Displaying publications 1 - 20 of 248 in total

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  1. Tan JY, Tan CY, Yahya MA, Shahrizaila N, Goh KJ
    Muscle Nerve, 2024 May;69(5):597-603.
    PMID: 38488306 DOI: 10.1002/mus.28081
    INTRODUCTION/AIMS: Muscle strength, functional status, and muscle enzymes are conventionally used to evaluate disease status in idiopathic inflammatory myopathies (IIM). This study aims to investigate the role of quantitative muscle ultrasound in evaluating disease status in IIM patients.

    METHODS: Patients with IIM, excluding inclusion body myositis, were recruited along with age- and sex-matched healthy controls (HC). All participants underwent muscle ultrasound and clinical assessments. Six limb muscles were unilaterally scanned using a standardized protocol, measuring muscle thickness (MT) and echo intensity (EI). Results were compared with HC, and correlations were made with outcome measures.

    RESULTS: Twenty IIM patients and 24 HC were recruited. The subtypes of IIM were dermatomyositis (6), necrotizing myositis (6), polymyositis (3), antisynthetase syndrome (3), and nonspecific myositis (2). Mean disease duration was 8.7 ± 6.9 years. There were no significant differences in demographics and anthropometrics between patients and controls. MT of rectus femoris in IIM patients was significantly lower than HC. Muscle EI of biceps brachii and vastus medialis in IIM patients were higher than HC. There were moderate correlations between MT of rectus femoris and modified Rankin Scale, Physician Global Activity Assessment, and Health Assessment Questionnaire, as well as between EI of biceps brachii and Manual Muscle Testing-8.

    DISCUSSION: Muscle ultrasound can detect proximal muscle atrophy and hyperechogenicity in patients with IIM. The findings correlate with clinical outcome measures, making it a potential tool for evaluating disease activity of patients with IIM in the late phase of the disease.

    Matched MeSH terms: Muscle, Skeletal
  2. Hamdan PNF, Hamzaid NA, Hasnan N, Abd Razak NA, Razman R, Usman J
    Sci Rep, 2024 Mar 18;14(1):6451.
    PMID: 38499594 DOI: 10.1038/s41598-024-56955-w
    Literature has shown that simulated power production during conventional functional electrical stimulation (FES) cycling was improved by 14% by releasing the ankle joint from a fixed ankle setup and with the stimulation of the tibialis anterior and triceps surae. This study aims to investigate the effect of releasing the ankle joint on the pedal power production during FES cycling in persons with spinal cord injury (SCI). Seven persons with motor complete SCI participated in this study. All participants performed 1 min of fixed-ankle and 1 min of free-ankle FES cycling with two stimulation modes. In mode 1 participants performed FES-evoked cycling with the stimulation of quadriceps and hamstring muscles only (QH stimulation), while Mode 2 had stimulation of quadriceps, hamstring, tibialis anterior, and triceps surae muscles (QHT stimulation). The order of each trial was randomized in each participant. Free-ankle FES cycling offered greater ankle plantar- and dorsiflexion movement at specific slices of 20° crank angle intervals compared to fixed-ankle. There were significant differences in the mean and peak normalized pedal power outputs (POs) [F(1,500) = 14.03, p 
    Matched MeSH terms: Muscle, Skeletal
  3. Zahari Z, Naga DNA, Bukry SA
    Med J Malaysia, 2024 Mar;79(Suppl 1):168-175.
    PMID: 38555902
    INTRODUCTION: Lower Cross Syndrome (LCS) is a prevalent condition that manifests as muscular tension due to the asymmetry in the strength of the lower extremity muscles. This imbalance could be due to the tautness of the iliopsoas, rectus femoris, tensor fascia latae, adductor group, gastrocnemius, and soleus muscles. LCS causes a postural imbalance in the individual, which triggers low back pain (LBP). When LCS is present alongside LBP, may cause the upper body to sway more in the transverse plane and at the lumbar level, making walking and termination of gait (GT) more difficult. However, the evidence of motor control and gait performance is scarce with inconclusive findings. Thus, this study aimed to review motor control on gait performance among individuals with lower crossed syndrome. This review is conducted to determine the motor control on gait performance in patients with LCS and how the conditions affect gait.

