AIM The aim of this study was to identify the immediate effects on cortical excitability and grip control of a short intervention of EMG-triggered neuromuscular electrical stimulation, compared to voluntary activation of the finger flexor muscles, in people with chronic stroke. STUDY DESIGN This experimental study used a within-subject design with experimental and control interventions. PARTICIPANTS Fifteen people with chronic stroke participated in the study. INTERVENTION Participants performed a simple force tracking task with or without EMG-triggered neuromuscular electrical stimulation of the finger flexor muscles. MAIN OUTCOME MEASURES Cortical excitability was measured by single and paired-pulse transcranial magnetic stimulation. Multi-digit grip control accuracy was measured during ramp and sine wave force tracking tasks. Maximal grip strength was measured before and after each intervention to monitor muscle fatigue. RESULTS No significant increases in cortico-motor excitability were found. Intracortical inhibition significantly increased following the EMG-triggered neuromuscular electrical stimulation intervention immediately post-intervention (t = 2.466, p = .036), and at 10 minutes post-intervention (t = 2.45, p = .04). Accuracy during one component of the force tracking tasks significantly improved (F(1, 14) = 4.701, p = .048), following both EMG-triggered neuromuscular electrical stimulation and voluntary activation interventions. Maximal grip strength reduced significantly following both interventions, after the assessment of cortical excitability (F(1, 8) = 9.197, p = .16), and grip control (F(1, 14) = 9.026, p = .009). CONCLUSIONS EMG-triggered neuromuscular electrical stimulation during short duration force tracking training does not increase cortical excitability in participants with chronic stroke. Short duration force tracking training both with and without EMG-triggered neuromuscular electrical stimulation leads to improvements in training-specific aspects of grip control in people with chronic stroke.

Osteocytes are the most abundant bone cells, however, they are also the least understood. They sense mechanical stress within the bone matrix to control remodelling, but there is debate about the way that this occurs. The bone matrix experiences changes in electrical charge through stress generated potentials in the canaliculi, and piezoelectricity of the collagen-hydroxyapatite junctions. External electrical stimulation (ES) has been shown to increase bone formation, indicating that the cells involved in remodelling are electrically sensitive. However, the effects of ES on osteocytes specifically are under-researched. Before applying ES in vitro the electrical characteristics of the culture media need to be understood to see if it will negatively impact cells in culture. ES in culture media causes pH changes and gas formation as well as precipitate formation directly on the electrode surface. The resistance of the media increases rapidly upon application of the electrical stimulus and plateaus after 100 - 200 minutes. The pH gradient disperses around the same time frame, with most stimulating currents causing no permanent change to the media pH. Stimulation parameters that cause minimal side effects will be better for the health of cells in culture. This should also make it more clear which outcomes are a result of the electrical stimulation and which come from the electrochemical reactions that are present in the media due to the ES. / Thesis / Master of Applied Science (MASc) / Osteocytes are the least understood bone cells and the way that they communicate with the bone matrix and other cells is widely debated. It is assumed that osteocytes sense mechanical stresses within the bone matrix through electrical charges that develop in areas of increased strain. External electrical stimuli have been shown to increase bone formation indicating that the cells are electrically sensitive. The electrical sensitivity of the osteocytes specifically is under-researched causing a gap in knowledge of the behaviour of the cell in the remodelling process. To study the effects of electrical stimulation on osteocytes, an experimental apparatus must be designed to deliver stimulation to the cells in vitro and maintain a stable environment. A culture medium is needed to keep cells alive in vitro To do this, the electrical characteristics of the cell culture medium must be understood in attempts to maintain homeostatic conditions for the cells.

