While producing the highest power output of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. By examining how electromyograms (EMGs) and wingbeat kinematics of hummingbirds change in response to varying aerodynamic power requirements during load lifting trials and air density reduction trials, we can better understand how aerodynamic power output is modulated via neuromuscular control. During both treatments increased lift was achieved through increased stroke amplitude, but wingbeat frequency only increased during air density reduction trials. These changes in wingbeat kinematics were matched by increased EMG intensities as aerodynamic power output requirements increased. Despite the relative symmetry of the hovering downstroke and upstroke, the timing of activation and number of spikes per EMG burst were consistently different in the supracoracoideus compared to the pectoralis, likely reflecting differences in muscle morphology.

While producing the highest power output of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. By examining how electromyograms (EMGs) and wingbeat kinematics of hummingbirds change in response to varying aerodynamic power requirements during load lifting trials and air density reduction trials, we can better understand how aerodynamic power output is modulated via neuromuscular control. During both treatments increased lift was achieved through increased stroke amplitude, but wingbeat frequency only increased during air density reduction trials. These changes in wingbeat kinematics were matched by increased EMG intensities as aerodynamic power output requirements increased. Despite the relative symmetry of the hovering downstroke and upstroke, the timing of activation and number of spikes per EMG burst were consistently different in the supracoracoideus compared to the pectoralis, likely reflecting differences in muscle morphology.

Objective: Lifting-seat devices are designed to raise the seat height to reduce biomechanical and neuromuscular demands of a sit-to-stand (STS). The goal of this thesis was to understand how seat height and lifting-seat devices with different mechanisms affect trunk, hip, and knee biomechanics and neuromuscular activity of surrounding muscles, and determine whether the effects are altered by age. Four conditions were tested; 1) no device normal seat height (ND-normal), 2) Seat Assist™ (SA), 3) Power Seat™ (PS), 4) no device raised height (ND-raised). Using a cross-sectional design, two objectives were completed. Objective one compared ND-normal and ND-raised to determine the effects of seat height. Objective two compared ND-raised, PS, SA to determine the effects of lifting-seats. Design: 10 healthy older and 10 healthy younger adults performed five trials of each STS condition. Bilateral lower limb and trunk three-dimensional motion, ground reaction forces and electromyography (EMG) from five muscles were collected.

It is well established that unaccustomed eccentric concentric exercise evokes delayed onset muscle soreness (DOMS) (MacIntyre et al., 2001; Dannecker et al., 2005, 2008; Fredsted et al., 2008; Lewis et al., 2012), muscle fibre disarrangement (Hortobagyi et., al., 1998; Stupka et al., 2001; Carlsson et al., 2007), inflammatory cell emission into blood (Stupka et al., 2001; Laaksonen et al., 2006), increase of the activity of blood plasma creatinkinasis (Stupka et al., 2000; Chen et al., 2010; Skurvydas et al., 2010), decrease of muscle force production (Chen et al., 2010; Semmler et al., 2007; Skurvydas et al., 2010) and decrease of aerobic work capacity (Black, Dobson, 2012). The aforementioned functional, sensory, biochemical and structural changes independently from each other are displayed immediately after eccentric exercise and stay for up to 7 days, dependence on the level of damage (Clarkson et al., 1992; Skurvydas et al., 2000; Stupka et al., 2000, 2001; MacIntyre, 2001; Totsuka et al., 2002; Nottle, Nosaka, 2007; Tofas et al., 2008; Lewis et al., 2012; Paulsen et al., 2012). It is still not clear what acute and residual effect of eccentric exercise on the pulmonary gas exchange is had during different intensity work. It was determined that one hour after eccentric concentric exercise, there increases absolute VO2 during moderate (Zaičenkovienė, Stasiulis, 2010) and heavy intensity loads (Ratkevičius et al., 2006). 48 hours after eccentric exercise, when the... [to full text] / Atlikta daug tyrimų, kuriais nustatyta, kad neįprasti ekscentriniai koncentriniai fiziniai pratimai sukelia vėluojantį raumenų skausmą (MacIntyre et al., 2001; Dannecker et al., 2005, 2008; Fredsted et al., 2008; Lewis et al., 2012), raumeninių skaidulų pažaidą (Hortobagyi et al., 1998; Stupka et al., 2001; Carlsson et al., 2007), uždegiminių ląstelių išskyrimą į kraują (Stupka et al., 2001; Laaksonen et al., 2006), kraujo plazmos kreatinkinazės aktyvumo padidėjimą (Stupka et al., 2000; Chen et al., 2010; Skurvydas et al., 2010), raumenų jėgos sumažėjimą (Chen et al., 2010; Semmler et al., 2007; Skurvydas et al., 2010) bei aerobinio darbo galingumo sumažėjimą (Black, Dobson, 2012). Minėti funkciniai, sensoriniai, biocheminiai ir struktūriniai pakitimai nepriklausomai vienas nuo kito pasireiškia iš karto po ekscentrinių krūvių ir išlieka iki 7 parų, priklausomai nuo pažaidos dydžio (Clarkson et al., 1992; Skurvydas et al., 2000; Stupka et al., 2000, 2001; MacIntyre, 2001; Totsuka et al., 2002; Nottle, Nosaka, 2007; Tofas et al., 2008; Lewis et al., 2012; Paulsen et al., 2012). Vis dar nėra aišku, koks yra ūminis ir liekamasis ekscentrinio krūvio poveikis kvėpavimo dujų apykaitos rodiklių kaitai įvairaus intensyvumo darbo metu. Nustatyta, kad, praėjus vienai valandai po ekscentrinio koncentrinio krūvio, padidėjo absoliučios VO2 reikšmės vidutinio (Zaičenkovienė, Stasiulis, 2010) ir didelio intensyvumo krūvių metu (Ratkevičius et al., 2006). Praėjus 48 val. po ekscentrinio... [toliau žr. visą tekstą]

