Integrated EMG Research Articles

A Study on the Effects of Gluteal Muscle Activation on the Electromyography of Lower Limb Muscles in Young Male Patients With Patellofemoral Pain Syndrome.

Patellofemoral pain syndrome (PFPS) is a common knee issue, and hip joint function significantly affects knee health. Gluteus activation exercises are a promising treatment for PFPS. This study aims to investigate the impact of gluteal muscle activation exercises on the muscle involvement and movement patterns of young male patients with PFPS. Our study was a randomized controlled clinical trial study from June 2020 to December 2021, included 18 young male patients with PFPS, randomly divided into two groups: the gluteus activation group (GAG) and control group (CON), with nine cases in each group. The GAG underwent gluteal muscle activation exercises for 40 min per session, three times per week, for 6 weeks; the CON received no intervention. At baseline and after 6 weeks, the integrated electromyography (IEMG), contribution rates (CRs), and activation times (ATs) of the gluteus maximus (GM), vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and semitendinosus (ST) muscles of the affected lower limb during stair-climbing exercise were assessed. Additionally, the explosive power (EP) of the lower limbs and the visual analog scale (VAS) pain value of the knee joint were evaluated. Paired sample t-tests and independent sample t-tests were used to compare the differences within and between groups. After 6 weeks, the GAG showed a significant increase in the IEMG of GM by 118 ± 67.09 μVs compared to CON (p < 0.05), and an increase in the CR of the GM by 6.75% (p < 0.05). Additionally, the AT of the GM and BF was significantly reduced (p < 0.05), and the lower limb EP increased by 14.66% compared to the CON (p < 0.05). Concurrently, there was a very significant reduction in the knee VAS pain score (p < 0.01). The CON exhibited no significant changes in the EMG indices of the lower limbs, EP, and VAS before and after the 6 weeks (p > 0.05). A 6-week gluteal muscle activation training program for patients with PFPS can adjust and optimize the IEMG, CR, and firing order of the lower limb muscle groups, enhance EP, and alleviate pain.

Analysis of a difficulty movement of aerobic gymnasts based on biomechanics

Background: With the progress of technology, an increasing number of studies on biomechanics in sports are being conducted. Objective: Based on biomechanical methods, the characteristics of aerobic gymnasts at different skill levels performing the difficulty movement C715 were compared to provide a reference for teaching and training. Methods: Sixteen aerobic gymnasts were divided into two groups, A and B, according to their skill levels. Kinematic data and surface electromyography were collected using modern equipment, analyzed, and compared. Results: Group A spent 0.64 ± 0.03 s during the upright restoration stage, which was longer than that of group B (p &lt; 0.05). In the pre-swing stage, the angle between the legs of group A at the moment of free leg landing was 46.52 ± 2.14°, which was significantly greater than that of group B. Muscle force was predominantly exerted on the right side, and there were obvious differences between group A and group B in the integral electromyogram (IEMG) of the right rectus abdominis, left and right gastrocnemius, and left rectus femoris (p &lt; 0.05). During the phase when the free leg swings forward, no significant differences in kinematic characteristics were found between the two groups; however, there were significant differences in IEMG of muscle activity for the right rectus abdominis, left and right biceps femoris, right gastrocnemius, and left rectus femoris (p &lt; 0.05). The right gastrocnemius force of group A reached 25.77 ± 3.64 μV·S, which was significantly higher. During the 360° leg-controlled rotation phase, the minimum angle of the right ankle in group A was significantly greater than group B (p &lt; 0.05), and the muscle activity showed significant differences in IEMG of the left biceps femoris, right biceps femoris, left gastrocnemius, left rectus femoris, and right rectus femoris. In the upright stage, the knee and ankle angles of group A were larger, and there was a remarkable difference in gastrocnemius force (p &lt; 0.05). Conclusion: There are biomechanical differences among aerobic gymnasts of varying levels when performing the difficulty movement C715.

Effects of victim's body posture and attacker's gender on slashing attacks: a biomechanical study.

