健身车转速与阻力对踩踏力量与下肢肌电的影响

目的比较骑车运动中以不同踩踏频率进行不同负荷强度运动时对于踩踏力量与下肢作用肌激发模式的影响。方法 12名健康成年男性在实验第1阶段以渐增负荷法测得各受试者的踏车运动最大稳定输出功率(poweroutput at VO2max,POV),实验第2阶段以平衡次序法进行3种不同运动强度(50%,65%,80%POV)与3种踩踏频率(60,75,90 r/min)的踏车运动测验,并分别记录9种实验情境中踩踏力量与下肢肌电图的变化。结果不同运动测验中,踩踏力量的负功随着踩踏频率的增加而上升,当曲柄角度在270°的位置时,踩踏合力随回转速的上升平均会增加1.84倍,且踩踏切线作用力峰值明显提前;整体而言,下肢肌群激活率会随踩踏频率的增加而上升。结论在未受自行车训练者中,踩踏频率为影响踩踏力量以及肌电结果的主要因素,踩踏作用力的作用趋势会随着踩踏频率的增加而前移,亦会随着踩踏频率的增加使力量输出曲线平滑化,且3种运动强度的结果相近。以整体踩踏效益而言,未受训练者较佳的踩踏回转速为60 r/min。

Neural function rebuilding on different bodies using microelectronic neural bridge technique

A microelectronic circuit is used to regenerate the neural signals between the proximal end and the distal end of an injured nerve.An experimental scheme is designed and carried out to verify the feasibility of the so-called microelectronic neural bridge（MNB）.The sciatic signals of the source spinal toad which are evoked by chemical stimuli are used as source signals to stimulate the sciatic of the controlled spinal toad.The sciatic nerve signals of the source spinal toad,the regenerated sciatic signals in the controlled spinal toad,and the resulting electromyography（EMG）signals associated with the gastrocnemius muscle movements of the controlled spinal toad are displayed and recorded by an oscilloscope.By analyzing the coherence between the source sciatic nerve signals and the regenerated sciatic nerve signals and the coherence between the regenerated nerve signals and the EMG signals,it is proved that the regenerated sciatic nerve signals have a relationship with the source sciatic nerve signals and control shrinkage of the leg of the controlled toad.

Detection of an increase in EMG regularity during fatiguing contractions

The changes in the evolvement patterns of surface electromyography（EMG）signals during both static and dynamic fatiguing contractions are studied.The main finding is that the EMG signal tends to be more and more regular as muscle fatigues.An increase in the summation of all the regular evolvement patterns denoted by Dreg reflects such a tendency.Compared with traditional measurements,Dreg shows less variability among subjects when characterizing a fatigue process.In addition,the calculation of Dreg in the time domain is free from the restrictions disturbing those of spectral parameters.The detection of an increase in the EMG regularity not only proposes a new and easy way to inspect changes in EMG during the fatigue process,but also provides strong supports to estimate muscle fatigue by means of nonlinear analysis methods such as entropy and complexity measures.The detection method of signal regularity can also be applied to other physiological signals.

Classification of forearm action surface EMG signals based on fractal dimension

Surface electromyogram （EMG） signals were identified by fractal dimension.Two patterns of surface EMG signals were acquired from 30 healthy volunteers＇ right forearm flexor respectively in the process of forearm supination （FS） and forearm pronation （FP）.After the raw action surface EMG （ASEMG） signal was decomposed into several sub-signals with wavelet packet transform （WPT）,five fractal dimensions were respectively calculated from the raw signal and four sub-signals by the method based on fuzzy self-similarity.The results show that calculated from the sub-signal in the band 0 to 125 Hz,the fractal dimensions of FS ASEMG signals and FP ASEMG signals distributed in two different regions,and its error rate based on Bayes decision was no more than 2.26%.Therefore,the fractal dimension is an appropriate feature by which an FS ASEMG signal is distinguished from an FP ASEMG signal.

