Displaying publications 1 - 20 of 83 in total

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  1. Mechanisms underlining gender differences in Phenylephrine contraction of normoglycaemic and short-term Streptozotocin-induced diabetic WKY rat aorta
    Aloysius UI, Achike FI, Mustafa MR
    Vascul. Pharmacol., 2012 Sep-Oct;57(2-4):81-90.
    PMID: 22172524 DOI: 10.1016/j.vph.2011.11.009
    The female gender reduces the risk, but succumbs more to cardiovascular disease. The hypothesis that short-term (8weeks) Streptozotocin-induced diabetes could produce greater female than male vascular tissue reactivity and the mechanistic basis were explored. Aortic ring responses to Phenylephrine were examined in age- and sex-matched normoglycaemic/diabetic rats. The normoglycaemic male tissue contracted significantly more than the normoglycaemic female and the male/female diabetic tissues. Endothelial-denudation, l-NAME or MB reversed these differences suggesting an EDNO-cGMP dependence. 17β-oestradiol exerted relaxant effect on all endothelium-denuded (and normoglycaemic endothelium-intact male) tissues, but not endothelium-intact normoglycaemic female. The greater male tissue contraction is attributable to absent 17β-oestradiol-modulated relaxation. Indomethacin blockade of COX attenuated male normoglycaemic and female diabetic tissue contraction (both reversed by l-NAME), but augmented diabetic male tissue contraction. These data are consistent with the raised contractile TXA(2) and PGE(2) in normoglycaemic male and diabetic female tissues, and the relaxant PGI(2) in diabetic male (and female). The higher levels of PGI(2) in the normoglycaemic and diabetic female perhaps explain their greater relaxant response to Acetylcholine compared to the respective male. In conclusion, there is an endothelium-dependent gender difference in the effect of short term diabetes on vascular tissue reactivity which is COX mediated.
    Matched MeSH terms: Muscle Contraction/drug effects
  2. Hydrogen peroxide modulates angiotensin II-induced contraction of mesenteric arteries from streptozotocin-induced diabetic rats
    Chin LC, Achike FI, Mustafa MR
    Vascul. Pharmacol., 2007 Mar;46(3):223-8.
    PMID: 17126611 DOI: 10.1016/j.vph.2006.10.005
    Hydrogen peroxide (H(2)O(2)) contributes in the regulation of vascular tone, especially in pathological states. The role of H(2)O(2) and superoxide anion free radicals in angiotensin II (Ang II)-induced contraction of diabetic tissues was examined with the aim of elucidating the underlying mechanisms. Isometric tension in response to various drug treatments was measured in isolated superior mesenteric arteries of streptozotocin (STZ)-induced diabetic WKY rats using the Mulvany wire myograph. Compared to the normal (euglycaemic) arteries, the Ang II-induced contraction was significantly reduced in diabetic arteries. Superoxide dismutase (SOD; converts superoxide to H(2)O(2)) significantly reduced the contraction in both types of arteries -- an effect abolished by catalase (H(2)O(2) scavenger), suggesting that the SOD effect was mediated by H(2)O(2). Treatment with catalase had no effect on the Ang II contraction in euglycaemic arteries, but it raised the contraction in diabetic arteries to euglycaemic levels. This increase was similar to that observed with diabetic arteries incubated with L-NAME. Combined catalase and L-NAME treatment further enhanced the contraction in diabetic arteries, suggesting that the catalase effect was not mediated by nitric oxide (NO). The catalase effect was abolished by indomethacin treatment. These results suggest that attenuation of Ang II-induced contraction in diabetic tissues is modulated by endogenous H(2)O(2), the scavenging of which unmasks an indomethacin-sensitive (and therefore cyclooxygenase product-mediated) Ang II-induced contraction.
    Matched MeSH terms: Muscle Contraction/drug effects
  3. Inhibition of calcium-dependent contractions of the isolated guinea-pig ileal longitudinal muscle and taenia coli by the total glycosidic extract of the plant Sarcolobus globosus
    Mustafa MR
    Toxicon, 1993 Jan;31(1):67-74.