Sharp force injury has been and will remain to be a major cause of violent death; however, scientific evaluations on the impact of body posture of the victim and gender of the perpetrator on sharp force injury have been scarce. The purpose of this study was to evaluate the biomechanical characteristics found in individuals (male and female) when using a Chinese kitchen knife to slash the neck of a dummy while it was in the standing and supine positions. This work offers a solid basis for forensic identifications, criminal investigations, and court trials. A total of 12 male and 12 female college students participated in this study. Kinematic, kinetic, and surface electromyography (sEMG) data were evaluated when slashing the neck of a dummy while it was in the standing and supine positions using a Chinese kitchen knife. When slashing the neck of a standing dummy, participants showed shorter contact time (19.5%) and slower shoulder velocities (30.9%) as well as higher hip velocity (26.0%) and increased root mean square (RMS) and integral electromyography (iEMG) for the anterior deltoid (51.3% and 51.2%, respectively) compared to those while the dummy was in the supine position (all p < 0.05), regardless of gender. When slashing a dummy's neck while it was in standing and supine positions, male participants showed higher shoulder, elbow, and wrist velocities (22.6%, 22.7%, and 24.4%, respectively) and higher slashing velocity (19.8%), slashing force (24.2%), and energy (46.2%) than female participants (all p < 0.05). In addition, male participants showed shorter contact time (17.8%), and the values of RMS and iEMG of the anterior deltoid, biceps brachii, extensor carpi radialis longus, and flexor carpi ulnaris were less than those of female participants (98.9%, 47.3%, 65.6%, and 33.4% for RMS and 115.1%, 59.4%, 80.1%, and 47.8% for iEMG, respectively). There was no difference in slashing speed, slashing force, and energy when using a Chinese kitchen knife to slash the dummy's neck while it was in different body postures (standing and supine), suggesting a similar level of injury severity. However, there were significant differences in slashing action patterns between the two body postures, with longer contact time, smaller hip velocity, greater shoulder velocity, and less muscle activation level of the deltoid exertion when slashing the dummy's neck in the supine position. Gender may have a greater effect on the severity of slashing, and the gender difference may be partly related to the body weight difference. The findings from this study may provide quantitative indicators and references for analyzing the motive behind the crime, as well as for case reconstruction, and for the court's conviction and sentencing processes.

EVALUATION OF NECK FATIGUE CAUSED BY WEARING HELMET IN MOTION: AN ELECTROMYOGRAPHY STUDY

The increased weight of multifunction and intelligent helmet systems can cause an exacerbation of the neck workload. Further, increased weight of the helmet can reduce the wearing comfort, and prolonged use may cause neck fatigue and even neck injury. This study evaluates the fatigue of neck muscles caused by wearing a helmet in motion using electromyography (EMG) measurement. Additionally, a comprehensive evaluation model for neck fatigue was established effectively. Twenty healthy subjects were selected to run for 10[Formula: see text]min continuously in each task by wearing two different helmets, respectively, during which the EMG signals of different neck muscles and subjective scores were recorded and analyzed. Two-way repeated measures analysis of variance (ANOVA) and Pearson correlation analysis were used to obtain indicators of neck fatigue, based on which the support vector machine (SVM) was used to construct a classification model of neck fatigue. By using integral EMG (IEMG) and root mean square (RMS) for assessing the neck injury in sternocleidomastoideus and trapezius muscles, it was observed that the mean power frequency (MPF) and median frequency (MF) in trapezius and splenius capitis could be used as effective evaluation indicators of neck fatigue. The EMG activity in trapezius was the highly sensitivity to fatigue when wearing helmets in motion. The classifier for distinguishing three different neck fatigue levels was 91.67% accurate. This study demonstrates the feasibility of an EMG-based method to evaluate the neck fatigue caused by wearing a helmet in motion, and also provides an evaluation method for the optimal design of helmets in the future.

Plantar Flexor Muscle Activity and Fascicle Behavior in Gastrocnemius Medialis During Running in Highly Cushioned Shoes With Carbon-Fiber Plates.

The purposes of this study were to clarify the electromyography (EMG) of plantar flexors and to analyze the fascicle and tendon behaviors of the gastrocnemius medialis (GM) during running in the carbon-fiber plate embedded in thicker midsole racing shoes, such as the Nike ZoomX Vaporfly (VF) and traditional racing shoes (TRAD). We compared the fascicle and series elastic element behavior of the GM and EMG of the lower limb muscles during running (14km/h, 45s) in athletes wearing VF or TRAD. GM EMGs in the push-off phase were approximately 50% lower in athletes wearing VF than in TRAD. Although the series elastic element behavior and/or mean fascicle-shortening velocity during the entire stance phase were not significantly different between VF and TRAD, a significant difference was found in both the mean EMG and integral EMG of the GM during the push-off phase. EMG of the gastrocnemius lateralis (GL) during the first half of the push-off phase was significantly different between VF and TRAD. Present results suggest that VF facilitates running propulsion, resulting in a decrease in GM and GL EMGs at a given running velocity during the push-off phase, leading to a reduction in metabolic cost.

