Dissertations / Theses: 'Muscle activation'

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Ljung, Carl. "Muscle Activation and Movement Coordination." Thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148773.

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The purpose of this project was to empirically develop a method of using electromyography to identify how humans coordinate their muscles during certain sequences of movement and the effect of an injured anterior cruciate ligament to muscle coordination. In this study, more simple movements of the lower extremities are examined and relatively accurate hypothesizes can be made solely based on anatomical theory. However, a general method for electromyographic studies would open up the possibility of exploring muscle coordination in more complex movements. This would facilitate further research in scientific fields such as biomechanics and neurophysiology. Surface electromyography was used to acquire data of muscle activation from the primary muscle groups of the lower extremities, while body movements were recorded using video cameras. The neural signals sampled were rectified for systematic interference by the removal of electrical background noise and by centering the signal baseline. To address the problem of the neural signal pattern being random, a smoothing algorithm called "RMS EMG" that reflects the mean power of the signal was applied. Additionally, a high-pass filter was applied to filter out filter out frequencies outside the range of neural signals in muscles. In order to correlate the body movement sequences with the electromyographic data, the video recordings were compared with activity-time plots of the electromyographic data. By localizing and interpreting local peaks and change of gradients, the motions where structured into distinct phases and the muscle coordination was evaluated. Through investigation of both bilateral and unilateral movements the effects on an injured anterior cruciate ligament were studied. Results showed predominant muscle activation in the knee extensors during squatting and similar motions. Even though the motions included significant hip extension, the hamstrings displayed a nearly constant level of muscle activation throughout the movement. Activation of the muscles occurred simultaneously, but the motion appeared to be primarily executed by the knee extensors. During gait, muscle activation in the gastrocnemius was observed to be significantly higher than in any other muscle prior to the hind foot leaving ground. Injury to the anterior cruciate ligament appeared to cause an increase of muscle activation in the lateral side of the knee extensors compared to the medial side.

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Tomc, Lyn Kathryn. "Role of MEF2 proteins in the activation of the c-jun and MCK genes in skeletal muscle /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ56210.pdf.

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Kyle, Natasha Flemming. "Muscle activation patterns during gait initiation." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27147.

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Gait initiation is a temporary movement between upright posture and steady-state gait. The activation of several postural muscles has been identified to precede changes observed in vertical reaction force. Previous research examining gait initiation has concentrated on the electromyographic activity of muscles of the lower limbs. Few studies, however, have looked at recruitment patterns of the muscles of the thigh and trunk. This study was conducted to determine the recruitment patterns and the roles of certain muscles of the trail and lead lower limbs and trunk for the duration from quiet stance to trail leg toe-off. Eleven healthy participants initiated gait with their right leg. Electromyographic data were collected bilaterally from the erector spinae, tensor fasciae latae, adductor magnus and tibialis anterior muscles. In addition, force platform data were recorded for the duration of quiet stance to toe-off of the trail limb. (Abstract shortened by UMI.)

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Peden, Ryan Stephen Medical Sciences Faculty of Medicine UNSW. "Activation of vascular smooth muscle cells." Awarded by:University of New South Wales. School of Medical Sciences, 2006. http://handle.unsw.edu.au/1959.4/24925.

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Vascular smooth muscle cells (VSMC) in the healthy adult arterial wall are a highlydifferentiated cell type with low levels of proliferation. However, when activated these cells can undergo a phenotypic change to become proliferative, migratory and excrete higher levels of extra-cellular matrix. While this cellular change is an essential element of the adaptable vasculature, excessive proliferation of VSMC underpins the development of a number of disease states, including atherosclerosis and restenosis after balloon angioplasty. The activation of VSMC is dependent on intracellular signalling pathways broadly altering gene expression. A key feature of this process is the initial potent regulation of transcription factors such as Egr-1, c-Jun and Ets-1, which then drive further transcriptional changes resulting in phenotypic change. The aim of this thesis was to discover novel genes, particularly transcription factors, regulated early upon stimulation and to characterise their contribution to the activation of VSMC. A key stimulus for activation of VSMC is the release of fibroblast growth factor 2 (FGF-2). A microarray used to explore the effects of FGF-2 exposure demonstrated the extensive nature of transcriptional modulation. In addition, it highlighted a number of transcription factors that were not previously described in VSMC: p8, ATF-4 and SHARP-2. In particular, SHARP-2 was potently upregulated and was reconfirmed in animal models of vascular injury. The subsequent contribution these factors make to VSMC activation was also demonstrated. p8 strongly induced VSMC proliferation, while ATF-4 contributed to cytokine production and SHARP-2 potently downregulated VSMC differentiation markers. A second area that was explored related to a gene known as YRDC, which was found to be upregulated upon stimulation of VSMC. YRDC is highly conserved across almost all cellular life, however its function remains unknown. A number of novel splice variants of YRDC were discovered and demonstrated to be differentially regulated in VSMC upon stimulation. Further work to commence characterising its function showed that it interacts with key ribosomal proteins and most likely plays a role in regulating translation. The discovery of the relevance of these genes to vascular biology in addition to their transcriptional regulation makes an important contribution to increasing our understanding of the molecular mechanisms behind vascular remodelling.

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Pettersson, Victor. "Repetitive climbing effect on muscle activation." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42144.

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Background. Climbing is growing as a recreational sport worldwide. Climbing is a physically demanding sport requiring well developed strength and endurance. Plenty of studies have been made in the area of climbing in order to understand how the body adapts, which muscles are being used and how to prevent injury. A lot of these studies uses electromyography (EMG), a tool that measures electrical currents in muscles to detect muscle activity, as measurement method in order to do findings within the area. Aim. The aim was to study differences in muscle activation in arm and leg muscles in climbers before and after 40 repeated attempts over two weeks on a boulder problem. Furthermore, correlation between climbing level and change in total measured muscle activation after repeated attempts was assessed. Methods. 15 participants (five women and ten men) participated in this study. Standardized electrode placements and maximal voluntary isometric contractions (MVIC) were made for muscles; Flexor Carpi Radialis (FCR), Bicep Brachii (BB), Rectus Femoris (RF) and Gastrocnemius Lateralis (GL) before each measurement in order to maintain good reliability. Participants repeated a specific climbing route, adapted to the participants climbing ability, 40 times, divided into four sessions over two weeks. Before the first measured attempt the participant got to practice the route twice to get familiar with the moves. Average muscle activation was calculated by dividing the total muscle activation from each muscle with the time it took to complete the climbing route. Peak muscle values were calculated by dividing the highest muscle activation value with the MVIC values to get a %MVIC value. Results. A decrease in average muscle activation for FCR and BB were found (p=0.038, 0.023) whereas an increase in average activation for GL was found (p=0.027). Peak muscle activation showed significant decreases regarding upper extremities FCR and BB (p=0.008, p=0.011) but no significant changes to lower extremities RF and GL. Total average muscular activation regarding all muscles combined showed a general decreased activation (p=0.001). Moderate correlation was found between red-point level and decrease in total average muscle activation (r=0.53). Conclusion. When repeating a climbing route, the climbers muscle activation differs in upper and lower extremities, with a decrease in upper extremities peak and average muscle values, and an increase in GL average muscle values. Repetitions improves technique and muscle memory which could be the reason for the overall decrease in total muscle activation. Hopefully, this study could enrich the climbing world with further knowledge in how to train for climbing.