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In osteoporosis treatment, current interventions suffer from challenges of guaranteed efficacy for patients. Electrical stimulation has been shown to improve bone mass in animal models of disuse, but there have been no studies of the effects of electrical stimulation on bone loss in a hormone deficiency model. The purpose of this study was to explore the effects of electrical stimulation on bone mass in the ovariectomized (OVX) rat model. We developed a custom electrical stimulation device capable of delivering a constant current, 15 Hz sinusoidal signal. We used 30 female Sprague Dawley rats (12-13 weeks old). Half were OVX, and half underwent sham OVX surgery (SHAM). These rats were divided into baseline, stimulation (stim), and no-stimulation (no-stim) groups. Stimulation groups received transdermal electrical stimulation to the right knee, while the left knee served as a non-stimulated contralateral control. The no-stimulation groups had electrodes placed on the right knee, but not connected. Rats underwent the procedure for one hour per day for six weeks. Rats were sacrificed (CO2) after six weeks. Femurs and tibias were scanned by microCT. MicroCT data were analyzed for trabecular and cortical bone measures. Femurs and tibias from OVX rats had significantly less trabecular bone than SHAM. In the distal femur of OVX-stim rats, bone volume fraction was significantly greater in the stimulated right than the non-stimulated contralateral (left). There were no differences between stim and no-stim groups for tibial trabecular measures, or cortical bone measures in either the femur or the tibia. This study presents novel findings that electrical stimulation can partially mitigate bone loss in the OVX rat femur, a model of human post-menopausal bone loss. Further work is needed to explore why there was a differential response of the tibial and femoral bone, and to better understand how bone cells respond to electrical stimulation. / Thesis / Master of Applied Science (MASc) / In osteoporosis treatment, current interventions, including pharmaceutical treatments and exercise protocols, suffer from challenges of guaranteed efficacy for patients and poor patient compliance. Moreover, bone loss continues to be a complication factor for conditions such as spinal cord injury, prescribed bed-rest, and space flights. A low-cost treatment modality could improve patient compliance. Electrical stimulation has been shown to improve bone mass in animal models of disuse, but there have been no studies of the effects of electrical stimulation on bone in the context of bone loss under hormone deficiency such as in post-menopausal osteoporosis. To explore whether electrical stimulation could positively affect bone mass, we developed and tested a custom electrical stimulation device in the ovariectomized rat model of post-menopausal osteoporosis.

Beef carcasses from F2 Nellore × Angus (n = 181) and half-blood Bos indicus × Bos taurus (n = 57) were used to evaluate the responsiveness of sire and family groups nested within sires to post-mortem electrical stimulation (ES). In the F2 population, biological response to ES was identified for myofibrillar fragmentation index, and 6 h post-mortem pH. The genetic contributions of sire and families nested within sires were found for the average Warner-Bratzler shear force (WBS), location of shear core extraction, post-mortem carcass temperatures, and carcass pH. ES sides had lower WBS values, higher carcass temperatures, and lower carcass pH. In the half-blood population, biological response to ES was found for WBS core location. Sire and families nested within sires significantly affected WBS core location and carcass temperature. The ES sides had lower WBS values, higher carcass temperatures, and lower carcass pH in the half-blood population. From a carcass temperature and pH standpoint, carcass weight and fat thickness were used as covariates in the analysis of variance. This covariate analysis still showed a genetic component to carcass temperature and pH. There are genetic factors that impact how carcasses respond to electrical stimulation, which is the first work to demonstrate this relationship between genetics and a post-mortem tenderization treatment.