Biomechanical analysis of lower limbs during stand-to-sit tasks in patients with early-stage knee osteoarthritis.

Background: Knee osteoarthritis (KOA) is a common degenerative disease among the older people that severely affects their daily life. Previous studies have confirmed that movement biomechanics are altered in patients with KOA during task performance. However, changes that occur in lower limb joints and muscles in the three planes during stand-to-sit (STS) tasks in patients with early-stage KOA are unclear. Method: Of the 36 participants recruited in this study, 24 (8 males and 16 females) and 12 (4 males and 8 females) were added to the KOA and control groups, respectively. The Nexus Vicon motion capture system along with Delsys wireless surface electromyography devices and plantar pressure measurement mat was used to record test data. A Visual 3D software was used to process the data and calculate the biomechanical and electromyographic parameters during STS tasks. Results: There was no significant difference in task duration between the two groups. Patients with KOA could perform a greater range of pelvic motion and smaller range of hip and knee joint motion with a lower maximum hip joint angular acceleration in the sagittal plane and greater knee and ankle joint motion in the coronal plane. There was no significant difference in the motion range in the horizontal plane. During the STS task, patients in the KOA group had a lower vertical ground reaction force (GRF) amplitude on the injured side but a higher integrated GRF on both sides than those in the control group. Moreover, patients with KOA demonstrated higher PERM and PABM of the lower limb joints and smaller knee PADM and ankle PEM. Additionally, maximum activation levels of GMed muscle, affected-side gluteus medius (GM), ST, rectus femoris (RF), and tibialis anterior (TA) muscles were lower in patients with KOA than in controls. Conversely, the activation level of biceps femoris (BF) was higher. Furthermore, the integral EMG values of GMed, GM, ST, VL, RF, vastus medialis VM, and TA muscles on the affected side were lower, except for the BF muscle, in patients with KOA. Conclusion: Compared with the participants in the control group, patients with early-stage KOA exhibited consistent changes in sEMG parameters and biomechanical alterations in the sagittal plane, as observed in previous studies. However, differences in parameters were observed in the coronal and transverse planes of these patients. The noninvasive analysis of the 3D parameters of the involved motion patterns may lead to the early detection of KOA.

Wet cupping with rehabilitation training for upper-limb poststroke spasticity: A systematic review and meta-analysis of randomized controlled trials

BackgroundUpper-limb poststroke spasticity (PSS) negatively impacts on patients’ quality of life. An increasing number of clinical trials have indicated that wet cupping with rehabilitation training is conductive to alleviate spastic muscle tone, thereby to improve upper-limb function. However, related evidence base is insufficient. This study systematically investigates the efficacy and safety of wet cupping with rehabilitation training on stroke patients with upper-limb spasticity. MethodsEight separate databases and two clinical trial registries were searched from their inception to December 6, 2022. Two reviewers extracted the data and assessed the quality of the literature, independently. The mean difference (MD) or risk ratio (RR) were used as measure of effect size in meta-analysis. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used for the certainty of evidence. ResultsEight randomized controlled trials (RCTs) were quantified for meta-analysis. The results indicated that in comparison with the control group, wet cupping with rehabilitation training was more effective in reducing modified Ashworth scale score (MD = −0.60, 95% CI: −0.74, −0.46; P < 0.00001) and the integral electromyography value of biceps muscle (MD = −4.71, 95% CI: −6.74, −2.67; P < 0.00001), but improving effective rate (RR = 1.28, 95% CI: 1.15, 1.41; P < 0.00001), Fugl-Myer Assessment score (MD = 4.84, 95% CI: 3.05, 6.64; P < 0.00001) as well as Barthel Index score (MD = 6.38, 95% CI: 2.20, 10.57; P = 0.003). However, no significant difference was found regarding the integral electromyography value of triceps muscle between groups (MD = 1.72, 95% CI: −2.05, 5.48; P = 0.37). ConclusionWet cupping with rehabilitation training should be included in a comprehensive therapeutic regimen for stroke patients with upper-limb spasticity. However, these results need to be further verified by more RCTs with rigorous design and large sample size.

