An isometric, zero-order (position), one dimensional pursuit tracking task was used to investigated the effects of alterations in the speed of target movement and the control/response ratio (C/R ratio) on human tracking performance. The speed of target movement was varied through different frequency sine-wave forcing functions. The C/R ratio was controlled by varying the force level required to track the target. This required force level was individually tailored I with force levels scaled to the isometric maximum voluntary contraction (MVC) of elbow extension for each subject. It was hypothesized that higher frequencies of forcing function (5 levels) and higher required force levels (5 levels) would result in degraded tracking performance. The dependent variable investigated was absolute tracking error as a proportion of the required force level for the trial. Results revealed significant main effects for both Frequency and Force, but not for any of the two- or three-way interactions. The trend was linear for Frequency, with superior tracking occurring at slower frequencies. The effect of Force level was modelled using a second-order polynomial, indicating that superior tracking occurred at the middle required force levels. Regression analysis provided a predicted optimal force level of approximately 65% extension MVC. Subjective mental workload evaluations using the Modified Cooper-Harper scale showed similar results. Results are interpreted with regards to selecting optimum system gains for human manual control. / Master of Science

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<p> The interrelationship of force, surface elecrograms (EMG) and joint position for static voluntary contractions of Quadriceps Femoris muscle group in man were investigated before and during partial curarization induced by d-tubocurarine. </p> <p> Four normal male volunteers were studied. Each performed a series of brief isometric contractions (by extension of the lower leg against resistance) at different levels of force and at three knee-joint positions while lying in the supine position. All series were repeated for both a normal state and a partially paralyzed state under the :influence of curare. Torque generated about the knee-joint was measured with a Cybex isokinetic system and the nyoelectric activity of three quadriceps muscles was monitored using bipolar surface electrodes. </p> <p> Traditional parameters of nyoelectric activity (mean-rectified-EMG [MRE], and root-mean-squared-DG [RMSE]) were calculated using a minicomputer (PDPll/34), which had also acquired and processed the data. In addition, EMG power spectra were computed by Fast Fourier Transform techniques in an attempt to provide further insight into the effects of curare on human muscle. </p> <p> In order to provide a basis for comparison of the normal state with the parially curarized state, force-EMG relationships were computed for each subject, muscle, knee-joint angle, and condition. Statistical methods (three-way ANOVA' s) were then employed to both quantify any differences that may have existed between the two states and to identify sources of differences within each state. A similar statistically- based comparison of the power spectra was undertaken utilizing several indices that described the shape of the spectra. A general description of the activities of the quadriceps femoris muscles followed after collating all the information that the surface DIG provided in conjunction with the external forces measured. </p> <p> It was concluded that curare did not have any significant effects on the force-EMG relationship. There appeared to be a slight effect of curare on the power spectra however, with a general trend of increasing lower frequency power. The greatest source of variation of force-EMG relationships and power spectra was attributed to the position of the knee-joint. </p> / Thesis / Master of Engineering (MEngr)

<p> Recent evidence has demonstrated that isometric handgrip training may improve resting arterial blood pressure. The current study evaluated the ability of simple, spring handgrips to reduce resting arterial blood pressure in normotensive participants using an 8-week randomized controlled design.</p> <p> Forty-nine (age: 66 ± 1) participants, 28 female and 21 males were recruited. All participants completed 5 pre-training sessions, used to familiarize and assess baseline blood pressure, heart rate and maximal hand strength. Maximal hand strength was assessed by three bilateral, maximal contractions with a hand dynamometer. Blood pressure and heart rate were assessed with an automated acquisition system. Participants were stratified to control and intervention groups based on baseline age and blood pressure by matched-pair randomization.