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Carter, Nicholas James. "Stretch activation in insect fibrillar flight muscle." Thesis, University of York, 1995. http://etheses.whiterose.ac.uk/14010/.

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Murtada, Sae-Il. "Smooth muscle modeling activation and contraction of contractile units in smooth muscle /." Licentiate thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11349.

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Simpson, Alec William Michael. "Stimulus-response coupling in smooth muscle." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253500.

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Tan, Yu Yin Nicole Medical Sciences Faculty of Medicine UNSW. "Gene expression during activation of smooth muscle cells." Publisher:University of New South Wales. Medical Sciences, 2009. http://handle.unsw.edu.au/1959.4/43615.

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Cardiovascular disease, which involves the cardiac, cerebrovascular and peripheral vascular system, is the major cause of morbidity and mortality in the western world. Changes in the vascular microenvironment trigger cascades of molecular events involving altered signaling, transcription and translation of a gene. The aim of this thesis was to increase our understanding on the molecular regulation of activated vascular smooth muscle cells. The first study looking at PDGF-D expression provides new insights into the regulatory mechanisms controlling the phosphorylation of Sp1. Studies performed identified three amino acids in Sp1 (Thr668, Ser670 and Thr681) that is phosphorylated by PKC-zeta activated by AngII. In the second study, the translational regulatory role of a novel gene YrdC induced by injury was investigated. Current knowledge of translational regulators controlling altered gene expression is little and studies in this thesis shows a splice variant of YrdC playing an important role in controlling mRNA translation and thus protein synthesis in the context of injury. The final study investigated in this study was the increased expression of the apoptotic FasL by the activation of GATA6. Although FasL has been extensively studied over the years, this is the first study linking a GATA factor with FasL in any cell type and provides key insights into the transcriptional events underpinning FasL-dependent SMC apoptosis following exposure to AngII.

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De, Nicola Gian Felice. "Stretch activation in muscle : a CaÂ²+ independent mechanism?" Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446294.

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Curtis, Sally Anne. "Superficial cervical muscle activation in chronic neck pain." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/153893/.

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Chronic neck pain can occur in a proportion of individuals who have suffered a whiplash injury and also in individuals that have not experienced a trauma to the neck. The mechanisms that cause chronic pain are unclear, and whether they differ in traumatic or non-traumatic onset is unknown. A review of the background literature identified differences in muscle activation for individuals with chronic neck pain, following a whiplash injury and from a non traumatic onset, compared to healthy controls. However, differences in the combined action or synergy of superficial neck muscles in these chronic neck pain groups, during non-forced activities, had not been widely reported. A new methodology was developed to address this area of research. A pilot study was undertaken to establish the reliability of the method and to identify areas for refinement. The main study employed the refined methodology to determine possible differences in activation and synergies of the upper trapezius and sternocleidomastoid muscles, alongside correlations of subjective pain and fatigue with surface electromyographic measures, using linear array electrodes. Some differences in muscles activation and synergy were observed between the groups. Individuals showed different strengths of relationships between subjective and objective measures and different proportions of significant correlations were shown between groups.

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Seitz, Laurent B. "Mechanisms affecting post-activation potentiation following voluntary isokinetic knee extension." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1557.

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The present research was designed to: 1) determine whether the voluntary PAP effects commonly observed after conditioning activity (CA; i.e. muscular contraction prior to a ‘test’ contraction) are a consequence of acute neuromuscular alterations relating to the CA itself, or whether they simply reflect warm-up and/or familiarisation effects; 2) clarify the influence of the contraction velocity, duration and total work characteristics of the CA on voluntary PAP; 3) determine the factors allowing stronger individuals to express higher level of voluntary PAP; and 4) determine the peripheral and central mechanisms of voluntary PAP in human skeletal muscle. In Study 1, the effects of different contraction velocity, duration and total work characteristics on PAP were examined after a complete warm-up. The contributions of peripheral and central mechanisms to PAP were also examined. Voluntary and electrically-evoked torques and electromyogram (EMG) data were captured before and after five different dynamic (isokinetic) CAs, after the participants had completed an extensive warm-up including extensive task-specific practice to the point where maximal voluntary contractile capacity was achieved. Vastus lateralis (VL) EMG amplitude normalised to the muscle compound action potentiation (M-wave) amplitude (EMG:M), was taken as a measure of central drive whereas twitch peak torque and M-wave amplitude were recorded to assess peripheral function. Even after a plateau in voluntary contractile capacity was achieved after the complete warm-up, the imposition of CAs elicited significant increases in both voluntary and twitch torques (i.e., PAP). CAs with longer total contraction duration (6s) and a minimum total work of ~750-900 J produced PAP, regardless of the velocity of the CA. No changes in EMG:M were detected after any CA suggesting that central drive was not a major factor influencing PAP under the present experimental conditions. However, the increases in twitch peak torques with lack of change in Mwave amplitude suggest that peripheral function, possibly including changes in myosin regulatory light chain (RLC) phosphorylation and increased intracellular Ca2+ release and sensitivity may have contributed to the observed PAP. It is clear from the literature and the results of Study 1 that there is a significant inter-individual variability in the PAP phenomenon. Typically, stronger individuals are able to express higher levels of PAP but it is unclear why this occurs. Therefore, in Study 2 peak knee extensor torque at 60o·s-1, quadriceps and VL crosssectional area (CSA) and volume, and the type II myosin heavy chain (MHC) isoform percentage (VL) were measured to determine their relative contribution to PAP elicited under voluntary conditions. There were large to very large correlations between PAP magnitude and peak knee extensor torque at 60o·s-1 (r=0.62), quadriceps (r=0.68) and VL (r=0.62) CSA, and quadriceps (r=0.63) and VL (r=0.65) volume. Nonetheless, these correlations were not statistically significant after adjusting for the influence of type II MHC percentage (using partial correlation analysis). By contrast, the strongest correlation was observed for type II MHC percentage (r=0.77), and this correlation remained significant (r=0.56-0.66) after adjusting for other variables. This finding suggests that PAP magnitude is most clearly associated with the type II MHC isoform percentage in the human quadriceps femoris. This might be explained by the fact that myosin RLC phosphorylation, one proposed mechanism responsible for PAP, has been shown to be greater in type II MHC isoforms. The results of Study 1 and Study 2 suggest that changes at the peripheral level, possibly including changes in myosin RLC phosphorylation (and increased intracellular Ca2+ release and sensitivity) may be a primary candidate mechanism of PAP induced by a voluntary CA, although more direct measurements are required to test this assumption. Therefore, tetanic stimulations and maximal isokinetic knee extensions at 180o·s-1 were used in Study 3 to provide a more detailed investigation of the role of changes in the excitation-contraction (E-C) coupling process (i.e. changes in myosin RLC phosphorylation or increased intracellular Ca2+ release and sensitivity) to the PAP response induced by a voluntary CA. Torques produced during voluntary knee extensions, 20 Hz and catch-inducing (20-Hz train preceded by a double pulse with 5-ms interval) stimulation trains, the 20- vs. 80-Hz torque ratio (20:80) as well as the force-augmenting effect of the catch-inducing train were recorded before and after a voluntary CA or a control condition (no CA, rest). Statistically significant increases in voluntary torque, torques elicited by 20-Hz and catch-inducing trains, and 20:80 were observed 1, 4 and 7 min after the CA. Moreover, the force-augmenting effects of the catch-inducing train diminished as the magnitude of PAP increased and then increased as the magnitude of PAP diminished. Statistically significant correlations (r=0.50-0.81) were also found between the changes in voluntary torque production (i.e. PAP) and the changes in these variables. These results suggest that increases in PAP following a voluntary CA are strongly associated with changes in peripheral function, most probably changes in the E-C coupling efficiency..