Vibration comfort assessment of tractor drivers based on sEMG and vibration signals

In order to comprehensively evaluate the driver’s vibration comfort under different vibration conditions, eighteen subjects were required to drive a tractor at different speeds on field and asphalt roads respectively in the real vehicle experiment. The sEMG signals and vibration acceleration signals of the subjects were recorded. And the time-frequency domain analysis of sEMG signals and acceleration signals were used to determine the relationship among the characteristic indexes, tractor speed and road surfaces. The relevance analysis showed that there was a significant correlation between the integral electromyography (iEMG) and median frequency (MF) of the middle scalene muscle, erector spinae muscle and gastrocnemius muscle, the RMS of weighted acceleration (aw) of the neck, waist and legs, and the subjective comfort feelings. It was proven that the tractor speed had a significant impact on human body vibration based on the ANOVA result (p < 0.05). With the increase of running speed, the time domain indexes of sEMG signals including iEMG, RMS and the vibration acceleration signals of the testing body parts increased significantly, while the amplitudes of frequency domain indexes decreased. Therefore, a quantitative regression evaluation model for the comfort of the neck, waist and legs integrating the sEMG and vibration signals was established, and its relative errors were 5.05, 4.38 and 6.12% respectively. This proposed assessment model can combine characteristics of the partial and overall vibration response of human body effectively, predict the tractor driver’s vibration comfort accurately, provide a theoretical basis for the evaluation of tractor cab vibration comfort.

PROGRAM FOR DETERMINING THE INFORMATIVE PARAMETERS OF SURFACE ELECTROMYOGRAPHIC SIGNALS

The article analyzes and calculates informative parameters of surface electromyographic signals (sEMS), which can be used to control biotechnical systems, as well as to diagnose the state of the musculoskeletal system. The analysis parameters in the time and frequency-time domains of the signal are considered. A program has been developed for calculating the informative indicators of the signal in the indicated areas. The program is implemented in the LabVIEW environment. To analyze the sEMG signal in the time domain, using the developed program, such indicators as Integral EMG, Average amplitude change, Wavelength, Simple quadratic integral, Absolute value of the 3rd time moment, and others were calculated; and to describe the signal spectrum by methods of time-frequency analysis, the average frequency of the spectrum (mean power frequency-MPF), the median frequency of the spectrum (median Frequency-MF), root mean square (RMS), power density spectrum (PDS), half width - the width of the spectrum at half maximum amplitude (HW). To test the program, files of real sEMQ signals were used. The calculated parameters of the sEMG analysis in the time and frequency-time domains make it possible to non-invasively and objectively assess the state of the musculoskeletal system. Keywords: Surface electromyographic signals, biotechnical systems, time-frequency analysis, Labvıew software.

Venous congestion affects neuromuscular changes in pigs in terms of muscle electrical activity and muscle stiffness.

Early detection of venous congestion (VC)-related diseases such as deep vein thrombosis (DVT) is important to prevent irreversible or serious pathological conditions. However, the current way of diagnosing DVT is only possible after recognizing advanced DVT symptoms such as swelling, pain, and tightness in affected extremities, which may be due to the lack of information on neuromechanical changes following VC. Thus, the goal of this study was to investigate acute neuromechanical changes in muscle electrical activity and muscle stiffness when VC was induced. The eight pigs were selected and the change of muscle stiffness from the acceleration and muscle activity in terms of integral electromyography (IEMG) was investigated in three VC stages. Consequently, we discovered a significant increase in the change in muscle stiffness and IEMG from the baseline to the VC stages (p < 0.05). Our results and approach can enable early detection of pathological conditions associated with VC, which can be a basis for further developing early diagnostic tools for detecting VC-related diseases.

Analysis of technical characteristics of typical lower limb balance movements in Tai Chi: a cross-sectional study based on AnyBody bone muscle modeling.

