Displaying publications 1 - 20 of 28 in total

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  1. Does performing drop jumps with additional eccentric loading improve jump performance?
    Aboodarda SJ, Byrne JM, Samson M, Wilson BD, Mokhtar AH, Behm DG
    J Strength Cond Res, 2014 Aug;28(8):2314-23.
    PMID: 24796986 DOI: 10.1519/JSC.0000000000000498
    Previous investigators have speculated that applying additional external load throughout the eccentric phase of the jumping movement could amplify the stretch-shortening cycle mechanism and modulate jumping performance and jump exercise intensity. The aims of this study, therefore, were to determine the effect of increased eccentric phase loading, as delivered using an elastic device, on drop jumps (DJs) performed from different drop heights. Of specific interest were changes in (a) the kinetics; eccentric and concentric impulse, rate of force development (RFD), concentric velocity and (b) the electromyographic (EMG) activity of leg muscles. In a randomized repeated-measure study, 15 highly resistance trained male subjects performed DJs from 3 heights (20, 35, and 50 cm) under 3 different conditions: body weight only (free DJ) and with elastic bands providing downward force equivalent to 20% (+20% DJ) and 30% (+30% DJ) of body mass. All DJs were recorded using video and force plate data that were synchronized with EMG data. Results demonstrated that using additional tensile load during the airborne and eccentric phases of the DJ could enhance eccentric impulse (p = 0.042) and RFD (p < 0.001) and resulted in small to moderate effect size (ES) increases in quadriceps intergrated EMG across the eccentric phase (0.23 > ES > 0.51). The observed greater eccentric loading, however, did not immediately alter concentric kinetics and jump height nor did it alter muscle activation levels during this phase. The findings indicated that, in addition to the conventional technique of increasing drop height, using a tensile load during the airborne and eccentric phases of the DJ could further improve eccentric loading of DJs. As it has been suggested that eccentric impulse and RFD are indicators of DJ exercise intensity, these findings suggest that the loaded DJs, using additional elastic load, may be an effective technique for improving DJ exercise intensity without acute effects on the jumping performance and neuromuscular activation level in highly trained athletes.
    Matched MeSH terms: Muscle Contraction/physiology*
  2. Strength and fatigue of lumbar extensor muscles in older adults
    Ajit Singh DK, Bailey M, Lee R
    Muscle Nerve, 2011 Jul;44(1):74-9.
    PMID: 21488056 DOI: 10.1002/mus.21998
    Loss of lumbar extensor muscle strength and fatigue resistance may contribute to functional disability.
    Matched MeSH terms: Muscle Contraction/physiology
  3. Potentiation of bradykinin-induced responses by indomethacin in the intact and denuded epithelium of guinea pig tracheal preparations
    Akbar A, Sharma JN, Yusof AP, Gan EK
    Int J Tissue React, 1998;20(3):95-100.
    PMID: 9894182
    We studied the effect of indomethacin, a cyclooxygenase inhibitor, on bradykinin-induced responses in the intact and denuded epithelium of the isolated tracheal smooth muscle in guinea pigs. Epithelium removal alone did not alter the responsiveness to bradykinin. Indomethacin (2.8 microM) enhanced the sensitivity to bradykinin of both intact and denuded preparations. This finding suggests that the tracheal epithelial may have no protective effect on the contractile responses induced by bradykinin. This may be due to the presence of high amounts of bradykinin-inactivating enzymes in the tracheal smooth muscle. Indomethacin-medicated potentiation caused by bradykinin in epithelium intact and denuded preparations may be an indication of removal of the bronchodilator prostaglandin biosynthesis. The significance of these findings is discussed.
    Matched MeSH terms: Muscle Contraction/physiology
  4. 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*
  5. 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*
  6. Characterization of surface electromyography using time domain features for determining hand motion and stages of contraction
    Bin Ahmad Nadzri AA, Ahmad SA, Marhaban MH, Jaafar H
    Australas Phys Eng Sci Med, 2014 Mar;37(1):133-7.
