Orientador: Antonio Carlos de Moraes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-18T17:14:16Z (GMT). No. of bitstreams: 1 Fontes_EduardoBodnariuc_D.pdf: 9503115 bytes, checksum: ace5f37f3ad02cc8337e62c4be60c8b2 (MD5) Previous issue date: 2011 / Resumo: O presente trabalho buscou um maior entendimento da formação da percepção subjetiva de esforço (PSE) durante esforços exaustivos. Dessa forma, o primeiro estudo verificou as associações da atividade muscular (EMG) com a PSE, bem como a determinação do limiar de esforço percebido (LEP) e de fadiga neuromuscular (LFN). Esse estudo analisou 11 adultos jovens durante testes de carga constante até a exaustão voluntária máxima com monitoramento constante de PSE e EMG. A taxa de aumento dessas variáveis (EMGslope e PSEslope) foram significativamente correlacionados e inversamente associados ao tempo de exaustão. LEP e LFN e não se diferiram significativamente. Assim, indicamos a estreita relação do recrutamento adicional de fibras com o aumento da PSE. O segundo estudo foi realizado durante estágio no exterior (sanduíche) na África do Sul no ano de 2009. Nesse trabalho, foi analisado os efeitos da diminuição de oferta de oxigênio (hipóxia) sobre variáveis centrais e periféricas e suas associações com PSE. Seis ciclistas realizaram testes exaustivos de carga constante em normoxia e hipóxia com contínua aquisição de respostas de PSE, EMG e oxigenação muscular (MOX) e cerebral (COX). Foi demonstrado que na condição hipóxia ocorre um significativo aumento sobre PSE em seus diferentes modos (local, respiração e geral), EMG e COX, mas não em MOX. Os slopes de PSE e valores finais de COX foram relacionados ao desempenho em normóxia, no entanto ainda maiores foram apresentados em hipóxia. Além disso, COX foi ainda significativamente relacionada RPE local em normóxia e novamente, hipóxia exerceu efeitos maiores nessas associações, mas dessa vez para todos os modos de PSE. No terceiro estudo, foram utilizado os mesmos dados do estudo anterior para verificamos os possíveis efeitos de hipóxia ao estimarmos LEP de maneira diferenciada (local, respiração e geral) e LFN pelo mesmo protocolo. Todos os modos de LEP diminuíram significativamente sob hipóxia, com maiores efeitos sobre LEP local. Já LFN não respondeu aos efeitos da condição experimental. Dessa forma, expandiu-se a utilização de LEP para altitudes moderadas e foi apresentado uma nova forma de predizer capacidade aeróbia referente aos membros envolvidos e respiração, além de PET para o corpo como um todo. Associando os achados dos estudos, podemos inferir a estreita relação de respostas periféricas e centrais sobre a formação de PSE, senda essas fortalecidas em condições de diminuídas ofertas de oxigênio. Mais adiante, essas associações justificam a ampliação de utilização prática de PSE, podendo ser para o exercício de alta intensidade ou monitoramento localizado da capacidade aeróbia / Abstract: The present study aimed to bring better understanding of ratings of perceived exertion (RPE) during exhaustive exercise. Thus, the first study verified the associations of the neuromuscular responses (EMG) with RPE, as well as the determination of the perceived exertion threshold (PET) and neuromuscular fatigue threshold (NFT). Eleven adults performed exhaustive constant-load tests with RPE and EMG recordings. The rate of increase of these variables (EMGslope e RPEslope) were significantly related and associated to performance. Além disso, PET and NFT did not differed. Therefore, it was shown the close relationship of the additional muscle recruitment and RPE. The second study was completed during the international internship in South Africa in 2009. At this investigation, were demonstrated the effects of decreased fraction of inspired oxygen (hypoxia) on central and peripheral responses, as well their relationship with RPE. Six trained cyclists completed exhaustive constant-load tests under normoxia and hypoxia having continuously monitoring of RPE, EMG and cerebral (COX) and muscle (MOX) oxygenation. It was shown that under hypoxia there is a significant increase for all RPE modes (legs, breathing and overall), EMG and COX, but not MOX. The RPE slopes and end values for COX were related to performance under normoxia, however higher associations were found under hypoxia. In addition, COX was significantly related to RPE for legs under normoxia, but again, hypoxia exert higher effects on this association, but this time to all RPE modes. During the third study, the data from last investigation was used to verify the possible effects of hypoxia when estimating differentiated PET (legs, breathing and overall) and NFT during same protocol. All PET modes decrease significantly under hypoxia, with higher effects of PET legs, however, NFT estimation was not affects by this experimental condition. Thus, PET's used was expanded to moderated altitudes and presented a new method to predict aerobic capacity associated to active limbs and breathing, in addition to whole body PET. Associating the studies' findings it is possible to conclude that there is a strict relationship of peripheral and central responses to RPE construct, being this sthrengthed by decreased oxygen availability. Furthermore, these relationship justifies the practical use RPE, as for prescription of high intensity exercise or localized monitoring of aerobic capacity / Doutorado / Ciencia do Desporto / Doutor em Educação Física

