and a fatigue index value was extracted for each parameter. The Bland-Altman plots were used to show the agreement between the methods based on the fatigue index values. The relationship between MNF, MDF and number of peaks (NoP) was described by using linear regression models. The results showed that the peak counting method measures the fatigue level of the muscles equivalent to MNF and MDF in terms of fatigue index values. The peak counting method has a stronger relationship with MNF than MDF, considering the R-squared values of the linear regression models. In conclusion, peak counting was found to be a valid method, and the NoP was evaluated as a reliable parameter in the quantitative analysis of muscle fatigue during dynamic contractions.

Automated Method for Tracking Human Muscle Architecture on Ultrasound Scans during Dynamic Tasks.

Existing approaches for automated tracking of fascicle length (FL) and pennation angle (PA) rely on the presence of a single, user-defined fascicle (feature tracking) or on the presence of a specific intensity pattern (feature detection) across all the recorded ultrasound images. These prerequisites are seldom met during large dynamic muscle movements or for deeper muscles that are difficult to image. Deep-learning approaches are not affected by these issues, but their applicability is restricted by their need for large, manually analyzed training data sets. To address these limitations, the present study proposes a novel approach that tracks changes in FL and PA based on the distortion pattern within the fascicle band. The results indicated a satisfactory level of agreement between manual and automated measurements made with the proposed method. When compared against feature tracking and feature detection methods, the proposed method achieved the lowest average root mean squared error for FL and the second lowest for PA. The strength of the proposed approach is that the quantification process does not require a training data set and it can take place even when it is not possible to track a single fascicle or observe a specific intensity pattern on the ultrasound recording.

Can we replace exercises targeted on core/hip muscles by exercises targeted on leg/foot muscles in women with patellofemoral pain? A randomized controlled trial

ObjectiveTo verify the effects of replacing exercises targeted on core/hip muscles by exercises targeted on leg/foot muscles in a rehabilitation program for patellofemoral pain (PFP). DesignRandomized Controlled Trial. ParticipantsFifty women with PFP. MethodsPFP participants were randomized into the standard rehabilitation group (SRG, n = 25) or distal exercise group (DEG, n = 25). Knee pain, patient-reported function, dynamic knee valgus and muscle strength were measured at baseline and after six and twelve weeks of the program start. ResultsSRG and DEG presented similar responses to rehabilitation (except for muscle strengthening). Knee pain reduced after 6 weeks (SRG: −37.7%, ES = 1.23; DEG: −30%, ES = 0.93) and 12 weeks (SRG: −47.4%, ES = 1.53; DEG: −43.3%, ES = 1.46). Patient-reported function improved after 6 weeks (SRG: +7.3%, ES = 0.45; DEG: +3.8%, ES = 0.22) and 12 weeks (SRG: +14.1%, ES = 0.80; DEG: +8.8%, ES = 0.50). Dynamic knee valgus reduced after 12 weeks (SRG: −29.7%, ES = 0.38; DEG: −34.5%, ES = 0.32). Both groups experienced increases in knee extension strength (SRG: +9%, ES = 0.28; DEG: +6%, ES = −0.29), but only SRG had strength gains for hip abduction (+10%, ES = 0.36) and extension (+11%, ES = 0.44). ConclusionExercises targeted on core/hip muscles can be replaced by exercises targeted on leg/foot muscles in a lower limb exercise-based rehabilitation program for women with PFP. Clinical trial registrationNCT03663595.

Association between Phase Angle from Bioelectric Impedance and Muscular Strength and Power in Physically Active Adults.