Tai Chi is an excellent traditional Chinese physical fitness exercise, and its unique balancing movements are very important for improving human balance. In this study, the two most representative Tai Chi balance movements, "knee lift balance" and "leg stirrup balance", were selected to establish the lower limb bone muscle model of Tai Chi balance movements by using computer simulation modeling technology, aiming to analyze the characteristics of the lower limb movement mechanisms of typical balance movements, to provide a quantitative theoretical basis for improving the scientific level of Tai Chi. A total of 16 subjects were recruited for this study. the BTS three-dimensional motion capture system and three-dimensional force platform were used for motion data acquisition, the physiological electromyographic signals were collected using BTS surface electromyography, and the lower limb bone muscle model of Tai Chi balance movements was established by AnyBody human simulation. In the knee lift balancing movement, the balance leg hip abduction/adduction angle, hip flexion/extension moment, and the strength of the rectus femoris muscle, biceps femoris short capitis, and iliacus muscle of the amateur group was significantly smaller than that of the professional group (P<0.01). In the leg stirrup balance movement, the knee flexion/extension angle of the balancing leg in the amateur group was significantly greater than that in the professional group (P<0.01), and the hip flexion/extension angle, hip inversion/abduction angle, knee flexion/extension moment, hip flexion/extension moment, the strength iliacus, gluteus maximus, and obturator internus were significantly smaller than those in the professional group (P<0.01). The integral EMG of the biceps femoris of the support leg in the amateur group was significantly smaller than that of the professional group (P<0.01). The integral EMG of the lateral femoral muscle of the balance leg was significantly smaller than that of the professional group (P<0.01). In this study, we found that the balancing leg of the balancing movement has a larger hip joint angle, the stirrup balancing knee joint angle is smaller, and the hip and knee joint moments are larger. This is related to joint activity and muscle activation, and amateurs should pay attention to increasing the range of motion of the hip joint and decreasing the range of motion of the knee joint when practicing to better stimulate exercise of the lower limb joints. In addition, the practice of balancing movements should strengthen the iliacus muscle, which plays an important role in maintaining the stable balance of the lower limbs, and strengthen the knee flexor and extensor muscles and hip adductor/abductor muscles of the balancing leg, thus promoting the stability of the balancing leg movements.

The use of nonnormalized surface EMG and feature inputs for LSTM-based powered ankle prosthesis control algorithm development.

Advancements in instrumentation support improved powered ankle prostheses hardware development. However, control algorithms have limitations regarding number and type of sensors utilized and achieving autonomous adaptation, which is key to a natural ambulation. Surface electromyogram (sEMG) sensors are promising. With a minimized number of sEMG inputs an economic control algorithm can be developed, whereas limiting the use of lower leg muscles will provide a practical algorithm for both ankle disarticulation and transtibial amputation. To determine appropriate sensor combinations, a systematic assessment of the predictive success of variations of multiple sEMG inputs in estimating ankle position and moment has to conducted. More importantly, tackling the use of nonnormalized sEMG data in such algorithm development to overcome processing complexities in real-time is essential, but lacking. We used healthy population level walking data to (1) develop sagittal ankle position and moment predicting algorithms using nonnormalized sEMG, and (2) rank all muscle combinations based on success to determine economic and practical algorithms. Eight lower extremity muscles were studied as sEMG inputs to a long-short-term memory (LSTM) neural network architecture: tibialis anterior (TA), soleus (SO), medial gastrocnemius (MG), peroneus longus (PL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) and gluteus maximus (GMax). Five features extracted from nonnormalized sEMG amplitudes were used: integrated EMG (IEMG), mean absolute value (MAV), Willison amplitude (WAMP), root mean square (RMS) and waveform length (WL). Muscle and feature combination variations were ranked using Pearson's correlation coefficient (r > 0.90 indicates successful correlations), the root-mean-square error and one-dimensional statistical parametric mapping between the original data and LSTM response. The results showed that IEMG+WL yields the best feature combination performance. The best performing variation was MG + RF + VM (rposition = 0.9099 and rmoment = 0.9707) whereas, PL (rposition = 0.9001, rmoment = 0.9703) and GMax+VM (rposition = 0.9010, rmoment = 0.9718) were distinguished as the economic and practical variations, respectively. The study established for the first time the use of nonnormalized sEMG in control algorithm development for level walking.

Effect of vitamin energy drinks on relieving exercise-induced fatigue in muscle group by ultrasonic bioimaging data analysis.