It has been well established that both carbohydrate-loading before and carbohydrate ingestion during exercise can enhance endurance performance by supplying carbohydrate for oxidation. However, the precise mechanism(s) underlying the proposed ergogenic effects of these procedures remain to be established. The studies in this thesis were therefore designed to examine the effects of carbohydrate-loading and carbohydrate ingestion on fuel substrate kinetics.

This study examined the relationship between average concentric velocity (ACV) and repetitions in reserve (RIR) in the back squat, bench press, and deadlift. Fourteen resistance-trained men performed three experimental sessions (one for each exercise), which was comprised of 4 sets to failure at 80% of one-repetition maximum. The ACV was recorded on every repetition of every set and cross-referenced with RIR. The main findings of this study were that RIR was a significant predictor of ACV for all three exercises; the mean set ACV was significantly different between exercises (p<0.001); and the relationship between RIR and ACV was set-dependent (p<0.001). However, the within-exercise difference in ACV from set-to-set is unlikely to be practically significant as all of these ACV differences were below the threshold of 0.06 m.s-1, which is the smallest worthwhile change in ACV. Therefore, these results suggest that the RIR/ACV relationship is exercise-specific, and is stable from set-to-set. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

There is epidemiological and experimental evidence suggesting that exercise training may reduce the mortality rate from coronary heart disease, in particular the sudden death rate, and that it may improve the peak functional capacity of the heart. This thesis includes experimental work that is relevant to both these questions.

Eight endurance~trained cyclists rode as far as possible in 1 h on a stationary cyclesimulator in a moderate environment (20°C, 60% relative humidity, 3 m/s wind speed) while randomly receiving either no fluid (NF) or attempting to replace their ~1.7 l sweat loss measured in a previous 1 h familiarisation performance ride at ~85% of peak oxygen uptake (VO₂ peak) with artificially sweetened, coloured water (F). During F the cyclists drank 1.49 ± 0.14 1 (values are mean± SEM), of which 0.27 ± 0.08 1 remained in the stomach at the end of exercise and 0.20 ± 0.05 1 was urinated after the trial. Thus, only 1.02 ± 0.12 l of the ingested fluid was available to replace sweat losses during the 1 h performance ride. That fluid decreased the average heart rate from 166 ± 3 to 157 ± 5 beats/min (P < 0.0001) and reduced the final serum [Na+] and osmolalities from 143 ± 0.6 to 139 ± 0.6 mEq/1 (P < 0.005) and from 294 ± 1.7 to 290 ± 1.9 mOsm/1 (P = 0.05), respectively. Fluid ingestion did not attenuate rises in plasma anti diuretic hormone and angiotensin concentrations, or decrease the ~-15% falls in estimated plasma volume in the F and NF trials. Nor did fluid ingestion significantly effect the ~1.7 l/h sweat rates, the rises in rectal temperature (~36.6° to 38.3°C) or the ratings of perceived exertion in the two trials. Ingestion of ~1.5 l of fluid produced an uncomfortable stomach fullness and reduced the distance covered in 1 h from 43.1 ± 0. 7 to 42.3 ± 0.6 km (P<0.05). Thus, trying to replace > 1.0 l/h sweat losses during high-intensity, short duration exercise in a moderate environment does not induce beneficial physiological effects, and may impair exercise performance.