Simple SummaryThis study compared muscle strength and power indicators in resistance-trained men by evaluating associations between phase angle and performance, while controlling for body composition. We evaluated dynamic muscle strength in bench press and back squat, and muscle power using the Wingate test and countermovement jump. Participants with higher phase angle displayed superior muscle strength of the upper limbs and greater muscle power of the lower limbs. Regarding countermovement jump and bench press, phase angle showed moderate association with performance, even after controlling for body composition. Still, lean soft tissue was the most important predictor of muscle strength and power.This study aimed to compare muscle strength and power indicators according to bioimpedance spectroscopy’s phase angle (PhA) values, in resistance-trained (RT) men, while exploring associations between PhA and performance. Forty-four men aged 18–45 years, engaged in RT, were allocated according to PhA tertiles. Lean soft tissue (LST) and fat mass (%FM) were assessed using dual-energy x-ray absorptiometry; dynamic muscle strength using 1 repetition maximum (1RM) of bench press (BP) and back squat (BS) and muscle power using Wingate test (WT) and countermovement jump (CMJ). For WT and CMJ, the 3rd tertile was significantly higher than the 1st tertile (p = 0.027 and p = 0.018, respectively). Regarding BP 1RM, the 3rd tertile was significantly higher than the 2nd tertile (p = 0.037). LST better explained the variability in the WT, BS and BP (p =< 0.001), while %FM better accounted for jump height in CMJ (p =< 0.001). PhA was a predictor of performance in both CMJ (p = 0.040) and BP (p = 0.012), independently of LST and %FM. Participants with higher PhA also displayed superior muscle strength of the upper limbs and greater muscle power of the lower limbs. PhA displayed significant moderate associations with performance in CMJ and BP, even after controlling for body composition. Still, LST was the most important predictor of muscle strength and power.

Fused ultrasound and electromyography-driven neuromuscular model to improve plantarflexion moment prediction across walking speeds

BackgroundImproving the prediction ability of a human-machine interface (HMI) is critical to accomplish a bio-inspired or model-based control strategy for rehabilitation interventions, which are of increased interest to assist limb function post neurological injuries. A fundamental role of the HMI is to accurately predict human intent by mapping signals from a mechanical sensor or surface electromyography (sEMG) sensor. These sensors are limited to measuring the resulting limb force or movement or the neural signal evoking the force. As the intermediate mapping in the HMI also depends on muscle contractility, a motivation exists to include architectural features of the muscle as surrogates of dynamic muscle movement, thus further improving the HMI’s prediction accuracy.ObjectiveThe purpose of this study is to investigate a non-invasive sEMG and ultrasound (US) imaging-driven Hill-type neuromuscular model (HNM) for net ankle joint plantarflexion moment prediction. We hypothesize that the fusion of signals from sEMG and US imaging results in a more accurate net plantarflexion moment prediction than sole sEMG or US imaging.MethodsTen young non-disabled participants walked on a treadmill at speeds of 0.50, 0.75, 1.00, 1.25, and 1.50 m/s. The proposed HNM consists of two muscle-tendon units. The muscle activation for each unit was calculated as a weighted summation of the normalized sEMG signal and normalized muscle thickness signal from US imaging. The HNM calibration was performed under both single-speed mode and inter-speed mode, and then the calibrated HNM was validated across all walking speeds.ResultsOn average, the normalized moment prediction root mean square error was reduced by 14.58 % (p=0.012) and 36.79 % (p<0.001) with the proposed HNM when compared to sEMG-driven and US imaging-driven HNMs, respectively. Also, the calibrated models with data from the inter-speed mode were more robust than those from single-speed modes for the moment prediction.ConclusionsThe proposed sEMG-US imaging-driven HNM can significantly improve the net plantarflexion moment prediction accuracy across multiple walking speeds. The findings imply that the proposed HNM can be potentially used in bio-inspired control strategies for rehabilitative devices due to its superior prediction.

A Tunable, Simplified Model for Biological Latch Mediated Spring Actuated Systems.