</p> <p> Participants in the training condition (n = 25) completed 8 weeks of thrice weekly handgrip training at approximately 30% of their baseline maximal hand strength using a spring handgrip. Seated blood pressure and heart rate were assessed prior to each training session following 10 minutes of isolated rest. Training included 4, 2-minute contractions separated by 2 minutes of rest and completed bilaterally. Control participants (n = 24) completed weekly-seated measurements of blood pressure and heart rate following 10 minutes of isolated rest. Following 8 weeks of intervention all participants completed 3 sessions of post-training measurements.</p> <p> In trained participants, resting systolic and diastolic pressure decreased significantly from pre- to post- (SBP: 122 ± 3 mmHg to 112 ± 3 mmHg, DBP: 70 ± 1 mmHg to 67 ± 1 mmHg) while heart rate remained unaltered. Pulse pressure was significantly reduced with handgrip training, from 52 ± 3 mmHg to 45 ± 3 mmHg. Control participants demonstrated no changes in blood pressure, heart rate and pulse pressure, over the course of the study.</p> <p> In conclusion, spring handgrip training results in significant decreases in systolic, diastolic and pulse pressure. The mechanisms behind these improvements remain unknown and require further investigation.</p> / Thesis / Master of Science (MSc)

<p> This study examined the effects of isometric handgrip training (IHG) on resting blood pressure and resting arterial compliance in the carotid and brachial arteries of medicated hypertensive individuals. Previous studies found that isometric training reduced resting arterial blood pressure (RBP) in high-normal and medicated hypertensive individuals. Investigators have also found an improvement in central arterial compliance with aerobic training and a reduction in central arterial compliance with age, cardiovascular disease and resistance training. The effects of isometric training on arterial compliance have not been examined previously.</p> <p> Ten participants participated in a one-hand IHG intervention, nine participants in a two-hand IHG intervention and 5 participants served as the non-exercising controls. Each experimental group performed four, 30% maximal voluntary IHG contractions for 2 minutes, 3 days a week, for 8 weeks. The one-hand group trained only their non-dominant hand, while the two-hand group trained both hands. Measurements of resting arterial blood pressure, and cross sectional compliance of the brachial and carotid arteries were made pre-training, after four weeks of training and after the completion of the eight-week training protocol.</p> <p> There were no changes in resting arterial blood pressure after training. Mean carotid and brachial artery diameters did not change with resistance training. There were no significant changes in brachial or carotid cross sectional compliance with isometric training. In conclusion, moderated level isometric training did not elicit changes in resting arterial blood pressure and resting muscular and elastic arterial compliance in medicated hypertensive individuals compared to a non-exercising control group.</p> / Thesis / Master of Science (MSc)

The purpose of this research was to study the relationship between muscle coordination and the performance of a simple manual tracking task. The study employed an isometric, zero order, pursuit tracking task with a laterally translating, periodic sine wave forcing function. The speed of the target was varied by altering the Frequency (3 levels) of the simple sine wave. The control/response ratio for each trial was manipulated by requiring a percentage of each subject’s flexion and extension maximum voluntary contraction effort (MVC, 5 levels) to track the target. Multiple electromyograms (EMGs) of the biceps and triceps muscle groups were taken to observe flexor and extensor activity during the tracking task. Muscle modeling techniques were used to quantify the force contributions from the biceps and triceps to the observed tracking force. It was hypothesized that significant levels of co-active muscle effort would be present during the tracking task and that this co-contraction would have a unique characteristic function about the tracking conditions which yielded optimal tracking performance. The dependent measures investigated were the absolute tracking error as a proportion of the required tracking force (proportional error, PE), the absolute antagonist muscle force (AAF), and the ratio of antagonist to agonist force (co-contraction ratio, CR). Each muscle group’s maximum muscle force (MMF) required to track each condition was also determined. The experimental design was a 3 by 5 by 2 mixed factor, repeated measures ANOVA with Gender (5 male, 5 female) as the blocking variable. The ANOVA results revealed that both target Frequency and tracking Force level had significant effects on tracking error (PE). Orthogonal polynomial contrasts showed that the Frequency effect was characteristically linear while the Force effect was quadratic in nature. A