No description available.

Many variations of conveyor, facility, and trailer designs are available to aid the human operator in manual materials handling (MMH). This thesis describes an investigation to determine which of four different designs used in trailer MMH place the least physical stress on the human operator when unloading materials. Each trailer MMH design was evaluated by the criteria of biomechanical loading, working posture, physiological measure, and subjective rating of exertion. These four methods were used to generate four dependent measures: L5/S1 Compression Force, OWAS Action Category, mean heart rate, and Borg CR-10 RPE. While no single assessment method provided a clear means for quantifying level differences in physical stress among MMH conditions, the methods employed furnished insight into which techniques and protocols might be useful in studying similar working situations. Based on relative sensitivity, ease of application, and administrative and equipment costs, the OWAS method was recommended as an assessment method useful for evaluating similar MMH work. The summary results of the four methods provided information to meet the experimental goals of this research and allowed conclusions to be drawn for the major areas of interest. Specifically, statistically significant differences were found between the Drop-frame - Floor Rollers condition and all other conditions in the SSPM - Placement analysis, between the Flat-floor - Power and the Drop-frame - Suspended Rollers conditions in the OWAS - Acquisition analysis, and between the Drop-frame - Suspended Rollers and the Drop-frame - Floor Rollers conditions in the OWAS - Placement analysis. / Master of Science

Perceived exertion is how hard or heavy an individual feels they are working. Perceived exertion is often quantified using the ratings of perceived exertion (RPE) scale and can be used to measure exercise intensity based on the experience of an individual. While objective methods of assessing exercise intensity, such as measurement of heart rate and percent of peak oxygen uptake, are useful, RPE is commonly implemented for the ease of use and feasibility. For example, RPE is commonly implemented in rehabilitation settings for people with a spinal cord injury and individuals with coronary artery disease because of their non-linear heart rate response to increases in exercise workload. The overarching purpose of this dissertation was to investigate a range of research questions designed to advance the knowledge and use of RPE guided exercise. Through a systematic review and meta-analysis, we examined evidence for the impact on cardiorespiratory fitness and peak power output using RPE-guided interventions in individuals with a spinal cord injury (SCI) and found that RPE-guided interventions improved both after a variety of exercise intervention types and lengths. In a separate retrospective cross-sectional analysis, we then demonstrated that perceived exertion, measured by leg cycling effort during a cardiopulmonary exercise test on a leg cycle ergometer in non-disabled individuals, was predicted by power and maximum power output. After further investigation we found that quadriceps strength predicted maximum power output and therefore is related to leg cycling effort. In the third study of the thesis, we conducted semi-structured interviews in individuals with an SCI and their healthcare practitioners and found that individuals commonly described their sensations associated with the 0-10 RPE scale using muscle sensations when both recalling exercise and after the completion of an acute exercise trial on an arm cycle ergometer. Lastly, we investigated the relationship between psychological and physiological measures and RPE during an arm cycling exercise during a maximal graded exercise test, high intensity interval training, and moderate intensity continuous training using a crossover experimental design in both non-disabled individuals and individuals who were mobility impaired due to SCI. While there were no relationships between any variable and RPE in non-disabled individuals, age and triceps strength predicted central RPE and peak feeling scale predicted peripheral RPE in individuals with an SCI. These mixed methods results collectively suggest that muscle strength, not heart rate, is the strongest predictor of perceived exertion especially in clinical populations completing high intensity exercise. Our novel findings suggest that RPE is regulated through a system of psychological and physiological phenomena, strongly related to muscle sensations arising from the working muscle groups and may have utility and relevance in complementing measures of exercise intensity for a broad range of individuals across the spectrum of health and disease. Future studies should examine the use of muscle sensation descriptions as descriptors of exercise intensity prior to the development of high intensity exercise guidelines in clinical populations, such as individuals with SCI. / Thesis / Candidate in Philosophy / It has been well established that heart rate and ratings of perceived exertion are related in young, healthy individuals, however the nuances of the relationships between other contributors and how clinical populations feel during exercise remain unclear. Using mixed methods, this research sought to determine what sensations help people determine how they feel during exercise, with a focus on high intensity interval training exercise. Our results show that muscle strength may be a key determinant in the perception of effort in individuals with a spinal cord injury and in clinical populations during arm and leg maximal graded exercise tests, but the relationships between physiological variables and perceptions of arm effort in non-impaired individuals remains to be determined. Sensations of effort are regulated through a variety of different mechanisms that vary with population, and the relationships depend on the parameters (e.g., exercise modality and intensity) of the exercise. Future studies should be conducted to determine the individual contributions of different body systems to perceived exertion during exercise in a wide range of populations.