Previous studies have suggested that protective responses in the pelvic floor muscles (PFMs), described in terms of hypertonicity and over-reactivity, are associated with and may worsen the symptoms of provoked vestibulodynia (PVD, i.e., chronic vulvar pain). A recent study reported that, upon manual palpation of the PFM, hypertonicity was consistently found in the superficial but not the deep PFM layers. The goals of this study were to compare superficial and deep PFM resting tone, protective response magnitude and onset timing to moderate perceived vulvar pain between women with and without PVD. Eleven women with PVD and eleven control women Tcompleted a gynecological examination and standardized PFM electromyography (EMG) testing. Three trials of sTurface EMG activity of the PFM were recorded while a pressure-pain stimulus (PPS) was applied to the vulvar vestibule. Increasing pressure was applied to achieve a perceived pain intensity rating of 6/10 using an 11-point numerical rating scale presented visually. The women with PVD had higher resting EMG activity in their superficial PFMs (p=0.04) as compared to the control group, while no difference was found at the level of the deep PFMs (p=0.12). Participants in both groups demonstrated contractile responses to the PPS in both the superficial and the deep PFM, and these responses were significantly higher (p=0.0001) in the superficial (50.06 vs 38.69 % maximal voluntary electrical activation [MVE]) as compared to the deep (24.88 vs 22.52 %MVE) PFM layers. Women with PVD had significantly higher PFM responses at the superficial layer as compared to the control women (p<0.0005). The onset of the superficial and deep EMG PFM responses followed the PPS application in both groups. No differences were found between the deep and superficial PFM onset latency to the timing of the PPS application.The results of this study suggest that women with PVD have superficial PFMs that are more responsive to vulvar pain than those in non-affected women. The findings also suggest that superficial PFM over-reactivity, rather than deep PFM over-reactivity, is part of the PFM dysfunction reported in women with PVD. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2008-09-26 15:46:22.84

Modelling of human motion is used in a wide range of applications. An important aspect of accurate representation of human movement is the ability to customize models to account for individual differences. The following work proposes a methodology using Hill-based candidate functions in the Fast Orthogonal Search (FOS) method to predict translational force at the wrist from flexion and extension torque at the elbow. Within this force estimation framework, it is possible to implicitly estimate subject-specific physiological parameters of Hill-based models of upper arm muscles. Surface EMG data from three muscles of the upper arm (biceps brachii, brachioradialis and triceps brachii) were recorded from 10 subjects as they performed isometric contractions at varying elbow joint angles. Estimated muscle activation level and joint kinematic data (joint angle and angular velocity) were utilized as inputs to the FOS model. The resulting wrist force estimations were found to be more accurate for models utilizing Hill-based candidate functions, than models utilizing candidate functions that were not physiologically relevant. Subject-specific estimates of optimal joint angle were determined via frequency analysis of the selected FOS candidate functions. Subject-specific optimal joint angle estimates demonstrated low variability and fell within the range of angles presented in the literature. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2008-10-30 01:32:01.606

Objectives: Determine the effect of contraction type and intensity, inertial loading, and visual feedback on various measures of hand tremor in subjects with essential tremor. Methods: Study 1. Twenty-three ET subjects and 22 controls held their hand in an outstretched position while supporting various submaximal loads (no-load, 5%, 15% and 25% 1-repetition maximum). Hand postural tremor and wrist extensor neuromuscular activity (EMG) were recorded. Study 2. Twenty-one ET subjects and 22 controls applied isometric wrist extension contractions with and without visual feedback. Various submaximal contraction intensities were evaluated (5%, 10%, 20% and 30% MVC). Force production and EMG were recorded. Study 3. Twenty-one ET subjects and 22 healthy controls performed slow wrist extension-flexion movements while supporting various submaximal loads (no-load, 5%, 15% and 25% 1-repetition maximum). Angular displacement and EMG were recorded. Results: Study 1. Inertial loading resulted in a reduction in postural tremor in ET subjects. The largest reduction in tremor amplitude occurred at the 15% load, which was associated with spectral separation of the mechanical reflex and central tremor component. Despite an increase in overall neuromuscular activity with inertial loading, EMG tremor power did not increase with loading. Study 2. Higher contraction intensities were associated with larger amplitude force fluctuations and greater EMG amplitudes. Tremor spectral power of force and EMG remained constant at all target intensities, resulting in a reduction in relative tremor power at higher contraction intensities. Visual feedback affected subjects in the control and ET groups similarly. Study 3. Subjects with more pronounced tremor spectral peaks had larger amplitude kinetic tremor, which was reduced with inertial loading. Despite an increase in overall neuromuscular activity with inertial loading, EMG tremor spectral power was only slightly increased with loading, which resulted in a large reduction in relative EMG tremor power. Conclusions: The effect of inertial loading on postural and kinetic tremor amplitude appears to be mediated in large part by its effect on the interaction between the mechanical reflex and central tremor components. The level of motor unit entrainment remains relatively constant in subjects with ET despite increasing contraction intensities. / Thesis (Ph.D, Rehabilitation Science) -- Queen's University, 2008-10-24 11:18:57.537