O cuidado com as áreas doadoras de enxertos de pele merece constante atenção, visto que desencadeia desconforto por dor e restrição de movimentos. Existem evidências de que a estimulação elétrica pode acelerar a cicatrização de feridas e produzir analgesia, e que diferentes parâmetros físicos podem interferir nas respostas apresentadas. O objetivo do estudo foi avaliar o efeito da polaridade da corrente na cicatrização e na dor. Para tanto foram comparados os efeitos da estimulação elétrica de alta voltagem (EAV), polarizada, e a estimulação elétrica nervosa transcutânea (ENT), despolarizada, no tratamento das áreas doadoras de pacientes queimados. Para tanto, foram avaliados 48 voluntários do sexo masculino randomizados em três grupos: submetidos à estimulação elétrica de alta voltagem (GEAV), média idade de 34,2(±9,8) anos, n=17; submetidos à estimulação elétrica nervosa transcutânea (GENT), com 34(±9,5) anos, n= 16; e não submetido à estimulação elétrica ou grupo controle (GC) média de idade 35(±9,5 anos), n= 15. Os procedimentos terapêuticos foram aplicados nas extremidades da área doadora, no primeiro pós-operatório, até a epitelização completa. As variáveis avaliadas foram avaliação clínica, o tempo (dias) de epitelização, estimado pelo desprendimento do curativo primário sobre a lesão, avaliação da dor pela escala numérica de dor, a temperatura cutânea pela termografia infravermelha, qualidade da cicatriz (book de fotos, escala ® Vancouver, software Image J ). Após a análise dos dados, foi aplicado o teste de Shapiro-Wilk, em seguida o comportamento pré e pós-intervenção intragrupo foi aplicado o teste Wilcoxon. Para comparação entre os grupos foi efetuado teste de Kruskal-Wallis seguido de post-hoc de Dunn, em todos os casos foi utilizado o nível de significância de 5% (p<0,05). Os achados apontam que o tempo de desprendimento do curativo Rayon das áreas doadoras foi significativamente menor para GEAV apresentando (p<0,033). Houve redução significativa da dor (p<0,05) para o GEAV e para o GENT, quando comparado ao GC. A quantidade relacionada a solicitação de analgésicos foi reduzida para os grupos estimulados, com diferença significativa do GEAV versus GC (p<0,002) e GENT versus GC (p<0,001). Não houve diferença significativa na temperatura cutânea entre os grupos. Não houve diferença significativa no escore final da escala Vancouver e nem quantidade de crostas entre os grupos. A polaridade da corrente pode ter influenciado no tempo de epitelização, porém não interferiu na dor e na qualidade da área doadora. / The cares with donor areas of skin grafts deserve constant attention, since it triggers discomfort due to pain and movement restriction. There are evidences that electric stimulation may accelerate wound healing and produce pain relief. The objective of this study was to evaluate the effect of electric current polarity on the healing and pain. Therefore, the effects of stimulation on high voltage pulsed current (HVPC) and nervous transcutaneous stimulation (TENS) were compared in the treatment of donor areas of burns victims. Therefore, 48 volunteers of the male sex were randomized between three groups: submitted to high voltage pulsed current stimulation (GHVPC), with 34.2 (± 9.8) years, n=17; submitted to nervous transcutaneous stimulation (GTENS), with 34 (±9.5) years, n=16; and nonsubmitted to stimulation group, or control group (GC), average age of 35 (± 9,5) years, n=15. The therapeutic procedures were applied on the edges of the donor area, at the first postoperative, until complete healing. The evaluated variables were ephitelization time (days), estimated by the unfastening of the primary curative on the wound, evaluation of pain by numerical scale of pain, skin temperature by infrared thermography, scar quality (photo book, Vancouver scale and Image J® software). After data analysis, the Shapiro-Wilk test was applied, and the Wilcoxon test was applied to the before and after intervention. Kruskal-Wallis test followed by Dunn post-hoc was used to compare the groups. In all cases, the significance level of 5% (p<0.05) was used. The findings indicate that the time of release of the Rayon dressing from the donor sites was significantly reduced for GEAV (p <0.033). A reduction of pain relief was significant (p<0.05) for the GEAV and for the GENT, when compared to the GC. Amount the number of solitation for analgesic drugs was decreased for the groups stimulated with significant difference of the GEAV verse GC (p<0.002) and GENT verse GC (p <0.001). Change in cutaneous temperature was not significant between groups. There was no difference significant in score of Vancouver scale and in the number of crusts in the groups. The polarity of the current might have influenced the healing time, however not the pain nor the quality of the donor site.

Masters of Science / BACKGROUND: Hamstring injuries remain a growing concern within a large variety of sports from the elite athlete to the weekend warrior. A copious amount of research has been performed in an attempt to reduce these injuries. The aim of this study was to understand the changes in lengthened state eccentric strength of the hamstrings following four separate protocols. METHODS: A quantitative research approach, using a true experimental design, was adopted for this study. A convenience sample of non-sedentary, 35 male participants, between the ages of 18 and 35 within the City of Cape Town was used. Participants were randomly allocated to one of four groups namely; Control group (C), resistance training alone (RT), neuromuscular electrical stimulation alone (NMES), or NMES superimposed with RT (NMES&RT). Participant’s eccentric hamstring strength was tested in a lengthened state, on the Biodex system 4 Pro™ for the pre- and post-test. The intervention spanned over four weeks. SPSS version 25 was used for data analysis. RESULTS: All groups demonstrated a mean increase in relative peak torque. However, a repeated-measures analysis of variance (ANOVA) showed no interaction effect (p = 0.411) between the four groups. Further analysis using Magnitude-based inferences (MBI), to identify the magnitude of changes, showed a small positive effect for both the NMES and NMES&RT group when compared to the C and RT groups. CONCLUSION: Although there are no statistically significant differences between the four groups employed in this study (C, RT, NMES, NMES&RT), NMES and NMES&RT did show small positive effects compared to C and RT with a very low likelihood of negative effects. Thus, using NMES either alone or superimposed with resistance training will be beneficial for trained athletes but it is not a necessity and the use of specific resistance training may be just as effective. / 2019-04-30

