Effects of Compression Garments on Lower Limb Muscle Activation via Electromyography Analysis during Running

Sports compression garments are common-selected sportswear to improve athletic performance and reduce sports injury. Since they consist of elastic textile that exerts compression and pressure onto the muscle,muscle activation is of interest to sports compression garment manufactures who seek to enhance sports performance through gradient compression garment design.However,there are few scientific investigations to explore this effect of muscle activation to evaluate the performance of sports compression garments during sport activity. In this paper, a systemic experimental protocol was presented to improve the quality of evaluation test under a standardized running test. Then muscle activation with and without wearing sport compression garments to highlight the changes caused by compression garment was investigated. The electromyography( EMG) signal was collected and processed by the proposed method to represent the muscle activation combined with gait analysis of running. As a result,the average muscle activation of gait cycle for the major muscles such as rectus femoris( RF) and gastrocnemius medialis( GM) revealed that they needed to exert more muscle force without wearing garment at certain periods for mid-stand and pre-swing phase within gait cycle. These lower muscle activation levels prolonged activity duration,reduced fatigue,and presented low risk for sport injury.Such an evaluation study therefore would scientifically prove the effect of compression garment and provide information on muscle activation and the ergonomic efficacy of gradient compression garment design.

Foot and Ankle Muscles Activation and Plantar Sensory Deficit in Leprosy and Its Implication to Foot Deformity and Walking Capacity

Objective: To observe extrinsic foot muscle activity ratio and sensory disturbance in Leprosy and its implication to foot deformity and walking capacity. Design: Cross sectional study in Singkawang, West Kalimantan. Materials and Methods: Thirty-three leprosy patients without walking aids and/or orthotic prosthetic were enrolled using consecutive sampling. Foot deformity score was calculated and muscle activity was measured using surface EMG. Muscle activation ratio was calculated in Tibialis anterior-to-Gastrocnemius (TA/GA) and Tibialis Anterior-to-Peroneal (TA/PE). Walking capacity was assessed using Timed up and Go test. Results: Significant differences of foot ulcer (p = 0.001) and foot deformities (p = 0.001) were found in plantar sensory deficit group. There was strong correlation between foot deformities and decreased TA/GA ratio (p = 0.001, r = ﹣0.787) and decreased TA/PE ratio (p = 0.001, r = ﹣0.663). There were significant differences of TA/GA ratio (p = 0.00) and TA/PE ratio (p = 0.09) based on the foot ulcer, and no significant difference of Timed Up and Go Test result within plantar sensory deficit group (p = 0.427). No significant correlation was found between walking capacity and TA/GA ratio (p = 0.055), and TA/PE ratio (p = 0.165). Conclusion: Plantar sensory deficit and decreased extrinsic muscle activation ratio during gait had been proven to affect foot impairment, but have not been proven to inhibit walking capacity.

Exploring Passive Exoskeleton-Induced Changes in Lumbar Muscle Activity

Purpose: The purpose of this study was to evaluate the effect of using a passive exoskeleton on lumbar muscle activity during lifting movements, and to determine whether muscle activity remains altered after exoskeleton removal. This study sought to identify the potential risks and benefits associated with the use of passive exoskeletons for the prevention and treatment of low back pain. Methods: Eighteen healthy adult participants lifted a 10 kg suitcase while wearing a passive exoskeleton. Muscle activity and postures were measured during lifting and before, during, and after exoskeleton use. This study examined whether the reduced muscle activity observed during exoskeleton use persisted after exoskeleton removal. Muscle activity was assessed using electromyography and postures were recorded using reflective markers and a camera. Results: The study found that Lumbar muscle activity decreased significantly (approximately 40%) during exoskeleton use compared to that without exoskeleton use. Importantly, lumbar muscle activity remained low after exoskeleton removal, at levels similar to those observed during exoskeleton use. This suggests that individuals adapted to the exoskeleton support and maintained altered muscle control, even without the exoskeleton. Conclusion: This study demonstrates that passive exoskeletons significantly reduce lumbar muscle activity during lifting tasks, and that this altered muscle control persists after exoskeleton removal. These findings contribute to the understanding of the risks and benefits of passive exoskeletons, potentially aiding their development and informing their use in the prevention and treatment of low back pain.