    PMID: 8446965
    The effect of the total glysosidic extract of the plant Sarcolobus globosus was investigated on the contractions of the smooth muscle of the guinea-pig ileal longitudinal muscle and taenia coli. In the ileal longitudinal muscle, addition of the extract inhibited the electrical field-stimulated twitches. Similarly to verapamil, it also reduced the contractions of the muscle to acetylcholine, histamine and KCl. However, only the tonic contraction to KCl was reversed by increasing the extracellular calcium concentration. In the taenia coli, lower concentrations of both the extract and verapamil induced a parallel displacement of the dose-response curves to calcium (0.30-30 mM). Addition of the extract also dose-dependently inhibited the KCl-induced contraction of the taenia coli. Increasing the calcium concentration increased the IC50 values of the extract. The result suggests that the inhibitory effect of the Sarcolobus globosus extract on the smooth muscle, like verapamil, is mainly due to inhibition of calcium influx.
    Matched MeSH terms: Muscle Contraction/drug effects
  4. Neuromuscular effects of four phospholipases A2 from the venom of Pseudechis australis, the Australian king brown snake
    Geh SL, Rowan EG, Harvey AL
    Toxicon, 1992 Sep;30(9):1051-7.
    PMID: 1440642
    Four homologous single chain phospholipases A2 (Pa-1G, Pa-5, Pa-12C and Pa-15) were tested for neuromuscular effects on chick biventer cervicis and mouse hemidiaphragm nerve-muscle preparations. The four isozymes blocked directly elicited (mouse hemidiaphragm) and indirectly elicited (mouse and chick nerve-muscle preparations) twitch responses in concentrations of 1-30 micrograms/ml. The order of potency seen in both types of preparations was Pa-1G = Pa-5 greater than Pa-12C much greater than Pa-15. All four isozymes caused slow-onset, sustained contractures and reduction of muscle membrane potentials. In the chick preparation, responses to acetylcholine, carbachol and KCl were reduced by exposure to the toxins. It is concluded that the toxins act primarily postsynaptically to depress muscle contractility, perhaps by directly damaging muscle fibres. The order of potency agrees with their phospholipase A2 activity. Pa-1G is unusual because it is an acidic molecule, most toxic phospholipases being basic.
    Matched MeSH terms: Muscle Contraction/drug effects
  5. The in vitro neuromuscular activity of Indo-Pacific sea-snake venoms: efficacy of two commercially available antivenoms
    Chetty N, Du A, Hodgson WC, Winkel K, Fry BG
    Toxicon, 2004 Aug;44(2):193-200.
    PMID: 15246769
    We examined the neurotoxicity of the following sea snake venoms: Enhydrina schistosa (geographical variants from Weipa and Malaysia), Lapemis curtus (Weipa and Malaysia), Laticauda colubrina, Aipysurus laevis, Aipysurus fuscus and Aipysurus foliosquamatus. Venom from a terrestrial snake, Notechis scutatus (tiger snake), was used as a reference. All venoms (1 and 3 microg/ml) abolished indirect twitches of the chick biventer cervicis muscle and significantly inhibited responses to ACh (1 mM) and CCh (20 microM), but not KCl (40 mM), indicating the presence of post-synaptic toxins. Prior administration (10 min) of CSL sea snake antivenom (1 unit/ml) attenuated the twitch blockade produced by N. scutatus venom and all sea snake venoms (1 microg/ml). Prior administration (10 min) of CSL tiger snake antivenom (1 unit/ml) attenuated the twitch blockade of all venoms except those produced by E. schistosa (Malaysia and Weipa) and A. foliosquamatus. Administration of CSL sea snake antivenom (1 unit/ml) at t90 (i.e. time at which 90% inhibition of initial twitch height occurred) reversed the inhibition of twitches (20-50%) produced by the sea snake venoms (1 microg/ml) but not by N. scutatus venom (1 microg/ml). CSL tiger snake antivenom (1 unit/ml) administered at t90 produced only minor reversal (i.e. 15-25%) of the twitch blockade caused by L. curtus (Weipa), A. foliosquamatus, L. colubrina and A. laevis venoms (1 microg/ml). Differences in the rate of reversal of the neurotoxicity produced by the two geographical variants of E. schistosa venom, after addition of CSL sea snake antivenom, indicate possible differences in venom components. This study shows that sea snake venoms contain potent post-synaptic activity that, despite the significant genetic distances between the lineages, can be neutralised with CSL sea snake antivenom. However, the effects of CSL tiger snake antivenom are more variable.
