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We aimed to investigate the relationship between pain extent, as a sign of sensitization, and sensory-related, cognitive and psychological variables in hospitalized COVID-19 survivors with post-COVID pain. One hundred and forty-six (67 males, 79 females) previously hospitalized COVID-19 survivors with post-COVID pain completed demographic (age, sex, height, weight), sensory-related (Central Sensitization Inventory, Self-Report Leeds Assessment of Neuropathic Symptoms), cognitive (Pain Catastrophizing Scale, Tampa Scale for Kinesiophobia) and psychological (Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index) variables. Pain extent and frequency maps were calculated from pain drawings using customized software. After conducting a correlation analysis to determine the relationships between variables, a stepwise linear regression model was performed to identify pain extent predictors, if available. Pain extent was significantly and weakly associated with pain intensity (r = −0.201, p = 0.014): the larger the pain extent, the lower the pain intensity. No other significant association was observed between pain extent and sensory-related, cognitive, or psychological variables in individuals with post-COVID pain. Females had higher pain intensity, more sensitization-associated symptoms, higher anxiety, lower sleep quality, and higher kinesiophobia levels than males. Sex differences correlation analyses revealed that pain extent was associated with pain intensity in males, but not in females. Pain extent was not associated with any of the measured variables and was also not related to the presence of sensitization-associated symptoms in our sample of COVID-19 survivors with long-term post-COVID pain.

Purpose The aim of this randomized placebo-controlled crossover study was to compare the acute effect on young athletes of a single session of roller massager (RM) with that obtained from passive static stretching (PSS) and a placebo intervention (PL) on hamstring flexibility and on strength. Methods Twenty-nine (23 male, 6 female) young athletes completed the study. Maximal voluntary contraction (MVC) and two-leg sit-and-reach test were performed before and immediately after PL, PSS and RM on three different days. Results Results showed that all three interventions increased the flexibility of the hamstring muscles compared to the pre-test measurements (Wilcoxon signed-rank test, p Conclusions RM can be considered as an effective alternative to stretching to increase the flexibility of the hamstring. This could be meaningful when stretching is contraindicated or evokes pain.

Objectives Changes in mechanical loading as well as pathology can modify the Achilles tendon mechanical properties and therefore detection of these changes is relevant for the diagnosis and management of Achilles tendinopathy. The aim of this study was to evaluate strain and shear wave sonoelastography for their ability to detect changes in the Achilles tendon mechanical properties during a series of isometric contractions. Methods Longitudinal sonoelastography images of the Achilles tendon were acquired from 20 healthy participants using four different ultrasound devices; two implementing strain sonoelastography technology (SE1, SE2) and two, shear wave elastography technology (SWE1, SWE2). Results SE1 measured a decreasing strain ratio (tendon become harder) during the different contraction levels from 1.51 (0.92) to 0.33 (0.16) whereas SE2 mesaured a decreasing strain ratio from 1.08 (0.76) to 0.50 (0.32). SWE1 measured decreasing tendon stiffness during contractions of increasing intensity from 33.40 (19.61) to 16.19 (2.68) whereas SWE2 revealed increasing tendon stiffness between the first two contraction levels from 428.65 (131.5) kPa to 487.9 (121.5) kPa followed by decreasing stiffness for the higher contraction levels from 459.35 (113.48) kPa to 293.5 (91.18) kPa. Conclusions Strain elastography used with a reference material was able to detect elasticity changes between the different contraction levels whereas shear wave elastography was less able to detect changes in Achilles tendon stiffness when under load. Inconsistent results between the two technologies should be further investigated.

Aim There are ongoing discussions whether cesarean section is the safest mode of childbirth to prevent pelvic floor disorders. Pelvic floor electromyography (EMG) allows the analysis of external anal sphincter (EAS) function during voluntary contractions. The primary objective of this study was the evaluation of EMG amplitude of external anal sphincter in women who had vaginal delivery, compared to women who had cesarean section. The secondary objective was to evaluate the anal incontinence score changes before and after delivery between the groups, and to look for any relationship between the clinical and EMG findings. Methods Multichannel surface EMG was detected during maximal contractions in three sessions: (i) during pregnancy, (ii) 6 weeks after delivery and (iii) 1 year after delivery. Women were divided into two groups: cesarean section and vaginal delivery. Results External anal sphincter EMG amplitude decreases 6 weeks after vaginal deliveries from 10.1 to 8.6 μV with effect size of 0.4, but returns to baseline after 1 year. No differences were observed between groups in all other variables. Conclusion No differences were observed after 1 year in EMG activity between the two groups; however, a slight decrease of sphincter muscle amplitude was noted 6 weeks after vaginal delivery. The delivery mode does not have effect on the EAS amplitude 1 year after delivery. Incontinence score slightly increased in both groups after delivery, with no significant differences between the two groups. No association was observed between the increase of incontinence score and the decrease of EMG signal amplitude.