Introduction: The primary purpose of this research was to determine whether women with stress urinary incontinence (SUI) demonstrate pelvic floor muscle (PFM) strength or endurance deficits and/or changes in the motor control patterns used during maximum voluntary PFM contractions (PFM MVCs) and coughing. A secondary purpose was to determine the effect of age on these parameters. Methods: After first validating the use of vaginal pressure to study the functional output of the PFMs, three studies were carried out to address these objectives. In two studies vaginal pressure and PFM and abdominal muscle electromyography (EMG) data were recorded simultaneously during PFM MVCs and maximum effort coughs in continent women, women with mild SUI and women with moderate to severe SUI in both supine and standing. In the final study, the effect of continence status and age on PFM strength and endurance was measured with vaginal pressure. Results: Changes in vaginal pressure induced by PFM MVCs and coughing were found to reflect changes in urethral pressure. The women with SUI and the continent women were found to be equally able to produce peak PFM EMG and vaginal pressure amplitudes during PFM MVCs and coughs. Compared to the continent women, the women with SUI delayed activating their abdominal muscles during the PFM MVCs. During coughing, vaginal pressure and PFM EMG peaked simultaneously in the continent women, while in the women with SUI vaginal pressure peaked after PFM EMG. During both the PFM MVCs and the coughs, the EMG activity in all of the muscles tested was higher at the onset of vaginal pressure generation in the women with SUI compared to the continent women. No difference was found in PFM endurance between the women with and without SUI. The ability to generate peak vaginal pressure during coughing decreased with age. Conclusions: PFM weakness does not appear to play a significant role in SUI. Rather, the results of this research suggest that a combination of motor control deficits and delays in pressure transmission are associated with SUI in women. / Thesis (Ph.D, Rehabilitation Science) -- Queen's University, 2009-09-21 09:37:12.923

Purpose: Intravaginal probes used for recording electromyography (EMG) from the pelvic floor muscles (PFMs) likely record activity from nearby muscles (crosstalk), and move during functional tasks, causing motion artifact data contamination, threatening the validity of results obtained. This study investigated the test-retest reliability and validity of surface EMG recordings from the PFMs using a novel, theoretically superior electrode in comparison to a commercially available intravaginal probe, the FemiscanTM. Methods: Healthy subjects (n=20) performed tasks with each vaginal electrode in situ: i) PFM maximal voluntary contractions (MVC), ii) coughs, iii) unilateral hip adductor/external rotator contractions at 25%MVC, 50%MVC, and MVC while keeping the PFMs relaxed or maximally contracted, and iv) transversus abdominis contractions (TrA; recorded using fine-wires) at 25%MVC, 50%MVC, MVC. Analyses: i) Intraclass correlation coefficients (ICC), ii) t-tests of proportions (α=0.05), iii) repeated measures ANOVAs and Tukey’s post-hoc testing (α=0.05) and iv) cross-correlation functions between peaks of transversus abdominis and PFM activity were used to determine the between-trial and between-day reliability of each vaginal electrode, a difference in prevalence of motion artifact contamination between electrodes, and the presence of crosstalk from the hip and TrA, respectively. Results: Between-trial reliability of both vaginal electrodes was excellent (ICC(3,1)=0.943-0.974). Between-day reliability was less consistent (ICC(3,1)=0.788-0.924 and 0.648-0.715 for the FemiscanTM and novel electrode, respectively). No significant difference in the proportion of files contaminated with motion artifact using each electrode existed. At submaximal intensities of hip muscle contractions, the FemiscanTM recorded significantly higher EMG amplitudes compared to what it recorded when the hip was relaxed, whereas the novel electrode did not, indicating that the FemiscanTM recorded crosstalk from the hip musculature. Low cross-correlation coefficients (<0.90) and large time delays (≥ 0.5 milliseconds) between peaks of PFM and TrA activity indicated that neither vaginal electrode recorded crosstalk from the TrA. Conclusion: The novel electrode is a promising tool to record EMG from the PFMs, as it records less crosstalk from the hip musculature than current technology while maintaining a high degree of reliability when comparing results collected within the same session; however, this electrode should not be used to compare one’s muscle activity between days. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2011-02-07 14:46:30.811

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