    MATERIALS AND METHODS: The databases Google Scholar, Science Direct, ResearchGate, PubMed, and Scopus were searched to identify potentially relevant documents. The keywords used for the search included "motor control" OR "motor learning" OR" core stability" AND "lower crossed syndrome" AND "gait". The search includes articles published between 1970 and 2022 and written in English. It is excluded when the paper is not a full-text article. After finding the articles, the information was extracted, including author, year of publication, country, objective, type of study, and motor control analysis summary.

    RESULTS: There were 107 articles retrieved from the search. but only seventeen articles were included for analysis. The finding demonstrates that LCS may associate with LBP and reduces the motor control of the core muscle stability which indirectly influences gait performance.

    CONCLUSIONS: This study suggests that individuals with LCS will have an alteration in their gait. However, there is still insufficient information on motor control in gait performance among lower crossed syndrome. Further research is needed to find what factors that may contribute to the adaptation of motor control in gait among LCS population.

    Matched MeSH terms: Muscle, Skeletal
  4. Li W, Hadizadeh M, Yusof A, Naharudin MN
    Sci Rep, 2024 Feb 27;14(1):4736.
    PMID: 38413632 DOI: 10.1038/s41598-024-54789-0
    The effects of IT and R.I.C.E. treatment on arm muscle performance in overhead athletes with elbow pain (EP) have been partially validated. However, there is a lack of research evidence regarding the efficacy of these two methods on arm muscle performance among swimmers with EP. The aim of this study was to investigate the trends and differences in the effects of IT and R.I.C.E. treatment on arm muscle performance among swimmers with EP. The main outcomes were the time effects and group effects of interventions on muscle voluntary contraction (MVC). Sixty elite freestyle swimmers from Tianjin, China, voluntarily participated in the study and completed a 10-week intervention program. Swimmers with EP in the IT group showed a positive trend in MVC, with an approximately 2% increase, whereas the MVC of subjects in the R.I.C.E. treatment group and control group decreased by approximately 4% and 5%, respectively. In comparison, the effects of the IT intervention on the MVC of the triceps and brachioradialis muscles in swimmers with EP were significant (p = 0.042 
    Matched MeSH terms: Muscle, Skeletal/physiology
  5. Tan SH, Khong TK, Selvanayagam VS, Yusof A
    Eur J Appl Physiol, 2024 Feb;124(2):403-415.
    PMID: 38038740 DOI: 10.1007/s00421-023-05350-w
    Rinsing the mouth with a carbohydrate (CHO) solution has been shown to enhance exercise performance while reducing neuromuscular fatigue. This effect is thought to be mediated through the stimulation of oral receptors, which activate brain areas associated with reward, motivation, and motor control. Consequently, corticomotor responsiveness is increased, leading to sustained levels of neuromuscular activity prior to fatigue. In the context of endurance performance, the evidence regarding the central involvement of mouth rinse (MR) in performance improvement is not conclusive. Peripheral mechanisms should not be disregarded, particularly considering factors such as low exercise volume, the participant's fasting state, and the frequency of rinsing. These factors may influence central activations. On the other hand, for strength-related activities, changes in motor evoked potential (MEP) and electromyography (EMG) have been observed, indicating increased corticospinal responsiveness and neuromuscular drive during isometric and isokinetic contractions in both fresh and fatigued muscles. However, it is important to note that in many studies, MEP data were not normalised, making it difficult to exclude peripheral contributions. Voluntary activation (VA), another central measure, often exhibits a lack of changes, mainly due to its high variability, particularly in fatigued muscles. Based on the evidence, MR can attenuate neuromuscular fatigue and improve endurance and strength performance via similar underlying mechanisms. However, the evidence supporting central contribution is weak due to the lack of neurophysiological measures, inaccurate data treatment (normalisation), limited generalisation between exercise modes, methodological biases (ignoring peripheral contribution), and high measurement variability.Trial registration: PROSPERO ID: CRD42021261714.
    Matched MeSH terms: Muscle, Skeletal/physiology
  6. Zuhri UM, Yuliana ND, Fadilah F, Erlina L, Purwaningsih EH, Khatib A
    J Ethnopharmacol, 2024 Jan 30;319(Pt 3):117296.
    PMID: 37820996 DOI: 10.1016/j.jep.2023.117296
    ETHNOPHARMACOLOGICAL RELEVANCE: Tinospora crispa (L.) Hook. f. & Thomson stem (TCS) has long been used as folk medicine for the treatment of diabetes mellitus. Previous study revealed that TCS possesses multi-ingredients and multi-targets characteristic potential as insulin sensitizer activity. However, its mechanisms of action and molecular targets are still obscure.