Sensitization mechanisms are thought to play a role in the perception of pain in people with cluster headache. No study has investigated the relation between the spatial extent of pain in cluster headache and measures of sensitization or other clinical features.Our aim was to investigate if the size of the painful area in people with cluster headache relates to widespread pressure sensitivity, headache features, and psychological outcomes.Forty men with episodic cluster headache reported their symptoms on a digital body chart and pain extent was calculated. Pressure pain thresholds were assessed locally over the temporalis muscle and the C5-C6 joint and at a remote site over the tibialis anterior to assess widespread pressure sensitivity. Clinical features of headache attacks, and anxiety/depressive levels were also assessed. Patients were assessed during a period of remission 6 months after their last pain attack and after treatment discontinuation.Thirty-two (80%) and thirty (75%) patients reported their headaches in the orbital and the frontal areas, respectively. No significant associations (rho values ranging from -0.228 to 0.187,Pain extent in the trigemino-cervical area was not related to the degree of pressure pain sensitivity or headache features in men with episodic cluster headache during a period of remission.

Shear wave tensiometry is a recent promising technology which can be used to evaluate tendon loading. Knowing the clinimetric features (e.g., reliability) of this technology is important for use in clinical and research settings.To evaluate the inter-session reliability of a novel shear wave tensiometer for the assessment of Achilles tendon loading. A further aim was to test the construct validity of this device by evaluating its precision in detecting Achilles tendon loading changes induced by a plantar flexor isometric contraction of increasing intensity.Ten healthy participants were recruited. Five measurements were performed at different time points to evaluate inter-session reliability. Shear wave speed along the Achilles tendon was evaluated during different isometric contractions using a shear wave tensiometer composed of an array of four accelerometers fixed on the tendon, ranging from 4 to 8.5 cm from the calcaneal insertion of the tendon. Test-retest, intra- and inter-session reliability were determined using intraclass correlation coefficient (ICCTest-retest reliability was good to excellent (ICCThis study confirms the reliability of this novel device. Future studies analyzing participants with Achilles tendinopathy are needed to evaluate the capability of shear wave tensiometry to detect transient changes in loading due to pathology.

The purpose of the present study was to evaluate the Pearson correlations between hemodynamic parameters obtained with near infrared spectroscopy (NIRS), namely total hemoglobin (tHb) and tissue oxygen index (TOI %), as indicators of blood flow and oxygen extraction, and myoelectric parameters obtained with surface multichannel electromyography (sEMG), namely fractal dimension (FD) and conduction velocity (CV) slopes, as descriptors of central and peripheral fatigue, during sustained high level isometric contractions at 60% maximal voluntary contraction (MVC), in elderly subjects. Ten recreationally healthy elderly subjects (age 67.7 ± 4.6 years), 5 males and 5 females, performed one isometric contraction of the elbow flexors at 120° joint angle at 60% of MVC until exhaustion in two subsequent trials 1 week apart, one for the sEMG and the other one for NIRS recordings from the biceps brachii. A negative strong Pearson’s correlation between TOI % slope in the functional hyperemic phase (HP) of contraction and a positive correlation between the slope of TOI % recorded during the ischemic phase (IP) and the CV slope were found (r = − 0.76, P