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Baudry, Stéphane. "Contribution à l'étude de la potentialisation de post-activation et de ses implications fonctionnelles chez l'homme." Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210743.

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Bampouras, Theodoros M. "Assessment of muscle activation capacity : methodological considerations of muscle mechanics and implications for testing." Thesis, Manchester Metropolitan University, 2016. http://e-space.mmu.ac.uk/617472/.

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Muscle activation capacity assessment could be affected by the mechanical behaviour of the muscle, but this aspect has received little attention. Understanding the effect the muscle's mechanical behaviour has on muscle activation capacity assessment can be paramount in achieving a better understanding of muscle function. The aim of the present Thesis was to examine the methodological implications of the mechanical behaviour of the muscle during muscle activation capacity assessment. Four studies were designed to examine the effect of the muscle-tendon unit on a) muscle activation capacity calculation methods and number of stimuli used, by manipulating quadriceps muscle length and consequently stiffness, b) stimulation intensity required and associated discomfort, by examining whether a lower than supramaximal stimulation intensity threshold, sufficient to stretch the muscle-tendon, exists, and c) the interplay between muscle mechanics and activation, by manipulating the testing position on the dynamometer, stabilisation and concurrent activation of remote muscles. Isometric knee extensions were used for all studies, and electrical stimuli was delivered to the muscle to quantify muscle activation capacity or induce muscular contractions by circumventing the voluntary neural drive. The results showed that a) altered muscle stiffness affects muscle activation values depending on the calculation method and number of stimuli used, suggesting caution to testing where muscle stiffness is likely to change, b) a lower stimulation intensity exists that can reduce subject discomfort while obtaining valid activation capacity results, widening the application of electrical muscle stimulation, and c) muscle activation must be considered in musculoskeletal models for more accurate predictions but the level of activation will ultimately depend on how stabilised the muscle is. Collectively, these results demonstrate the considerable effect muscle mechanics have on muscle activation capacity and that muscle strength assessment must take into account this aspect for more accurate inferences on muscle function.

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Nottle, Carmel. "Proprioceptive and muscle activation changes in triceps surae associated with exercise induced muscle damage." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2004. https://ro.ecu.edu.au/theses/779.

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The aim of this thesis was to examine proprioceptive and activation changes that occur in triceps surae in response to exercise induced muscle damage (EIMD). While proprioceptive changes have previously been demonstrated in association with EIMD, the present investigation examined the role of a number of potential contributing factors to these changes, following both single and repeated bouts of eccentric exercise.

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Creps, Justin Michael. "An Investigation of Simulated Core Muscle Activation during Running and its Effect on Knee Loading and Lower Extremity Muscle Activation Using OpenSim." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397696075.

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Drake, Joshua C. "Long term AMPK activation limits obesity induced muscle atrophy." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/10954.

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Thesis (M.S.)--West Virginia University, 2010.
Title from document title page. Document formatted into pages; contains vii, 72 p. : ill. (some col). Vita. Includes abstract. Includes bibliographical references (p. 63-70).

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Hnot, Melanie L. "Muscle activation and strain in the guinea pig hindlimb /." Connect to online version, 2006. http://ada.mtholyoke.edu/setr/websrc/pdfs/www/2006/139.pdf.

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Pilipowicz, Orest J. "Early satellite cell activation on isolated single muscle fibers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0019/MQ53205.pdf.

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Gabriel, David Abraham. "Muscle activation patterns for goal-directed multijoint arm movements." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28748.

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The purpose of this dissertation was to determine if the CNS produces relatively simple alterations in muscle activity to accomplish goal-directed reaching motions of the upper limb under a variety of movement conditions.
To this end, six subjects performed goal-directed arm movements in the horizontal plane. Two movement amplitudes (300 mm and 400 mm) were completed at a moderate speed (1050 mm/s) and as-fast-as possible. The speed and amplitude conditions were repeated for the 45$ sp circ$ and 90$ sp circ$ movement directions. Finally, each of the movement conditions mentioned thus far, were performed within the right and left sections of the work-space. Surface electro-myographic activity was recorded from the pectoralis major, posterior deltoid, biceps brachii short head, brachioradialis, triceps brachii long head, and triceps brachii lateral head. Motion recordings were obtained with a spatial imaging system that monitored the positions of infrared emitting diodes attached to the subject's upper arm and forearm-hand complex.
Several simplification schemes were found to be operative at the level of the electro-myogram. These include: (a) simple timing relationships for agonists between joints and agonist/antagonist intermuscle latencies within each joint; (b) tightly coupled timing between agonists within a single joint; (c) for a particular movement direction, the form and shape of EMG burst activity followed a strategy associated with modulation of pulse height and width; (d) the slope, duration, and onset were further affected by the direction of hand movement which resulted in the greatest RMS-EMG signal amplitude, changing in a predictable manner, and finally (e) there was tuning in which elbow muscles were activated earlier for goal-directed arm movements in the left area of the work-space.