Application of the neuromuscular fatigue threshold treadmill test to muscles of the quadriceps and hamstrings

Purpose:The purposes of the present study were:(1)to determine whether the physical working capacity at the fatigue threshold(PWCFT)model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis(VL)during incremental treadmill running could also be applied to the vastus medialis(VM),biceps femoris(BF),and semitendinosus(ST)muscles;and(2)if applicable,to compare the running velocities associated with the PWCFT among these muscles.Methods:Eleven subjects(age 21.7±1.8 years)performed an incremental treadmill test to exhaustion with electromyographic signals recorded from the VL,VM,BF,and ST.Results:The results indicated there were no significant(p>0.05)mean differences in the running velocities associated with the PWCFT for the VL(14.4±2.0 km/h),VM(14.3±1.9 km/h),BF(13.8±1.8 km/h),and ST(14.7±2.3 km/h).In addition,there were significant inter-correlations(r=0.68-0.88)among running velocities associated with the PWCFT of each muscle.Individual results also indicated that 9 of the 11 subjects exhibited identical PWCFT values for at least 3 of the 4 muscles,but there were no uniform patterns for any intra-individual differences.Conclusion:The findings of the present study suggested that the PWCFT test is a viable method to identify neuromuscular fatigue in the quadriceps and hamstrings during incremental treadmill exercise and results in consistent PWCFT values among these muscles.

Muscle-Strengthening Exercise Links with Lower Odds for Depression in Adolescents

Purpose:Physical activity is a well-recognized protective factor against depression in adolescents.As a compo-nent of physical activity,muscle strengthening exercise(MSE)is also viewed as a correlate associated with lower risks of depression in adults.However,little is known about the association in adolescents.This study aimed to explore the association between MSE and depression in a sample of Chinese adolescents.Method:A self-reported questionnaire was used for data collection including variables of MSE,depression(assessed by Children’s Depres-sion Inventory)and selected sociodemographic factors(e.g.,sex,grade,height and weight[for body mass index]).Generalized Linear Models was utilized to estimate the association between MSE and depression.Results:Results showed a negative association between MSE and depression(Beta=–0.66;both MSE and depression were treated as continuous variables).When treating MSE(meeting or not meeting the recommendations)and depression as binary variables,odds ratio for depression in adolescents not meeting the MSE recommendation was significant higher(odd ratio=1.50,95%CI:1.15–1.96)than those meeting the MSE recommendations.Conclusions:This study found that MSE may be a protective factor against MSE in adolescents.Future studies are encouraged to confirm or negate our studyfinding using improved study design.

Effect of Fertilizer Diammonium Phosphate on Liver,Kidney and Muscle 5-Nucleotidase Activity of Fresh Water Teleost Fish Clarias batrachus

The toxic effect of fertilizer Diammonium phosphate resulted in alterations of 5'-Nucleotidase activity of tissues liver, kidney and muscles offish C. batrachus at varying intervals and exposures. Alterations in 5'-Nuclcotidase activity of body organs gave an idea of the toxicity caused by the fertilizer. Thus the enzyme 5'-Nucleotidase can be used to monitor the pollution in aquatic ecosystem.

Association between the fMRI manifestations of activated brain areas and muscle strength in patients with space-occupying lesions in motor cortex