    PMID: 24443218 DOI: 10.1007/s13246-014-0243-3
    Surface electromyography (SEMG) signals can provide important information for prosthetic hand control application. In this study, time domain (TD) features were used in extracting information from the SEMG signal in determining hand motions and stages of contraction (start, middle and end). Data were collected from ten healthy subjects. Two muscles, which are flexor carpi ulnaris (FCU) and extensor carpi radialis (ECR) were assessed during three hand motions of wrist flexion (WF), wrist extension (WE) and co-contraction (CC). The SEMG signals were first segmented into 132.5 ms windows, full wave rectified and filtered with a 6 Hz low pass Butterworth filter. Five TD features of mean absolute value, variance, root mean square, integrated absolute value and waveform length were used for feature extraction and subsequently patterns were determined. It is concluded that the TD features that were used are able to differentiate hand motions. However, for the stages of contraction determination, although there were patterns observed, it is determined that the stages could not be properly be differentiated due to the variability of signal strengths between subjects.
    Matched MeSH terms: Muscle Contraction/physiology*
  7. 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*
  8. 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*
  9. 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*
  10. Reliability of measurement of muscle fiber conduction velocity using surface EMG
    Harba MI, Teng LY
    Front Med Biol Eng, 1999;9(1):31-47.
    PMID: 10354908
    Cross-correlating two surface EMG signals detected at two different locations along the path of flow of action potential enables the measurement of the muscle fiber average conduction velocity in those active motor units monitored by the electrodes. The position of the peak of the cross-correlation function is the time delay between the two signals and hence the velocity may be deduced. The estimated velocity using this technique has been observed previously to depend on the location of the electrodes on the muscle surface. Different locations produced different estimates. In this paper we present a measurement system, analyze its inherent inaccuracies and use it for the purpose of investigating the reliability of measurement of conduction velocity from surface EMG. This system utilizes EMG signals detected at a number of locations on the biceps brachii, when under light tension, to look for any pattern of variations of velocity as a function of location and time. It consists of a multi-electrode unit and a set of eight parallel on-line correlators. The electrode unit and the parallel correlators ensure that these measurements are carried out under the same physical and physiological conditions of the muscle. Further, the same detected signals are used in different measurement configurations to try to understand the reasons behind the observed variations in the estimated velocity. The results obtained seem to suggest that there will always be an unpredictable random component superimposed on the estimated velocity, giving rise to differences between estimates at different locations and differences in estimates with time at the same location. Many factors contribute to this random component, such as the non-homogeneous medium between the muscle fibers and the electrodes, the non-parallel geometry and non-uniform conduction velocity of the fibers, and the physical and physiological conditions of the muscle. While it is not possible to remove this random component completely from the measurement, the user must be aware of its presence and how to reduce its effects.
    Matched MeSH terms: Muscle Contraction/physiology
  11. Role of nitric oxide in skeletal muscle glucose uptake during exercise
    Hong YH, Betik AC, McConell GK
    Exp Physiol, 2014 Dec 1;99(12):1569-73.
    PMID: 25192731 DOI: 10.1113/expphysiol.2014.079202
    Nitric oxide is produced within skeletal muscle fibres and has various functions in skeletal muscle. There is evidence that NO may be essential for normal increases in skeletal muscle glucose uptake during contraction/exercise. Although there have been some discrepant results, it has been consistently demonstrated that inhibition of NO synthase (NOS) attenuates the increase in skeletal muscle glucose uptake during contraction in mouse and rat muscle ex vivo, during in situ contraction in rats and during exercise in humans. The NO-mediated increase in skeletal muscle glucose uptake during contraction/exercise is probably due to the modulation of intramuscular signalling that ultimately increases glucose transporter 4 (GLUT4) translocation and is, surprisingly, independent of blood flow. In this review, we discuss the evidence for and against a role of NO in regulating skeletal muscle glucose uptake during contraction/exercise and outline the possible mechanism(s) involved. Emerging findings regarding the role of neuronal NOS mu (nNOSμ) in this process are also discussed.
    Matched MeSH terms: Muscle Contraction/physiology*
  12. Fulltext No effect of NOS inhibition on skeletal muscle glucose uptake during in situ hindlimb contraction in healthy and diabetic Sprague-Dawley rats
    Hong YH, Betik AC, Premilovac D, Dwyer RM, Keske MA, Rattigan S, et al.
    Am J Physiol Regul Integr Comp Physiol, 2015 May 15;308(10):R862-71.