    AIM OF THE STUDY: In the present study, we investigated the effects of TCS against insulin resistance in muscle cells through integrating in vitro experiment and identifying its active biomarker using metabolomics and in molecular docking validation.

    MATERIALS AND METHODS: We used centrifugal partition chromatography (CPC) to isolate 33 fractions from methanolic extract of TCS, and then used UHPLC-Orbitrap-HRMS to identify the detectable metabolites in each fraction. We assessed the insulin sensitization activity of each fraction using enzyme-linked immunosorbent assay (ELISA), and then used confocal immunocytochemistry microscopy to measure the translocation of glucose transporter 4 (GLUT4) to the cell membrane. The identified active metabolites were further simulated for its molecular docking interaction using Autodock Tools.

    RESULTS: The polar fractions of TCS significantly increased insulin sensitivity, as measured by the inhibition of phosphorylated insulin receptor substrate-1 (pIRS1) at serine-312 residue (ser312) also the increasing number of translocated GLUT4 and glycogen content. We identified 58 metabolites of TCS, including glycosides, flavonoids, alkaloids, coumarins, and nucleotides groups. The metabolomics and molecular docking simulations showed the presence of minor metabolites consisting of tinoscorside D, higenamine, and tinoscorside A as the active compounds.

    CONCLUSIONS: Our findings suggest that TCS is a promising new treatment for insulin resistance and the identification of the active metabolites in TCS could lead to the development of new drugs therapies for diabetes that target these pathways.