polynomial regression function was used to predict PE from the Force and Frequency conditions. This model accounted for over 96% of the variance in the PE cell means. Further analysis revealed the optimal Force level for isometric tracking to be approximately 61% MVC. Analysis of the force contributions from each muscle group revealed quadratic relationships for the actual muscle force (%MMF) of the biceps during flexion and of the triceps during extension. These results show that optimal tracking performance during flexion occurs at approximately 66% of the biceps MMF and 65% of the triceps MMF during extension. Actual MMF values were consistently larger than net force values indicating that due to the presence of co-contraction, the measured force output at the wrist underestimated the actual muscle forces involved in tracking. Neither Force nor Frequency had significant effects on absolute co-activity (AAF) showing that antagonist activity remained largely constant over the tracking conditions. However, co-activity was higher for the extension phase than for the flexion phase of the task. Both Force and Frequency had significant effects on the co-contraction ratio (CR). However, no characteristic function of co-activity was found to explain the optimal tracking performance at median levels of flexion and extension force. CR increased with increasing target speed (Frequency) while it decreased with higher tracking Force levels. Since antagonist activity (AAF) remained almost constant, these results for CR must be due to changes in the level of agonist activity needed to perform the tracking task. Higher co-contraction was also found during decreasing force production (release) than for increasing force production (exertion). Since there was no significant difference in tracking error for these parts of the task, co-activity may serve to facilitate tracking performance by controlling the rate of force release. / Master of Science

An isometric, zero-order, two-dimensional pursuit tracking task utilizing a tracking path that incorporated both linear and circular segments was used to examine the effects of variation in force magnitude, force direction, and direction of target movement upon tracking performance. A contralateral force-matching procedure was also employed to assess the effects of variation in force level and force direction upon force discrimination capabilities. Increases in force demand were hypothesized to result in degradation of both force discrimination capabilities and accuracy of tracking performance. Variation in force direction was hypothesized to result in tracking performance degradation and force discrimination deterioration that were inversely related to strength-related differences associated with each direction. It was hypothesized that linear tracking performance during inward (force-decreasing) movement of the target would be superior to linear tracking performance in the outward (force-increasing) direction. Finally, it was hypothesized that the direction-sensitive strength:demand ratio, SDR, (a measure of the relationship between strength and the magnitude of force demand) would correlate with both tracking performance and force discrimination measures and that force discrimination measures would correlate with tracking performance. The findings robustly supported the hypothesized Force Level effect. The strength-related Force Direction effects were also supported, but somewhat less consistently than those for Force Level. As also hypothesized, linear inward tracking was superior to linear outward tracking. Previously unreported direction-of-movement effects were found for the circular tracking conditions. When measured along the path, clockwise (CW) tracking was superior to counterclockwise (CCW) tracking with the differences being greatest at the higher force level and in the longitudinal (forward and aft) directions. CCW tracking was superior to CW tracking when measured orthogonal to path. The hypothesized correlations among SDR, two of the three force discrimination measures, and tracking performance were found to be small but significant. / Ph. D.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The effects of isometric exercises on blood pressure (BP) and heart rate (HR) indexes have been investigated. However, the samples are usually reduced, which makes it difficult to generalize the data. Systematic reviews with meta-analyzes are presented as alternatives because it allows the grouping of data from different studies. Thus, the objective of this study was to evaluate the influence of age on acute PA and HR changes in adults generated by isometric exercise (Study I), as well as to investigate the chronic effects on these same parameters (Study II). To do so, we searched the PubMed, Lilacs, Scopus and PeDro databases for clinical trials published until May 23, 2016 that evaluated changes in BP and HR in