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McAdams, R. P. "Factors modifying activation of alpha-adrenoceptors in smooth muscle." Thesis, Brunel University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370137.

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Reardon, Danielle. "Do Changes in Muscle Architecture Effect Post- Activation Potentiation." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6008.

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Purpose: To examine the effect of three muscle potentiation protocols on changes in muscle architecture and the subsequent effect on jump power performance. Methods: Maximal (1RM) squat strength (Mean SD=178.3 &"177; 36.6kg), vertical jump power, and muscle architecture were obtained in 12 resistance trained men (25.2&"177;3.6y; 90.67&"177;12.7kg). Participants randomly completed three squatting protocols at 75% (3 x 10 reps), 90% (3 x 3 reps) or 100% (1 x 1) of their 1RM, or no workout (CON), with each protocol being separated by one week. During each testing session ultrasound and vertical jump testing were assessed at baseline (BL), 8min post (8P) and 20min post (20P) workout. Ultrasound measures of the rectus femoris (RF) and vastus lateralis (VL) muscles included; cross sectional area (CSA) and pennation angle (PNG). Following each ultrasound, peak (PVJP) and mean (MVJP) vertical jump power (using hands for maximum jump height) were measured using an accelerometer. Results: Magnitude based inferences analysis indicated that in comparison to CON, 75% resulted in a likely greater change in RF-CSA and VL-CSA (BL-8P and BL–20P), 90% resulted in a likely greater RF-CSA and VL-CSA (BL–20P), and 100% resulted in a very likely or likely decrease in VL-PNG at BL-8P and BL–20P, respectively). Meanwhile, changes in PVJP and MVJP for the 75% trial was likely decreased at BL-8P and BL–20P; and for the 90% trial MVJP was likely decreased at BL-8P and BL–20P. Analysis of the magnitude of the relationships indicated a likely negative relationship between VL-PNG and MVJP (r = -0.35; p < 0.018) at BL-8P, while at BL–20P, a negative relationship was observed between PVJP and RF-CSA (r = -0.37; p < 0.014). Conclusion: Acute increases in muscle size and acute decreases in pennation angle did not result in any potentiation in vertical jump power measures. Although the inverse relationships observed between muscle architecture variables and power suggests a potential effect, the change in position (i.e. movement from standing to supine for ultrasound measures) may negate, as a result of potential fluid shifts or muscle relaxation, the potentiating effects of the exercise. It is also possible that the fatiguing nature of the squat protocols in trained but not competitive participants may have also contributed to the results.
M.S.
Masters
Child, Family, and Community Sciences
Education and Human Performance
Sport and Exercise Sciences; Applied Exercise Physiology

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Russold, Michael Friedrich. "Surgical construction, conditioning and activation of functional muscle grafts." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419009.

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Drechsler, Wendy Isobel. "Quadriceps femoris muscle activation : evaluation after major knee injury." Thesis, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274625.

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Radhakrishnan, Ganesh Balaji. "Simulation Of Lower Extremity Muscle Activation During Obstacle Clearance." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244006.

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Exoskeletons can be helpful to patients who suffer from muscular dysfunctions. Recent studies focus on exoskeletons which can perform complex human movements. Further analysis is needed in the area of unusual movements like obstacle clearance to design an assistive device which can deliver effective aid to the intended patients in need. It is necessary to understand the behavior of lower limb muscles when they are subjected to complex physical activity. This study is aimed to analyze the activity of muscles in the lower body during obstacle clearance. Two different levels of obstacle have been maintained, analyzed and compared with a normal gait. The muscle groups taken for the study are quadriceps, hamstrings and plantar flexors. The primary hypothesis is that the quadriceps, Hamstrings, and dorsi flexors tend to have higher muscle activation while performing a complex physical task like stepping over an obstacle with the heights of 20 cms and 36 cms than a normal walking gait. The muscles from those three mentioned groups contribute more to the obstacle clearance compare to that of normal gait. Further research is recommended to expand knowledge about muscle activation.

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Saito, Yoshitomo Saito. "Upper Extremity Muscle Activation and Motion in Active Males." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1525348361907357.

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Anderson, Charles Dudley Jr. "Kinase pathways underlying muscarinic activation of colonic longitudinal muscle." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/2365.

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The longitudinal muscle layer in gut is the functional opponent to the circular muscle layer during the peristalsis reflex. Differences in innervation of the layers allow for the contraction of one layer that corresponds with the simultaneous relaxation of the other, enabling the passage of gut contents in a controlled fashion. Differences in development have given the cells of the two layers differences in receptor populations, membrane lipid handling, and calcium handling profiles/behaviors. The kinase signaling differences between the two layers is not as well characterized. Upon activation of cells from the circular muscle layer, it is known that Rho kinase and ERK1/2 promote contraction, while CaMKK/AMPK and CaMKII perform inhibitory/self-inhibitory roles. Such behaviors are poorly understood in the longitudinal muscle layer. In longitudinal muscle strips, we measured muscarinic receptor-mediated contraction following incubation with kinase inhibitors. Upon comparison to control, contributions of Rho Kinase and ERK1/2 were similar to those seen in circular muscle. Inhibition of both of these enzymes leads to diminished contraction. However, CaMKK/AMPK and CaMKII have effects in longitudinal muscle opposite to their regulation in circular muscle – their inhibition also diminishes the contractile response. These contractile data from strips were supported by immunokinase assay measurements of MLCK activity from strip homogenates with and without kinase inhibition. Therefore, we suggest that the activities of CaMKK/AMPK and CaMKII in longitudinal muscle are indeed different from their regulatory roles in circular muscle, perhaps a consequence of the different calcium handling modalities of the two muscle types.

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Stein, Wendy K. "α-Adrenoceptors and calcium activation mechanisms in vascular muscle." Thesis, Aston University, 1987. http://publications.aston.ac.uk/12536/.

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Johnson, Aaron W. "Whole-Body Vibration Compared to Traditional Physical Therapy in Individuals with Total Knee Arthroplasty." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/837.

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The purpose of the present study was to compare total knee arthroplasty (TKA) rehabilitation with and without whole-body vibration (WBV) to 1) understand if WBV is a useful treatment during TKA rehabilitation to increase quadriceps strength and function, and 2) to investigate the effect of WBV on quadriceps voluntary muscle activation. Subject and Methods. Individuals post TKA (WBV n=8, control n=8) received physical therapy with and without WBV for four weeks. Quadriceps strength and muscle activation, function, perceived pain, and knee range of motion were measured. Results. No adverse side effects were reported in either group. There was a significant increase in strength and function for both groups (P<0.01). There was no difference pre to posttest between groups for strength, muscle activation, or pain (Hotelling’s T2=0.42, P=.80) or for function (F=0.54, P=0.66). Discussion and Conclusion. In individuals with TKA, WBV showed equal strength and function improvement to physical therapy directed progressive resistive exercise. Influence of WBV on muscle activation remains unclear, as initial muscle activation was near established normal quadriceps levels and remained so post treatment.