This work was aimed to analyze the effect of vitamin energy drink on muscle fatigue by surface electromyography (SEMG) and ultrasonic bioimaging (USBI). 20 healthy men were selected to do increasing load fatigue test. Surface electromyographic signals and ultrasonic biological images were collected based on wavelet threshold function with improved thresholds. Time domain and frequency domain characteristic integrated electromyography (IEMG), root mean square amplitude (RMS), average power frequency (MPF), and surface and deep muscle morphological changes were analyzed. Hemoglobin concentration (HB), red blood cell number (RBC), mean volume of red blood cell (MCV), blood lactic acid (BLA), malondialdehyde (MDA), and phosphocreatine kinase (CK) were measured. 1) the Accuracy (94.10%), Sensitivity (94.43%), Specificity (93.75%), and Precision (94.07%) of the long and short-term memory (LSTM) specificity for muscle fatigue recognition were higher than those of other models. 2) Compared with the control group, the levels of BLA, MDA, and CK in the experimental group were decreased and HB levels were increased after exercise (P < 0.05). 3) IEMG and RMS of the experimental group were higher than those of the control group, and increased with time (P < 0.05). 4) The mean amplitude of the response signal decreased with time. Compared with the control group, the surface muscle thickness, deep muscle thickness, total muscle thickness, contrast, and homogeneity (HOM) decreased in the experimental group; while the angular second moment (ASM) and contrast increased, showing great differences (P < 0.05). Surface electromyographic signal and ultrasonic biological image can be used as auxiliary monitoring techniques for muscle fatigue during exercise. Drinking vitamin energy drinks before exercise can relieve physical fatigue to a certain extent and promote the maintenance of muscle microstructure.

Dynamic electromyography findings of the lower leg muscles during walking in spastic cerebral palsy children with hindfoot valgus

BackgroundHindfoot valgus is one of the most prevalent foot deformities in cerebral palsy children. Investigating the muscle activation patterns of cerebral palsy children with hindfoot valgus is crucial to understand their abnormal gait different from typically developing children. MethodsElectromyography data of 20 cerebral palsy children with hindfoot valgus and 20 typically developing children were recorded for tibialis anterior, peroneal longus, and gastrocnemius medialis. The activation onset and offset times, normalized peak electromyography amplitude, average electromyography amplitude and integral electromyography amplitude for 20 completed cycles were averaged for data analysis. The co-activation index and activation percentage of peroneal longus were used to evaluate the co-activation level for tibialis anterior and peroneal longus muscles. FindingsCompared with typically developing children, the activation onset of tibialis anterior and the activation offset of tibialis anterior, peroneal longus, and gastrocnemius medialis were significantly delayed in cerebral palsy children; moreover, the muscle activation durations of tibialis anterior, peroneal longus, and gastrocnemius medialis were significantly longer, and the normalized average electromyography amplitude of tibialis anterior, peroneal longus and gastrocnemius medialis, and the normalized integral electromyography amplitude of tibialis anterior were significantly lower in cerebral palsy children. Furthermore, for cerebral palsy children, the co-activation index was greater, and the peroneal longus muscles activation percentage was lower in the stance phase and greater in the swing phase than that of typically developing children. InterpretationThe lower leg muscle activation patterns in cerebral palsy children were found to be abnormal.

Characteristics of the postural stability of the lower limb in different visual states of undergraduate students with moderate myopia.

Objective: To explore the characteristics of lower limb postural stability in undergraduates with moderate myopia in three different visual states. Methods: Twenty male undergraduate students were recruited to complete respectively the static and dynamic postural stability tests under eyes-closed, myopia (taking off their glasses immediately) and corrected vision conditions. A three-dimensional force platform (Bertec, United States) was used to test static postural stability, which calculated the total path length of the Center of Pressure (COP), path length in the antero-posterior (A/P) and medio-lateral (M/L) directions, COP area, SampleEntropy (SampEn), and low-, medium-, and high-frequency spectrum energies. Dynamic postural stability was tested using the Y-balance test, and the Y-balance test scores were calculated. The Vicon three-dimensional motion capture system (Oxford, United Kingdom) measured the maximum flexion angles of the ankle, knee, and hip joints. The electromyography (EMG) root mean square (RMS) and integral EMG (iEMG) of the tibialis anterior and lateral gastrocnemius of the lower extremity were simultaneously measured using wireless surface electromyography (Noraxon, United States). Results: The SampEn-A/P and SampEn-M/L of corrected vision state higher than myopia and eyes-closed states, and myopia state larger than eyes-closed state (χ2 = 51.631, p < .001). The original and standard scores of the anterior, postero-medial and comprehensive values of the three visual states had significant differences (F = 32.125, p < .001). The original and standard values of postero-lateral corrected vision and myopia were larger than those of eyes-closed states (F = 37.972, p < .001). The maximum flexion angles of the ankle and knee joints were in the following order: corrected vision, myopia and eyes-closed (F = 10.93, p < .001). The iEMG and RMS had significant differences in the three different states (χ2 = 12.700, p < .001) in the all directions of YBT. Conclusion: Compared with corrected vision, the stability of static posture in the state of myopia was decreased, and the postural regularity was more regular. The dynamic postural stability in the state of myopia was also lower than that corrected vision, and the activation and work of ankle muscles were also increased.