Objective To assess the influence of clinical, psychological, and psychophysical variables on long-term clinical outcomes after the application of either physical therapy or surgery in women presenting with carpal tunnel syndrome (CTS). Methods A secondary analysis of a randomized trial investigating the efficacy of manual therapy including desensitization maneuvers of the central nervous system against surgery in 120 women with CTS was performed. Clinical outcomes including pain intensity, function, or symptom severity were assessed at 6 and 12 months post-intervention. Participants completed at baseline several clinical (pain intensity, function, and symptom severity), psychological (depression), and psychophysical (pressure pain thresholds and pain extent) variables, which were included as predictors. Multiple regression analyses were conducted to assess the relationship between baseline variables and clinical outcomes at 6 and 12 months post-intervention. Results The regression models indicated that higher scores of each clinical outcome (ie, intensity of pain or symptom severity) at baseline predicted better outcomes at 6 and 12 months post-intervention (from 15% to 65% of variance) in both groups. Lower pressure pain thresholds over the carpal tunnel at baseline predicted poorer clinical outcomes at 6 and 12 months post-intervention (from 5% to 20% of variance) in the physical therapy group, whereas higher depressive symptoms at baseline contributed to poorer outcomes at 6 and 12 months post-intervention (from 5% to 15% of the variance) within the surgery group. Conclusion This study found that baseline localized pressure pain sensitivity and depression were predictive of long-term clinical outcomes in women with CTS following physical therapy or surgery, respectively.

The shoulder complex (SC) consists of joints with little congruence and its active and passive structures ensure its stability. Stability of the SC rotation centre during upper arm movements can be estimated through the analysis of Helical Axes (HAs) dispersion. The aim of this study was to describe shoulder HAs dispersion during upper limb movements performed with dominant and non-dominant arms by young and elderly subjects. Forty subjects participated in the study (20 young: age 24.8 ± 2.8 years and 20 elderly: age 71.7 ± 6.3 years). Subjects were asked to perform four cycles of 15 rotations, flexions, elevations and abductions with one arm at a time at constant speed. Reflective markers were placed on participants' arms and trunk in order to detect movements and the HAs dispersion with an optoelectronic system. Mean Distance (MD) from the HAs barycenter and Mean Angle (MA) were used as HAs dispersion indexes. Young subjects showed significant lower MD compared to the elderly during all motion ranges of rotation, flexion and elevation (p 0.001). Moreover, the MD was lower in the dominant arm compared to the contralateral for rotation (p = 0.049) and flexion (p = 0.019). The results may be due to joint degeneration described in elderly subjects and differences in neuromuscular control of SC stability.

Information pertaining to the helical axis during humeral kinematics during shoulder rotation may be of benefit to better understand conditions such as shoulder instability. The aim of this study is to quantify the behavior of humeral rotations using helical axis (HA) parameters in three different conditions. A total of 19 people without shoulder symptoms participated in the experiment. Shoulder kinematics was measured with an optoelectric motion capture system. The subjects performed three different full range rotations of the shoulder. The shoulder movements were analyzed with the HA technique. Four parameters were extracted from the HA of the shoulder during three different full-range rotations: range of movement (RoM), mean angle (MA), axis dispersion (MDD), and distance of their center from the shoulder (D). No significant differences were observed in the RoM for each condition between left and right side. The MA of the axis was significantly lower on the right side compared to the left in each of the three conditions. The MDD was also lower for the right side compared to the left side in each of the three conditions.The four parameters proposed for the analysis of shoulder kinematics showed to be promising indicators of shoulder instability.

Background Temporomandibular disorders (TMD) are characterised by complex symptomatology and their assessment can be enhanced using pain drawings (PD). Objectives To evaluate the location and extent of pain in people TMD using digital PD, and to explore their association with clinical features. Reliability of pain extent and pain location using PD was also assessed. Methods Forty volunteers with TMD completed two consecutive digital PDs. Clinical features were captured from self-reported questionnaire. Additionally, secondary hyperalgesia was measured using the pressure pain threshold (PPT). The correlation between pain extent and clinical features was investigated using Spearman rank correlation coefficients. Reliability of pain extent was evaluated using intraclass correlation coefficient (ICC) and Bland-Altman plots. The Jaccard index was computed to assess the reliability of pain location. Results Analysis of the PDs indicated that people with TMD commonly experience pain in other body regions including the neck, the shoulder and the low back. Except for PPT and pain catastrophising, all other clinical features were significantly correlated with pain extent. The ICCs of pain extent for all body charts were very high (ICCs 95% CI from 0.73 to 0.96), and Bland-Altman plots showed mean biases close to zero with narrow limits of agreement. The reliability of pain location was also supported by Jaccard index mean scores above 0.68. Conclusions People with TMD showed widespread pain, and pain extent was associated with pain intensity, neck and headache-related disability, depression, anxiety, hyperventilation and central sensitivity. The reliability of measuring pain extent and pain location was confirmed.