We develop a model of latch-mediated spring actuated (LaMSA) systems relevant to comparative biomechanics and bioinspired design. The model contains five components: two motors (muscles), a spring, a latch, and a load mass. One motor loads the spring to store elastic energy and the second motor subsequently removes the latch, which releases the spring and causes movement of the load mass. We develop freely available software to accompany the model, which provides an extensible framework for simulating LaMSA systems. Output from the simulation includes information from the loading and release phases of motion, which can be used to calculate kinematic performance metrics that are important for biomechanical function. In parallel, we simulate a comparable, directly actuated system that uses the same motor and mass combinations as the LaMSA simulations. By rapidly iterating through biologically relevant input parameters to the model, simulated kinematic performance differences between LaMSA and directly actuated systems can be used to explore the evolutionary dynamics of biological LaMSA systems and uncover design principles for bioinspired LaMSA systems. As proof of principle of this concept, we compare a LaMSA simulation to a directly actuated simulation that includes either a Hill-type force-velocity trade-off or muscle activation dynamics, or both. For the biologically-relevant range of parameters explored, we find that the muscle force-velocity trade-off and muscle activation have similar effects on directly actuated performance. Including both of these dynamic muscle properties increases the accelerated mass range where a LaMSA system outperforms a directly actuated one.

Evaluation of dynamic spinal alignment changes and compensation using three-dimensional gait motion analysis for dropped head syndrome

BACKGROUND CONTEXTDynamic kinematic evaluation of spino-pelvic alignment during gait using three-dimensional (3D) motion analysis has been proposed for adult spinal thoracolumbar deformity. That is because conventional full-spine radiographs cannot be used to evaluate dynamic factors. However, dynamic changes in spino-pelvic alignment during gait for dropped head syndrome (DHS) have not been studied using this approach. PURPOSE: This study aimed to assess the dynamic changes in spinal-pelvic alignment during gait in patients with DHS using 3D motion analysis. STUDY DESIGNRetrospective review of collected radiographic and kinematic data. PATIENT SAMPLENineteen DHS patients with neck pain and/or anterior gaze disturbance. OUTCOME MEASURESStatic spino-pelvic radiological alignment, dynamic spino-pelvic kinematic parameters and electromyogram (EMG) data. METHODSCenter of gravity of the head - C7 sagittal vertical axis (CGH-C7 SVA), C2-C7 SVA, T1 slope; cervical lordosis (CL), C7SVA, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT) and pelvic incidence (PI) were assessed using full-spine radiographs in a standing position to assess static spino-pelvic alignment. The 3D gait motion analysis was conducted during gait. Dynamic kinematic parameters were divided into spinal segments: cervical (C-), thoracic (T-), lumbar (L-) and pelvis (P-). Each spinal segment coronal angle to the pelvic angle, each spinal segment sagittal angle to the pelvic angle and pelvic sagittal angle to the horizontal axis were assessed as dynamic spino-pelvic kinematic parameters. Trunk and lower limb muscle activity during gait were assessed using wireless surface EMG analysis. Dynamic spino-pelvic kinematic variables and muscle activity were compared between the first walking lap and the final lap during gait analysis. The change in dynamic kinematic parameters was correlated with static radiological alignment and electromyographic muscular activity change. RESULTSCervical and thoracic anterior tilt increased significantly after an extended period of walking, indicating that dropped head worsened during gait. An increase of cervical anterior tilt during walking was significantly associated with decreased muscle activity in the cervical paraspinal muscles (r=-0.463, P<.05) and latissimus dorsi (r=-0.763, p<.01). Furthermore, significant correlations were found between a change in thoracic sagittal angle to pelvic angle and C7SVA (r=0.683, p<.01) and LL (r=-0.475, p<.05). This means that a larger C7SVA and smaller LL were associated with increased thoracic anterior tilt during gait. CONCLUSIONSThe 3D motion analysis for DHS showed that cervical and thoracic anterior tilt significantly increased after extended walking, resulting in worsening of dropped head. Decreased muscle activity of the neck extensor muscles during gait suggests insufficient neck extensor muscle endurance, which was associated with increased cervical anterior tilt. A greater increase in the thoracic anterior tilt during gait was found in DHS patients with a larger C7SVA and smaller LL due to insufficient thoracolumbar compensation for the dropped head. Correction of the cervical spine alone would not be sufficient to improve dropped head in cases with increased thoracic anterior tilt during gait. The results suggest that C7SVA and LL are crucial parameters in the surgical strategy for DHS.