Effects of powered versus passive-elastic ankle foot prostheses on leg muscle activity during level, uphill and downhill walking.

People with transtibial amputation (TTA) using passive-elastic prostheses have greater leg muscle activity and metabolic cost during level-ground and sloped walking than non-amputees. Use of a stance-phase powered (BiOM) versus passive-elastic prosthesis reduces metabolic cost for people with TTA during level-ground, +3° and +6° walking. Metabolic cost is associated with muscle activity, which may provide insight into differences between prostheses. We measured affected leg (AL) and unaffected leg (UL) muscle activity from ten people with TTA (6 males, 4 females) walking at 1.25 m s-1 on a dual-belt force-measuring treadmill at 0°, ±3°, ±6° and ±9° using their own passive-elastic and the BiOM prosthesis. We compared stride average integrated EMG (iEMG), peak EMG and muscle activity burst duration. Use of the BiOM increased UL lateral gastrocnemius iEMG on downhill slopes and AL biceps femoris on +6° and +9° slopes, and decreased UL rectus femoris on uphill slopes, UL vastus lateralis on +6° and +9°, and soleus and tibialis anterior on a +9° slope compared to a passive-elastic prosthesis. Differences in leg muscle activity for people with TTA using a passive-elastic versus stance-phase powered prosthesis do not clearly explain differences in metabolic cost during walking on level ground and slopes.

Experimental Analysis of Handcart Pushing and Pulling Safety in an Industrial Environment by Using IoT Force and EMG Sensors: Relationship with Operators’ Psychological Status and Pain Syndromes

Non-ergonomic execution of repetitive physical tasks represents a major cause of work-related musculoskeletal disorders (WMSD). This study was focused on the pushing and pulling (P&P) of an industrial handcart (which is a generic physical task present across many industries), with the aim to investigate the dependence of P&P execution on the operators’ psychological status and the presence of pain syndromes of the upper limbs and spine. The developed acquisition system integrated two three-axis force sensors (placed on the left and right arm) and six electromyography (EMG) electrodes (placed on the chest, back, and hand flexor muscles). The conducted experiment involved two groups of participants (with and without increased psychological scores and pain syndromes). Ten force parameters (for both left and right side), one EMG parameter (for three different muscles, both left and right side), and two time-domain parameters were extracted from the acquired signals. Data analysis showed intergroup differences in the examined parameters, especially in force integral values and EMG mean absolute values. To the best of our knowledge, this is the first study that evaluated the composite effects of pain syndromes, spine mobility, and psychological status of the participants on the execution of P&P tasks—concluding that they have a significant impact on the P&P task execution and potentially on the risk of WMSD. The future work will be directed towards the development of a personalized risk assessment system by considering more muscle groups, supplementary data derived from operators’ poses (extracted with computer vision algorithms), and cognitive parameters (extracted with EEG sensors).

A comparison of muscle activation and concomitant intermuscular coupling of antagonist muscles among bench presses with different instability degrees in untrained men.

The aim of this study was to analyze and compare the muscle activation and concomitant intermuscular coupling of antagonist muscles among bench presses with different instability degrees. Twenty-nine untrained male college students performed bench press exercises at an intensity of 60% 1 RM on three conditions: small unstable bench press with Smith machine (SBP), medium unstable bench press of free weight (FWBP), and large unstable bench press with increased instability by suspending the load with elastic bands (IIBP). One-way repeated measures analysis of variance was used to compare integrated EMG activity values of the biceps brachii (BB), posterior deltoid (PD), long head of the triceps brachii (TB), anterior deltoid (AD), upper portion of the pectoralis major (PM) muscles, and phase synchronization index (PSI) of BB-TB and PD-AD antagonist muscle pairs. A higher integrated EMG of BB muscle was found during bench press with a more unstable condition. IIBP showed a higher integrated EMG of prime movers (TB, AD, and PM) and stabilizing of BB than SBP and FWBP. PSI between muscle pairs of BB-TB in the gamma frequency band was higher in SBP than the other bench presses with unstable conditions, which may be related to the optimal “internal model” for antagonist muscles during bench press exercise. Therefore, IIBP training may be an effective accessory exercise to maintain a higher level of muscle activation across primary and stabilizing muscles with a lighter load for untrained men, while SBP may be a suitable bench press exercise for untrained participants who have not developed the neuromuscular adaptations necessary for correct stabilization of the elbow joint.