    Matched MeSH terms: Muscle Contraction/drug effects*
  6. Fulltext Effect of noni (Morinda citrifolia Linn.) fruit and its bioactive principles scopoletin and rutin on rat vas deferens contractility: an ex vivo study
    Pandy V, Narasingam M, Kunasegaran T, Murugan DD, Mohamed Z
    ScientificWorldJournal, 2014;2014:909586.
    PMID: 25045753 DOI: 10.1155/2014/909586
    This study examined the effect of methanolic extract of Morinda citrifolia Linn. (MMC) and its bioactive principles, scopoletin and rutin, on dopamine- and noradrenaline-evoked contractility in isolated rat vas deferens preparations. MMC (1-40 mg/mL), scopoletin (1-200 μg/mL), and rutin hydrate (0.6-312.6 μg/mL) dose-dependently inhibited the contractility evoked by submaximal concentrations of both dopamine and noradrenaline, respectively. Haloperidol and prazosin, reference dopamine D2, and α 1-adrenoceptors antagonists significantly reversed the dopamine- and noradrenaline-induced contractions, respectively, in a dose-dependent manner. Interestingly, MMC per se at higher doses (60-100 mg/mL) showed dose-dependent contractile response in rat vas deferens which was partially inhibited by high doses of haloperidol but not by prazosin. These results demonstrated the biphasic effects of MMC on dopaminergic system; that is, antidopaminergic effect at lower concentrations (<40 mg/mL) and dopaminergic agonistic effect at higher concentrations (>60 mg/mL). However, similar contractile response at high doses of scopoletin (0.5-5 mg/mL) and rutin hydrate (0.5-5 mg/mL) per se was not observed. Therefore, it can be concluded that the bioactive principles of MMC, scopoletin, and rutin might be responsible for the antidopaminergic and antiadrenergic activities of MMC.
    Matched MeSH terms: Muscle Contraction/drug effects*
  7. Fulltext Objective triceps muscle strength measurement using computerized adaptation
    Amalourde A, Vinayaga P, Naveed N, Choon SK, Zaleha O
    Med J Malaysia, 2004 Dec;59 Suppl F:8-13.
    PMID: 15941154
    In our centre the non-availability computerized exercise machines limits the objective monitoring of strength rehabilitation. We undertook this research programme to objectively measure triceps muscle strength by interfacing NORSK-Gym machine with accelerometer and positional transducers to a computer. This data was tabulated and processed using Microsoft Excel. The positional transducer was first calibrated and it showed an excellent Pearson Correlation Coefficients against a standard metric reading (r = 0.9999). Peak Force was used as a test parameter for isotonic triceps muscle strength measurements. The criterion-referenced validity was established as the peak forces measured using the accelerometer and positional transducer demonstrated identical Peak Forces (r = 0.94). Analysis of our mean Peak Force measurements using non-biological force as well as the intra-individual reproducibility demonstrated excellent Pearson Correlation Coefficients (r) = 0.982-0.998 and 0.929-0.972 respectively. This computerized adaptation of the NORSK-Gym machine produced an objective, valid and reproducible triceps muscle strength measurement.
    Matched MeSH terms: Muscle Contraction/physiology*
  8. Fulltext Cardiovascular and metabolic responses to isometric exercise of athletes and non-athletes
    Rajikin MH
    Med J Malaysia, 1980 Sep;35(1):46-52.