    Matched MeSH terms: Muscle, Skeletal
  7. Uwamahoro R, Sundaraj K, Feroz FS
    Sensors (Basel), 2023 Sep 29;23(19).
    PMID: 37836995 DOI: 10.3390/s23198165
    Neuromuscular electrical stimulation plays a pivotal role in rehabilitating muscle function among individuals with neurological impairment. However, there remains uncertainty regarding whether the muscle's response to electrical excitation is affected by forearm posture, joint angle, or a combination of both factors. This study aimed to investigate the effects of forearm postures and elbow joint angles on the muscle torque and MMG signals. Measurements of the torque around the elbow and MMG of the biceps brachii (BB) muscle were conducted in 36 healthy subjects (age, 22.24 ± 2.94 years; height, 172 ± 0.5 cm; and weight, 67.01 ± 7.22 kg) using an in-house elbow flexion testbed and neuromuscular electrical stimulation (NMES) of the BB muscle. The BB muscle was stimulated while the forearm was positioned in the neutral, pronation, or supination positions. The elbow was flexed at angles of 10°, 30°, 60°, and 90°. The study analyzed the impact of the forearm posture(s) and elbow joint angle(s) on the root-mean-square value of the torque (TQRMS). Subsequently, various MMG parameters, such as the root-mean-square value (MMGRMS), the mean power frequency (MMGMPF), and the median frequency (MMGMDF), were analyzed along the longitudinal, lateral, and transverse axes of the BB muscle fibers. The test-retest interclass correlation coefficient (ICC21) for the torque and MMG ranged from 0.522 to 0.828. Repeated-measure ANOVAs showed that the forearm posture and elbow flexion angle significantly influenced the TQRMS (p < 0.05). Similarly, the MMGRMS, MMGMPF, and MMGMDF showed significant differences among all the postures and angles (p < 0.05). However, the combined main effect of the forearm posture and elbow joint angle was insignificant along the longitudinal axis (p > 0.05). The study also found that the MMGRMS and TQRMS increased with increases in the joint angle from 10° to 60° and decreased at greater angles. However, during this investigation, the MMGMPF and MMGMDF exhibited a consistent decrease in response to increases in the joint angle for the lateral and transverse axes of the BB muscle. These findings suggest that the muscle contraction evoked by NMES may be influenced by the interplay between actin and myosin filaments, which are responsible for muscle contraction and are, in turn, influenced by the muscle length. Because restoring the function of limbs is a common goal in rehabilitation services, the use of MMG in the development of methods that may enable the real-time tracking of exact muscle dimensional changes and activation levels is imperative.
    Matched MeSH terms: Muscle, Skeletal/physiology
  8. Ibitoye MO, Hamzaid NA, Ahmed YK
    Biomed Tech (Berl), 2023 Aug 28;68(4):329-350.
    PMID: 36852605 DOI: 10.1515/bmt-2021-0195
    Leg exercises through standing, cycling and walking with/without FES may be used to preserve lower limb muscle and bone health in persons with physical disability due to SCI. This study sought to examine the effectiveness of leg exercises on bone mineral density and muscle cross-sectional area based on their clinical efficacy in persons with SCI. Several literature databases were searched for potential eligible studies from the earliest return date to January 2022. The primary outcome targeted was the change in muscle mass/volume and bone mineral density as measured by CT, MRI and similar devices. Relevant studies indicated that persons with SCI that undertook FES- and frame-supported leg exercise exhibited better improvement in muscle and bone health preservation in comparison to those who were confined to frame-assisted leg exercise only. However, this observation is only valid for exercise initiated early (i.e., within 3 months after injury) and for ≥30 min/day for ≥ thrice a week and for up to 24 months or as long as desired and/or tolerable. Consequently, apart from the positive psychological effects on the users, leg exercise may reduce fracture rate and its effectiveness may be improved if augmented with FES.
    Matched MeSH terms: Muscle, Skeletal/physiology
  9. Marconi G, Gopalai AA, Chauhan S
    Med Biol Eng Comput, 2023 May;61(5):1167-1182.
    PMID: 36689083 DOI: 10.1007/s11517-023-02778-2
    This simulation study aimed to explore the effects of mass and mass distribution of powered ankle-foot orthoses, on net joint moments and individual muscle forces throughout the lower limb. Using OpenSim inverse kinematics, dynamics, and static optimization tools, the gait cycles of ten subjects were analyzed. The biomechanical models of these subjects were appended with ideal powered ankle-foot orthoses of different masses and actuator positions, as to determine the effect that these design factors had on the subject's kinetics during normal walking. It was found that when the mass of the device was distributed more distally and posteriorly on the leg, both the net joint moments and overall lower limb muscle forces were more negatively impacted. However, individual muscle forces were found to have varying results which were attributed to the flow-on effect of the orthosis, the antagonistic pairing of muscles, and how the activity of individual muscles affect each other. It was found that mass and mass distribution of powered ankle-foot orthoses could be optimized as to more accurately mimic natural kinetics, reducing net joint moments and overall muscle forces of the lower limb, and must consider individual muscles as to reduce potentially detrimental muscle fatigue or muscular disuse. OpenSim modelling method to explore the effect of mass and mass distribution on muscle forces and joint moments, showing potential mass positioning and the effects of these positions, mass, and actuation on the muscle force integral.