Purpose In facioscapulohumeral muscular dystrophy (FSHD) fatigue is a major complaint. We aimed to investigate whether during isometric sustained elbow flexions, performance fatigability indexes differ in patients with FSHD with respect to healthy controls. Methods Seventeen patients with FSHD and seventeen healthy controls performed two isometric flexions of the dominant biceps brachii at 20% of their maximal voluntary contraction (MVC) for 2 min and then at 60% MVC until exhaustion. Muscle weakness was characterized as a percentage of predicted values. Maximal voluntary strength, endurance time and performance fatigability indices (mean frequency of the power spectrum (MNF), muscle fiber conduction velocity (CV) and fractal dimension (FD)), extracted from the surface electromyogram signal (sEMG) were compared between the two groups. Results In patients with FSHD, maximal voluntary strength was 68.7% of predicted value (p p r = 0.62) and lower levels of performance fatigability, characterized by reduced rate of changes in MNF (p r = 0.56), CV (p p r = 0.51) and increased endurance time (p r = 0.63), during the isometric contraction at 60% MVC. Conclusion A decreased reduction in the slopes of all the considered sEMG parameters during sustained isometric elbow flexions suggests that patients with FSHD experience lower levels of performance fatigability compared to healthy controls.

Background Ultrasound imaging techniques have been used to assess the characteristics of skeletal muscles and tendons. Such techniques (gray scale analysis) allow qualitative evaluation and have been used recently to assess the internal structure of muscles and tendons by computer-aided gray scale analysis. We hypothesized that changes in the internal structure of the Achilles and patellar tendons after a ski mountaineering race competition could be detected with ultrasound. Methods Twenty athletes were recruited during the 19th Millet Tour du Rutor extreme, a three-day ski mountaineering competition. Ultrasound measurements of the Achilles and patellar tendons were carried out before the first race and immediately after each of the three competition days. Tendon thickness, cross-sectional area (CSA), and ultrasound gray scale analysis were calculated. Results Significant differences (p p Conclusions Achilles and patellar tendons of healthy athletes are highly responsive to an acute increase in mechanical load. Those changes can be detected from classical (thickness and CSA) and innovative (gray scale) ultrasound-based parameters. Trial registration This study was approved by the Azienda USL Valle d’Aosta Ethics Committee (protocol no. 23/03/2018.0026243.I).

The relationship between fractal dimension of the surface electromyogram (sEMG) and the intensity of muscle contraction is still controversial in simulated and experimental conditions. To support the use of fractal analysis to investigate myoelectric fatigue, it is crucial to establish the interdependence between fractal dimension and muscle contraction intensity. We analyzed the behavior of fractal dimension, conduction velocity, mean frequency, and average rectified value in twenty-eight volunteers at nine levels of isometric force. sEMG was obtained using bidimensional arrays in the biceps brachii muscle. The values of fractal dimension and mean frequency increased with force unless a plateau was reached at 30% maximal voluntary contraction. Overall, our findings suggest that, above a certain level of force, the use of fractal dimension to evaluate the myoelectric manifestations of fatigue may be considered, regardless of muscle contraction intensity.

To evaluate the test-retest reliability of the ultrasound echo intensity parameters on healthy Achilles tendon using a semi-automatic tracing procedure. Eighteen healthy volunteers participated. B-mode images were acquired in the transverse plane (mid-tendon; insertion) and used to analyze tendon echogenicity. Grayscale distribution of the pixels within the selected ROIs was represented as a histogram. Descriptive statistics of the grayscale distribution (mean, variance, skewness, kurtosis, and entropy) and parameters from the co-occurrence matrix (contrast, energy, and homogeneity) were calculated. Reliability of echo intensity parameters of the mid-Achilles tendon ranged from high to very high with an ICC2.k of 0.94 for echogenicity, 0.87 for variance, 0.80 for skewness, 0.72 for kurtosis, 0.89 for entropy, 0.90 for contrast, 0.91 for energy, and 0.93 for homogeneity, while for tendon insertion they ranged from moderate to high with an ICC2.k of 0.74 for echogenicity, 0.88 for variance, 0.75 for skewness, 0.55 for kurtosis, 0.87 for entropy, 0.70 for contrast, 0.77 for energy, and 0.56 for homogeneity. Ultrasound echo intensity is a reliable technique to characterize the internal structure of the Achilles tendon.