    PMID: 6973059
    Seven non-anthletes [21-26 yrs] and five athletes [23-29 yrs] have participated in the study of cardiovascular and metabolic responses to 15 minutes isometric leg exercise at 15% of each of their maximal voluntary contraction force [MVC]. Oxygen consumption [V02 ]. heart rate [HR] and blood pressure (BP]. were measured during resting. exercise and recovery! periods. The results show that there were a significant increase in V02. HR and BP of the two groups studied during exercise, but no significant difference between groups has been found. This study indicates that although cardiovascular response between the rwo groups was not significantly different, 15 minutes isometric leg exercise at 15% MVC has challenged this system in a such a way to fulfill the metabolic requirement of the
    working muscle ill both groups. This finding was
    discussed in light of the available literatures.
    Matched MeSH terms: Muscle Contraction
  9. Salbutamol in premature labour--a preliminary report
    Ken DK, Ng KH
    Med J Malaysia, 1974 Mar;28(3):191-3.
    PMID: 4278259
    Matched MeSH terms: Muscle Contraction/drug effects
  10. Prostaglandin F 2 for induction of labour
    Cheah SF, Khairuddin Y
    Med J Malaysia, 1973 Mar;27(3):211-6.
    PMID: 4268927
    Matched MeSH terms: Muscle Contraction/drug effects
  11. A demonstration of the use of the polygraph to record Schultz-Dale reactions utilizing sera of monkeys infected with Brugia malayi as sources of both antibody and antigen
    Guest MF, Kek CL, Wong MM, Cheong LK
    Med J Malaya, 1966 Jun;20(4):325-6.
    PMID: 4224346
    Matched MeSH terms: Muscle Contraction/physiology*
  12. Characterization of the possible mechanisms underlying the hypotensive and spasmogenic effects of Loranthus ferrugineus methanolic extract
    Ameer OZ, Salman IM, Siddiqui MJ, Yam MF, Sriramaneni RN, Sadikun A, et al.
    Am J Chin Med, 2009;37(5):991-1008.
    PMID: 19885958
    In the present study, L. ferrugineus methanol extract (LFME) was evaluated for its blood pressure lowering effect in anesthetized normotensive Sprague Dawley (SD) rats and its spasmogenic effect in isolated guinea pig ileum. The possible mechanism(s) of action were also investigated. LFME was obtained by Soxhlet extraction. The rats were fasted overnight and anesthetized with sodium pentobarbitone (60 mg/kg i.p.). LFME was administered in i.v. boluses in the concentrations of 25, 50, 100 and 200 mg/kg respectively, with concomitant monitoring of mean arterial pressure (MAP). It was found that LFME dose-dependently reduced MAP. An i.v. bolus injection of atropine significantly decreased the blood pressure lowering effect of LFME. Similarly, L-NAME (Nomega-nitro-L-arginine methyl ester) significantly lowered both the MAP and the action duration. Conversely, no significant change in MAP was seen following i.v. injections of neostigmine, hexamethonium, prazosin and propranolol. LFME also produced a dose-dependent contractile effect in guinea pig ileum. This contraction was significantly reduced in atropine pre-incubated tissue segments, yet it was significantly enhanced in the presence of neostigmine. No appreciable change in the ability of LFME to contract guinea pig ileum was seen in the presence of hexamethonium. Accordingly, it can be postulated that LFME possesses a marked hypotensive effect that can be attributed to stimulation of muscarinic receptors and/or stimulation of nitric oxide (NO) release. Moreover, LFME retains a considerable spasmogenic action due to its cholinergic properties. The hypotensive and spasmogenic effects of LFME justify its traditional uses.
    Matched MeSH terms: Muscle Contraction/drug effects
  13. Evaluation of repetitive isometric contractions on the heads of triceps brachii muscle during grip force exercise
    Ali MA, Sundaraj K, Ahmad RB, Ahamed NU, Islam MA, Sundaraj S
    Technol Health Care, 2014;22(4):617-25.
