BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of cor...BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of core muscle activation and a person's ability to stabilize the lumbopelvic complex.Preparatory cues and images can be used to increase the activation of these muscles.To attain optimal movement patterns,it will be necessary to determine what cueing will give the most effective results for core stability.AIM To investigate the effects of external and internal cues on core muscle activation during the Sahrmann five-level core stability test.METHODS Total 68 participants(21.83±3.47 years)were randomly allocated to an external(n=35)or internal cue group(n=33).Participants performed the Sahrmann fivelevel core stability test without a cue as baseline and the five-level stability exercises with an internal or external cue.External cue group received a pressure biofeedback unit(PBU),and the internal cue group received an audio cue.A Delsys Trigno^(TM)surface electromyography unit was used for muscle activation from the rectus abdominis,external oblique,and transverse abdominis/internal oblique muscles.RESULTS Linear mixed effects model analysis showed that cueing had a significant effect on core muscle activation(P=0.001);however,there was no significant difference between cue types(internal or external)(P=0.130).CONCLUSION Both external and internal cueing have significant effects on core muscle activation during the Sahrmann five-level core stability test and the PBU does not create higher muscle activation than internal cueing.展开更多
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 ac...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.展开更多
The exoskeleton is employed to assist humans in various domains including military missions,rehabilitation,industrial operation,and activities of daily living(ADLs).Walking is a fundamental ADL,and exoskeletons are ca...The exoskeleton is employed to assist humans in various domains including military missions,rehabilitation,industrial operation,and activities of daily living(ADLs).Walking is a fundamental ADL,and exoskeletons are capable of reducing the activation and metabolism of lower extremity muscles through active assistance during walking.To improve the performance of active assistance strategy,this article proposes a framework using an active hip exoskeleton.Subsequently,it correlates to an already established Bayesian-based human gait recognition algorithm,with a particular focus on linear and circular walking within industrial and ADL contexts.In theorizing this strategy for exoskeletons,this study further reveals,in part,the activation characteristics of human hip muscles for the instruction and regulation of active assistance duration and onset timing.This proposed active assistance strategy provides new insights for enhancing the performance of assistive robots and facilitating human robot interaction within the context of ADLs.展开更多
<strong>Objective</strong><span style="font-family:;" "=""><strong>:</strong> To observe extrinsic foot muscle activity ratio and sensory disturbance in Leprosy a...<strong>Objective</strong><span style="font-family:;" "=""><strong>:</strong> To observe extrinsic foot muscle activity ratio and sensory disturbance in Leprosy and its implication to foot deformity and walking capacity. <b>Design: </b>Cross sectional study in Singkawang, West Kalimantan. <b>Materials and Methods</b>: Thirty-three leprosy patients without walking aids and/or orthotic prosthetic were enrolled using consecutive sampling. Foot deformity score was calculated and muscle<span style="color:red;"> </span>activity w</span><span style="font-family:;" "="">as</span><span style="font-family:;" "=""> 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.<b> Results</b>: 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 = <span style="white-space:nowrap;">﹣</span>0.787) and decreased TA/PE ratio (p = 0.001, r = <span style="white-space:nowrap;">﹣</span>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 <span>difference of Timed Up and Go Test result within plantar sensory deficit </span>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). <b>Conclusion</b>: 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.</span>展开更多
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 exoskelet...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.展开更多
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 vas...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.展开更多
Background:Forefoot strike(FFS) and rearfoot strike(RFS) runners differ in their kinematics,force loading rates,and joint loading patterns,but the timing of their muscle activation is less clear.Methods:Forty recreati...Background:Forefoot strike(FFS) and rearfoot strike(RFS) runners differ in their kinematics,force loading rates,and joint loading patterns,but the timing of their muscle activation is less clear.Methods:Forty recreational and highly trained runners ran at four speeds barefoot and shod on a motorized treadmill. "Barefoot" runners wore thin,five-toed socks and shod runners wore neutral running shoes.Subjects were instructed to run comfortably at each speed with no instructions about foot strike patterns.Results:Eleven runners landed with an FFS when barefoot and shod and eleven runners landed with an RFS when barefoot and shod.The 18remaining runners shifted from an FFS when barefoot to an RFS when shod(shifters).Shod shifters ran with a lower stride frequency and greater stride length than all other runners.All FFS runners landed with more plantarflexed ankles and more vertical lower legs at the beginning of stance compared to RFS runners.FFS runners activated their plantarflexor muscles 1 1%earlier and 10%longer than RFS runners.Conclusion:This earlier and longer relative activation of the plantarrlexors likely enhances the capacity for the passive structures of the foot and ankle to store elastic energy,and may also enhance the performance of the active muscle by increasing the storage of elastic strain energy in the cross-bridaes and activated thin.展开更多
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 l...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.展开更多
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...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.展开更多
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 signi...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.展开更多