Effect of Core Stability Training on Correction and Surface Electronic Signals of Paravertebral in Adolescent Idiopathic Scoliosis.

Objective To observe the effect of 12-week core stability training on Cobb angle and the ratios of AEMG (averaged EMG) and IEMG (integral EMG) of paravertebral electromyography in thoracic and lumbar segments in adolescent idiopathic scoliosis (AIS) patients and offer a practical-based evidence for the rehabilitation treatment for AIS patients. Methods 31 AIS female middle school students were randomly divided into an exercise group (n = 16, 12 weeks of core stability training, 3 times/week) and AIS group (n = 15). In addition, 15 female secondary school students without scoliosis were included as the normal group (the AIS group and normal group did not perform any regular physical exercise throughout the trial period and only receive regular evaluation and guidance). Before and after the experiment, the digital diagnostic equipment of Philips was used to examine the Cobb angle and Noraxon was used to measure the surface EMG signals of the back thoracic and lumbar paravertebral muscles. Results Compared with that before training, after 12 weeks of core stability training, the Cobb angle in the exercise group significantly decreased, and the ratio of AEMG (convex/concave) and IEMG (convex/concave) of paravertebral muscles in the thoracolumbar segment significantly decreased (P < 0.01, respectively); there was no significant difference in the above indicators in the AIS group before and after the experiment (P > 0.05, respectively). After 12 weeks of core stability training, compared with the AIS group, the Cobb angle decreased significantly (P < 0.01), and the ratio of AEMG (convex/concave) and IEMG (convex/concave) of paravertebral muscles in thoracolumbar segment decreased significantly (P < 0.01, P < 0.05). Compared with the normal group, the ratio of AEMG and IEMG of paravertebral muscles in thoracolumbar segment significantly increased (P < 0.01) in the AIS group (P < 0.01, respectively). Conclusions The core stability training can significantly reduce the Cobb angle of AIS and correct the bad posture of scoliosis patients, which may be related to the balance of the electromyographic activities (convex concave side) of paravertebral muscles in AIS patients.

Clinical assessments and gait analysis for patients with Trimalleolar fractures in the early postoperative period

BackgroundTrimalleolar fracture is a common ankle fracture with serious complications and costly healthcare problem. Most studies used clinical assessments to evaluate the functional status of the patients. Although clinical assessments are valid, they are static and subjective. Dynamic, objective and precise evaluations such as gait analysis are needed. Ankle biomechanics studies on gait in patients with trimalleolar fractures are still rare. This study aimed to investigate the clinical outcomes and gait biomechanics in patients with trimalleolar fractures in the early postoperative period and compared to healthy controls.MethodsThis was a cross-sectional study. 12 patients with trimalleolar fractures were recruited, and 12 healthy people served as controls. All patients underwent clinical assessments: Olerud and Molander ankle score (OMAS), ankle swelling and passive range of motion (ROM) of ankle, and completed gait biomechanical analysis when weight-bearing was allowed: temporal-spatial parameters, plantar pressure distributions, and surface electromyography (sEMG). The control group only performed gait test.ResultsPatients had poor outcomes of clinical assessments in the short-term. During gait analysis, patients presented compromised gait patterns: shorter step length, larger step width, slower walking speed and shorter single support compared to healthy controls (P < 0.001), and patients showed asymmetrical gait. Symmetry index of step width and walking speed were mainly correlated with the difference of ankle inversion ROM between two sides (R = -0.750, P = 0.005; R = -0.700, P = 0.011). During walking, patients showed abnormal dynamic plantar pressure features (mainly in the hindfoot and forefoot regions), and the IEMG (integrated electromyography) of tibial anterior muscle (TA) and peroneal longus muscle (PL) were larger than healthy controls (P = 0.002, 0.050).ConclusionsPatients with trimalleolar fractures showed physical impairments of the ankle, and presented altered gait parameters compared to healthy subjects in the short-term. The ankle stability of patients declined, and deficits in TA and PL muscle ability might contribute to it. Restoring complete muscle functions and improving passive ankle ROM are significant to promote the recovery of a normal gait pattern.