    PMID: 24990168 DOI: 10.3233/THC-140833
    Normally, surface electromyography electrodes are used to evaluate the activity of superficial muscles during various kinds of voluntary contractions of muscle fiber. The objective of the present study was to investigate the effect of repetitive isometric contractions on the three heads of the triceps brachii muscle during handgrip force exercise.
    Matched MeSH terms: Muscle Contraction/physiology*
  14. Electrical stimulation-evoked contractions blunt orthostatic hypotension in sub-acute spinal cord-injured individuals: two clinical case studies
    Hamzaid NA, Tean LT, Davis GM, Suhaimi A, Hasnan N
    Spinal Cord, 2015 May;53(5):375-9.
    PMID: 25366533 DOI: 10.1038/sc.2014.187
    STUDY DESIGN: Prospective study of two cases.

    OBJECTIVES: To describe the effects of electrical stimulation (ES) therapy in the 4-week management of two sub-acute spinal cord-injured (SCI) individuals (C7 American Spinal Injury Association Impairment Scale (AIS) B and T9 AIS (B)).

    SETTING: University Malaya Medical Centre, Kuala Lumpur, Malaysia.

    METHODS: A diagnostic tilt-table test was conducted to confirm the presence of orthostatic hypotension (OH) based on the current clinical definitions. Following initial assessment, subjects underwent 4 weeks of ES therapy 4 times weekly for 1 h per day. Post-tests tilt table challenge, both with and without ES on their rectus abdominis, quadriceps, hamstrings and gastrocnemius muscles, was conducted at the end of the study (week 5). Subjects' blood pressures (BP) and heart rates (HR) were recorded every minute during pre-test and post-tests. Orthostatic symptoms, as well as the maximum tolerance time that the subjects could withstand head up tilt at 60°, were recorded.

    RESULTS: Subject A improved his orthostatic symptoms, but did not recover from clinically defined OH based on the 20-min duration requirement. With concurrent ES therapy, 60° head up tilt BP was 89/62 mm Hg compared with baseline BP of 115/71 mm Hg. Subject B fully recovered from OH demonstrated by BP of 105/71 mm Hg during the 60° head up tilt compared with baseline BP of 124/77 mm Hg. Both patients demonstrated longer tolerance time during head up tilt with concomitant ES (subject A: pre-test 4 min, post-test without ES 6 min, post-test with ES 12 min; subject B: pre-test 4 min, post-test without ES 28 min, post-test with ES 60 min).

    CONCLUSIONS: Weekly ES therapy had positive effect on OH management in sub-acute SCI individuals.

    Matched MeSH terms: Muscle Contraction/physiology*
  15. Fulltext Mechanomyographic parameter extraction methods: an appraisal for clinical applications
    Ibitoye MO, Hamzaid NA, Zuniga JM, Hasnan N, Wahab AK
    Sensors (Basel), 2014;14(12):22940-70.
    PMID: 25479326 DOI: 10.3390/s141222940
    The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories of the methods used to extract parameters of the signal is vital to the application of the signal during experimental and clinical practices, especially in areas where electromyograms are contraindicated or have limited application. As we highlight the underpinning technical guidelines and domains where each method is well-suited, the limitations of the methods are also presented to position the state of the art in MMG parameters extraction, thus providing the theoretical framework for improvement on the current practices to widen the opportunity for new insights and discoveries. Since the signal modality has not been widely deployed due partly to the limited information extractable from the signals when compared with other classical techniques used to assess muscle performance, this survey is particularly relevant to the projected future of MMG applications in the realm of musculoskeletal assessments and in the real time detection of muscle activity.
    Matched MeSH terms: Muscle Contraction*
  16. Fulltext The effectiveness of FES-evoked EMG potentials to assess muscle force and fatigue in individuals with spinal cord injury
    Ibitoye MO, Estigoni EH, Hamzaid NA, Wahab AK, Davis GM
    Sensors (Basel), 2014;14(7):12598-622.