    Matched MeSH terms: Muscle, Skeletal/physiology
  10. Jayaraman A, Pettersson S
    EMBO Mol Med, 2023 Mar 08;15(3):e17324.
    PMID: 36843560 DOI: 10.15252/emmm.202217324
    Duchenne muscular dystrophy (DMD) is a devastating neuromuscular degenerative disease with no known cure to date. In recent years, the hypothesis of a "gut-muscle axis" has emerged suggesting that bidirectional communication between the gut microbiota and the muscular system regulates the muscular function and may be perturbed in several muscular disorders. In addition, the excessive consumption of sugar and of lipid-rich processed food products are factors that further aggravate the phenotype for such diseases and accelerate biological aging. However, these unhealthy microbiota profiles can be reversed by individualized dietary changes to not only alter the microbiota composition but also to reset the production of microbial metabolites known to trigger beneficial effects typically associated with prolonged health span. Two recent studies (in this issue of EMBO Mol Med) highlight the interesting potential of microbiota-informed next-generation dietary intervention programs to be considered in genetically linked muscle disorders like DMD.
    Matched MeSH terms: Muscle, Skeletal/metabolism
  11. Leduc-Gaudet JP, Franco-Romero A, Cefis M, Moamer A, Broering FE, Milan G, et al.
    Nat Commun, 2023 Mar 02;14(1):1199.
    PMID: 36864049 DOI: 10.1038/s41467-023-36817-1
    Autophagy is a critical process in the regulation of muscle mass, function and integrity. The molecular mechanisms regulating autophagy are complex and still partly understood. Here, we identify and characterize a novel FoxO-dependent gene, d230025d16rik which we named Mytho (Macroautophagy and YouTH Optimizer), as a regulator of autophagy and skeletal muscle integrity in vivo. Mytho is significantly up-regulated in various mouse models of skeletal muscle atrophy. Short term depletion of MYTHO in mice attenuates muscle atrophy caused by fasting, denervation, cancer cachexia and sepsis. While MYTHO overexpression is sufficient to trigger muscle atrophy, MYTHO knockdown results in a progressive increase in muscle mass associated with a sustained activation of the mTORC1 signaling pathway. Prolonged MYTHO knockdown is associated with severe myopathic features, including impaired autophagy, muscle weakness, myofiber degeneration, and extensive ultrastructural defects, such as accumulation of autophagic vacuoles and tubular aggregates. Inhibition of the mTORC1 signaling pathway in mice using rapamycin treatment attenuates the myopathic phenotype triggered by MYTHO knockdown. Skeletal muscles from human patients diagnosed with myotonic dystrophy type 1 (DM1) display reduced Mytho expression, activation of the mTORC1 signaling pathway and impaired autophagy, raising the possibility that low Mytho expression might contribute to the progression of the disease. We conclude that MYTHO is a key regulator of muscle autophagy and integrity.
    Matched MeSH terms: Muscle, Skeletal*
  12. Hashim NNA, Mat S, Myint PK, Kioh SH, Delibegovic M, Chin AV, et al.
    Eur J Clin Invest, 2023 Feb;53(2):e13874.
    PMID: 36120810 DOI: 10.1111/eci.13874
    Matched MeSH terms: Muscle, Skeletal
  13. Yap YT, Gouwanda D, Gopalai AA, Chong YZ
    J Biomech Eng, 2023 Feb 01;145(2).
    PMID: 36082472 DOI: 10.1115/1.4055564
    Musculoskeletal modeling and simulation have been an emerging trend in human gait analysis. It allows the user to isolate certain biomechanical conditions and elucidate the dynamics of joints and muscles. This study used an open-source musculoskeletal modeling and simulation tool, opensim to investigate the biomechanical effect of knee brace. It collected gait data from thirty-eight participants and examined the gait spatio-temporal parameters, joint angles, and joint moments. Static optimization was performed to estimate the lower extremity muscle force. Statistical analysis was conducted to identify the difference between normal and braced gaits. The results demonstrated the feasibility of this method to investigate the interaction and coordination of lower extremity joints and muscles. The knee brace constrained the range of the motion of the knee during walking. It also changed the walking speed, step length, and stance-to-swing ratio. Several significant differences were found in the joint moments and muscle forces of the rectus femoris, gastrocnemius, soleus and tibialis anterior. Musculoskeletal modeling and simulation tool offers a less invasive and practical alternative to analyze human motion. It also provides a means to investigate the effect of medical devices such as knee brace, which can be potentially beneficial for the future design and development of such devices and for the derivation of future rehabilitation treatment to improve patient's gait.
    Matched MeSH terms: Muscle, Skeletal/physiology
  14. Jamaluddin FN, Ibrahim F, Ahmad SA
    J Healthc Eng, 2023;2023:1951165.
    PMID: 36756137 DOI: 10.1155/2023/1951165