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Langton, P. D. "Calcium channels and activation of rat vas deferens smooth muscle." Thesis, Lancaster University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233561.

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Nilsen, Kristian Bernhard. "Autonomic activation and muscle activity in relation to musculoskeletal pain." Doctoral thesis, Norwegian University of Science and Technology, Department of Neuroscience, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1746.

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Background and objectives:

Musculoskeletal pain is frequent and the most common cause of sick leave in Norway. Although chronic musculoskeletal pain is conceived to be related to social or mental stress, the mechanism for such a relation is not known. The overall objective of the present thesis was to elucidate whether stress-associated musculoskeletal pain and stress-induced muscle activity may be related to activation of the autonomic nervous system.

Methods:

The present work is carried out in the laboratory where subjects performed a complex two-choice reaction time test designed to mimic mental load in a work place, resembling stressful and repetitive office work. Subjects were investigated while performing this stressful task for one hour, as well as during a baseline period immediately before and during a recovery period. We measured muscle activity and different parameters indicative of activity in the autonomic nervous system, as well as subjective variables as pain, tension and fatigue. We included patients with generalised (fibromyalgia) and patients with regionalised (shoulder/neck) musculoskeletal pain, as well as healthy controls. A group of patients with musculoskeletal pain were also subject to a block of peripheral sympathetic nerves with a unilaterally anaesthetic block of the lower cervical sympathetic ganglion before the stressful task.

Results:

We found the vascular response to the stressful task to be more protracted than other bodily responses (paper I). We found the muscular responses to the stressful task to be an unlikely explanation for the simultaneously developing pain response for all subjects, irrespective of diagnostic group (paper II). We found delayed pain recovery in both patients groups, but not in the healthy controls (paper II). We found an attenuated cardiovascular response to the stressful task in the fibromyalgia group compared to the healthy controls, with the shoulder/neck pain patients in an intermediate position (paper III). We also found an inverse relation between the heart rate response and the pain response for the fibromyalgia group (paper III). Lastly, we found that a block of peripheral sympathetic fibres did not affect neither pain nor muscle responses to the stressful task for patients with musculoskeletal pain.

Conclusions:

From the studies presented in the present thesis one may conclude that stress-associated musculoskeletal pain is probably not directly related to muscle activity or autonomic activation at a peripheral level. We found indications of central sensitisation of pain in both patient groups. In patients with generalised musculoskeletal pain (fibromyalgia), the pain may be related to a reduced physiological ability to respond adequately to stress.

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Wise, Andrew 1972. "Skeletal muscle : activation strategies, fatigue properties and role in proprioception." Monash University, Dept. of Physiology, 2001. http://arrow.monash.edu.au/hdl/1959.1/8355.

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Somasekharan, Arun. "Muscle activation mapping of skeletal hand motion : an evolutionary approach." Thesis, Bournemouth University, 2012. http://eprints.bournemouth.ac.uk/20980/.

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Creating controlled dynamic character animation consists of mathe- matical modelling of muscles and solving the activation dynamics that form the key to coordination. But biomechanical simulation and control is com- putationally expensive involving complex di erential equations and is not suitable for real-time platforms like games. Performing such computations at every time-step reduces frame rate. Modern games use generic soft- ware packages called physics engines to perform a wide variety of in-game physical e ects. The physics engines are optimized for gaming platforms. Therefore, a physics engine compatible model of anatomical muscles and an alternative control architecture is essential to create biomechanical charac- ters in games. This thesis presents a system that generates muscle activations from captured motion by borrowing principles from biomechanics and neural con- trol. A generic physics engine compliant muscle model primitive is also de- veloped. The muscle model primitive forms the motion actuator and is an integral part of the physical model used in the simulation. This thesis investigates a stochastic solution to create a controller that mimics the neural control system employed in the human body. The control system uses evolutionary neural networks that evolve its weights using genetic algorithms. Examples and guidance often act as templates in muscle training during all stages of human life. Similarly, the neural con- troller attempts to learn muscle coordination through input motion samples. The thesis also explores the objective functions developed that aids in the genetic evolution of the neural network. Character interaction with the game world is still a pre-animated behaviour in most current games. Physically-based procedural hand ani- mation is a step towards autonomous interaction of game characters with the game world. The neural controller and the muscle primitive developed are used to animate a dynamic model of a human hand within a real-time physics engine environment.

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Gago, Paulo. "Post activation potentiation : Modulating factors and mechanisms for muscle performance." Doctoral thesis, Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-4280.

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Introduction: Acute enhancements of muscle contractile properties and performance subsequent to a maximal or near maximal conditioning contraction are often termed post activation potentiation (PAP). Although still controversial, PAP is commonly linked to enhancements in the myosin regulatory light chain phosphorylation, leading to improvements in the excitation–contraction coupling. The PAP seen after a conditioning task often coexists with fatigue and is known to depend on strength level, muscle fiber type and age. Less is known about how factors such as static and dynamic changes in muscle length affect PAP, and on the relative contribution of contractile and tensile components to PAP. Aim: To enhance our understanding of how, and under what conditions, a single maximal isometric contraction affects plantar flexor muscle contractile performance, and other muscle tendon properties, in power athletes. Methods: Supramaximal twitches were evoked via electrical stimulation of the tibial nerve of athletes before and on several occasions after a 6-second maximal voluntary isometric contraction (6-s MVIC) in both static muscle, and during passive muscle lengthening and shorting at different angular velocities. Several contractile variables were measured from the twitches. The effects of a 6-s MVIC on Achilles tendon stiffness was calculated from torque and ultrasonography based measurements of tendon length at two submaximal contraction intensities. Overall stiffness index was calculated by analyzing the passive lengthening torque/angle curve.Results: A single MVIC enhanced muscle contractile properties and electromechanical delay for up to 5 minutes. Plantar flexor twitch variables such as peak twitch, rate of torque development and rate of torque relaxation were enhanced during shortening compared to lengthening muscle actions, and in an extended as compared to a flexed knee position. Achilles tendon stiffness and overall stiffness index were not significantly modulated by a single 6-s MVIC. Conclusion: The results of this thesis imply that functional enhancements from a 6-s conditioning MVIC would mainly come from improvements in contractile rather than tensile components. Stiffness changes should be monitored in future PAP-related studies since they may still occur after more extensive conditioning protocols than the current one. Improvements in contractile components subserving muscle strength after a conditioning MVIC suggests that enhancements in muscle power after a conditioning task should be greatest in fast concentric muscle actions, though still present in muscle lengthening. Conditioning should be performed in a position where full activation is easy to achieve and tailored to mach an athlete or group of athlete’s current status and characteristics, maximizing performance in a specific sport event.