    PMID: 25786487 DOI: 10.1152/ajpregu.00412.2014
    Nitric oxide (NO) has been shown to be involved in skeletal muscle glucose uptake during contraction/exercise, especially in individuals with Type 2 diabetes (T2D). To examine the potential mechanisms, we examined the effect of local NO synthase (NOS) inhibition on muscle glucose uptake and muscle capillary blood flow during contraction in healthy and T2D rats. T2D was induced in Sprague-Dawley rats using a combined high-fat diet (23% fat wt/wt for 4 wk) and low-dose streptozotocin injections (35 mg/kg). Anesthetized animals had one hindlimb stimulated to contract in situ for 30 min (2 Hz, 0.1 ms, 35 V) with the contralateral hindlimb rested. After 10 min, the NOS inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME; 5 μM) or saline was continuously infused into the femoral artery of the contracting hindlimb until the end of contraction. Surprisingly, there was no increase in skeletal muscle NOS activity during contraction in either group. Local NOS inhibition had no effect on systemic blood pressure or muscle contraction force, but it did cause a significant attenuation of the increase in femoral artery blood flow in control and T2D rats. However, NOS inhibition did not attenuate the increase in muscle capillary recruitment during contraction in these rats. Muscle glucose uptake during contraction was significantly higher in T2D rats compared with controls but, unlike our previous findings in hooded Wistar rats, NOS inhibition had no effect on glucose uptake during contraction. In conclusion, NOS inhibition did not affect muscle glucose uptake during contraction in control or T2D Sprague-Dawley rats, and this may have been because there was no increase in NOS activity during contraction.
    Matched MeSH terms: Muscle Contraction/physiology*
  13. Fulltext Glucose uptake during contraction in isolated skeletal muscles from neuronal nitric oxide synthase μ knockout mice
    Hong YH, Frugier T, Zhang X, Murphy RM, Lynch GS, Betik AC, et al.
    J Appl Physiol (1985), 2015 May 1;118(9):1113-21.
    PMID: 25749441 DOI: 10.1152/japplphysiol.00056.2015
    Inhibition of nitric oxide synthase (NOS) significantly attenuates the increase in skeletal muscle glucose uptake during contraction/exercise, and a greater attenuation is observed in individuals with Type 2 diabetes compared with healthy individuals. Therefore, NO appears to play an important role in mediating muscle glucose uptake during contraction. In this study, we investigated the involvement of neuronal NOSμ (nNOSμ), the main NOS isoform activated during contraction, on skeletal muscle glucose uptake during ex vivo contraction. Extensor digitorum longus muscles were isolated from nNOSμ(-/-) and nNOSμ(+/+) mice. Muscles were contracted ex vivo in a temperature-controlled (30°C) organ bath with or without the presence of the NOS inhibitor N(G)-monomethyl-l-arginine (L-NMMA) and the NOS substrate L-arginine. Glucose uptake was determined by radioactive tracers. Skeletal muscle glucose uptake increased approximately fourfold during contraction in muscles from both nNOSμ(-/-) and nNOSμ(+/+) mice. L-NMMA significantly attenuated the increase in muscle glucose uptake during contraction in both genotypes. This attenuation was reversed by L-arginine, suggesting that L-NMMA attenuated the increase in muscle glucose uptake during contraction by inhibiting NOS and not via a nonspecific effect of the inhibitor. Low levels of NOS activity (~4%) were detected in muscles from nNOSμ(-/-) mice, and there was no evidence of compensation from other NOS isoform or AMP-activated protein kinase which is also involved in mediating muscle glucose uptake during contraction. These results indicate that NO regulates skeletal muscle glucose uptake during ex vivo contraction independently of nNOSμ.
    Matched MeSH terms: Muscle Contraction/physiology*
  14. Mechanomyography and muscle function assessment: a review of current state and prospects
    Ibitoye MO, Hamzaid NA, Zuniga JM, Abdul Wahab AK
    Clin Biomech (Bristol, Avon), 2014 Jun;29(6):691-704.
    PMID: 24856875 DOI: 10.1016/j.clinbiomech.2014.04.003
    Previous studies have explored to saturation the efficacy of the conventional signal (such as electromyogram) for muscle function assessment and found its clinical impact limited. Increasing demand for reliable muscle function assessment modalities continues to prompt further investigation into other complementary alternatives. Application of mechanomyographic signal to quantify muscle performance has been proposed due to its inherent mechanical nature and ability to assess muscle function non-invasively while preserving muscular neurophysiologic information. Mechanomyogram is gaining accelerated applications in evaluating the properties of muscle under voluntary and evoked muscle contraction with prospects in clinical practices. As a complementary modality and the mechanical counterpart to electromyogram; mechanomyogram has gained significant acceptance in analysis of isometric and dynamic muscle actions. Substantial studies have also documented the effectiveness of mechanomyographic signal to assess muscle performance but none involved comprehensive appraisal of the state of the art applications with highlights on the future prospect and potential integration into the clinical practices. Motivated by the dearth of such critical review, we assessed the literature to investigate its principle of acquisition, current applications, challenges and future directions. Based on our findings, the importance of rigorous scientific and clinical validation of the signal is highlighted. It is also evident that as a robust complement to electromyogram, mechanomyographic signal may possess unprecedented potentials and further investigation will be enlightening.