Acute skeletal muscle loss in SARS-CoV-2 infection contributes to poor clinical outcomes in COVID-19 patients.

BackgroundChronic disease causes skeletal muscle loss that contributes to morbidity and mortality. There are limited data on the impact of dynamic muscle loss on clinical outcomes in COVID‐19. We hypothesized that acute COVID‐19‐related muscle loss (acute sarcopenia) is associated with adverse outcomes.MethodsA retrospective analysis of a prospective clinical registry of COVID‐19 patients was performed in consecutive hospitalized patients with acute COVID‐19 (n = 95) and compared with non‐COVID‐19 controls (n = 19) with two temporally unique CT scans. Pectoralis muscle (PM), erector spinae muscle (ESM) and 30 day standardized per cent change in cross sectional muscle area were quantified. Primary outcomes included mortality and need for intensive care unit (ICU) admission. Multivariate linear and logistic regression were performed. Cox proportional hazard ratios were generated for ICU admission or mortality for the per cent muscle loss standardized to 30 days.ResultsThe COVID‐19 CT scan cohort (n = 95) had an average age of 63.3 ± 14.3 years, comorbidities including COPD (28.4%) and diabetes mellitus (42.1%), and was predominantly Caucasian (64.9%). The proportion of those admitted to the ICU was 54.7%, with 10.5% requiring tracheostomy and overall mortality 16.8%. Median duration between CT scans was 32 days (IQR: 16–63 days). Significant reductions in median per cent loss was noted for PM (−2.64% loss [IQR: −0.28, −5.47] in COVID‐19 vs. −0.06 loss [IQR: −0.01, −0.28] in non‐COVID‐19 CT controls, P < 0.001) and ESM (−1.86% loss [IQR: −0.28, −5.47] in COVID‐19 vs. −0.06 loss [IQR: −0.02, −0.11]) in non‐COVID‐19 CT controls, P < 0.001). Multivariate linear regression analysis of per cent loss in PM was significantly associated with mortality (−10.8% loss [95% CI: −21.5 to −0.19]) and ICU admission (−11.1% loss [95% CI: −19.4 to −2.67]), and not significant for ESM. Cox proportional hazard ratios demonstrated greater association with ICU admission (adj HR 2.01 [95% CI: 1.14–3.55]) and mortality (adj HR 5.30 [95% CI: 1.19–23.6]) for those with significant per cent loss in PM, and greater association with ICU admission (adj HR 8.22 [95% CI: 1.11–61.04]) but not mortality (adj HR 2.20 [95% CI: 0.70–6.97]) for those with significant per cent loss in ESM.ConclusionsIn a well‐characterized cohort of 95 hospitalized patients with acute COVID‐19 and two temporally distinct CT scans, acute sarcopenia, determined by standardized reductions in PM and ESM, was associated with worse clinical outcomes. These data lay the foundation for evaluating dynamic muscle loss as a predictor of clinical outcomes and targeting acute sarcopenia to improve clinical outcomes for COVID‐19.

Protein signalling in response to ex vivo dynamic contractions is independent of training status in rat skeletal muscle.