BACKGROUND ： Functional magnetic resonance imaging （fMRI） studies have disclosed the changes of the motor function in the motor cortex of ipsilateral and contralateral hemispheres of tumor, which have special significance for making the surgical planning and most greatly minimizing the postoperative functional damages. OBJECTIVE： To analyze the association between the manifestation characteristics of hand functional area and motor dysfunction using fMRI in patients with space-occupying lesions of tumor in motor cortex. DESIGN ： A case-controlled observation SETTING： Department of Radiology, Second Affiliated Hospital, Shantou University Medical College .PARTICIPANTS： Twenty-three patients （13 males and 10 females） with space-occupying lesions of central sulcus area, aged 21-53 years with a mean age of （47±1） years were selected from the Second Affiliated Hospital of Shantou University Medical College. All the patients were diagnosed by MR scanning as space-occupying lesions of motor area, and pathologically confirmed that the lesions involved central sulcus and central Iobule; Lesions occurred in left and right hemispheres in 13 and 10 cases respectively. The tumor types were astrocytoma （n =8）, metastatic tumours （n =7）, meningiomas （n =5） and oligodendroglioma （n =3）. The muscle strength was normal in 11 cases （grade 5） and obviously decreased in 12 cases （grade 2-3 in 3 cases and grade 4 in 9 cases）; muscle strengths of both upper and lower limbs were decreased in 7 cases, and only that of upper limbs was decreased in 5 cases. Informed consents were obtained from all the subjects. Meanwhile, 9 healthy physical examinees （5 males and 4 females） of 20-56 years old with an average of （34±1） years were taken as controls. All the patients and healthy subjects were right-handed. METHODS： All the enrolled subjects were examined with MR scanning and functional imaging. Twenty cases whose clinical symptoms were mild in the patient group and 9 healthy volunteers adopted simple active finger-tapping movements, and for the 3 cases whose clinical symptoms were severe in the patient group, the simple passive finger-tapping movements were used. The manifestations in the activated brain areas were analyzed in the patients with brain tumor of different muscle strength and the controls. The motor deficit and activation of contralateral primary motor cortex （M1） in simple finger-tapping movements were observed in the patient group. MAIN OUTCOME MEASURES： （1） Brain areas activated by finger-tapping movements in each group： （2） Activated volumes in hemisphere by finger-tapping movements between groups. RESULTS： The contralateral M1 area could not be activated in 1 case in the patient group,, all the other 22 patients and 9 healthy subjects were involved in the analysis of results. （1） In the control group, unilateral finger tapping movement activated the contralateral primary motor cortex （M1）, bilateral SMA and bilateral PMC. The activation volume was the largest in contralateral primary motor cortex （M1）, smaller in the SMA, and the smallest in PMC. The finger tapping movement in healthy subjects could activate contralateral primary motor cortex （M1）, bilateral SMA and bilateral PMC, which had no obvious differences from the manifestations of brain functional area activated by active finger tapping. There was no significant difference in the volume of activated functional areas between right and left hands. In the patient group, the central sulcos around the tumor in the activated M1 area displaced towards dorsal or ventral side, also extended. The distance of displacement in the functional area was determined as compared with the contralateral central sulcus, and the results suggested the M1 displacement, including that there were 10 cases with the M1 displacement larger than 10 mm in the patients with motor deficit, which were obviously more than in those without motor deficit （n =1, P 〈 0.01）, and the activated volume in contralateral M1 area was obvious smaller in the patients with motor deficit than in those without motor deficit （P 〈 0.01）. （2） The M1 activation and changes were observed in contralateral hemisphere in the patient group, and the activated volume was obviously larger than that in the control group （P 〈 0.01）. The activated volumes of M1 and PMC in ipsilateral hemisphere were obviously larger than those in the control group （P 〈 0.05）, but that of SMA had no obvious difference between the two groups （P 〉 0.05）. CONCLUSION： fMRI can be used to observe the activation of the brain motor functional areas of patient with space-occupying lesions in motor area, and evaluate the state of their motor function. The larger the distance of displacement of M1 compressed by tumor, the more obviously the muscle strength decreases in the patients.

Effects of compression garments on surface EMG and physiological responses during and after distance running

Background:The few previous studies that focused on the effects of compression garments(CG)on distance running performance have simultaneously measured electromyogram,physiological,and perceptual parameters.Therefore,this study investigated the effects of CG on muscle activation and median frequency during and after distance running,as well as blood-lactate concentration and rating of perceived exertion(RPE)during distance running.Methods:Eight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials,one with CG,and the other with control garment made of normal cloth.The RPE and the surface electromyography(EMG)of 5 lower extremity muscles including gluteus maximus(GM),rectus femoris(RF),semitendinosus(ST),tibialis anterior(TA),and gastrocnemius(GAS)were measured during the running trial.The blood-lactate levels before and after the running trial were measured.Results:Wearing CG led to significant lower muscle activation(p<0.05)in the GM(decreased 7.40%-14.31%),RF(decreased 4.39%-4.76%),and ST(decreased 3.42%-7.20%)muscles;moreover,significant higher median frequency(p<0.05)in the GM(increased 5.57%)and ST(increased 10.58%)muscles.Wearing CG did not alter the RPE values or the blood-lactate levels(p>0.05).Conclusion:Wearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running.This finding suggested that wearing CG may improve muscle function,which might enhance running performance and prevent muscle fatigue.

