Diss. (sammanfattning) Uppsala : Univ. / Härtill 5 uppsatser.

Thesis--Wisconsin. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [129]-139).

The purpose of this research was to investigate how accurate trained lifters were at gauging intra-set rating of Perceived Exertion (RPE) in the squat, bench press, and deadlift. Ten resistance-trained males completed four sets to failure with 80% of their one-repetition maximum (1RM) and verbally indicated when they believed they were at a “6” and “9” RPE. Across all sets and all lifts, the called 9 RPE was more accurate than the called 6 RPE. Additionally, RPE calls were more accurate during set four vs. set one on the squat and deadlift at both the called 6 and 9 RPEs. Further bench press RPE calls were more accurate than squat and deadlift RPE at the called 6, while both bench and deadlift RPE calls were more accurate than squat RPEs at the called 9. Importantly across all sets all RPE calls assessed repetitions in reserve within one repetition of precision. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--University of Wisconsin. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 47-52).

Thesis (M.S.)--University of Wisconsin-Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 96-110).

Thesis (M.S.)--University of Wisconsin-Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 50-53).

The effect of exercise on the total ketone body (acetoacetate + D-3-hydroxybutyrate) concentrations in the blood was studied to find out whether the susceptibility of non-athletes, compared with athletes, to develop post-exercise ketosis is the result of the former's increased reliance on glycolysis during exercise. In the first experiments, use was made of the diving reflex to induce peripheral vasoconstriction during exercise in both physically trained and untrained subjects. It was hoped that under these circumstances athletes and non-athletes would utilize similar amounts of muscle glycogen during exercise, and therefore develop similar degrees of ketosis after exercise, if the glycogen content of the muscles was in fact the factor which determined post-exercise ketosis. Ten non-athletic subjects, six long-distance runners, and three competitive swimmers were therefore studied before, and for 9½ hours after swimming in the early morning. The last meal was eaten during the evening before the swim. On the first test day the subjects swam underwater for as far as they could go three times in succession. A week later the same distance was swum on the surface without breath-holding. There was no increase in the post-exercise blood ketone body concentrations in any of the subjects after either form of the exercise, compared with control day values (when the subjects fasted, but did not swim at 07h30). Similar results were obtained when healthy young medical students (aged 18 - 23 years; trained and untrained) performed maximal exercise for 15 minutes, or moderate exercise for up to 90 minutes, on a bicycle ergometer. When six older subjects (aged 30 - 51 years) exercised at 75 W for 90 minutes, three of them developed ketonaemia, which reached its maximum intensity about three hours after exercise. The exercising heart rates of these older subjects were similar to those of the younger non-athletic subjects who had performed the same exercise, but had not developed post-exercise ketosis., An extra 60 - 90 g sucrose in the diet of the subject who had developed the most marked post-exercise ketonaemia, abolished the response, whereas carbohydrate restriction intensified it. A protein-fat diet caused two well trained marathon runners to develop the highest post-exercise blood ketone body levels yet recorded (3,88 mmoles/l). Free fatty acid, glucose, growth hormone and insulin concentrations in the serum followed patterns different from the ketone body levels during, and for 7 ½ hours after exercise, but were also affected more by diet than by training. Post-exercise ketosis, previously ascribed to a lack of athletic training, could equally well be ascribed to the lower carbohydrate intake of sedentary subjects compared with athletes: the two marathon runners were estimated to eat about twice as much carbohydrate in their regular diet than the sedentary subject who had developed post-exercise ketonaemia without carbohydrate restriction. The final experiments were designed to find out whether post-exercise ketosis was the result of the low levels of glycogen in the body, or of the gluconeogenesis which occurs after exercise to replenish the carbohydrate stores. Twenty-four highly trained athletes were therefore studied after prolonged exercise following a protein-fat diet to induce post-exercise ketosis. Six of them were then given 100 g alanine to take by mouth, six ingested 100 g glucose, six ingested 100 g starch, and the remaining six acted as controls. It was found that both alanine and glucose ingestion reduced the blood ketone body concentration from about 2 mmoles/l to less than 0,4 mmoles/l in 3 hours. Starch had a minimal effect on the blood ketone body levels during the 5-hour observation period. Alanine and glucose exerted their antiketogenic effects in the context of widely different serum insulin, glucagon and growth hormone concentrations. Similar results were obtained in starvational ketosis, and even in normoketonaemic subjects. The results indicate that ketogenesis is not the result of gluconeogenesis, nor of a low insulin/glucagon (+ growth hormone) ratio in the blood. It is concluded that low levels of glycogen, or of a metabolic intermediary of glycogen metabolism (such as glucose-1-phosphate, or glucose-6-phosphate) in the liver is probably the single most important stimulus for ketogenesis after exercise and starvation.