    Matched MeSH terms: Muscle Contraction/physiology*
  15. Analysis of crosstalk in the mechanomyographic signals generated by forearm muscles during different wrist postures
    Islam A, Sundaraj K, Ahmad RB, Sundaraj S, Ahamed NU, Ali MA
    Muscle Nerve, 2015 Jun;51(6):899-906.
    PMID: 25204740 DOI: 10.1002/mus.24454
    In this study, we analyzed the crosstalk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles of the forearm during wrist flexion (WF) and extension (WE) and radial (RD) and ulnar (UD) deviations.
    Matched MeSH terms: Muscle Contraction/physiology*
  16. Fulltext Mechanomyogram for muscle function assessment: a review
    Islam MA, Sundaraj K, Ahmad RB, Ahamed NU
    PLoS One, 2013;8(3):e58902.
    PMID: 23536834 DOI: 10.1371/journal.pone.0058902
    BACKGROUND: Mechanomyography (MMG) has been extensively applied in clinical and experimental practice to examine muscle characteristics including muscle function (MF), prosthesis and/or switch control, signal processing, physiological exercise, and medical rehabilitation. Despite several existing MMG studies of MF, there has not yet been a review of these. This study aimed to determine the current status on the use of MMG in measuring the conditions of MFs.

    METHODOLOGY/PRINCIPAL FINDINGS: Five electronic databases were extensively searched for potentially eligible studies published between 2003 and 2012. Two authors independently assessed selected articles using an MS-Word based form created for this review. Several domains (name of muscle, study type, sensor type, subject's types, muscle contraction, measured parameters, frequency range, hardware and software, signal processing and statistical analysis, results, applications, authors' conclusions and recommendations for future work) were extracted for further analysis. From a total of 2184 citations 119 were selected for full-text evaluation and 36 studies of MFs were identified. The systematic results find sufficient evidence that MMG may be used for assessing muscle fatigue, strength, and balance. This review also provides reason to believe that MMG may be used to examine muscle actions during movements and for monitoring muscle activities under various types of exercise paradigms.

    CONCLUSIONS/SIGNIFICANCE: Overall judging from the increasing number of articles in recent years, this review reports sufficient evidence that MMG is increasingly being used in different aspects of MF. Thus, MMG may be applied as a useful tool to examine diverse conditions of muscle activity. However, the existing studies which examined MMG for MFs were confined to a small sample size of healthy population. Therefore, future work is needed to investigate MMG, in examining MFs between a sufficient number of healthy subjects and neuromuscular patients.

    Matched MeSH terms: Muscle Contraction/physiology
  17. The Association Between Levator-Urethra Gap Measurements and Symptoms and Signs of Female Pelvic Organ Prolapse
    Kamisan Atan I, Shek KL, Furtado GI, Caudwell-Hall J, Dietz HP
    Female Pelvic Med Reconstr Surg, 2016 Nov-Dec;22(6):442-446.
    PMID: 27465815
    OBJECTIVES: Levator avulsion is associated with pelvic organ prolapse in women. It is diagnosed clinically by a widened gap on palpation between the insertion of the puborectalis muscle on the inferior pubic ramus and the urethra. This gap can also be assessed on imaging. This study aimed to determine the association between sonographically determined levator-urethral gap (LUG) measurements and symptoms and signs of prolapse.

    METHODS: This is a retrospective study on 450 women seen in a tertiary urogynecological center for symptoms of pelvic floor dysfunction between January 2013 and February 2014. All had a standardized interview, International Continence Society Pelvic Organ Prolapse Quantification assessment and 4-dimensional translabial ultrasound. Post-imaging analysis of archived ultrasound volumes for LUG measurement was undertaken on tomographic slices at the plane of minimal hiatal dimensions and within 5-mm cranial to this plane, bilaterally at an interslice interval of 2.5 mm, blinded against all clinical data. A LUG of 25 mm or greater was considered abnormal.