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,...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.展开更多
: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 vario...: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.展开更多
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 con...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.展开更多
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 sy...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.展开更多
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...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.展开更多
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 ...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.展开更多
Cycling is an eco-friendly method of transport and recreation. With the intent of reducing the energy cost of cycling without providing an additional energy source, we have proposed the use of a torsion spring for kne...Cycling is an eco-friendly method of transport and recreation. With the intent of reducing the energy cost of cycling without providing an additional energy source, we have proposed the use of a torsion spring for knee-extension support. We developed an exoskeleton prototype using a crossing four-bar mechanism as a knee joint with an embedded torsion spring. This study evaluates the passive knee exoskeleton using constant-power cycling tests performed by eight healthy male participants. We recorded the surface electromyography over the rectus femoris muscles of both legs, while the participants cycled at 200 and 225 W on a trainer with the developed wheel-accelerating system. We then analyzed these data in time-frequency via a continuous wavelet transform. At the same cycling speed and leg cadence, the median power spectral frequency of the electromyography increases with cycling load. At the same cycling load, the median power spectral frequency decreases when cycling with the exoskeleton. Quadriceps activity can be relieved despite the exoskeleton consuming no electrical energy and not delivering net-positive mechanical work. This fundamental can be applied to the further development of wearable devices for cycling assistance.展开更多
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 ...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.展开更多
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- dipheny...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.展开更多
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...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.展开更多
文摘BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of core muscle activation and a person's ability to stabilize the lumbopelvic complex.Preparatory cues and images can be used to increase the activation of these muscles.To attain optimal movement patterns,it will be necessary to determine what cueing will give the most effective results for core stability.AIM To investigate the effects of external and internal cues on core muscle activation during the Sahrmann five-level core stability test.METHODS Total 68 participants(21.83±3.47 years)were randomly allocated to an external(n=35)or internal cue group(n=33).Participants performed the Sahrmann fivelevel core stability test without a cue as baseline and the five-level stability exercises with an internal or external cue.External cue group received a pressure biofeedback unit(PBU),and the internal cue group received an audio cue.A Delsys Trigno^(TM)surface electromyography unit was used for muscle activation from the rectus abdominis,external oblique,and transverse abdominis/internal oblique muscles.RESULTS Linear mixed effects model analysis showed that cueing had a significant effect on core muscle activation(P=0.001);however,there was no significant difference between cue types(internal or external)(P=0.130).CONCLUSION Both external and internal cueing have significant effects on core muscle activation during the Sahrmann five-level core stability test and the PBU does not create higher muscle activation than internal cueing.
基金the Special Fund for Basic Scientific Research of Central Colleges,Chang'an University,China(Nos.2014G2320006,2013G3322009,and 2014G1321040)the Key Science and Technology Program of Shaanxi Province,China(No.2014K05-59)
文摘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.
文摘The exoskeleton is employed to assist humans in various domains including military missions,rehabilitation,industrial operation,and activities of daily living(ADLs).Walking is a fundamental ADL,and exoskeletons are capable of reducing the activation and metabolism of lower extremity muscles through active assistance during walking.To improve the performance of active assistance strategy,this article proposes a framework using an active hip exoskeleton.Subsequently,it correlates to an already established Bayesian-based human gait recognition algorithm,with a particular focus on linear and circular walking within industrial and ADL contexts.In theorizing this strategy for exoskeletons,this study further reveals,in part,the activation characteristics of human hip muscles for the instruction and regulation of active assistance duration and onset timing.This proposed active assistance strategy provides new insights for enhancing the performance of assistive robots and facilitating human robot interaction within the context of ADLs.
文摘<strong>Objective</strong><span style="font-family:;" "=""><strong>:</strong> To observe extrinsic foot muscle activity ratio and sensory disturbance in Leprosy and its implication to foot deformity and walking capacity. <b>Design: </b>Cross sectional study in Singkawang, West Kalimantan. <b>Materials and Methods</b>: Thirty-three leprosy patients without walking aids and/or orthotic prosthetic were enrolled using consecutive sampling. Foot deformity score was calculated and muscle<span style="color:red;"> </span>activity w</span><span style="font-family:;" "="">as</span><span style="font-family:;" "=""> 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.<b> Results</b>: 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 = <span style="white-space:nowrap;">﹣</span>0.787) and decreased TA/PE ratio (p = 0.001, r = <span style="white-space:nowrap;">﹣</span>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 <span>difference of Timed Up and Go Test result within plantar sensory deficit </span>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). <b>Conclusion</b>: 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.</span>
文摘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.