New Findings What is the central question of this study? Are myofibre protein signalling responses to ex vivo dynamic contractions altered by accustomization to voluntary endurance training in rats? What is the main finding and its importance? In response to ex vivo dynamic muscle contractions, canonical myofibre protein signalling pertaining to metabolic transcriptional regulation, as well as translation initiation and elongation, was not influenced by prior accustomization to voluntary endurance training in rats. Accordingly, intrinsic myofibre protein signalling responses to standardized contractile activity may be independent of prior exercise training in rat skeletal muscle. Skeletal muscle training status may influence myofibre regulatory protein signalling in response to contractile activity. The current study employed a purpose‐designed ex vivo dynamic contractile protocol to evaluate the effect of exercise‐accustomization on canonical myofibre protein signalling for metabolic gene expression and for translation initiation and elongation. To this end, rats completed 8 weeks of in vivo voluntary running training versus no running control intervention, whereupon an ex vivo endurance‐type dynamic contraction stimulus was conducted in isolated soleus muscle preparations from both intervention groups. Protein signalling response by phosphorylation was evaluated by immunoblotting at 0 and 3 h following ex vivo stimulation. Phosphorylation of AMP‐activated protein kinase α‐isoforms and its downstream target, acetyl‐CoA carboxylase, as well as phosphorylation of eukaryotic elongation factor 2 (eEF2) was increased immediately following the dynamic contraction protocol (at 0 h). Signalling for translation initiation and elongation was evident at 3 h after dynamic contractile activity, as evidenced by increased phosphorylation of p70 S6 kinase and eukaryotic translation initiation factor 4E‐binding protein 1, as well as a decrease in phosphorylation of eEF2 back to resting control levels. However, prior exercise training did not alter phosphorylation responses of the investigated signalling proteins. Accordingly, protein signalling responses to standardized endurance‐type contractions may be independent of training status in rat muscle during ex vivo conditions. The present findings add to our current understanding of molecular regulatory events responsible for skeletal muscle plasticity.

Correlation between dynamic balance ability and lower limb muscle strength of university students

Objective: To study the correlation between dynamic balance ability and lower limb muscle strength of university students. Methods: 50 students of Zunyi Medical University (23 boys and 27 girls) were selected as the subjects. The dynamic balance ability of university students was tested by the YBT test system. Isokinetic muscle strength tester tests knee flexion and extension muscle strength under different angular velocity conditions. Results: 1) At different angular velocities, there was a moderate positive correlation between knee flexion and extension muscle strength and YBT reaching all directions. Only when the angular velocity was set to 200° / s, there was a low positive correlation between knee flexion muscle strength and the front side of the YBT test. 2) There is a more significant correlation between the maximum distance of each direction of dynamic balance and the peak torque of knee extensor than that of flexor. Research conclusions: For university students, there is a significant indigenous correlation between the directions of YBT arrival, and the correlation between the posterolateral and the posterolateral is stronger. The stronger the lower limb muscle strength is, the better the dynamic balance ability is, and the correlation between dynamic ability and knee extensor muscle strength is higher, which may be related to the fact that knee flexion control balance can more effectively activate knee extensor muscle group. University students generally have bilateral asymmetry of the lower limbs.

Neuromuscular characteristics of front and back legs in junior fencers

In elite fencers, muscle strength and muscle mass of the front leg (FL) are greater than those of the back leg (BL) due to characteristic physiological and biomechanical demands placed on each leg during fencing. However, the development of laterality in their neural and muscular components is not well-understood. The present study investigated neuromuscular characteristics of FL and BL in junior fencers. Nineteen junior fencers performed neuromuscular performance tests for FL and BL, separately. There were no significant differences in the isometric knee extension strength (MVC), unilateral vertical jump (UVJ), vastus lateralis muscle thickness (MT), or motor unit firing rate of the vastus lateralis muscle (MUFR) between FL and BL (p > 0.05). In subgroup analyses, a significantly greater MUFR in FL than BL was noted only in fencers with > 3 years of fencing experience, and significantly greater UVJ in FL than BL was observed solely in fencers with < 3 years of fencing experience (p < 0.05). Strong positive correlations between FL and BL were identified in MVC, MT, and MUFR in fencers with > 3 years of fencing experience, but not in those with < 3 years of experience. These findings suggest that in junior fencers, laterality in neuromuscular performance has not manifested, whereas longer fencing experience induces fencing-dependent laterality in neural components, and laterality in dynamic muscle strength is decreased with fencing experience.

Modified McLaughlin's Dynamic Muscle Support in the 21st Century? A Retrospective Study With a Prospective Follow-Up Analysis for Patients With Long Standing Facial Paralysis.

