No description available.

The goal of the present investigation was to evaluate the role of the pulmonary diffusion capacity (as measured by DLco) in relation to exercise-induced hypoxemia in elite athletes working at near maximal exercise intensities. Twenty-four elite cyclists were submitted to a direct measurement of VO$ sb2$ max on cycle ergometer which permitted classification into one of two groups. "Desaturaters" (N = 13) if oxyhemoglobin saturation (SaO$ sb2$%), as determined by finger oxymetry, fell below 91% or "non-desaturaters" if SaO$ sb2$% remained above 91%. Subsequent determinations of the transfer capacity for CO (DLco) were made using a 3 second breath-hold technique (Gould 2400/2450), at rest as well as at 60% and 90% of previously determined VO$ sb2$ max ($>$4.0 1/min). The results show an increase in DLco from rest to the first exercise intensity (desat: 41.7 $ pm$ 5.7 to 55.1 $ pm$ 4.7; non-desat: 41.1 $ pm$ 5.8 to 57.2 $ pm$ 6.9 mlsCO/mmHg/min) without much further increase to the maximal workload (desat: 61.0 $ pm$ 6.0; non-desat: 61.4 $ pm$ 9.5 mls CO/mmHg/min). No significant differences in DLco were found between the two groups at rest or either of the two exercise intensities. Significant differences between the desat and non-desat groups were found for FVC, post-exercise FEF$ sb{25-75 %}$, and VE/VO$ sb2$. / The present results are in agreement with previous reports showing arterial desaturation in 50% of highly-trained subjects when VO$ sb2$ max $>$4.0 1/min. The present investigation cannot clearly establish the role of DLco in this response. (Abstract shortened by UMI.)

The detection of visual stimuli involves neurons which are selectively responsive to components of a visual scene. In the early stages of visual processing, it is commonly accepted that neurons respond to the changes in luminance associated with objects and object boundaries. However, recent experiments have demonstrated that some neurons can also respond to features which are not defined by luminance variations. These features are termed "second-order" because they require more complex processing, and neurons which respond to second-order features are necessarily nonlinear. / In this thesis, I undertook a three dimensional physiological characterization (i.e. tuning of orientation, spatial frequency and temporal frequency) of such nonlinear neurons in order to shed light on their processing capabilities. In particular we sought to address the following issues: (1) whether the temporal and spatial properties underlying second-order motion are similar to those underlying luminance based ("first-order") motion; (2) whether these properties remain constant using different types of second-order stimuli, suggesting that neurons' responses are invariant to the physical attributes comprising the stimulus; and (3) whether second-order processing is a cortical mechanism or can occur at an earlier stage of the visual system (e.g. in the lateral geniculate nucleus). Taken together these results have a dual function; they provide insight into the complex cellular processing of higher order features, and they provide a general framework for the generation of second-order models.

In a cross-sectional study we examined lipoprotein composition and CETP mass in 15 sedentary and 12 exercising, healthy male volunteers, aged between 17-35 years. The exercising group were defined as individuals participating in at least five weekly 45 minute exercise sessions of an aerobic nature (60-85% estimated maximal oxygen uptake). The sedentary subjects were only irregularly engaged in bouts of physical activity, not more than 45 minutes per week. Seasonal data were collected: one data collection in the fall and one in the spring. A 20 day food and exercise journal was maintained during each season's data collection period. Blood lipids were measured on two and anthropometric and aerobic capacity testing were performed on 1 occasion during each season. Statistical analyses consisted of a two way ANOVA (exercise and season) to control for seasonal effects on blood lipids and lipoprotein levels. Pearson product moment correlations were calculated between those variables that showed significant seasonal or level of activity changes. Exercising males consumed significantly greater amounts of energy (p $<$ 0.001), carbohydrates (p $<$ 0.0001), protein (p $<$ 0.0001), and dietary fibre (p $<$ 0.0001) than sedentary males; sedentary males however, consumed significantly greater amounts of alcohol than exercising males. Exercising males had significantly higher aerobic capacities and degrees of mesomorphy than sedentary subjects and exhibited significantly lower apo AI values. No differences were noted between the 2 groups in BMI, % body fat, other plasma lipids or CETP mass. In summary, regular physical activity in young, healthy male subjects was associated with increased energy and carbohydrate intake and improved aerobic capacity as compared to sedentary subjects. Moderate differences in physical activity were not however associated with alterations in plasma lipoprotein composition or CETP concentration.