Objective to examine potential association between mediolateral episiotomy and reduced incidence of obstetrical anal sphincter injuries (OASIS) diagnosed by endoanal ultrasound. Design prospective cohort study. Setting tertiary referral university hospital. Participants sixty nulliparous women at 28–33 weeks of gestation with singleton pregnancies were included between 2010 and 2012. Measurements and findings participants were examined with endoanal ultrasound at 28–33 weeks gestation and at 6–7 weeks post-partum. At both visits, symptoms of anal incontinence were assessed using Cleveland Clinic (Wexner) faecal incontinence scoring system. Mann Whitney U -test and χ 2 test was used to compare groups with vs. without episiotomy and groups with vs. without OASIS diagnosed by ultrasound. χ 2 test was used to assess correlation between OASIS and anal incontinence symptoms ( p ≤0.05 considered significant). None of the women included had sphincter injury or anal incontinence before childbirth. All delivered vaginally. Mediolateral episiotomy was performed in 33 (55%) cases. Six (10%) had OASIS on endoanal ultrasound (two were also diagnosed clinically), and 11 had symptoms of anal incontinence post-partum. No significant differences were seen in clinical characteristics between groups with vs. without episiotomy. No significant differences were seen in episiotomy rate ( p =0.14), angle ( p =0.42) and length ( p =0.14) between groups with vs. without OASIS on ultrasound. Correlation between anal incontinence symptoms and sonographically diagnosed OASIS was statistically significant ( p =0.04). Key conclusions mediolateral episiotomy does not seem to be protective against clinically or sonographically diagnosed OASIS even when episiotomy technique is considered. Endoanal ultrasound allows a significantly better detection of symptomatic OASIS compared to clinical examination alone. Implications for practice mediolateral episiotomy should be considered only when shortening the second stage of labour is indicated due to foetal distress, and not as a means of OASIS prevention.

The central- and peripheral mechanisms by which heat strain limits physical performance are not fully elucidated. Nevertheless, pre-cooling is often used in an attempt to improve subsequent performance. This study compared the effects of pre-cooling vs. a pre-thermoneutral application on central- and peripheral fatigue during 60% of isometric maximum voluntary contraction (MVC) of the right quadriceps femoris muscle. Furthermore, the effects between a pre-cooling and a pre-thermoneutral application on isometric MVC of the right quadriceps femoris muscle and subjective ratings of perceived exertion (RPE) were investigated. In this randomized controlled trial, 18 healthy adults voluntarily participated. The participants received either a cold (experimental) application (+8 °C) or a thermoneutral (control) application (+32 °C) for 20 min on their right thigh (one cuff). After the application, central (fractal dimension – FD) and peripheral (muscle fiber conduction velocity – CV) fatigue was estimated using sEMG parameters during 60% of isometric MVC. Surface EMG signals were detected from the vastus medialis and lateralis using bidimensional arrays. Immediately after the submaximal contraction, isometric MVC and RPE were assessed. Participants receiving the cold application were able to maintain a 60% isometric MVC significantly longer when compared to the thermoneutral group (mean time: 78 vs. 46 s; p=0.04). The thermoneutral application had no significant impact on central fatigue (p>0.05) compared to the cold application (p=0.03). However, signs of peripheral fatigue were significantly higher in the cold group compared to the thermoneutral group (p=0.008). Pre-cooling had no effect on isometric MVC of the right quadriceps muscle and ratings of perceived exertion. Pre-cooling attenuated central fatigue and led to significantly longer submaximal contraction times compared to the pre-thermoneutral application. These findings support the use of pre-cooling procedures prior to submaximal exercises of the quadriceps muscle compared to pre-thermoneutral applications.