基金funded by a Faculty Research Grant through the University of Wisconsin-La Crosse,La Crosse,Wisconsin,USA.
文摘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.
基金the Purves Summer Research AwardSherman Fairchild Foundation+1 种基金National Science Foundation (NSF-0634592)Howard Hughes Medical Institute Undergraduate Science Program award 52006301 to Harvey Mudd College
文摘Background:Forefoot strike(FFS) and rearfoot strike(RFS) runners differ in their kinematics,force loading rates,and joint loading patterns,but the timing of their muscle activation is less clear.Methods:Forty recreational and highly trained runners ran at four speeds barefoot and shod on a motorized treadmill. "Barefoot" runners wore thin,five-toed socks and shod runners wore neutral running shoes.Subjects were instructed to run comfortably at each speed with no instructions about foot strike patterns.Results:Eleven runners landed with an FFS when barefoot and shod and eleven runners landed with an RFS when barefoot and shod.The 18remaining runners shifted from an FFS when barefoot to an RFS when shod(shifters).Shod shifters ran with a lower stride frequency and greater stride length than all other runners.All FFS runners landed with more plantarflexed ankles and more vertical lower legs at the beginning of stance compared to RFS runners.FFS runners activated their plantarflexor muscles 1 1%earlier and 10%longer than RFS runners.Conclusion:This earlier and longer relative activation of the plantarrlexors likely enhances the capacity for the passive structures of the foot and ankle to store elastic energy,and may also enhance the performance of the active muscle by increasing the storage of elastic strain energy in the cross-bridaes and activated thin.
文摘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.
文摘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.
基金a grant from theMedical Scientific ResearchFoundation of GuangdongProvince, No. A2003526
文摘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.
文摘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.
基金work was supported by the National Research Foundation of Korea(NRF)Grant funded by the Korean government(MSIT)(NRF-2016R1D1A1A03934816)and by Chowis。
文摘: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.
文摘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.
基金Supported by National Natural Science Foundation of China(Grant No.51005133)National Hi-tech Research and Development Program of China(863 Program,Grant No.2011AA11A244)Special Financial Grant of National Science Foundation for Post-doctoral Scientists of China(Grant No.201104098)
文摘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.
文摘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.
基金supported by the University of Massachusetts Amherst(SP:Graduate School Fellowship,and School of Public Health and Health Sciences Dean’s PhD Summer FellowshipGEC:Faculty Research Grant).
文摘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.
文摘Cycling is an eco-friendly method of transport and recreation. With the intent of reducing the energy cost of cycling without providing an additional energy source, we have proposed the use of a torsion spring for knee-extension support. We developed an exoskeleton prototype using a crossing four-bar mechanism as a knee joint with an embedded torsion spring. This study evaluates the passive knee exoskeleton using constant-power cycling tests performed by eight healthy male participants. We recorded the surface electromyography over the rectus femoris muscles of both legs, while the participants cycled at 200 and 225 W on a trainer with the developed wheel-accelerating system. We then analyzed these data in time-frequency via a continuous wavelet transform. At the same cycling speed and leg cadence, the median power spectral frequency of the electromyography increases with cycling load. At the same cycling load, the median power spectral frequency decreases when cycling with the exoskeleton. Quadriceps activity can be relieved despite the exoskeleton consuming no electrical energy and not delivering net-positive mechanical work. This fundamental can be applied to the further development of wearable devices for cycling assistance.
基金funded by 2016 Hunan Province Social Science Key Project(Grant No.16ZDB015)2017 National Social Science Foundation of China(Grant No.21BTY032)+1 种基金2020 Hainan Province Tertiary School Research Project(Grant No.HNKY2020-53)2021 Hainan Province Philosophy and Social Development Project(Grant No.HNSK[ZC]21-173).
文摘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.
基金Supported by the National Natural Science Foundation of China(No.81172938)the Program for the Top Science and Technology Innovation Teams of Higher Learning Institutions of Shanxi Province,China+1 种基金the Shanxi Foundation for Overseas Returned,China(No.2008-51)the Program for the Top Young and Middle-aged Innovative Talents of Higher Learning Institutions of Shanxi Province,China
文摘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.
基金supported in part by the National Natural Science Foundation of China under Grant 62073224the National Key Research and Development Program of China under Grant 2018YFB1307303the program of China Scholarships Council under Grant 202108310200.
文摘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.