abstract: Vagus nerve stimulation (VNS) has shown benefits beyond its original therapeutic application, though there is a lack of research into these benefits in healthy and athletic populations. To address this gap in the VNS literature, the present study addresses the feasibility and possible efficacy of transcutaneous VNS (tVNS) in improving performance and various biometrics during two athletic tasks: golf tee shots and baseball pitching. Performance, cortical dynamics, anxiety measures, muscle excitation, and heart rate characteristics were assessed before and after stimulation using electroencephalography (EEG), the State-Trait Anxiety Inventory (STAI), and electrocardiography (ECG) during the baseball and golf tasks as well as electromyography (EMG) for muscle excitation in the golf participants. Golfers exhibited increased perceived quality of each repetition (independent from outcome) and an improvement in state and trait anxiety after stimulation. Golfers in the active stimulation group also showed a greater reduction in right upper trapezius muscle excitation when compared to the sham stimulation group. Baseball pitchers exhibited an increase in perceived quality of each repetition (independent from outcome) after active stimulation but not an improvement of state and trait anxiety. No significant effects of stimulation Priming, stimulation Type, or the Priming×Type interaction were seen in heart rate, EEG, or performance in the golf or baseball tasks. The present study supports the feasibility of tVNS in sports and athletic tasks and suggests the need for future research to investigate further into the effects of tVNS on the performance, psychologic, and physiologic attributes of athletes during competition. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2019

A forward dynamic model was developed to predict the performance of Spinal Cord Injured (SCI) individuals cycling an isokinetic ergometer using Neuromuscular Electrical Stimulation (NMES) to elicit contractions of the quadriceps, hamstring and gluteal muscles. Computer simulations were performed using three inter-connected models: a kinematic model of segmental linkages, a muscle model predicting forces in response to stimulation, and a kinetic model predicting ergometer pedal forces resulting from muscle stimulation. Specific model parameters for SCI individuals were determined through measurements from isometric and isokinetic contractions of the quadriceps muscles elicited using surface stimulation. The muscle model was fitted to data resulting from these isolated experiments in order to tailor the model's parameters to characteristics of muscles from SCI individuals. Isometric data from a range of knee angles were used to fit tendon slack lengths to the rectus femoris and vastus muscles. Adjustments to the quadriceps moment arm function were not able to improve the match between measured and modelled knee extension torques beyond those using moment arms taken from available literature. Similarly, literature values for constants from the muscle force - velocity relationship provided a satisfactory fit to the decline in torque with angular velocity, and parameter fitting did not improve this fit. Passive visco-elastic resistance remained constant for all velocities of extension except the highest (240 deg/s). Since knee angular velocities this high were not experienced during cycling, a visco-elastic dampener was not included within the present cycling model. The rise and fall in torque following NMES onset and cessation were used to fit constants to match the rate of change in torque. Constants for the rise in torque following NMES onset were significantly altered by changes in knee angle, with more extended angles taking longer for torque to rise. This effect was small, however, within the range of angles used during cycling, and consequently was not included within the cycling model. The decline in torque after NMES cessation was not affected by knee angle. A period of five minutes cyclical isometric activity of the quadriceps resulted in torque declining by more than 75% from rested levels. The activation time constants were largely unaffected by this fatigue, however, with only a small increase in the time for torque to decline, and no change in rise time or the delay between stimulation changes and resulting torque changes. The cycling model, therefore, did not incorporate any effect for changes in activation timing with fatigue. Performance of the full model was evaluated through measurements taken from SCI individuals cycling a constant velocity ergometer using NMES elicited contractions of the quadriceps, hamstring and gluteal muscles. Pedal transducers measured forces applied to the pedals for comparison between measured and modelled values. A five minute period of continuous cycling using just the quadriceps muscles produced similar results to those found for isolated knee extension. External power output dropped by 50% over the five-minute period, however there was no change in the pattern of torque production with fatigue. Cycling experiments were conducted using single muscle groups across a range of NMES firing angles. Experimental protocols were designed to seek the firing angles for each muscle that maximised power output by that group. Changes in power output in response to firing angle changes were not large, however, in comparison to the effects of cumulative fatigue and inconsistent power output between trials. This lead to large uncertainties in the determination of those firing angles that maximised power output by each muscle. Results suggest that NMES firing angles to maximise power output by the quadriceps muscles were relatively similar for each subject. For the hamstring muscles, however, substantial differences were observed in the range of firing angles that maximised power output. Results for the gluteal muscles were variable, with some subjects not applying any measurable torque to the cranks, even with maximal stimulation applied. The model produced a good match to experimental data for the quadriceps muscles, both in the shape of pedal force curves and the firing angles that maximised external power output. The individual variability in hamstring responses was not, however, predicted by the model. Modification of the relative size of the hamstrings' moment arms about the hip and knee substantially improved the match between measured and modelled data. Analysis of results suggests that individual variability in the relative size of these moment arms is a major cause of variation in individual's response to hamstring stimulation. There were apparent limitations in the model's ability to predict the shape of crank torques resulting from stimulation of the gluteus maximus muscle. It is suggested that further research be conducted to enable modelling of this muscle using a range of fibre lengths and moment arms.