Timing and Classication of Patellofemoral Osteoarthritis Patients Using Fast Large Margin Classifier

:Surface electromyogram(sEMG)processing and classication can assist neurophysiological standardization and evaluation and provide habitational detection.The timing of muscle activation is critical in determining various medical conditions when looking at sEMG signals.Understanding muscle activation timing allows identication of muscle locations and feature validation for precise modeling.This work aims to develop a predictive model to investigate and interpret Patellofemoral(PF)osteoarthritis based on features extracted from the sEMG signal using pattern classication.To this end,sEMG signals were acquired from ve core muscles over about 200 reads from healthy adult patients while they were going upstairs.Onset,offset,and time duration for the Transversus Abdominus(TrA),Vastus Medialis Obliquus(VMO),Gluteus Medius(GM),Vastus Lateralis(VL),and Multidus Muscles(ML)were acquired to construct a classication model.The proposed classication model investigates function mapping from real-time space to a PF osteoarthritis discriminative feature space.The activation feature space of muscle timing is used to train several large margin classiers to modulate muscle activations and account for such activation measurements.The fast large margin classier achieved higher performance and faster convergence than support vector machines(SVMs)and other state-of-the-art classiers.The proposed sEMG classication framework achieved an average accuracy of 98.8%after 7 s training time,improving other classication techniques in previous literature.

A review on assessment and treatment of the trunk in stroke A need or luxury

Trunk function has been identified as an important early predictor of functional outcome after stroke and the same deteriorates on both contralateral and ipsilateral sides of the body following stroke. The primary contribution of the trunk muscles is to allow the body to remain upright, adjust weight shifts, and control movements against constant pull of gravity and is considered central key point of the body. Proximal stability of the trunk is a pre-requisite for distal limb mobility, balance, gait and functional activities and its positive correlation in hemiplegia has been demonstrated in a cross- sectional study. Both isokinetic and handheld dynamometer muscle strength testing demonstrated the weakness of bilateral trunk flexors, extensors and rotator muscles in both acute and chronic hemiplegic patients. This was confirmed by electromyography analysis which identified poor bilateral trunk muscles activity in patients with stroke. Trunk impairment scale is sensitive to evaluate the selective muscle control of upper and lower trunk, and it has been reported that lateral flexion of the trunk is easier than rotation of the trunk and the clinical observation concurs to the difficulty in lower trunk rotation of stroke patients. However, trunk exercises given early after stroke could produce enhanced balance performance post- stroke. This review attempts to report the evidence supporting the involvement of the trunk and its influence on balance and functional performance in post-stroke hemiplegia.

A Novel Estimating Method for Steering Efficiency of the Driver with Electromyography Signals

The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system, aiming at designing and optimizing the mechanism of steering system. In the development of assist steering system especially the evaluation of its comfort, the steering efficiency of driver physiological output usually are not considered, because this physiological output is difficult to measure or to estimate, and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective. In order to take a further step to the objective evaluation of steering comfort, an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity. First, the steering forces in the steering wheel plane and the electromyography （EMG） signals of the primary muscles were measured. These primary muscles are the muscles in shoulder and upper ann which mainly produced the steering torque, and their functions in steering maneuver were identified previously. Next, based on the multiple regressions of the steering force and EMG signals, both the effective steering force and the total force capacity of driver in steering maneuver were calculated. Finally, the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity, which represented the information of driver physiological output of the primary muscles. This research develops a novel estimating method for driver steering efficiency of driver physiological output, including the estimation of both steering force and the force capacity of primary muscles with EMG signals, and will benefit to evaluate the steering comfort with an objective perspective.