Facial nerve paralysis can dramatically affect the life of a patient as it leads to significant alterations of the facial symmetry and functional limitations. Various methods exist including free neuromuscular flaps to reanimate patients suffering from uni- or even bilateral facial nerve paralysis. The more than 60-year-old technique described by McLaughlin continues to offer an alternative with distinct advantages for the individual patient. The present study aimed to evaluate clinical outcome and satisfaction of patients treated with a modified McLaughlin's Dynamic Muscle Support. A total of 13 patients (mean age of 58.4 years) who received a modified McLaughlin's Dynamic Muscle Support due to uni- or bilateral long-standing facial paralysis were included. Medical records were reviewed retrospectively, and patients were contacted for additional follow-up. Patients who agreed to participate in the follow-up study were asked to answer a self-developed questionnaire. In all patients, a rehabilitation of facial symmetry with an improvement of the mimic expression could be achieved. Mean length of inpatient stay was 6.5 days and average duration of surgery was 121 minutes. No surgical site infection occurred. Mean follow-up was 23 months. Most of the patients were fully satisfied with the result and could experience functional and esthetic improvement.Patients who participated in the prospective follow-up study were very satisfied with the esthetic result and functional outcome. Even in times of advanced microsurgical techniques, McLaughlin's Dynamic Muscle Support appears to be a good alternative for the successful treatment of long-standing facial paralysis.

Concomitant osteochondral lesions of the talus affect the stair descent biomechanics of patients with chronic ankle instability: A pilot study

BackgroundPrevious studies on the kinematics of patients with chronic ankle instability (CAI) that did not incorporate MRI and arthroscopic assessment could not differentiate between patients with CAI without osteochondral lesion of the talus (OLT) and patients with CAI and OLT and have thus presented contradictory results. Research questionThis study aimed to investigate the kinematic and electromyographic differences between patients with and without OLT. MethodsSixteen subjects with CAI (eight without OLT and eight with OLT confirmed through MRI and arthroscopic assessment) and eight healthy subjects underwent gait analysis in a stair descent setting. The three groups’ patient-reported outcomes; ankle joint range of motion in flexion, inversion and rotation; and muscle activation of the peroneus, tibialis anterior, and gastrocnemius during a gait cycle were analyzed and compared. A curve analysis, namely, one-dimensional statistical parametric mapping, was performed to compare the dynamic ankle kinematics and muscle activation curves over the entire normalized time series. ResultsThe patients with and without OLT had no difference in patient-reported outcomes. The maximal ankle plantarflexion of the patients without OLT and the healthy subjects was significantly larger than that of patients with OLT (p = 0.005). The maximal ankle internal rotation of patients without OLT was significantly larger than that of patients with OLT (p = 0.048). The peroneal activation during 0–6% of the gait cycle of patients with OLT was reduced compared with the healthy subjects. SignificancePatients with CAI and OLT and patients with CAI without OLT have no difference in patient-reported outcomes, but patients with OLT can be differentiated using the post-initial-contact peroneal activation deficit and the restriction of ankle plantarflexion and internal rotation during stair descent. These variables can be utilized to monitor the function of patients with CAI and their possibility of developing OLT.

Effects of Static and Dynamic Exercises on Core Muscle Strength and Endurance

Background. Rehabilitation research is currently focused on the effects of exercise on patients with acute or chronic low back pain. However, there is a lack of preventive research investigating the effects of dynamic and static exercises on the strength and endurance of the core stability muscle in individuals engaged in leisure-time non-professional sports activities.&#x0D; The aim. To determine the effect of static and dynamic muscle exercises on core stability muscle strength and endurance.&#x0D; Methods. The study involved 12 volunteers (20–30 years old) engaged in leisure-time non-professional sports activities that did not experience back pain. Two groups were formed: the first (n = 7), in which the subjects performed static exercises, and the second (n = 5), in which the subjects performed dynamic exercises. The strength and endurance of the core flexor and extensor muscles were assessed at the beginning and end of the study. The study lasted 5 weeks. Exercise sessions were held 3 times a week for 20–30 minutes.&#x0D; Results. Strength and endurance of the core flexor and extensor muscles significantly increased in both groups. Comparing the effects of static and dynamic exercises on core flexor and extensor muscle strength and endurance, a statistically significant difference was observed in the change in core extensor muscle strength.&#x0D; Conclusions. The strength and endurance of the core flexor and extensor muscles increased both after dynamic exercise and static exercise interventions. Core muscle strength increased more after the dynamic exercise intervention.&#x0D; Keywords: core stability, isometric strength, physical therapy, exercise, young individuals.&#x0D;

Surgical management of concurrent lateral ankle instability and osteochondral lesions of the talus increases dynamic sagittal ankle range of motion.

