A "velocity-video" system was developed with the intent of measuring forward body velocity changes and technical skill during swimming. The system consists of a "swim-meter", video camera, A-D converter, Apple IIE computer, Microkey system, VCR and monitor. A correlation of 1.0 was found between the velocity computed by the "velocity-video" system and a known speed. Furthermore, comparison of the velocity pattern of breaststroke from video with digitized film revealed a correlation of 0.95. These results suggest that the "velocity-video" system is a valid method of describing swimming velocity and corresponding changes in body position. The second part of this investigation examined the relationship between physiological economy (ml 02-U_1-LBW-7L), technical skill, swim power, and performance between "superior" and "good" male and female breaststrokers. Swimmers were categorized based on best 100 yd performance time. To study physiological economy oxygen uptake was determined after a 400 yd submaximal breaststroke swim. No significant difference in economy (ml 02•m-1 -LBW-1) was noted between the superior and good swimmers for both males and females. The superior male swimmers, however, were found to have lower blood lactate values compared to the good male breaststrokers', 1.85 + 0.39 vs. 4.49 ± 0.86 mM•1-1. The superior males and females were found cover a greater distance per stroke compared to the good males and females, respectively. The ability to generate power and/or peak power was found to be an important factor in sprint performance (r = 0.91 and 0.92, respectively). During a submaximal effort the superior swimmers spent a greater amount of time during the glide and leg recovery phases of the breaststroke cycle than the good swimmers. The results of the present study suggest that the superior breaststrokers were characterized by there ability to minimize drag during the glide and leg recovery phases of the stroke cycle. This suggests greater technical skill as evidenced by the superior swimmers' ability to cover a greater distance per stroke cycle at a given speed.

The purpose of this study was to determine if increasing physical activity to 100,000 steps/week would lead to improvements in cardiovascular risk factors for the "somewhat active" to "active" population. Thirty-one subjects, 13 male (mean age 43.5 ± 14.5 years) and 18 female (mean age 38.9 ± 12.6 years) who volunteered to participate in this study completed the full 16 weeks. Subjects were eligible for the study if they were healthy, could ambulate, and their baseline activity level met the step count criteria (> 7,500 - <12,500 steps/day). Subjects underwent laboratory testing comprised of resting heart rate, resting blood pressure, body composition, blood lipid analysis, bone mineral density, and a surrogate measure of cardio-respiratory fitness, prior to and 16 weeks after completing the 100,000 steps/week intervention. After the completion of preliminary assessments, subjects were asked to wear a pedometer continuously for 16 weeks; increasing their number of steps from baseline to 100,000 steps/week. Fifty-eight percent of subjects adhered (> 90,000 steps/week) to the 100,000 steps/week physical activity program. Subjects demonstrated significant reductions in body composition measurements overtime with increased physical activity. These improvements included body mass index 27.2 ± 3.6 to 26.8 ± 3.6 kg/m2, total percent body fat 35.4 ± 9.9 to 33.9 ± 10.3%, and waist circumference 83.9 ± 10.3 to 81.6 ± 10.1cm from pre to post measurements. In conclusion, individuals already meeting minimal physical activity recommendations (i.e. somewhat active/active) can gain health benefits particularly in body composition by increasing to 100,000 steps/week with the use of a pedometer.Key Words: physical activity, pedometer, walking, weight loss, adherence, dose-response, intervention. / School of Physical Education, Sport, and Exercise Science

Digitized by Kansas Correctional Industries

No description available.