Quantify work load and muscle functional activation patterns in neck-shoulder muscles of female sewing machine operators using surface electromyogram

Background Work-related musculoskeletal disorders （WMSDs） have high prevalence in sewing machine operators employed in the garment industry. Long work duration, sustained low level work and precise hand work are the main risk factors of neck-shoulder disorders for sewing machine operators. Surface electromyogram （sEMG） offers a valuable tool to determine muscle activity （internal exposure） and quantify muscular load （external exposure）. During sustained and/or repetitive muscle contractions, typical changes of muscle fatigue in sEMG, as an increase in amplitude or a decrease as a shift in spectrum towards lower frequencies, can be observed. In this paper, we measured and quantified the muscle load and muscular activity patterns of neck-shoulder muscles in female sewing machine operators during sustained sewing machine operating tasks using sEMG. Methods A total of 18 healthy women sewing machine operators volunteered to participate in this study. Before their daily sewing machine operating task, we measured the maximal voluntary contractions （MVC） and 20%MVC of bilateral cervical erector spinae （CES） and upper trapezius （UT） respectively, then the sEMG signals of bilateral UT and CES were monitored and recorded continuously during 200 minutes of sustained sewing machine operating simultaneously which equals to 20 time windows with 10 minutes as one time window. After 200 minutes＇ work, we retest 20%MVC of four neck-shoulder muscles and recorded the sEMG signals. Linear analysis, including amplitude probability distribution frequency （APDF）, amplitude analysis parameters such as roof mean square （RMS） and spectrum analysis parameter as median frequency （MF）, were used to calculate and indicate muscle load and muscular activity of bilateral CES and UT. Results During 200 minutes of sewing machine operating, the median load for the left cervical erector spinae （LCES）, right cervical erector spinae （RCES）, left upper trapezius （LUT） and right upper trapezius （RUT） were 6.78%MVE, 6.94%MVE, 6.47%MVE and 5.68%MVE, respectively. Work load of right muscles are significantly higher than that of the left muscles （P〈0.05）; sEMG signal analysis of isometric contractions indicated that the amplitude value before operating was significantly higher than that of after work （P 〈0.01）, and the spectrum value of bilateral CES and UT were significantly lower than those of after work （P 〈0.01）; according to the sEMG signal data of 20 time windows, with operating time pass by, the muscle activity patterns of bilateral CES and UT showed dynamic changes, the maximal amplitude of LCES, RCES, LUT occurred at the 20th time window, RUT at 16th time window, spectrum analysis showed that the lower value happened at 7th, 16th, 20th time windows. Conclusions Female sewing machine operators were exposed to high sustained static load on bilateral neck-shoulder muscles; left neck and shoulder muscles were held in more static positions; the 7th, 16th, and 20th time windows were muscle fatiQue period that erQonomics intervention can protocol at these periods.

Muscular activity patterns in 1-legged vs. 2-legged pedaling

Background:One-legged pedaling is of interest to elite cyclists and clinicians.However,muscular usage in 1-legged vs.2-legged pedaling is not fully understood.Thus,the study was aimed to examine changes in leg muscle activation patterns between 2-legged and 1-legged pedaling.Methods:Fifteen healthy young recreational cyclists performed both 1-legged and 2-legged pedaling trials at about 30 Watt per leg.Surface electromyography electrodes were placed on 10 major muscles of the left leg.Linear envelope electromyography data were integrated to quantify muscle activities for each crank cycle quadrant to evaluate muscle activation changes.Results:Overall,the prescribed constant power requirements led to reduced downstroke crank torque and extension-related muscle activities(vastus lateralis,vastus medialis,and soleus)in 1-legged pedaling.Flexion-related muscle activities(biceps femoris long head,semitendinosus,lateral gastrocnemius,medial gastrocnemius,tensor fasciae latae,and tibialis anterior)in the upstroke phase increased to compensate for the absence of contralateral leg crank torque.During the upstroke,simultaneous increases were seen in the hamstrings and uni-articular knee extensors,and in the ankle plantarflexors and dorsiflexors.At the top of the crank cycle,greater hip flexor activity stabilized the pelvis.Conclusion:The observed changes in muscle activities are due to a variety of changes in mechanical aspects of the pedaling motion when pedaling with only 1 leg,including altered crank torque patterns without the contralateral leg,reduced pelvis stability,and increased knee and ankle stiffness during the upstroke.