No description available.

Work-related musculoskeletal disorders (WMSDs) are prevalent among health care workers worldwide and underreporting among nurses may mask the true impact of these injuries. Nursing staff are consistently among the top 10 occupations at risk for experiencing WMSDs and patient-handling tasks are the precipitating event in the majority of back injuries experienced among nursing staff. Existing research has focused on patient-handling issues within long-term care facilities, and identifying physically demanding patient-handling tasks. The first study in this dissertation (Chapter 3) was conducted to determine whether nurses in acute care facilities are exposed to the same hazards as their cohorts in long-term care. The aim was to identify the top 10 patient-handling tasks being conducted and to rank these tasks by perceived physical demand. This two-phase study consisted of a procedural task analysis of patient-handling activities, and a questionnaire to identify the characteristics of the study population and obtain a ranking of physically demanding patient-handling tasks. All nurses providing direct inpatient care were recruited to participate in both phases of this study. Compared to long-term care facilities, in which the majority of tasks have been shown to be associated with performance of ADL tasks, the most frequently observed tasks in the acute care facility were repositioning tasks. Therefore, it is important to determine the patient-handling demands and needs that are unique to each type of healthcare facility. Generalizing across facilities or units may lead to incorrect assumptions and conclusions about physical demands being placed on nurses. A laboratory simulation was used for the second study (Chapter 4). The top four physically demanding patient-handling tasks (taken from Chapter 3) were simulated to determine the effect of an assistive device and assistance from another person. Sixteen nurse volunteers were recruited and provided perceptual responses regarding exertion and injury risk. Nurses perceived that assistance decreased their physical exertion and injury risk; however they consistently perceived exertion to be relatively higher than their injury risk. The aim of the third study (Chapter 5) was to determine the level of agreement between and within different expert groups. Three groups of participants were involved, with different levels of ergonomics expertise (i.e. researchers, consultants, and graduate students). These groups viewed digitized video clips from the laboratory simulation (Chapter 4) and provided ratings of perceived exertion, perceived injury risk and common WMSD risk factors (effort, posture, and speed). The major finding from this study was that poor agreement existed between nurses and the other expert groups (researchers, consultants and students). The current research laid the groundwork for measuring the magnitude of physical exposure to injury risk in the patient-handling environment. The research supports earlier evidence that suggests nurses underreport their discomfort and injury, which, in turn, contributes to increased exposure and risk. This knowledge will enable practitioners to focus interventions and designs on those factors in the work environment that contribute significantly to increased exposure and thereby more effectively reduce WMSD risk. / Ph. D.