adults after isometric exercises and performed with subjects> 18 years. The studies that studied the responses after an isometric exercise session were selected and separated according to the age of the sample, <and> 60 years, to analyze the influence of age on the acute effect. Those with intervention period ≥4 weeks were selected for chronic effect assessment. Thus, 4 articles were included in study I and, although half of the studies were performed with adults and the other with the elderly, the direct comparison of the studies was not performed, due to divergences between the exercise characteristics used. In study II, 2 studies were identified that demonstrated that isometric manual grip training is able to significantly reduce SBP and MAP only, -1.58 [-2.64, -0.51], p = 0.004, and -0.91 [-1.58, -0.24], p = 0.008, respectively, after an intervention period of 8-10 weeks. Thus, it was observed a need to produce studies that seek to evaluate the acute responses to isometric exercise protocols with similar characteristics used in current chronic training programs, especially in the elderly and hypertensive, so that questions about risk and differences between Populations are identified. In addition, isometric manual grip training significantly reduces systolic BP and mean BP of adults. However, studies with different samples and modalities of different isometries are still necessary to safely subsidize the use of this training modality in the management of hypertension. / Os efeitos de exercícios isométricos sobre os índices de pressão arterial (PA) e frequência cardíaca (FC) vêm sendo investigado. No entanto, as amostras costumam ser reduzidas o que dificulta a generalização dos dados. Revisões sistemáticas com meta-análises se apresentam como alternativas por possibilitar o agrupamento dos dados de diferentes estudos. Assim, o objetivo deste trabalho foi avaliar na literatura a influência da idade sobre as alterações agudas de PA e FC de adultos geradas pelo exercício isométrico (Estudo I), bem como investigar os efeitos crônicos sobre estes mesmos parâmetros (Estudo II). Para tal, foram realizadas buscas nas bases de dados: PubMed, Lilacs, Scopus e PeDro, por ensaios clínicos publicados até 23 de Maio de 2016 que avaliaram mudanças de PA e FC em adultos após exercícios isométricos e realizados com sujeitos com idade >18. Os estudos que estudaram as respostas após uma sessão de exercício isométrico foram selecionados e separados de acordo com a idade da amostra, < e > 60 anos, para análise da influência da idade sobre o efeito agudo. Aqueles com período de intervenção ≥4 semanas foram selecionados para avaliação de efeito crônico. Assim, foram incluídos 4 artigos no estudo I e, apesar de metade dos trabalhos ter sido realizada com adultos e a outra com idosos, a comparação direta dos estudos não foi realizada, devido às divergências entre as características de exercício utilizadas. No estudo II, foram identificados 2 trabalhos que demonstraram que o treino isométrico de preensão manual é capaz de reduzir significativamente apenas a PAS e a PAM, -1,58 [ -2,64 , -0,51 ] , p = 0,004, e -0,91 [-1,58 , -0,24], p = 0,008, respectivamente, após um período de intervenção de 8-10 semanas. Com isso, observou-se uma necessidade de produção de trabalhos que busquem avaliar as respostas agudas a protocolos de exercicio isométrico com caracteristicas similares as utilizadas nos programas de treinamentos crônicos atuais, sobretudo em idosos e hipertensos, para que questões sobre o risco e diferenças entre as populações sejam identificadas. Além disso, o treino de preensão manual isométrico reduz significativamente a PA sistolica e PA média de adultos. Todavia ,estudos com amostras diferentes e modalilidades de isometrias diferentes ainda são necessarios para subsidiar com segurança a utilização desta modalidade de treino no manejo da hipertensão. / São Cristóvão, SE

Muskelstärkande fysisk aktivitet kan likställas med styrketräning och definieras som fysisk aktivitet med avsikt att förbättra eller bibehålla muskulär styrka, muskelvolym och/eller muskulär uthållighet. Explosiv styrka kan beskrivas som kraftutveckling per tidsenhet och är en produkt av styrka/kraft och hastighet. Tidigare studier har visat att en god explosiv och maximal styrka bland annat kan ge hälsovinster, förbättra idrottslig förmåga, minska risken för idrottsskador och kan förebygga fallrisken hos äldre. Isometric mid-thigh pull-test (IMTP) har under de senaste 10 åren blivit ett vanligt test för att mäta helkroppsstyrka hos idrottare. Testet är lätt att administrera och har en god validitet samt reliabilitet. Studiens syfte var att undersöka sambandet mellan explosiv- och maximal styrka hos styrketränande personer vid ett IMTP-test. Tio deltagare med minst ett års erfarenhet av styrketräning rekryterades. Resultatet visade en måttligt stark korrelation (r = 0,48) mellan explosiv och