    In sports, fatigue management is vital as adequate rest builds strength and enhances performance, whereas inadequate rest exposes the body to prolonged fatigue (PF) or also known as overtraining. This paper presents PF identification and classification based on surface electromyography (EMG) signals. An experiment was performed on twenty participants to investigate the behaviour of surface EMG during the inception of PF. PF symptoms were induced in accord with a five-day Bruce Protocol treadmill test on four lower extremity muscles: the biceps femoris (BF), rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL). The results demonstrate that the experiment successfully induces soreness, unexplained lethargy, and performance decrement and also indicate that the progression of PF can be observed based on changes in frequency features (ΔF med and ΔF mean) and time features (ΔRMS and ΔMAV) of surface EMG. This study also demonstrates the ability of wavelet index features in PF identification. Using a naïve Bayes (NB) classifier exhibits the highest accuracy based on time and frequency features with 98% in distinguishing PF on RF, 94% on BF, 9% on VL, and 97% on VM. Thus, this study has positively indicated that surface EMG can be used in identifying the inception of PF. The implication of the findings is significant in sports to prevent a greater risk of PF.
    Matched MeSH terms: Muscle, Skeletal
  15. Wong RSY, Cheong SK
    Malays J Pathol, 2022 Dec;44(3):429-442.
    PMID: 36591711
    Sarcopenia is a common condition in the geriatric population. It refers to age-related and progressive decline in muscle mass and function, which has a great impact on one's mobility and quality of life. Patients with sarcopenia are mainly treated with nutritional therapy, exercise therapy, or a combination of both. Since the identification of mesenchymal stem cells (MSCs) several decades ago, many studies have explored the application of MSCs in the field of regenerative medicine. MSCs are popular candidates for cell-based therapy owing to their multipotent nature and immunomodulatory properties. Even though MSCs do not naturally differentiate into myogenic cells, they are important players in skeletal muscle health, as MSCs support myogenic differentiation of other cells and promote recovery of injured skeletal muscle. Recent studies have found that MSCs may be of benefits in the treatment of sarcopenia. This article gives an overview of sarcopenia and the role of MSCs in skeletal muscle homeostasis. It also discusses the therapeutic potential of MSCs and their derivatives, as well as the underlying mechanisms of the therapeutic effects of MSCs and MSC-based products in sarcopenia.
    Matched MeSH terms: Muscle, Skeletal/physiology
  16. Talib I, Sundaraj K, Hussain J, Lam CK, Ahmad Z
    Sci Rep, 2022 Sep 27;12(1):16086.
    PMID: 36168025 DOI: 10.1038/s41598-022-20223-6
    This study aimed to analyze anthropometrics and mechanomyography (MMG) signals as forearm flexion, pronation, and supination torque predictors. 25 young, healthy, male participants performed isometric forearm flexion, pronation, and supination tasks from 20 to 100% maximal voluntary isometric contraction (MVIC) while maintaining 90° at the elbow joint. Nine anthropometric measures were recorded, and MMG signals from the biceps brachii (BB), brachialis (BRA), and brachioradialis (BRD) muscles were digitally acquired using triaxial accelerometers. These were then correlated with torque values. Significant positive correlations were found for arm circumference (CA) and MMG root mean square (RMS) values with flexion torque. Flexion torque might be predicted using CA (r = 0.426-0.575), a pseudo for muscle size while MMGRMS (r = 0.441), an indication of muscle activation.
    Matched MeSH terms: Muscle, Skeletal/physiology
  17. Alkhayl FFA, Ismail AD, Celis-Morales C, Wilson J, Radjenovic A, Johnston L, et al.
    Sci Rep, 2022 Feb 15;12(1):2469.
    PMID: 35169204 DOI: 10.1038/s41598-022-06446-7
    The aims of the current study, therefore, were to compare (1) free-living MPS and (2) muscle and metabolic adaptations to resistance exercise in South Asian and white European adults. Eighteen South Asian and 16 White European men were enrolled in the study. Free-living muscle protein synthesis was measured at baseline. Muscle strength, body composition, resting metabolic rate, VO2max and metabolic responses (insulin sensitivity) to a mixed meal were measured at baseline and following 12 weeks of resistance exercise training. Free-living muscle protein synthesis was not different between South Asians (1.48 ± 0.09%/day) and White Europeans (1.59 ± 0.15%/day) (p = 0.522). In response to resistance exercise training there were no differences, between South Asians and White Europeans, muscle mass, lower body strength or insulin sensitivity. However, there were differences between the ethnicities in response to resistance exercise training in body fat, resting carbohydrate and fat metabolism, blood pressure, VO2max and upper body strength with responses less favourable in South Asians. In this exploratory study there were no differences in muscle protein synthesis or anabolic and metabolic responses to resistance exercise, yet there were less favourable responses in several outcomes. These findings require further investigation.
    Matched MeSH terms: Muscle, Skeletal/metabolism*
  18. Abuajwa B, Hamlin M, Hafiz E, Razman R
    PeerJ, 2022;10:e14049.
    PMID: 36193438 DOI: 10.7717/peerj.14049
    BACKGROUND: The intensity of strength training exercise is generally regarded to be the most essential element in developing muscle strength and power. The exercise intensity of strength training is known as one-repetition maximum (1RM). Velocity-based training (VBT) has been proposed as a different approach for determining training intensity. VBT relies on the use of linear position transducers and inertial measurement units, providing real-time feedback to objectively adjust the exercise intensity based on an athlete's velocity zone.