Antiarrhythmic Efficacy of Neferine Assessed by Programmed Electrical Stimulation in a Canine Model of Electropharmacology

An ishemic ventricular tachyarrhythmias canine model was established in open-chest dogs subjected to programmed electrical stimulation (PES)for 5-8 days after acute myocardial infarction. The electrophysiologic effects of neferine (Nef) and procainamide (PA) were observed in this model. With routine methods of PES,ventricular tachycardia (VT)and ventricular fibrillation (VF) could be reproducibly initiated. Both drugs lengthened the QTc interval (P【0.01) and effective refractory period(ERP)of normal and ischemic ventricular myocardia (NERP and IERP) respectively (P【0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P【0.01), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardia (P【0.01). The two compounds prevented the PES-induced VT or VF (Nef group P【0.01, PA group P【0.05) and ischemia-induced VF (P【0.05). The results indicated that neferine and procainamide may be effective in preventing the onset of reentrant ventricular tachyarrhythmias after myocardial ischemic damage in dogs.

Electrophysiologic-electropharmacologic Method for Evaluating the Effects of Antagonizing Ventricular Tachyarrhythmic Drugs

Objective To establish a canine model of electrophysiologic - electropharmacology as assessed by programmed electrical stimulation (PES),and to observe the electrophysiologic effects of Procainamide(PA) on normal and ischemic myocardium in case of ischemic ventricular tachyarrhythmia in this model. Methods A ishemic ventricular tachyarrhythmias canine model was established in open-chest dogs subjected to programmed electrical stimulation(PES)for 5-8 days after acute myocardial infarction. The electrophysiologic effects of procainamide were observed in this model. With routine methods of PES,ventricular tachycardia(VT) and ventricular fibrillation (VF) could be reproducibly initiated. Results Procainamide distinctly lengthened the QTc interval (P【0.01) and effective refractory period(ERP) of normal and ischemic ventricular myocardium(NERP and IERP) respectively (P【0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P【0.01), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardium remarkably (P【0.01). Procainamide effectively prevented the PES-induced VT or VF (P【0.05) and ischemia-induced VF (P【0.05). Conclusion The results indicated that PES-induced VT/VF were highly reproducible and reliable, this canine model is a worthy and reliable one, procainamide may be effective in preventing the onset of VT and VF after myocardial ischemic damage, and deserves further attention as an antifibrillatory agent.

Electrophysiologic Effects of Sophoridine on a Canine Model of Ischemic Ventricular Tachyarrhythmias

A canine model of ischemic ventricular tachyarrhythmias was established in open-chest dogs subjected to programmed electrical stimulation (PES) for 5￣8 days after acute myocardial infarction. The electrophysiologic effects of sophoridine (Sop) and procainamide (PA) were observed in this canine model. With routine methods of PES, ventricular tachycardia (VT) and ventricular fibrilation (VF) could be reproducibly initiated in this model. Both drugs distinctly lengthened the QTc interval ( P <0.01) and the effective refractory period (ERP) in normal and ischemic ventricular myocardium ( P <0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P <0.05), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardium remarkably ( P <0.01). Both drugs effectively prevented the PES-induced VT or VF and ischemia-induced VF ( P <0.05). The results indicated that this canine model is a good and reliable one, sophoridine and procainamide may be effective in preventing the onset of reentrant ventricular tachyarrhythmias after myocardial ischemic damage.

Effects of 2-[p-(Dimethylamino)Styrl] PyridineMethiodide on Slow Response Action Potentialand Slow lnward Current of Guinea PigPapillary Muscles

The effects of 2-[p-(Dimethylamino)styryl] pyridine methiodide(DSPM)on slow response action potential(SRAP)and slow inward current(Isi) of guinea pig papillary muscles were studied by intracellular microelectrodes and voltage clamp techniques.The APA and V_(max) of SRAP induced by high K￣+were decreased after 50 min of perfusion with DSPM solu- tion. Isi was suppressed from a peak value of8.8± 1.6μA to 5.7± 1.8μA, The results indicated that DSPM has a selective blocking effect on calcium channel.