    RESULTS: Mean LUG and maximum LUG in individuals were 22.5 mm (SD, 4.6) and 26.4 mm (SD, 6.0), respectively, with at least 1 abnormal LUG in 51% (n = 222). An abnormal LUG in all 3 slices involving the plane of minimal hiatal dimensions and within 5 mm cranial to this plane on at least 1 side was fulfilled in 24% (n = 103). The LUG measurements were strongly associated with bother, symptoms and signs of prolapse (P < 0.001 to 0.002). This remained significant on multivariate analysis controlling for potential confounding factors.

    CONCLUSIONS: Sonographically determined LUG is strongly associated with symptoms, symptom bother, and pelvic organ prolapse on clinical examination and imaging.
    Matched MeSH terms: Muscle Contraction/physiology
  18. Changes in Muscle Activity in Response to Assistive Force during Isometric Elbow Flexion
    Loh PY, Hayashi K, Nasir N, Muraki S
    J Mot Behav, 2020;52(5):634-642.
    PMID: 31571525 DOI: 10.1080/00222895.2019.1670128
    This study investigated the muscle activity and force variability in response to perturbation of assistive force during isometric elbow flexion. Sixteen healthy right-handed young men (age: 22.0 ± 1.1 years; height: 171.9 ± 4.8 cm; weight 68.4 ± 11.2 kg) were recruited and the muscle activity of biceps brachii and triceps brachii were assessed using surface electromyography. Workload force and assistive force applied on isometric elbow flexion significantly affected the changes in both biceps and triceps muscle activities. A higher assistive force was shown to result in reduced biceps muscle activity compared to the unassisted period. In contrast, the efficiency of the assistive force acting on the biceps decreased as the assistive force increased. In general, the force variability of the biceps muscle remained approximately the same at lower workload force conditions than that at higher workload force conditions. In conclusion, higher assistive force may not yield a higher performance efficiency in human-assistive force interaction.
    Matched MeSH terms: Muscle Contraction/physiology
  19. Cyclic adenosine 3',5'-monophosphate content and bronchial smooth muscle contractility of hyper- and hypothyroid lungs
    Nabishah BM, Morat PB, Alias AK, Kadir BA, Khalid BA
    Clin Exp Pharmacol Physiol, 1992 Dec;19(12):839-42.
    PMID: 1335381
    1. Male Sprague-Dawley rats were made either hyper- or hypothyroid with thyroxine or 4-methyl-2-thiouracil, respectively. Bronchial smooth muscle (BSM) contractility and lung cyclic adenosine 3',5'-monophosphate (cAMP) content were measured in both conditions. 2. Bronchial smooth muscle contractility was significantly weaker in hyperthyroid rats, while the BSM contractility of hypothyroid rats was the same as controls. 3. The cAMP content of hyperthyroid rat lungs was similar to controls but was decreased in hypothyroid rats. 4. These studies demonstrated that both the hyper- and hypothyroid states affect respiration, although the mechanisms involved with different for each condition.
    Matched MeSH terms: Muscle Contraction/physiology
  20. Mechanomyography-based muscle fatigue detection during electrically elicited cycling in patients with spinal cord injury
    Naeem J, Hamzaid NA, Islam MA, Azman AW, Bijak M
    Med Biol Eng Comput, 2019 Jun;57(6):1199-1211.
    PMID: 30687901 DOI: 10.1007/s11517-019-01949-4
    Patients with spinal cord injury (SCI) benefit from muscle training with functional electrical stimulation (FES). For safety reasons and to optimize training outcome, the fatigue state of the target muscle must be monitored. Detection of muscle fatigue from mel frequency cepstral coefficient (MFCC) feature of mechanomyographic (MMG) signal using support vector machine (SVM) classifier is a promising new approach. Five individuals with SCI performed FES cycling exercises for 30 min. MMG signals were recorded on the quadriceps muscle group (rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM)) and categorized into non-fatigued and fatigued muscle contractions for the first and last 10 min of the cycling session. For each subject, a total of 1800 contraction-related MMG signals were used to train the SVM classifier and another 300 signals were used for testing. The average classification accuracy (4-fold) of non-fatigued and fatigued state was 90.7% using MFCC feature, 74.5% using root mean square (RMS), and 88.8% with combined MFCC and RMS features. Inter-subject prediction accuracy suggested training and testing data to be based on a particular subject or large collection of subjects to improve fatigue prediction capacity. Graphical abstract ᅟ.
    Matched MeSH terms: Muscle Contraction/physiology
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