“Lifting More” is Associated with Lower Risks of Depression in University Students

Research on the population in western world showed that,MSE(muscle-strengthening exercise)is beneficial to the treatment of mental disorders.However,the situation in Chinese adults is little known.For this reason,the study is performed to understand the connection between depression and MSE among college and university students in China aged between 18 to 24.1793 college students have been recruited,and their average age is 20.67.A questionnaire has been developed and it is self-reported and designed to collect information about MSE and participants,including body mass index and sex and so on.Sleep and physical activity have been evaluated by introducing two scales,that is,Pittsburgh Sleep Quality Index and International Physical Activity Questionnaire-Short Form,respectively.Moreover,Patient Health Questionnaire-9 has been adopted to indicate the severity of depression of participants.The link between depression and MSE has been studied by introducing multilevel linear regression.Among all these study participants,just 24.87%of them met the MSE standards of World Health Organization,that is,more than 2 days every week.The average depression score was 6.80(±5.19).Greater num-ber of days for MSE shows negative association with the depression,with (beta=-0.17,95%CI:-0.31 to-0.03,p=0.015).Those students failing to meet MSE standards are more susceptible to the depression risk(beta=0.63,95%CI:0.09–0.19,p=0.027).The results show that,there is a relationship between MSE participation and relieved status of depression among young adults in China.Interventions designed to relieve depression can be developed on the basis of MSE.

Synthesis and Anti-VSMC Vegetation Activities of New Aurone Derivatives

A series of new aurone derivatives was prepared by means of a practical route and their anti-vascular smooth muscle cells（VSMC） vegetation activities were evaluated by the 3-（4,5-dimethylthlazol-2-yl）-2,5- diphenyltetrazolium bromide（MTT） method with tetrandrine as a positive contrast drug. The structures of the com- pounds were confirmed by 1H NMR, 13C NMR and electrospray ionization mass spectrometry（ESI-MS）. Several new compounds exhibited promising activity against VSMC proliferation and the preliminary structure-activity relation- ships（SAR） were discussed in order to investigate the essential structures required for their bioactivities.

Hybrid Active–Passive Prosthetic Knee:A Gait Kinematics and Muscle Activity Comparison with Mechanical and Microprocessor-Controlled Passive Prostheses

Existing microprocessor-controlled passive prosthetic knees(PaPKs)and active prosthetic knees(AcPKs)cannot truly simulate the muscle activity characteristics of the active–passive hybrid action of the knee during the normal gait.Differences in EMG between normal and different prosthetic gait for different phases were never separately analyzed.In this study,a novel hybrid active–passive prosthetic knee(HAPK)is proposed and if and how muscle activity and kinematics changes in different prosthetic gait are analyzed.The hybrid hydraulic-motor actuator is adopted to fully integrate the advantages of hydraulic compliance damping and motor efficiency,and the hierarchical control strategy is adopted to realize the adaptive predictive control of the HAPK.The kinematic data and EMG data of normal gait and different prosthetic gait were compared by experiments,so as to analyze the changes in the muscle activity and spatio-temporal data per phase compared to normal walking and the adaptations of amputees when walking with a different kind of prosthesis(the mechanical prosthesis(MePK),the PaPK and the HAPK).The results show that changes in prosthetic gait mainly consisted of decreased self-selected walking speed,gait symmetry and maximum knee flexion,increased first double support phase duration,muscle activation in both opposed and prosthetic limb and inter-subject variability.The differences between controls and MePK,PaPK and HAPK decreases sequentially.These results indicate that the hybrid active–passive actuating mode can have positive effects on improving the approximation of healthy gait characteristics.

The Effects of Short-Term Resistance Training and Subsequent Detraining on Neuromuscular Function,Muscle Cross-Sectional Area,and Lean Mass