A Higher Plant Myosin in Luffa cylindrica: Electron Microscopic Visualization

The molecular structure of a higher plant myosin with two 174 kD heavy chains purified from the tendrils of Luffa cylindrica (L.) Roem. was viewed by electron microscopy. The myosin exhibited actin_activated MgATPase activity and could be recognized immunologically by a monoclonal antibody against the skeletal muscle myosin. Electron micrographs of rotary shadowed images of this protein revealed that it had two heads with size and shape similar to those of the skeletal muscle myosin and a relatively short tail in comparison with the conventional myosin. Luffa tendril actin filaments were also visualized and occasionally other Luffa myosin_like proteins with globular structure at the tail ends were also observed. The structural similarity and immunological cross reactivity with antibodies against muscle myosin demonstrate that the 174 kD Luffa tendril myosin is a double_headed myosin. The possible involvement of myosin_actin interactions in Luffa tendril contact coiling will be the subject of further research.

Myoelectric activity and motility of the Roux limb after cut or uncut Roux-en-Y gastrojejunostomy

AIM: To explore the mechanisms of uncut Roux-en-Y gastrojejunostomy, which is used to decrease the occurrence of Roux stasis syndrome.METHODS: The changes of myoelectric activity, mechanic motility and interstitial cells of Cajal (ICC) of the Roux limb after cut or uncut Roux-en-Y gastrojejunostomy were observed. RESULTS: When compared with the cut group, the amplitude (1.15 ± 0.15 mV vs 0.48 ± 0.06 mV, P < 0.05) and frequency (14.4 ± 1.9 cpm vs 9.5 ± 1.1 cpm, P < 0.01) of slow waves and the incidence (98.2% ± 10.4% vs 56.6% ± 6.4%, P < 0.05) and amplitude (0.58 ± 0.08 mV vs 0.23 ± 0.06 mV, P < 0.01) of spike potential of the Roux limb in the uncut group were significantly higher. The migrating myoelectric complexes (MMC) phase Ⅲ duration in the uncut group was significantly prolonged (6.5 ± 1.1 min vs 4.4 ± 0.8 min, P < 0.05), while the MMC cycle obviously shortened (42.5 ± 6.8 vs 55.3 ± 8.2 min, P < 0.05). Both gastric emptying rate (65.5% ± 7.9% vs 49.3% ± 6.8%, P < 0.01) and intestinal impelling ratio (53.4% ± 7.4% vs 32.2% ± 5.4%, P < 0.01) in the uncut group were significantly increased. The contractile force index of the isolated jejunal segment in the uncut group was significantly higher (36.8 ± 5.1 vs 15.3 ± 2.2, P < 0.01), and the expression of c-kit mRNA was significantly increased in the uncut group (0.82 ± 0.11 vs 0.35 ± 0.06, P < 0.01). CONCLUSION: Uncut Roux-en-Y gastrojejunostomymay lessen the effects of operation on myoelectric activity such as slow waves, spike potential, and MMC, decrease the impairment of gastrointestinal motility, and remarkably increase the expression of c-kit mRNA.

sEMG Feature Analysis on Forearm Muscle Fatigue During Isometric Contractions

In order to detect and assess the muscle fatigue state with the surface electromyography(sEMG) characteristic parameters,this paper carried out a series of isometric contraction experiments to induce the fatigue on the forearm muscles from four subjects,and recorded the sEMG signals of the flexor carpi ulnaris.sEMG's median frequency(MDF) and mean frequency(MF) were extracted by short term Fourier transform(STFT),and the root mean square(RMS) of wavelet coefficients in the frequency band of 5—45 Hz was obtained by continuous wavelet transform(CWT).The results demonstrate that both MDF and MF show downward trends within 1 min; however,RMS shows an upward trend within the same time.The three parameters are closely correlated with absolute values of mean correlation coefficients greater than 0.8.It is suggested that the three parameters above can be used as reliable indicators to evaluate the level of muscle fatigue during isometric contractions.

Effect of electroacupuncture at Sibai on the gastric myoelectric acitivities of denervated rats