A biomechanical study, in which imaging modalities are used to strictly include patients with concurrent lateral ankle instability (LAI) and osteochondral lesions of the talus (OLT), is needed to demonstrate the static and dynamic ankle range of motion (ROM) restriction in these patients, and determine whether ankle ROM restriction can be corrected postoperatively. Eight patients with concurrent LAI and OLT treated with the arthroscopic modified Broström procedure and microfracture were recruited from June 2019 to January 2020. Patients were assessed using outcome scales, static ankle ROM, and a stair descent gait analysis for dynamic ankle ROM, a day prior to surgery and one year postoperatively. Eight healthy subjects were assessed using the same modalities upon recruitment. Operative outcomes and variables during stair descent were documented and compared among the preoperative, postoperative, and healthy groups. A curve analysis, one-dimensional statistical parametric mapping, was performed to compare the dynamic ankle kinematics and muscle activation curves over the entire normalised time series. The functional outcomes of patients with concurrent LAI and OLT were significantly worse than those of healthy subjects preoperatively, but were partially improved postoperatively. Patients had decreased static and dynamic ROM preoperatively, and static ROM did not significantly increase postoperatively (preoperative, 39.6 ± 11.3; postoperative, 44.9 ± 7.1; healthy, 52.0 ± 4.6; p = 0.021). Patients showed increased dynamic ankle flexion ROM (preoperative, 41.2 ± 11.6; postoperative, 53.6 ± 9.0; healthy, 53.9 ± 3.4; p = 0.012) postoperatively, as well as increased peroneus longus activation (preoperative, 35.8 ± 12.0; postoperative, 55.4 ± 25.1; healthy, 71.9 ± 13.4; p = 0.002) and muscle co-contraction of the tibialis anterior and peroneus longus (preoperative, 69.4 ± 23.4; postoperative, 88.4 ± 9.3; healthy, 66.2 ± 18.1; p = 0.045). Patients with concurrent LAI and OLT had decreased static and dynamic sagittal ankle ROM and altered neuromuscular activation patterns. The arthroscopic modified Broström procedure and microfracture did not significantly increase the static sagittal ankle ROM. However, the dynamic sagittal ankle ROM, peroneus longus activation and muscle co-contraction of the tibialis anterior and peroneus longus increased postoperatively. IV.

Dynamic magnetic resonance imaging of muscle contraction in facioscapulohumeral muscular dystrophy

Quantitative muscle MRI (water-T2 and fat mapping) is being increasingly used to assess disease involvement in muscle disorders, while imaging techniques for assessment of the dynamic and elastic muscle properties have not yet been translated into clinics. In this exploratory study, we quantitatively characterized muscle deformation (strain) in patients affected by facioscapulohumeral muscular dystrophy (FSHD), a prevalent muscular dystrophy, by applying dynamic MRI synchronized with neuromuscular electrical stimulation (NMES). We evaluated the quadriceps muscles in 34 ambulatory patients and 13 healthy controls, at 6-to 12-month time intervals. While a subgroup of patients behaved similarly to controls, for another subgroup the median strain decreased over time (approximately 57% over 1.5 years). Dynamic MRI parameters did not correlate with quantitative MRI. Our results suggest that the evaluation of muscle contraction by NMES-MRI is feasible and could potentially be used to explore the elastic properties and monitor muscle involvement in FSHD and other neuromuscular disorders.

