Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that can present without cardiovascular disease (lone AF). Frequent high-intensity endurance exercise is a risk factor for lone AF, and the pathophysiology of AF induced by intense endurance exercise is unknown. We found that after 6 weeks of intense swimming and running, mice were far more susceptible to AF, but not ventricular arrhythmias. Exercise induced atrial fibrosis, inflammation and slowed conduction without detectible changes in ventricles. Since AF is associated with stretch and since a tumor necrosis factor-α (TNFα) is a mechanosensitive inflammatory factor, mice were treated with the TNFα inhibitor etanercept. Etanercept treatment blocked inflammation, fibrosis, and AF vulnerability in the exercised mice. Consistent with these findings, we found that exercise caused large elevations in atrial pressures. Our findings support the conclusion that mechanical loading of atria during exercise induces TNFα release, leading to structural remodeling and enhanced AF vulnerability.

Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that can present without cardiovascular disease (lone AF). Frequent high-intensity endurance exercise is a risk factor for lone AF, and the pathophysiology of AF induced by intense endurance exercise is unknown. We found that after 6 weeks of intense swimming and running, mice were far more susceptible to AF, but not ventricular arrhythmias. Exercise induced atrial fibrosis, inflammation and slowed conduction without detectible changes in ventricles. Since AF is associated with stretch and since a tumor necrosis factor-α (TNFα) is a mechanosensitive inflammatory factor, mice were treated with the TNFα inhibitor etanercept. Etanercept treatment blocked inflammation, fibrosis, and AF vulnerability in the exercised mice. Consistent with these findings, we found that exercise caused large elevations in atrial pressures. Our findings support the conclusion that mechanical loading of atria during exercise induces TNFα release, leading to structural remodeling and enhanced AF vulnerability.

The purpose of this study was to analyze the coach-athlete interactions occurring in a successful sport program for athletes with disabilities and their able-bodied siblings. The successful nature of this program was established by its athletes’ competitive achievements and by the athletes’ reports of positive experiences within this sport environment. This study utilized state space grid and observational methodology and was the second application of this methodology in field-based sport psychology research (Erickson, Côté, Hollenstein, & Deakin, in press). The head coach of the program and twenty-four athletes were observed over multiple practice sessions. Both coach and athlete behaviour was coded continuously for the duration of each practice session. Measures of coach-athlete interaction structure, based on dynamic systems concepts, were derived from these coded behaviours. These measures were examined for the team as a whole and compared between groups within the team (competitive vs. recreational athletes and athletes with disabilities vs. able-bodied athletes). Results indicated that the coach-athlete interactions of the team were highly patterned. Within this consistent pattern, the coach spent most of her time silently observing the athletes. Other commonly exhibited behaviours included individualized technical instruction, organization, and positive feedback. With regards to behavioural sequencing, the coach’s time spent observing the athletes was often interspersed with periods of organization, instruction, and feedback. The coach appeared to adapt her coaching style according to the competitive levels of the athletes, but no differences emerged when comparing the coach-athlete interactions between athletes with disabilities and able-bodied athletes. Overall, this successful sport environment was characterized by positive coach-athlete interactions that were deliberately patterned and mutually respectful. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2011-06-29 11:00:23.466

Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Chiropractic at Durban Institute of Technology, 2007. / Objectives The objectives were to compare the relative effect of manipulation and core rehabilitation in the treatment of acute mechanical lower back pain in athletes. Project Design: The study design was a randomized controlled parallel group trial. A quantitative study was performed, by making use of a pre à à à ¢ and post experimental investigation (Nansel et al. 1993 and Naidoo, 2002). Setting: Participants presenting with acute low back pain with an onset of 7 days or less, to the Chiropractic Day Clinic at the Durban University of Technology. Subjects: Thirty athletic participants, either male or female, between the ages of 18 and 45 years presented at the initial consultation which included participant screening and establishment of their suitability for the study. These were then divided into either group A (which received a manipulation) or group B (which received core exercises). Outcome measure: A correct contraction of the core stability muscles was maintained, with a decrease in pressure (in mm Hg) on a Pressure Biofeedback Unit, and an increase in length of time (in seconds). Results: It was found that there was no significant difference between the manipulation and the core rehabilitation groups. Although both groups showed v improvement with regards to their acute mechanical low back pain, the core rehabilitation group improved at a significantly faster rate than the manipulation group with regards to endurance on the stabilizer. Conclusions: Both treatments were equally beneficial for most of the quantitative outcomes measured in this study. However, for the outcome of time on the stabilizer, the core rehabilitation group improved at a significantly faster rate than the manipulation group (p=0.006).

This thesis examines the attitudes and justifications athletes have in regards to doping in sport, and specifically the current doping ban. A historical analysis of anti-doping policy development in Canada was completed to determine how the current anti-doping system operates in Canada. Semi-structured interviews were then conducted with retired and current members of the Women’s and Men’s Canadian National Volleyball Teams. Content analysis was used to analyze the interview transcripts and to draw out the resulting themes. From the interviews it emerged that the Canadian volleyball athletes participating in this study viewed the doping ban as a list of rules they must follow in order to remain eligible to compete. The athletes’ perspectives on the doping ban differ from the reasons historically and currently provided by anti-doping organizations, as the athletes participating in this study did not discuss values in their reasons for following the doping ban in sport.

The role of food intake and nutrition in athletic performance has gained much recognition in recent years. Therefore, the purpose of the present investigation was to assess whether female runners who consumed a modified vegetarian diet had different iron parameters than female runners who consumed a diet that included red meat. Methods: Two groups of female runners (n=18) volunteered as subjects for this study. One group was composed of women who regularly consumed a modified vegetarian diet (V group) and the other group was composed of women who consumed a diet which included red meat (RM group). The groups were comparable in age, weight, aerobic capacity, number of pregnancies and years since last pregnancy. Dietary analyses and biochemical analyses for the three stages of iron deficiency characterized by iron depletion, iron deficient erythropoiesis and iron deficiency anemia were performed to compare iron status of the two groups of athletes. Results: Serum ferritin values of the V group were significantly lower (p=.001) than those of the RM group. Of all the athletes examined, 56% had serum ferritin values indicative of storage iron depletion. Mean values for serum iron, total iron binding capacity (TIBC) and percent transferrin saturation were in the normal range for both groups, but TIBC values of the V group were significantly higher (p=.02) than the TIBC values of the RM group. Individually, four of the subjects, 22%, (3 V group and 1 RM group), had iron values indicative of iron deficient erythropoiesis. None of the other iron parameters was significantly different between the groups and none of the subjects was clinically anemic. The mean daily iron intake was not significantly different between the groups, but both groups averaged less than the RDA. The total caloric intake of both groups averaged less than 1800 kcals/day with 50% of the athletes consuming less than 1800 kcals/day, and another 28% consumed between 1800-2100 kcals/day. The V group consumed significantly more carbohydrate (p=.02) and less protein (p=.001) than the RM group, but none of the other dietary variables were significantly different between the groups. Conclusion: The two groups of subjects ingested almost the same amount of iron/day, however, the bioavailability of the iron in the diets may have affected iron absorption as the iron stores of the V group were lower than those of the RM group.

There is no abstract available for this thesis.

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Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 41-47). / vii, 77 leaves, bound 29 cm