The purpose of the research conducted in this thesis was two-fold. First, it was to examine the impact of temporal processing on the capability of participants to determine the order of perception and the identity of components in mixtures of three tastants. Secondly, it was to determine if interaction occurs between the two modalities of taste and olfaction, and to determine the capacity of humans to identify the components of taste-odour mixtures. Overall, the results of the studies provide new information about the capacity of humans to analyse chemosensory mixtures, which can be applied in studies of the impact of real food components. / Master of Science (Hons)

Experienced runners naturally optimize stride rate in a manner that minimizes oxygen uptake at given running speeds. However, as runners become fatigued, preferred stride rate often decreases. Whether such changes with fatigue occur in parallel with changes in optimal stride rate is unknown. This study's focus was on determining whether experienced runners self-optimize stride rate throughout a near-maximal one-hour run. A secondary focus was to determine if vertical stiffness is associated with decreases in stride rate. Seventeen subjects completed a one-hour near-maximal effort run on a treadmill. After the first five minutes, preferred and optimal stride rates were measured. Ground reaction force data were used to determine preferred stride rate averaged over ten strides. Runners completed five two-minute segments of running at preferred stride rate, 4% and 8% above and below their preferred rate. Oxygen uptake was measured during the second minute of each two-minute segment. Fitting a second-degree polynomial through oxygen uptake versus stride rate data provided a minimum value for oxygen uptake from which optimal stride rate was determined. Fifty minutes into the run, optimal stride rate was measured again. Repeated measures ANOVA showed no difference between preferred and optimal stride rates at the beginning or at the end of the run, but a decrease in optimal stride rate was observed from beginning to end. About half of the subjects decreased preferred and optimal stride rate over the course of the hour run while the other half showed little or no change. Vertical stiffness was measured based upon center of mass vertical displacement and active peak force. Decreases in preferred stride rate over the course of the hour run were expected to be associated with decreases of vertical stiffness. However, the changes in stride rate and vertical stiffness were small; no strong relationship was observed (R²=0.12). Experienced runners have demonstrated the capability to self-optimize stride rate at the beginning and near the end of a one hour run. This ability was observed for runners with substantial shifts of stride rate with fatigue as well as for runners with no change of stride rate with fatigue. / Graduation date: 2002

published_or_final_version / Psychology / Doctoral / Doctor of Philosophy

Multiple gut hormones are involved in the regulation of food intake. Secretin (SCT), a classical gut hormone, is released into the circulation from the duodenal S-cells when acidic chyme enters the duodenum and performs the major functions of delaying gastric emptying, stimulating fluid secretion from pancreas and liver to optimize the digestion process. In recent years, SCT and its receptor (SCTR) have been identified in discrete nuclei of the hypothalamus, including the paraventricular nucleus (PVN) and the arcuate nucleus (Arc). The occurrence of SCT and SCTR in the brain regions that are engaged in regulating body energy homeostasis and the release pattern of SCT after meals support a functional role of SCT in appetite control. In this study, the effect of SCT on feeding behavior was investigated using wild-type (wt), SCT?/?, and SCT receptor-deficient (SCTR?/?) mice. We found that both central and peripheral administration of SCT could reduce food intake in wt but not in SCTR?/?mice. SCT induce Fos expression in the PVN and Arc, suggesting the activation of hypothalamic feeding centers by this peptide. Consistent with this notion, SCT was found to increase proopiomelanocortin (POMC), but reduce agouti-related protein (AgRP) transcripts in the Arc, and augment thyrotropin-releasing hormone (TRH) and melanocortin-4 receptor (MC4R) mRNA expression in the PVN. In addition, pretreatment with SHU9119, an antagonist for MC4R, abolished the anorexia induced by SCT, suggesting that SCT may inhibit food intake via a melanocortin-dependent pathway. Gut hormones signals the brain to modulate the feeding behavior via the vagal afferent nerve, bloodstream or both. Here we showed that peripheral SCT-induced anorexia was attenuated in mice with subdiaphragmatic vagotomy, capsaicin treatment and bilateral midbrain transections. In summary, our data identify peripheral SCT as an anorectic peptide exerting its action via the melanocortin system and the vagal afferent contributes a major route in mediating the inhibitory effect of peripheral SCT on food intake. The present findings advance our understanding of the role of gut hormones in the regulation of appetite. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

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