Objective. The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Approach. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1 week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays. Main results. Initial values and slope of CV and FD were used for the reliability analysis. The intraclass correlation coefficient (ICC) values for the isometric contraction at 20% MVC were (−0.09) and 0.67 for CV and FD respectively; whereas the ICC values at 60% MVC were 0.78 and 0.82 for CV and FD respectively. The Bland Altman plots for the two isometric contractions showed a mean difference close to zero, with no evident outliers between the repeated measurements: at 20% MVC 0.001 53 for FD and −0.0277 for CV, and at 60% MVC 0.006 66 for FD and 0.009 07 for CV. Significance. Overall, our findings suggest that during isometric fatiguing contractions, CV and FD slopes are reliable variables, with potential application in clinical populations.

This study aimed to investigate the variation in muscle activity and movement in the lumbar and lumbothoracic region during a singular mono-planar lifting task, and how this is altered in individuals experiencing low back pain (LBP). Muscle activity from the lumbar and lumbothoracic erector spinae of 14 control and 11 LBP participants was recorded using four 13 × 5 high-density surface electromyography (HDEMG) grids. Root mean squared HDEMG signals were used to create spatial maps of the distribution of muscle activity. Three-dimensional kinematic data were recorded focusing on the relationship between lumbar and thoracic movements. In the task, participants lifted a 5 kg box from knee height to sternal height, and then returned the box to the starting position. The center of muscle activity for LBP participants was found to be systematically more cranial throughout the task compared to the control participants (P < 0.05). Participants with LBP also had lower signal entropy (P < 0.05) and lower absolute root mean squared values (P < 0.05). However, there were no differences between groups in kinematic variables, with no difference in contributions between lumbar and thoracic motion segments (P > 0.05). These results indicate that participants with LBP utilize an altered motor control strategy to complete a singular lifting task which is not reflected in their movement strategy. While no differences were identified between groups in the motion between lumbar and thoracic motion segments, participants with LBP utilized a less homogenous, less diffuse and more cranially focussed contraction of their erector spinae to complete the lifting movement. These results may have relevance for the persistence of LBP symptoms and the development of new treatments focussing on muscle retraining in LBP.

Background: Tecar therapy (TT) is an endogenous thermotherapy used to generate warming up of superficial and deep tissues. TT capability to affect the blood flow is commonly considered to be the primary mechanism to promote tissue healing processes. Despite some preliminary evidence about its clinical efficacy, knowledge on the physiologic responses induced by TT is lacking. Objective: The aim of this quantitative randomized pilot study was to determinate if TT, delivered in two modes (resistive and capacitive), affects the perfusion of the skin microcirculation (PSMC) and intramuscular blood flow (IMBF). Design: A randomized controlled pilot feasibility study. Subjects: Ten healthy volunteers (n = 4 females, n = 6 males; mean age 35.9 ± 10.7 years) from a university population were recruited and completed the study. Intervention: All subjects received three different TT applications (resistive, capacitive, and placebo) for a period of 8 min. Outcome measures: PSMC, IMBF, and the skin temperature (ST) were measured pre- and post-TT application using power Doppler sonography, laser speckle contrast imaging (LSCI), and infrared thermography. Results: Compared with placebo application, statistically significant differences in PSMC resulted after both the resistive (p = 0.0001) and the capacitive (p = 0.0001) TT applications, while only the resistive modality compared with the placebo was capable to induce a significant change of IMBF (p = 0.013) and ST (p = 0.0001). Conclusions: The use of power Doppler sonography and LSCI enabled us to evaluate differences in PSMC and IMBF induced by TT application.

AIM To apply topographical mapping of the electromyography (EMG) amplitude recorded from the upper trapezius muscle to evaluate the distribution of activity and the location of peak activity during a shoulder elevation task in participants with and without myofascial pain and myofascial trigger points (MTrP) and compare this location with the site of the MTrP. MATERIALS AND METHODS Thirteen participants with myofascial pain and MTrP in the upper trapezius muscle and 12 asymptomatic individuals participated. High-density surface EMG was recorded from the upper trapezius muscle using a matrix of 64 surface electrodes aligned with an anatomic landmark system (ALS). Each participant performed a shoulder elevation task consisting of a series of 30 s ramped contractions to 15% or 60% of their maximal voluntary contraction (MVC) force. Topographical maps of the EMG average rectified value were computed and the peak EMG amplitude during the ramped contractions was identified and its location determined with respect to the ALS. The location of the MTrP was also determined relative to the ALS and Spearman correlation coefficients were used to examine the relationship between MTrP and peak EMG amplitude location. RESULTS The location of the peak EMG amplitude was significantly (P