    METHODS: This study investigated the effects of two different training interventions based on individualized load velocity profiles (LVP) on maximal bench press strength (i.e., 1RM), maximum throwing velocity (TV), and skeletal muscle mass (SKMM). Twenty-two university handball players were randomly assigned to Group 1 (low-movement speed training) or Group 2 (high-movement speed training). Group 1 exercised with a bar speed of 0.75-0.96 m/s, which corresponds to a resistance of approximately 60% 1RM, whereas Group 2 trained at 1.03-1.20 m/s, corresponding to a resistance of approximately 40% 1RM. Both groups exercised three times a week for five weeks, with strength and throwing tests performed at baseline and post-intervention.

    RESULTS: A two-way repeated measures ANOVA was applied, and the results showed the interaction between group and time was not statistically significant for SKMM (p = 0.537), 1RM (p = 0.883), or TV (p = 0.774). However, both groups significantly improved after the five weeks of training: SKMM (3.1% and 3.5%, p 

    Matched MeSH terms: Muscle, Skeletal/physiology
  19. Burrows M, Ghosh A, Sutton GP, Yeshwanth HM, Rogers SM, Sane SP
    J Exp Biol, 2021 12 01;224(23).
    PMID: 34755862 DOI: 10.1242/jeb.243361
    Lantern bugs are amongst the largest of the jumping hemipteran bugs, with body lengths reaching 44 mm and masses reaching 0.7 g. They are up to 600 times heavier than smaller hemipterans that jump powerfully using catapult mechanisms to store energy. Does a similar mechanism also propel jumping in these much larger insects? The jumping performance of two species of lantern bugs (Hemiptera, Auchenorrhyncha, family Fulgoridae) from India and Malaysia was therefore analysed from high-speed videos. The kinematics showed that jumps were propelled by rapid and synchronous movements of both hind legs, with their trochantera moving first. The hind legs were 20-40% longer than the front legs, which was attributable to longer tibiae. It took 5-6 ms to accelerate to take-off velocities reaching 4.65 m s-1 in the best jumps by female Kalidasa lanata. During these jumps, adults experienced an acceleration of 77 g, required an energy expenditure of 4800 μJ and a power output of 900 mW, and exerted a force of 400 mN. The required power output of the thoracic jumping muscles was 21,000 W kg-1, 40 times greater than the maximum active contractile limit of muscle. Such a jumping performance therefore required a power amplification mechanism with energy storage in advance of the movement, as in their smaller relatives. These large lantern bugs are near isometrically scaled-up versions of their smaller relatives, still achieve comparable, if not higher, take-off velocities, and outperform other large jumping insects such as grasshoppers.
    Matched MeSH terms: Muscle, Skeletal
  20. Mohamad Ismail MR, Lam CK, Sundaraj K, Rahiman MHF
    J Musculoskelet Neuronal Interact, 2021 12 01;21(4):481-494.
    PMID: 34854387
    OBJECTIVE: This paper presents the analyses of the fatigue effect on the cross-talk in mechanomyography (MMG) signals of extensor and flexor forearm muscles during pre- and post-fatigue maximum voluntary isometric contraction (MVIC).

    METHODS: Twenty male participants performed repetitive submaximal (60% MVIC) grip muscle contractions to induce muscle fatigue and the results were analyzed during the pre- and post-fatigue MVIC. MMG signals were recorded on the extensor digitorum (ED), extensor carpi radialis longus (ECRL), flexor digitorum superficialis (FDS) and flexor carpi radialis (FCR) muscles. The cross-correlation coefficient was used to quantify the cross-talk values in forearm muscle pairs (MP1, MP2, MP3, MP4, MP5 and MP6). In addition, the MMG RMS and MMG MPF were calculated to determine force production and muscle fatigue level, respectively.

    RESULTS: The fatigue effect significantly increased the cross-talk values in forearm muscle pairs except for MP2 and MP6. While the MMG RMS and MMG MPF significantly decreased (p<0.05) based on the examination of the mean differences from pre- and post-fatigue MVIC.

    CONCLUSION: The presented results can be used as a reference for further investigation of cross-talk on the fatigue assessment of extensor and flexor muscles' mechanic.

    Matched MeSH terms: Muscle, Skeletal
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