maximal styrka, men ingen statistisk signifikans (p = 0,158). Deltagarnas Peak Force var i genomsnitt 2644 ± 404 N och Peak force vid 250ms var medel 1808 ± 231 N (i medel hade deltagarna uppnått 69% av Peak Force vid 250ms). Sammanfattningsvis noterades att det möjligen kan finnas en trend i korrelationen mellan explosiv och maximal styrka. Detta indikerar att maximal och explosiv styrka troligen överlappar varandra, det kan däremot inte bekräftas då det inte fanns något statistiskt samband. Vidare rekommenderas att framtida forskning undersöker explosiv styrka och maximal styrka som distinkta styrkeförmågor med fler deltagare och standardiserade testmetoder krävs för att vidare undersöka sambandet mellan maximal och explosiv styrka. / Muscle-strengthening physical activity can be equated with strength training and is defined as physical activity with the intention of improving or maintaining muscular strength, muscle volume, and/or muscular endurance. Explosive strength can be described as force development per unit of time and is a product of strength/power and speed. Previous studies have shown that good explosive and maximal strength can yield health benefits, improve athletic performance, reduce the risk of sports related injuries, and prevent the risk of falls in older adults. The Isometric Mid-Thigh-Pull-test (IMTP) has become a common test for measuring whole body strength in athletes over the past 10 years. The test is easy to administer and has good validity and reliability. The aim of the study was to investigate the relationship between explosive and maximal strength in resistance-trained individuals using an IMTP-test. Ten participants with at least one year’s experience of resistance training were recruited. The results showed a moderately strong correlation (r = 0,48) between explosive and maximal strength, but no statistical significance (p = 0,158). The participants’ Peak Force averaged 2644 ± 404 N, Peak Force at 250ms averaged 1808 ± 231 N (on average, participants had received 69% of Peak Force at 250ms). In summary, it was noted that there might be a trend in the correlation between explosive and maximal strength. This suggests that maximal and explosive strength likely overlap, but this cannot be confirmed as there was no statistical significance. Furthermore, it is recommended that future research investigates explosive strength as distinct strength abilities. More participants and standardized testing methods are required to further explore the relationship between maximal and explosive strength

Diabetic patients are prone to complications and need foot care education. The purposes of this study were to (1) examine the effectiveness of instruction on knowledge of foot care in diabetics, and practice of foot care in diabetics, and (2) examine the relationship between health promoting behaviors and foot care practices. The theoretical framework for this study was Nola Pender's Health Promotion Model. The sample for the study consisted of 69 individuals, ages 18 and older with diabetes mellitus (Type I or Type II).Control and experimental groups completed a demographic sheet and Pender's Health Promoting Lifestyle Profile. The control group received the traditional intervention of a written handout (Novo Nordisk Pharmaceuticals, Inc.) and a packet including an emery board, moisturizing lotion, and a hand-held mirror. The experimental group received a specialized nursing intervention of one-on-one instruction along with a written handout, and a packet including an emery board, moisturizing lotion, and a handheld mirror. Both groups were informed of a $10.00 stipend obtainable and paid by the researcher, for those who completed the study. Two weeks following the office visit, both groups received by mail: a follow-up letter, post-tests on knowledge (Knowledge Questionnaire) and practice (Practice Profile), and a stamped return envelope.There was a significant difference between the control group and the experimental group in knowledge of foot care. There was no significant difference between the control group and the experimental group in practices of foot care. There was a significant, positive correlation (r=.306, p=.012) between the practices of health promoting behaviors and foot care practices. Also, educational level was positively correlated (r=.432, p=.001) with knowledge of foot care.Several studies have been done on diabetic foot care instruction but few have been done to compare different methods of instruction with foot care knowledge and practice. One-on-one education provides an opportunity for the learner to play an active role in the discussion of alternative methods of foot care while allowing for immediate feedback from the nurse educator. Packets that include a well-written instruction sheet and foot care items for patient use can be helpful when educating patients about foot care. / School of Physical Education