This study examined the validity of the twitch interpolation technique for evaluating side-to-side asymmetries in quadriceps neuromuscular function. Fifty-six subjects with a wide range of asymmetries (19 healthy, 24 with unilateral and 13 with bilateral anterior cruciate ligament reconstruction) took part in the study. Supramaximal electrical paired stimuli were delivered to the quadriceps muscle during and immediately after a maximal voluntary contraction (MVC) of the knee extensors (twitch interpolation technique). MVC torque, voluntary activation and resting doublet-evoked torque were measured separately for the two sides, and percent side-to-side asymmetries were calculated for each parameter. MVC torque asymmetry was plotted against voluntary activation asymmetry and doublet-evoked torque asymmetry, and a multiple regression analysis was also conducted. Significant positive correlations were observed between MVC torque asymmetry and both voluntary activation asymmetry (r=0.40; p=0.002) and doublet-evoked torque asymmetry (r=0.53; p

An increased fatigability associated with anterior cruciate ligament (ACL) injury may persist several months after surgery. The purpose of this study was to investigate the behavior of muscle fiber conduction velocity (CV) as a descriptor of myoelectric fatigue, at different stages after rehabilitation, post-ACL reconstruction. Nineteen subjects acted as control group (CG), 10 patients had undergone surgery within 12 months (R12), and 23 patients were more than 24 months post-surgery (R24+). Surface electromyography (EMG) signals were detected from the quadriceps femoris using bidimensional arrays during isometric contractions at 20% and 60% maximal voluntary contraction (MVC). We observed a lower fatigability in the R24+ group during the 60% MVC contraction, with respect to the other groups. Lower fatigability of quadriceps muscle after ACL reconstruction in the long term may be linked to a recovery from a transitory altered motor unit recruitment strategy due to surgery, observed in the R12 group. Therefore, the findings of this study do not suggest an impaired fatigability of the quadriceps muscle during sustained isometric contractions in active patients in the long term.

Shoulder complex control of motion is influenced by neuromuscular function and can be quantified through the analysis of helical axes (HAs) dispersion. Muscle fatigue is a variable able to influence neuromuscular control, altering muscle activation timing and proprioception. The aim of the study was to describe shoulder complex HAs dispersion after muscle fatigue during upper limb movements of young healthy subjects. Thirty healthy right-handed volunteers (age 23.2 ± 2.6 years) were asked to perform a test made up of 15 humerothoracic flexion and rotation movements using both upper limbs in two different recording sessions. After each session, muscles of the tested movement were fatigued in isometric condition at dominant side. After fatigue, subjects repeated the test. Kinematics was recorded by an optoelectronic system and HAs dispersion was computed using Mean Distance (MD) and Mean Angle (MA) for the entire Range of Motion (RoM) and in portions of RoM. After fatigue of shoulder flexion muscles, greater MD (p = 0.001) and MA (p = 0.019) were found on the dominant side. After fatigue of shoulder rotation muscles, greater MD and MA were found on the dominant (p = 0.002 for MD; p = 0.047 for MA) and non-dominant (p = 0.038 for MD; p = 0.019 for MA) sides. Independently of fatigue, greater MA was found in portions of RoM with higher external resistance torque in flexion and rotation tasks. Muscle fatigue increases shoulder complex HAs dispersion, probably due to alteration in neuromuscular control. This data should be considered when exercise involving upper arms are proposed to subjects undergoing fatigue.