    PMID: 25025551 DOI: 10.3390/s140712598
    The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05) between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population.
    Matched MeSH terms: Muscle Contraction*
  17. Fulltext Surface electromyography signal processing and classification techniques
    Chowdhury RH, Reaz MB, Ali MA, Bakar AA, Chellappan K, Chang TG
    Sensors (Basel), 2013;13(9):12431-66.
    PMID: 24048337 DOI: 10.3390/s130912431
    Electromyography (EMG) signals are becoming increasingly important in many applications, including clinical/biomedical, prosthesis or rehabilitation devices, human machine interactions, and more. However, noisy EMG signals are the major hurdles to be overcome in order to achieve improved performance in the above applications. Detection, processing and classification analysis in electromyography (EMG) is very desirable because it allows a more standardized and precise evaluation of the neurophysiological, rehabitational and assistive technological findings. This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG signals. This study then compares the numerous methods of analyzing EMG signals, in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.
    Matched MeSH terms: Muscle Contraction/physiology*
  18. Fulltext Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression
    Ibitoye MO, Hamzaid NA, Abdul Wahab AK, Hasnan N, Olatunji SO, Davis GM
    Sensors (Basel), 2016 Jul 19;16(7).
    PMID: 27447638 DOI: 10.3390/s16071115
    The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES) in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG) of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR) due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70%) and testing (30%) subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R²) between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE) of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation.
    Matched MeSH terms: Muscle Contraction
  19. Fulltext A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions
    Nazmi N, Abdul Rahman MA, Yamamoto S, Ahmad SA, Zamzuri H, Mazlan SA
    Sensors (Basel), 2016 Aug 17;16(8).
    PMID: 27548165 DOI: 10.3390/s16081304
    In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.
    Matched MeSH terms: Muscle Contraction/physiology
  20. Fulltext Mechanomyography and Torque during FES-Evoked Muscle Contractions to Fatigue in Individuals with Spinal Cord Injury
    Mohamad NZ, Hamzaid NA, Davis GM, Abdul Wahab AK, Hasnan N
    Sensors (Basel), 2017 Jul 14;17(7).
    PMID: 28708068 DOI: 10.3390/s17071627
    A mechanomyography muscle contraction (MC) sensor, affixed to the skin surface, was used to quantify muscle tension during repetitive functional electrical stimulation (FES)-evoked isometric rectus femoris contractions to fatigue in individuals with spinal cord injury (SCI). Nine persons with motor complete SCI were seated on a commercial muscle dynamometer that quantified peak torque and average torque outputs, while measurements from the MC sensor were simultaneously recorded. MC-sensor-predicted measures of dynamometer torques, including the signal peak (SP) and signal average (SA), were highly associated with isometric knee extension peak torque (SP: r = 0.91, p < 0.0001), and average torque (SA: r = 0.89, p < 0.0001), respectively. Bland-Altman (BA) analyses with Lin's concordance (ρC) revealed good association between MC-sensor-predicted peak muscle torques (SP; ρC = 0.91) and average muscle torques (SA; ρC = 0.89) with the equivalent dynamometer measures, over a range of FES current amplitudes. The relationship of dynamometer torques and predicted MC torques during repetitive FES-evoked muscle contraction to fatigue were moderately associated (SP: r = 0.80, p < 0.0001; SA: r = 0.77; p < 0.0001), with BA associations between the two devices fair-moderate (SP; ρC = 0.70: SA; ρC = 0.30). These findings demonstrated that a skin-surface muscle mechanomyography sensor was an accurate proxy for electrically-evoked muscle contraction torques when directly measured during isometric dynamometry in individuals with SCI. The novel application of the MC sensor during FES-evoked muscle contractions suggested its possible application for real-world tasks (e.g., prolonged sit-to-stand, stepping,) where muscle forces during fatiguing activities cannot be directly measured.
    Matched MeSH terms: Muscle Contraction
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