The ratings of perceived exertion are commonly employed within both a clinical and exercise setting to quantify, monitor and evaluate an individual’s exercise tolerance and level of exertion. Recent advances in the area of perceived exertion have led to novel applications in the use of the ratings of perceived exertion scale as a means of predicting an individual’s maximal functional capacity (VO2max) for exercise (Eston, Lamb, Parfitt, & King, 2005; Eston, Faulkner, Mason, & Parfitt, 2006; Eston, Lambrick, Sheppard, & Parfitt, 2008; Faulkner, Parfitt, & Eston, 2007). Yet the utility of such procedures with low-fit individuals or children has received little or no research attention. As such, one aim of this thesis was to assess the efficacy of the ratings of perceived exertion in predicting the VO2max of low-fit men and women, and healthy children. It is often presumed that like adults, a child’s perception of exertion rises linearly with increases in exercise intensity, despite a limited amount research suggesting otherwise. Moreover, there is a lack of empirical evidence to suggest that children regulate their power output during a closed-loop exercise task in order to complete a given distance in the fastest time possible. Therefore, a further aim of this thesis was to explore the nature of the perceptual responses of young children across differing modes of exercise, and to examine whether children employ pacing strategies during running. In relation to this latter aim, it was of particular interest to explore pacing in relation to the ratings of perceived exertion during running, as the ratings of perceived exertion have been proposed as a key component of such a regulatory system during exercise (Tucker, 2009). This thesis comprises a qualitative review of relevant literature, and six study chapters which were borne out of five empirical studies. The findings of studies 1 and 2 (chapters 3 & 4, respectively) support the utility of the ratings of perceived exertion to estimate VO2max in low-fit men and women, during cycle ergometry exercise. Importantly, this has been shown from a single exercise test at a low-moderate exercise intensity, during either a step-incremental (study 1) or ramp-incremental (study 2) protocol. Studies 3 and 4 (chapters 5 & 6, respectively) provide evidence to suggest that a child’s perception of exertion may rise linearly or curvilinearly in relation to increasing work, during either cycle ergometry or treadmill exercise. These studies support the utility of a unique, curvilinear, paediatric ratings of perceived exertion scale in obtaining accurate exertional responses from young children, across differing modes of exercise. In contrast to studies 1 and 2, study 5 (chapter 7) suggests that the novel means of predicting maximal functional capacity from submaximal ratings of perceived exertion in adults is inaccurate with young children. This was particularly evident in the low intraclass correlation coefficients and wide limits of agreement obtained between measured- and predicted VO2max, for both cycle ergometry and treadmill exercise. Study 6 (chapter 8) demonstrated that young children employ pacing strategies during an 800 m run, similar to adults, and that this improves with trial familiarisation. Moreover, the presence of other competitors has a detrimental effect on performance, particularly for girls.

Thesis (M.S.)--University of Wisconsin--Madison, 1985. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 75-78).

Extreme physical exertion is commonly associated with acute physiological changes in immune variables known to disturb host defences. Likely induced by the production of stress hormones (e.g., cortisol), partaking in ultra-endurance events with accompanying physiological stressors (e.g., environmental extremes, sleep deprivation and compromised hydration and (or) nutritional status) may amplify stress hormone responses and compromise immune status to a greater extent. To date, research investigating the impact of extreme physical exertion (e.g., ultra-marathon events) on physiological variables is extremely limited. More recently, the potential use of probiotics with known immunomodulatory effects may be considered an appropriate nutritional strategy to improve host defences and minimise and (or) prevent sub-clinical or clinically significant outcomes in active populations.