The project recived financial support from the Swedish National Centre for Research in Sports (CIF). Paulo Gago also wishes to thank the Fundação para a Ciência e Tecnologia (FCT), Portugal for the Ph.D. Grant (SFRH/BD/103572/2014).

New version 2015-01-25 updates the previous one by correcting the errors described in the correction list file (errata).

Doctoral project: Post activation potentiation - Modulating factors and mechanisms for muscle performance.

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Park, Changmin. "Inter-limb Differences in Quadriceps Strength and Voluntary Muscle Activation." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1292855316.

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Welch, Sarah. "Effects of Bench Height Variation on Muscle Activation in Pianists." Ohio University Honors Tutorial College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1429837251.

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Smith, Nigel Anthony. "Oxygen consumption and muscle activation patterns during constant load exercise." Thesis, Queensland University of Technology, 2000. https://eprints.qut.edu.au/36769/1/36769_Digitised%20Thesis.pdf.

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The collective purpose of these two studies was to determine a link between the V02 slow component and the muscle activation patterns that occur during cycling. Six, male subjects performed an incremental cycle ergometer exercise test to determine asub-TvENT (i.e. 80% of TvENT) and supra-TvENT (TvENT + 0.75*(V02 max - TvENT) work load. These two constant work loads were subsequently performed on either three or four occasions for 8 mins each, with V02 captured on a breath-by-breath basis for every test, and EMO of eight major leg muscles collected on one occasion. EMG was collected for the first 10 s of every 30 s period, except for the very first 10 s period. The V02 data was interpolated, time aligned, averaged and smoothed for both intensities. Three models were then fitted to the V02 data to determine the kinetics responses. One of these models was mono-exponential, while the other two were biexponential. A second time delay parameter was the only difference between the two bi-exponential models. An F-test was used to determine significance between the biexponential models using the residual sum of squares term for each model. EMO was integrated to obtain one value for each 10 s period, per muscle. The EMG data was analysed by a two-way repeated measures ANOV A. A correlation was also used to determine significance between V02 and IEMG. The V02 data during the sub-TvENT intensity was best described by a mono-exponential response. In contrast, during supra-TvENT exercise the two bi-exponential models best described the V02 data. The resultant F-test revealed no significant difference between the two models and therefore demonstrated that the slow component was not delayed relative to the onset of the primary component. Furthermore, only two parameters were deemed to be significantly different based upon the two models. This is in contrast to other findings. The EMG data, for most muscles, appeared to follow the same pattern as V02 during both intensities of exercise. On most occasions, the correlation coefficient demonstrated significance. Although some muscles demonstrated the same relative increase in IEMO based upon increases in intensity and duration, it cannot be assumed that these muscles increase their contribution to V02 in a similar fashion. Larger muscles with a higher percentage of type II muscle fibres would have a larger increase in V02 over the same increase in intensity.

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Mazzetti, Scott A. "Akt and ERK activation in human skeletal muscle : dose-dependency of responses to increasing muscle contractions." Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1259313.

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Akt activation mediates increases in glycogen synthesis in response to insulin in humans, while extracellular signal-regulated kinase (ERK) activation increases gene transcription and protein translation in response to endurance and resistance exercise. Akt activation increases only in response to intense muscle contractions and during hypertrophy in rats. No study has examined Akt and ERK activation with increasing numbers of intense muscle contractions in humans. Therefore, the primary objectives of this investigation were to determine if Akt activation increases in response to resistance exercise in humans, and to compare the changes in Akt and ERK activation in response to increasing numbers of muscle contractions.Akt and ERK activation were compared in muscle biopsy samples from 7 men before (Pre) and after (Post) knee extension and control protocols using enzyme linkedimmunosorbent assays. Baseline information was obtained including body composition and maximal strength (1-RM). Subjects were familiarized with knee extensions performed at 70% of 1-RM and a specified repetition cadence (2sec up, 2sec down). Once/wk, subjects performed one protocol in random order: 1 repetition (rep), 10reps, 3 sets of l0reps (3x10), or 6min of sitting. Akt activation decreased 42%, while ERK activation increased 108% in response to 3x10 (p<0.05). Akt and ERK activation did not change with 1 and 10reps, and thus their responses were not dose-dependent with resistance exercise in humans. The findings from this study represent the first indication that Akt activation is reduced in response to resistance exercise in human skeletal muscle, possibly to help mediate reductions in glycogen synthesis.
Human Performance Laboratory

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DeLacy, Michael. "Postural muscle activation timing in children with and without cerebral palsy /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19973.pdf.

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Kellis, Eleftherios. "Muscle activation and joint loading during isokinetic eccentric and concentric exercise." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321116.

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Roberts, Andrew James. "Biomechanical, muscle activation and clinical characteristics of chronic exertional compartment syndrome." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30669.