AIM： To explore the mechanism of the exciting effects of electro-acupuncture （EA） at Sibai on the gastric myoelectric activities. METHODS： A total of 32 rats were randomly divided into four groups. Through intraperitoneal injection with atropine （the anti-cholinergic agent by blockade of muscarinic receptors）, hexarnethonium （automatic nerve ganglion-blocking agent） and reserpine （anti-adrenergic agent by depleting the adrenergic nerve terminal of its norepinephrine store）, effects of EA at Sibai on the gastric myoelectric activities of the denervated rats were observed. RESULTS： After intraperitoneal injection of atropine and hexamethonium, the average amplitude and ratio of period to time in the phase of high activity of gastric myoelectric slow wave, and the average numbers of the peaks of gastric myoelectric fast wave were significantly decreased （P 〈 0.01, P 〈 0.05, P 〈 0.01）, while after intraperitoneal injection of reserpine, the aforementioned three parameters were increased （P 〈 0.01, P 〈 0.05, P 〈 0.01）. EA at Sibai point partially relieved the inhibitory effect of atropine and hexamethonium on the gastric myoelectric activities in the rats （P 〈 0.05 or P 〉 0.05）. CONCLUSION： Cholinergic and adrenergic nervous systems and autonomic nerve ganglion participate in the peripheral passage of the controlling effects of EA at Foot Yangming Channel on gastrointestinal tract.

The Effect of Benzyltetrahydropalmatine (BTHP) on Action Potentials and the Two Components of Delayed Rectifying Potassium Currents in Guinea Pig Ventricular Myocytes

The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp technique. BTHP 30 μmol·L -1 significantly prolonged APD 90 from 143±16 ms to 184±21 ms ( P 【0.01, n=5) without affecting either the RP or APA, and the APD prolonging effects of BTHP were independent of extracellular Ca 2+ . BTHP inhibited both I kr (IC 50 =7 9 μmol·L -1 ) and I ks (IC 50 =22 4 μmol·L -1 ) in a concentration dependent fashion. The results demon strated that BTHP had no obvious selectivity for I kr and I ks .

Characterization of surface EMG signals using improved approximate entropy

An improved approximate entropy (ApEn) is presented and applied to characterize surface electromyography (sEMG) signals. In most previous experiments using nonlinear dynamic analysis, this certain processing was often confronted with the problem of insufficient data points and noisy circumstances, which led to unsatisfactory results. Compared with fractal dimension as well as the standard ApEn, the improved ApEn can extract information underlying sEMG signals more efficiently and accu- rately. The method introduced here can also be applied to other medium-sized and noisy physiological signals.

Analysis and Comparison of Safety and Fatigue Comfort of Postal Bicycles Based on Finite Element Method and sEMG

The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.

Motion Classification of EMG Signals Based on Wavelet Packet Transform and LS-SVMs Ensemble

This paper presents an effective method for motion classification using the surface electromyographic (sEMG) signal collected from the forearm. Given the nonlinear and time-varying nature of EMG signal, the wavelet packet transform (WPT) is introduced to extract time-frequency joint information. Then the multi-class classifier based on the least squares support vector machine (LS-SVM) is constructed and verified in the various motion classification tasks. The results of contrastive experiments show that different motions can be identified with high accuracy by the presented method. Furthermore, compared with other classifiers with different features, the performance indicates the potential of the SVM techniques combined with WPT in motion classification.

The distribution of motilin receptor in the amygdala of rats and its role in migrating myoelectric complex

Objective:To investigate the distribution of the motilin receptor in the amygdala of rats and its role in regulating the duodenal migrating myoelectric complex(MMC).Methods:The distribution of motilin receptor in the amygdala in adult SD rats was detected by immunohistochemistry methods,and the duodenal interdigestive MMC was recorded via the electrodes implanted in the duodenum and analyzed us- ing a multichannel recorder.Results:Motilin receptor was observed in the amygdala of rats.The great amount of motilin receptor was found in the medial amygdaloid nucleus,which was also abundant in the basolateral nucleus but less abundant in the basomedial amygdaloid nucleus,the central amygdaloid nucle- us and the lateral amygdaloid nucleus.The shortening of the duodenal MMC cycle duration and the in- crease of the amplitude and the frequency of phase $ were recorded after motilin receptors being bound with exogenous motilin in the amygdala.The effects could be completely blocked by the subdiaphragmatic vagotomy but not by the intravenous injections of atropine,phentolamine or propranolol.Anti-motilin serum could partially block these effects,and the destruction of the basolateral nucleus of the amygdala had no significant effects on the duodenal MMC.Conclusion:Motilin receptor is present in all the subnu- clei of the amygdala,with the greatest amount of motilin receptor present in the medial amygdaloid nucle- us.Microinjections of motilin in the amygdala can shorten the duodenal MMC cycle duration and increase the amplitude and the frequency of phaseⅢ.These effects might be accomplished via the amygdala-hy- pothalamus-brainstem-vagus pathway,indicating the important role of the amygdala motilin receptor in the duodenal MMC regulation.