Dynamic muscle discord in the context of non-surgical lip enhancement

Dynamic muscle discord (DMD) is a fundamental concept in facial soft tissue augmentation with dermal fillers, particularly in perioral rejuvenation and lip enhancement. It is frequently observed in patients with facial skeletal and soft tissue deficiencies. The lack of adequate structural support may result in compensatory muscle hypertonicity or confer a mechanical advantage in certain muscle groups over their antagonistic counterparts. This discord in activity between the various muscle groups can affect the posture and profile of mobile facial features both at rest and during facial expression. Unfortunately, despite being a condition that commonly presents to varying degrees in patients seeking lip enhancement, DMD is often poorly diagnosed and undertreated. The author describes the causes, consequences and treatment of this condition in relation to the perioral region, as illustrated by a case study discussion.

Protein Kinase C Epsilon Contributes to the Exaggerated Mechanoreflex in Rats with Heart Failure

BackgroundDuring exercise, skeletal muscle contraction stimulates mechanically sensitive channels on the sensory endings of thin fiber muscle afferents. Stimulation of these mechanically sensitive channels initiates a reflex, termed the mechanoreflex, which contributes importantly to reflex increases in sympathetic nerve activity (SNA) and mean arterial blood pressure (MAP). In patients and animals with heart failure with reduced ejection fraction (HF‐rEF), mechanoreflex activation contributes to exaggerated increases in SNA and is linked to decreased exercise tolerance and increased mortality. The exaggerated mechanoreflex in HF‐rEF is partially attributed to an increased responsiveness of thin fiber skeletal muscle afferents to mechanical stimulation. Several lines of evidence demonstrate that signaling within sensory neurons mediated by the non‐traditional protein kinase c epsilon (PKCε) isoform augments mechanically activated channel function and produces mechanical hyperalgesia. Whether PKCε‐mediated signaling within sensory neurons contributes the exaggerated mechanoreflex in HF‐rEF is unknown.Purpose &amp; HypothesisWe determined the role played by PKCε within sensory endings of thin fiber muscle afferents in evoking the mechanoreflex in rats with HF‐rEF and healthy control rats. We tested the hypothesis that injection of the selective PKCε inhibitor PKCε141 (44μg) into the arterial supply of the hindlimb would reduce the reflex increase in renal SNA (RSNA) and MAP evoked during 30 seconds of 1 Hz dynamic hindlimb muscle stretch (a model of mechanoreflex activation) in HF‐rEF rats, but not in healthy control rats.MethodsExperiments were performed on Sprague‐Dawley rats subjected to coronary artery ligation surgery to produce myocardial infarction and HF‐rEF or a sham ligation. At least six weeks after the initial surgery, in decerebrate, unanesthetized rats we compared (Student’s t‐tests) the mechanoreflex evoked by hindlimb skeletal muscle stretch before and after injection of PKCε141 into the arterial supply of the hindlimb.ResultsEjection fraction (determined via echocardiography) was significantly reduced in HF‐rEF rats (48±1%) compared to sham rats (80±2%, P&lt;0.01). Intra‐arterial PKCε141 injection reduced the pressor and RSNA response to hindlimb muscle stretch in HF‐rEF rats (n=6, 4M/2F, peak ΔMAP pre: 34±8; post: 19±7 mmHg; P=0.04; peak ΔRSNA pre: 121±32; post: 70±24%; P=0.04), but not SHAM rats (n=4, 3M/1F, peak ΔMAP pre: 14±4; post: 14±3 mmHg; P=0.87; peak ΔRSNA pre: 62±32; post: 58±26%; P=0.80) rats. In control experiments (n=3 HF‐rEF rats, 2M/1F), injection of PKCε141 into the jugular vein had no effect on the pressor or RSNA response to muscle stretch demonstrating a lack of central nervous system effects.ConclusionsThese data suggest that that PKCε signaling within the sensory neuron endings contributes to the exaggerated mechanoreflex in HF‐rEF and enhance the understanding of the sympathetic and cardiovascular adjustments to exercise in the ~6 million Americans with HF‐rEF.

Cryotherapy has no deleterious effects on dynamic balance and muscle tone: a preliminary analysis

Cryotherapy has no deleterious effects on dynamic balance and muscle tone: a preliminary analysis