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Chronic exertional compartment syndrome (CECS) is a common problem within both military and athletic populations that can be difficult to diagnose. Furthermore, it is unclear what causes the development of CECS, particularly in the military population, as personnel undertake a variety of activities that can cause pain with CECS such as fast walking, marching and running. Chronic exertional compartment syndrome has been hypothesised to develop due to excessive muscle activity, foot pronation and abnormal biomechanics predominantly at the ankle. Treatment of CECS through running re-education to correct these abnormalities has been reported to improve symptoms. However no primary research has been carried out to investigate the biomechanical, muscle activation and clinical characteristics of military patients with CECS. The purpose of this thesis was to provide an original contribution to the knowledge through the exploration of these characteristics; and the development of insights into the development of CECS, with implications for prevention and treatment. Study one investigated the clinical characteristics of 93 service personnel with CECS. Plantar pressure variables, related to foot type and anterior compartment muscle activity, and ankle joint mobility were compared during walking between 70 cases and 70 controls in study two. Study three compared three-dimensional whole body kinematics, kinetics and lower limb muscle activity during walking and marching between 20 cases and 20 controls. Study four compared kinematics and lower limb muscle activity during running in a separate case-control cohort (n=40). Differences in electromyography (EMG) intensity during the gait cycle were compared in the frequency and time domain using wavelet analysis. All studies investigated subject anthropometry. Cases typically presented with bilateral, ‘tight’ or ‘burning’ pain in the anterior and lateral compartments of the lower leg that occurred within 10 minutes of exercise. This pain stopped all cases from exercising during marching and/or running. As such subsequent studies investigated the biomechanics of both ambulatory and running gaits. Cases in all case-control studies were 2-10 cm shorter; and were typically overweight resulting in a higher body mass index (BMI) than controls. There was strong evidence from study 3 that cases had greater relative stride lengths than controls during marching gait. This was achieved through an increase in ankle plantarflexion during late stance and a concomitant increase in the gastrocnemius medialis contraction intensity within the medium-high frequency wavelets. Given the differences in height observed, this may reflect ingrained alterations in gait resulting from military training; whereby all personnel are required to move at an even cadence and speed. These differences in stride length were also observed in walking and running gaits although to a lesser extent. There was no evidence from the EMG data that cases had greater tibialis anterior activation than controls during any activity tested, at any point in the gait cycle or in any frequency band. In agreement, there was also no evidence of differences between groups in plantar pressure derived measures of foot type, which modulate TA activity. Toe extensor - related plantar pressure variables also did not differ between groups. In summary, contrary to earlier theories, increased muscle activity of the anterior compartment musculature does not appear to be associated with CECS. The kinematic differences observed during running only partially matched the clinical observations previously described in the literature. Cases displayed less anterior trunk lean and less anterior pelvic tilt throughout the whole gait cycle and a more upright shank inclination angle during late swing (peak mean difference 3.5°, 4.1° and 7.3° respectively). However, no consistent differences were found at the ankle joint suggesting that running is unlikely to be the cause of CECS in the military; and that the reported success of biomechanical interventions may be due to reasons other than modifying pathological aspects of gait. In summary, the data presented in the thesis suggest that CECS is more likely to develop in subjects of shorter stature and that this is associated with marching at a constant speed and cadence. Biomechanical interventions for CECS, such as a change in foot strike or the use of foot orthotics, are unlikely to be efficacious for the military as personnel will continue to be required to march at prescribed speeds to satisfy occupational requirements. Preventative strategies that allow marching with a natural gait and/or at slower speeds may help reduce the incidence of CECS. The lack of association with foot type or muscle activity suggests that foot orthoses would not be a useful prevention strategy or treatment option for this condition.

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Kelson, Denean M. "Muscle Activation Patterns and Chronic Neck-Shoulder Pain in Computer Work." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83759.

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Prolonged computer work is associated with high rates of neck and shoulder pain symptoms, and as computers have become increasingly more common, it is becoming critical that we develop sustainable interventions targeting this issue. Static muscle contractions for prolonged periods often occur in the neck/shoulder during computer work and may underlie muscle pain development in spite of rather low relative muscle load levels. Causal mechanisms may include a stereotypical recruitment of low threshold motor units (activating type I muscle fibers), characterized by a lack of temporal as well as spatial variation in motor unit recruitment. Based on this theory, although studies have postulated that individuals with chronic neck-shoulder pain will show less variation in muscle activity compared to healthy individuals when engaged in repetitive/monotonous work, this has seldom been verified in empirical studies of actual computer work. Studies have rarely addressed temporal patterns in muscle activation, even though there is a consensus that temporal activation patterns are important for understanding fatigue and maybe even risks of subsequent musculoskeletal disorders. This study applied exposure variation analysis (EVA) to study differences in temporal patterns of trapezius muscle activity as individuals with and without pain performed computer work. The aims of this study were to: Assess the reliability of EVA to measure variation in trapezius muscle activity in healthy individuals during the performance of computer work; Determine the extent to which healthy subjects differ from those with chronic pain in trapezius muscle activity patterns during computer work, measured using EVA. Thirteen touch-typing, right-handed participants were recruited in this study (8 healthy; 5 chronic pain). The participants were asked to complete three 10-minute computer tasks (TYPE, CLICK and FORM) in two pacing conditions (self-paced, control-paced), with the healthy group completing two sessions and the pain group completing one. Activation of the upper trapezius muscle was measured using surface electromyography (EMG). EMG data were organized into 5x5 EVA matrices with five amplitude classes (0-6.67, 6.67-20, 20-46.67, 46.67-100, >100% Reference Voluntary Exertion) and five duration classes (0- 1, 1-3, 3-7, 7-15, >15 seconds). EVA marginal distributions (along both amplitude and duration classes) for each EVA class, as well as summary measures (mean and SD) of the marginal sums along each axis were computed. Finally, “resultant” mean and SD across all EVA cells were computed. The reliability in EVA indices was estimated using intra-class correlation coefficients (ICC), coefficient of variation (CV) and standard error of measurement (SEM), computed from repeated measurements of healthy individuals (aim 1), and EVA indices were compared between groups (aim 2). Reliability of EVA amplitude marginal sums ranged from moderate to high in the self-paced condition and low to moderate in the control-paced condition. The duration marginal sums were moderate in the self-paced condition and moderate to high in the control-paced condition. The summary measures (means and SDs) were moderate to high in both the self-paced and control-paced condition. Group comparisons revealed that individuals with chronic pain spent longer durations of work time in higher EVA duration categories, exhibited larger means along the amplitude, duration and in the resultant, and higher EVA SD in the amplitude and duration axes as compared to the healthy group. To our knowledge, this is the first study to report on the reliability of EVA applied specifically to computer work. Furthermore, EVA was used to assess differences in muscle activation patterns as individuals with and without chronic pain engaged in computer work. Individuals in the pain group seemed to exhibit prolonged sustained activation of the trapezius muscle to a significantly greater extent than controls, even though they did not experience pain during the performance of the computer tasks (as obtained through self-reports). Thus, these altered muscle recruitment patterns observed in the pain subjects, even in the absence of task-based pain/discomfort, are suggestive of chronic motor control changes occurring in adaptation to pain, and may have implications for the etiology of neck and upper-limb musculoskeletal disorders.
Master of Science
This study aims to assess the reliability of exposure variation analysis (EVA) to measure variation in trapezius muscle activity in healthy individuals during the performance of computer work, and to determine the extent to which healthy subjects differ from those with chronic pain in trapezius muscle activity patterns during computer work, measured using EVA. Muscle activation was recorded for eight healthy individual and five suffering from chronic neck-shoulder pain. The data were then categorized into amplitude and continuous time categories, and summary measures of resulting distributions were calculated. These measures were used to assess the reliability of participant responses to computer work of healthy individuals, as well as quantify differences between those with and without chronic pain. We found that individuals with pain activated their neck-shoulder muscles for longer continuous durations than healthy individuals, thus showing an inability to relax their muscles when performing work.

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Thompson, William Kevin. "T2 Mapping of Muscle Activation During Single-Leg Vertical Jumping Exercise." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1194982561.

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Reeder, Adam. "Ankle Muscle Activation During Unilateral and Bilateral Lower Body Strength Exercises." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1396623200.