Effect of a combined inversion and plantarflexion surface on ankle kinematics and EMG activities in landing

Purpose： The purpose of this study was to examine the effects of landing kinematics and electromyographic （EMG） activities of medial gastrocnemius on a combined inversion and plantarflexion surface on the ankle （MG）, peroneus longus （PL）, and tibialis anterior （TA） muscles. Methods： Twelve recreational athletes performed five drop landings from an overhead bar of 30 cm height on to three surfaces： a flat surface, a 25° inversion surface, and a combined surface of 25° inversion and 25° plantarflexion. The kinematic variables and integrated EMG （IEMG） of the three muscles were assessed using a one-way repeated measures ANOVA and a 3 × 3 （surface × muscle） ANOVA, respectively （p 〈 0.05）. Results： The IEMG results showed a significant muscle by surface interaction. The flat surface induced higher TA activity than the two tilted surfaces. The inverted surface produced significantly higher inversion peak angle and velocity than the flat surface, but similar PL activity across the surfaces. The MG IEMG, ankle plantarflexion angle, and inversion range of motion were significantly higher for the combined surface compared to the inverted surface. Conclusion： These findings suggest that compared to the inversion surface, the combined plantarflexion and inversion surface seems to provide a more unstable surface condition for lateral ankle sprains during landing.

Impaired gastric myoelectricity in patients with chronic pancreatitis: Role of maldigestion

AIM: To investigate whether gastric myoelectrical activity was impaired in patients with chronic pancreatitis (CP) and to explore the role of pancreatic enzyme in regulating gastric myoelectrical activity. METHODS: Twenty CP patients and 20 controls participated in the study. Gastric myoelectrical activity was recorded by a homemade electrogastrography (EGG) device. Two experiments were carried out. In experiment one, EGG was recorded in both controls and CP patients. While in experiment two, either pancreatic enzymes or placebo was given together with test meals. Spectral analysis was used to generate various EGG parameters. RESULTS: The control subjects, but not the CP patients, showed typically increased postprandial dominant frequency. The postprandial dominant power (DP) increment (2.24±1.13 vs 5.35±0.96 dB, P= 0.04) and the percentage of normal 2-4 cpm slow waves (63.0±3.8% vs 77.4±3.1%, P<0.05) were lower in CP patients when compared with the control. In the 20 CP patients, the DP increment (4.76±1.02 vs 2.53±1.20 dB, P<0.05) and the postprandial percentage of normal 2-4 cpm (74.4±2.8% vs 64.8±5.7%, P<0.05) were significantly higher with pancreatic enzyme replacement than the placebo. CONCLUSION: CP patients have an abnormal postprandial stomach myoelectricity showing poor response in dominant frequency/power and regularity, whereas these abnormalities are corrected after pancreatic enzyme replacement. Maldigestion is likely to be the factor leading to abnormal postprandial gastric myoelectricity of CP patients.

Determine an effective golf swing by swing speed and impact precision tests

Background： To understand an effective golf swing, both swing speed and impact precision must be thoroughly and simultaneously examined. The aim of this study was to perform both swing speed test and impact precision test to ascertain what swing type determines an effective impact. Methods： Seven golfers from a college team （handicap： 0--12） were recruited to complete a swing speed test and impact precision test using a 5-iron club, A force plate and electromyography （EMG） system were used to collect data in the swing speed test to compare the difference between two motion sequences. High speed video cameras were used to determine the displacement of rotation center for impact precision test. Results： The results showed a significant difference （p 〈 0.01） in clubhead speed with different motion sequences and muscle contraction patterns. In the impact precision test, the displacement of the rotation center which defined as the inner center point of the C7 was significantly different （p 〈 0.05） between different ball impacted marks on club face. Conclusion： The vertical peak ground reaction force on left foot occurring before impact and the left latissimus dorsi contracting prior to the right pectoralis major represent a superior skill by allowing the club to strike the ball with normal collision at a faster speed.