Purpose To examine and compare the effects of three days of dynamic constant external resistance(DCER)and isokinetic(ISOK)training and subsequent detraining on thigh muscle cross-sectional area(TMCSA)and thigh lean mass(TLM),ISOK peak torque(PT),DCER strength,isometric force,muscle activation,and percent voluntary activation(%VA).Methods Thirty-one apparently-healthy untrained men(mean±SD age=22.2±4.2 years;body mass=77.9±12.9 kg;height=173.9±5.4 cm)were randomly assigned to a DCER training group(n=11),ISOK training group(n=10)or control(CONT)group(n=10).Subjects visited the laboratory eight times.The first visit was a familiarization session,the second visit was a pre-training assessment,the subsequent three visits were for unilateral training of the quadriceps(if assigned to a training group),and the last three visits were the post-training assessments conducted at three days,one week,and two weeks after training ended.Results DCER strength increased from pre-to post-training assessment 1 in both limbs for the DCER group only,and remained elevated during post-training assessments 2 and 3(P<0.05).In addition,surface EMG for the biceps femoris was higher at post-training assessment 3 than at the pre-training assessment,and post-training assessments 1 and 2(P<0.05).No other training-related changes were found.Conclusion The primary finding of this study was that DCER strength of the trained and untrained limbs can be increased with three days of training.This has important implications for injury rehabilitation,where in the initial period post-injury strength gains on an injured limb can possibly be obtained with short-term contralateral resistance training.

Experimental and Numerical Study of Cervical Muscle Contraction in Frontal Impact

In a crash situation,drivers typically make evasive maneuvers before an upcoming impact,which can affect the kinematics and injury during impact.The purpose of the current study was to investigate the response and effect of drivers’cervical muscles in a frontal impact.A crash scenario was developed using a vehicle driving simulator,and 10 volunteers were employed to drive the simulator at 20 km/h,50 km/h,80 km/h and 100 km/h.Electromyography(EMG)was recorded from the sternocleidomastoideus(SCM),splenius cervicis(SPL)and trapezium(TRP)muscles using a data acquisition system,and the level of muscle activation was calculated.A numerical study was conducted using data collected in the experiment.The results revealed that the cervical muscles were activated during drivers’protective action.EMG activity of cervical muscles before impact was greater than that during normal driving.EMG activity increased with driving speed,with the SCM and TRP exhibiting larger increases than the SPL.The kinematics and load of the driver were influenced by muscle activation.Before the collision,the head of an active model stretched backward,while the passive model kept the head upright.In low-speed impact,the torque and shear of the cervical muscle in the active model were much lower than those in the passive model,while the tension of the cervical muscle was higher in the active model compared with the passive model.The results indicated that the incidence of cervical injury in high-speed impact is complex.

A high-fidelity human cervical muscle finite element model for motion and injury studies

Active muscle response is a key factor in the motion and injury of the human head and neck.Due to the limitations of experimentation and the shortcomings of previous finite element models,the influence of material parameters of cervical muscle on motions of the head and neck during a car crash have not been comprehensively investigated.In the present work,a model of the cervical muscle in a 50th-percentile adult male was constructed.The muscles were modelled using solid finite elements,with a nonlinear-elastic and viscoelastic material and a Hill material modelling the passive and active parts of each muscle,respectively.The head dynamic responses of the model were validated using results obtained from volunteer sled tests.The influence of the material parameters of a muscle on head and neck motions were determined.Our key finding was that the greater the stiffness and the contraction strength of the neck muscles,the smaller the rotation angle of the head and the neck,and,hence,the lower the risk of head and neck injury to occupants in a car crash.

A Musculoskeletal Modeling of Hand-foot Crawling with Different Heights

As a bionic therapy,hand-foot crawling has been reported to be used for the rehabilitation of low back pain.However,there have been few relevant biomechanical studies about this type of exercise.The purpose of this study was to calculate muscle activation and lumbar spinal load based on the examined limb kinematics and kinetics,which associated with hand-foot crawling at the different Centre of Mass(CoM)heights.A total of 14 men performed hand-foot crawling at three CoM heights.The kinematics and kinetics data were collected.One-way repeated measure analysis of variance was used to analyze the efFect of the CoM height on crawling parameters.The crawling data from one subject at the three heights were used to calculate the muscle activation and compressive lumbar load with an OpenSim musculoskeletal model.The CoM heights had no significant effect on kinematics,kinetics or muscle activation.The spinal load was larger at higher heights.Hand-foot crawling was associated with lower trunk muscle activity.This study helps us to understand hand-foot crawling from the perspective of biomechanics.The findings from this study may help physical therapists choose hand-foot crawling as an appropriate exercise for patients with low back pain during early rehabilitation.