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Russ, Anne C. "Sex, Hormones, and Use of Contraceptives on Muscle Strength and Activation." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/161946.

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Kinesiology
Ph.D.
Women are more likely to sustain knee injuries (e.g., ACL tears) than their male counterparts. The mechanisms responsible for this disparity are unclear. However fluctuating hormones during the menstrual cycle may be an influencing factor since more ACL injuries have been observed preceding ovulation when estrogen levels increase. Previous research shows females to have increased muscle strength and altered neuromuscular activation prior to ovulation. These findings have not been replicated in females using oral contraceptives (OC). To date, no study has examined all of these factors simultaneously. The purpose of this study was to determine the effect of sex, hormones, and contraceptive use on neuromuscular function at 3 points during a menstrual cycle. A prospective cohort design with independent variables of group [male (n=10), female no-OC (n=10), female OC (n=10)], and testing session (1,2,3) was used to assess knee function (i.e., tibial translation, isometric strength, vertical leg stiffness, and neuromuscular activation) on physically active college-aged participants. Three testing sessions were scheduled throughout a typical menstrual cycle. Tibial translation was measured at the start of each testing session to assess ACL laxity, for handgrip, knee extensors and knee flexors strength. Area EMG activity of the rectus femoris (representing quadriceps) and biceps femoris (representing hamstrings) was recorded over 3 46cm drop jumps, and vertical leg stiffness was calculated based on measurements obtained by a force plate. A 3 (group) x 3 (testing session) MANOVA (p ≤ 0.05) was used to assess knee function, as defined by tibial translation, strength, EMG activation and vertical leg stiffness. A significant difference was found with respect to strength, as males overall displayed greater strength than both female groups. No other significant differences were found. Although this study attempted to explain the effect of estrogen on strength and neuromuscular function with an improved design, no conclusive evidence was found to further explain this relationship. Future studies should use more sensitive and objective measures to explore this dynamic on a greater sample size over multiple menstrual cycle phases.
Temple University--Theses

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Doix, Aude-Clémence. "Stratégies d’activation neuromusculaires de la fatigue musculaire volontairement et électriquement induite : mécanismes sous-jacents et implications cliniques." Thesis, Nice, 2013. http://www.theses.fr/2013NICE4098/document.

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La prise en charge thérapeutique de la fatigue musculaire par le biais d’exercices physiques vise à améliorer la qualité de vie et implique habituellement des exercices unilatéraux ou l’électrostimulation neuromusculaire pour compenser une fonction musculaire altérée aussi bien chez les personnes saines ou dites vulnérables (e.g. atteintes d’une pathologie ou d’un traumatisme). La fatigue musculaire est une réduction de la capacité de production maximale de force, induite par l’exercice, que la tâche puisse être maintenue ou non (Bigland-Ritchie et al. 1983; Gandevia 2001; Enoka and Duchateau 2008). L’objectif général de cette thèse était d’étudier les stratégies d’activation neuromusculaire lors de la fatigue musculaire, de l’endurance musculaire et sur la performance musculaire au cours et/ou après des contractions volontaires et évoquées électriquement chez des personnes saines ou vulnérables tels que des enfants atteints d’infirmité motrice cérébrale (IMC) et des patients atteints de dystrophie musculaire facio-scapulo-humérale (DMFSH)
The clinical care of muscle fatigue with exercise therapies aim at quality of life improvement and usually involve unilateral exercises or neuromuscular electrical stimulation to compensate impaired muscle function in both healthy and health-compromised people. Muscle fatigue is a decline in maximal force production, induced with exercising, whether or not the task can be maintained (Bigland-Ritchie et al. 1983a; Gandevia 2001a; Enoka and Duchateau 2008). The overall objective of this thesis was to study the effect of neuromuscular activation strategies during muscle fatigue, endurance and muscle performance after voluntary and electrically evoked contractions in healthy and health-compromised populations such as children with cerebral palsy (CP) and patients with facioscapulohumeral muscular dystrophy (FSHD)

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Norman, Catalina. "Influence of the thin filament calcium activation on muscle force production and rate of contraction in cardiac muscle." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1178751966.

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Clark, Linnette. "Effect of transverse abdominus muscle activation on a pelvic muscle exercise program in women with stress urinary incontinence." Thesis, NSUWorks, 2008. https://nsuworks.nova.edu/hpd_pt_stuetd/12.

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Purpose: The literature indicates that normal healthy women can increase the strength of the pelvic floor muscles (PFMs) by simultaneously contracting the transverse abdominus (TrA) muscle. This study investigated the relationship of the PFMs and the TrA in women with stress urinary incontinence (SUI). Subjects: 15 women with SUI, verified by scores on the Questionnaire of Urinary Incontinence Diagnosis (QUID), were randomly assigned, blocked by age, into 2 exercise groups. The 6 women in the PFM only group had a mean age of 63 years and the 9 women in the PFM+TrA group had a mean age of 49 years. Method: For 2 weeks, all women were trained by rehabilitative ultrasound imaging (RUSI) to correctly contract the TrA or relax the TrA during a PFM contraction depending upon the group assignment. Each woman was examined using the PERFECT scheme and prescribed a patient-specific PFM exercise program. The exercise protocols required 6 weeks of supervised patient specific exercises. Data collection occurred at 3 time periods (before intervention, after intervention, and follow-up) and included: measurement of TrA thickness changes and PFM lift by RUSI, PFM strength and endurance with pressure perineometry, number of incontinence episodes and pad use from bladder diaries, and quality of life (QOL) measurements using the Incontinence Impact Questionnaire (IIQ) and the Patient Specific Functional Scale (PSFS). Results: MANOVA identified no significant difference after interventions between groups. All women significantly improved in PFM strength (PConclusion: PFM exercises done in isolation or with recruitment of the TrA increased PFM strength, endurance, lift and decreased incontinence in women with SUI. Recommendations: Women with SUI can benefit from physical therapists prescribing PFM exercises in isolation or in combination with TrA contractions.

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Rehg, Maranda. "Abdominal muscle activation and caloric expenditure : Ab Circle versus traditional exercise modalities /." View online, 2010. http://repository.eiu.edu/theses/docs/32211131576496.pdf.

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Nilsson, Isak. "Inverse Modeling of Biomechanical Tongue Control : From Articulation Data to Muscle Activation." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153771.

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We map real articulation data for five Swedish phonemen sequences onto parameters of a biomechanical tongue model that produces movement and muscle activations from position data. The movement produced is broadly correct and could likely be improved by a more fine tuned mapping. The muscle activations were found to vary between simulations using the same data but matched well with previous studies on muscle activity for vowels.

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Dissertations / Theses on the topic 'Muscle activation'

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