People with acute neck pain commonly present with restricted neck movement. However, it is unknown whether the presence of acute pain affects the quality of neck movement; specifically neck movement variability. We examined the effects of acute neck muscle soreness induced via eccentric exercise in healthy volunteers, on the variability of neck movement by examining changes in parameters of the helical axis during active neck movements. An experimental, single-arm repeated measures study recruited 32 healthy participants, male and female, aged between 18 to 55. Repetitive active neck movements (flexion-extension, bilateral lateral flexion and bilateral rotation) were performed at different speeds, either at full range of motion (RoM) or restricted to 45° RoM at baseline pre-exercise (T0), immediately following eccentric neck exercise (T1), 24 hours (T2) and 48 hours post-exercise (T3). The mean distance (MD) and mean angle (MA) parameters of the helical axis were extracted to quantify movement variability. MD, measured during movements performed at full RoM, reduced significantly at T2 compared to T0 (P = 0.001) regardless of direction or speed of movement. MA was significantly lower at T2 and T3 compared to T1 (P = 0.029 and P = 0.033, respectively). When RoM was restricted to 45°, significantly lower MD values were observed at T3 compared to T1 (P = 0.034), and significantly lower MA values were measured at T3 compared to T0, T1 and T2 (all P This study uniquely demonstrates that neck movement variability is reduced immediately after, 24 hours and 48 hours after eccentric exercise, indicating that acute neck muscle soreness modifies the quality of neck movement.

Knee joint rotation center displacement can be estimated in vivo through the analysis of helical axis (HAs) dispersion. HAs can be analyzed during walking, providing information on joint stability. The study aim was to describe knee HAs dispersion during walking in dominant and non-dominant legs of young and elderly healthy subjects. Twenty young (YG: age 23.3 ± 2.4 years) and twenty elderly (EG: age 69.3 ± 4.6 years) healthy subjects were asked to walk on a treadmill at a self-selected speed with reflective markers placed bilaterally on thighs and shanks to detect HAs dispersion and knee kinematics with an optoelectronic system. HAs dispersion was described during the following four phases of gait cycle: (1) flexion from 95% of the previous gait cycle to 10% of the subsequent gait cycle, (2) extension from 10% to 40%, (3) flexion from 40% to 75% and (4) extension from 75% to 95% of the gait cycle. Mean Distance (MD) and Mean Angle (MA) were used as HAs dispersion indexes during each gait phase. Participants showed greater MD and MA in sagittal and frontal planes during the first and second phases. EG revealed higher MD (p = 0.001) and MA (p < 0.001) during the first phase and higher MA (p = 0.001) during the fourth phase in both dominant and non-dominant legs on the sagittal plane. HAs dispersion could be related to the amount of forces acting on knee (first two phases) and knee degeneration (elderly). These results may be used as reference data in further studies on HAs dispersion in presence of knee pathologies or after knee surgery or rehabilitation.

To counteract muscle mass, muscle strength and power loss during aging, and to study age-related change of neuromuscular manifestation of fatigue in relation to nutritional supplementation.randomized controlled double-blind study.Twice-daily consumption for 12 weeks of an Essential Amino Acids (EAA)-based multi-ingredient nutritional supplement containing EAA, creatine, vitamin D and Muscle Restore Complex®.38 healthy elderly subjects (8 male, 30 female; age: 68.91±4.60 years; body weight: 69.40±15.58 kg; height: 1.60±0.09 m) were randomized and allocated in supplement (SUPP) or placebo (PLA) group. Mean Measurements: Vitamin D blood level; Appendicular Lean Mass (ALM); Visceral Adipose Tissue (VAT); Maximal Voluntary Contraction (MVC) and Peak Power (PP); myoelectric descriptors of fatigue: Fractal Dimension and Conduction Velocity initial values (FD iv, CV iv), their rates of change (FD slopes, CV slopes) and the Time to perform the Task (TtT). Mean Results: Significant changes were found in SUPP compared to baseline: Vitamin D (+8.73 ng/ml; p0.001); ALM (+0.34 kg; p0.001); VAT (-76.25 g; p0.001); MVC (+0.52 kg; p0.001); PP (+4.82 W; p0.001). Between group analysis (SUPP Vs. PLA) showed improvements: vitamin D blood levels (+11,72 ng/ml; p0.001); Legs FFM (+443.7 g; p0.05); ALM (+0.53 kg; p0.05); MVC (+1.38 kg; p0.05); PP (+9.87 W; p0.05). No statistical changes were found for FD iv, CV iv, FD and CV slopes and TtT, either compared to baseline or between groups. Significant correlations between mean differences in SUPP group were also found.The study demonstrates that in healthy elderly subjects an EAA-based multi-ingredient nutritional supplementation of 12 weeks is not effective to change myoelectric manifestation of fatigue and TtT failure but can positively affect muscle mass, muscle strength, muscle power and VAT, counterbalancing more than one year of age-related loss of muscle mass and strength.