No description available.

No description available.

The purpose of this study was to determine the physiological response of an in-line submaximal skate on two surfaces using two wheel types and two bearing types. The variables measured were V0$ sb2$ and HR. Ten male varsity hockey players volunteered as subjects. The subjects, after being assigned one of two wheel types with varying durometers, skated the submaximal test twice for each surface (concrete and asphalt) using a different type of bearing (precision and semi-precision) each time. These results were compared to a similar on-ice submaximal skating test session. / Results revealed no significant difference between in-line skating with wheels of 78 and 82 Shore A durometers (p $<$.05) with both V0$ sb2$ and HR as markers. A significant difference was found between in-line skating with precision and semi-precision bearings with V0$ sb2$ as a marker (p $<$.05), however, not with HR as a marker (p = 0.31). On-ice skating was significantly different from in-line skating on concrete and asphalt surfaces for both physiological markers. In-line skating on asphalt and concrete surfaces resulted in similar physiological responses. It was concluded that hockey players training with in-line skates obtain the same training benefits using either wheel durometers, but will have greater oxygen costs when training with semi-precision bearings than training with precision bearings.

The role of the dorsal hippocampus, entorhinal cortex, amygdala and fimbria fornix in spatial discrimination was investigated using temporary inactivation and lesioning methods. Spatial learning was tested in a conditioned cue preference (CCP) paradigm involving three phases of behavioral testing on an 8-arm radial maze. In the first phase (pre-exposure) rats were given unreinforced pre-exposure trials in which they were free to move on two adjacent arms of the maze on three consecutive days. Rats were then alternately confined to the ends of the arms for eight days (training), one arm that contained food (Paired-arm) and one that did not (Unpaired-arm). The rats were then given a choice between the two arms with no food present. Only when given unreinforced pre-exposure trials did rats spend more time in the Paired-arm than in the Unpaired-arm, a CCP. Rats with muscimol induced inactivation of the dorsal hippocampus during unreinforced pre-exposure acquired a CCP for the Paired-arm but were impaired with hippocampal inactivation during training or testing. Inactivation of the entorhinal cortex resulted in impairment in all phases of the paradigm. Inactivation of the dorsal hippocampus in the Unpaired but not Paired-arm only resulted in impairment. The effects of dorsal hippocampus inactivation in either the Paired or Unpaired arms were reversed in rats with combined amygdala lesions\dorsal hippocampus inactivation. Rats with fimbria fornix\entorhinal cortex disconnections during pre-exposure were also impaired. These results reveal that spatial learning may rely on the interactions between the hippocampus, entorhinal cortex, amygdala, and fimbria fornix and that the dogma that the hippocampus mediates all forms of spatial learning requires revision.

This study examined the effects of exercise on glucose metabolism in adipocytes from female rats. Female rats were exercised by swimming six hours per day, five days per week for eight weeks. There was no variation in body weight gain (P > 0.05) between the exercise and control animals through the experimental period. The swimmers' fat cells were smaller (P < 0.05) than those of the sedentary controls of the same age. The rates of glucose oxidation of both C-1 and C-6 glucose were significantly higher (P < 0.05) in the exercise rats' adipocytes at all insulin concentrations. The sedentary control rats' adipocytes showed no significant response at any insulin concentration. Thus, exercise is a significant stimulus to cause increased oxidation rates in the adipocytes from exercising rats. These data also indicate that glucose transport, not defective glucose oxidation, is the limiting mechanism that accounts for the decreased responsiveness of adipocytes from sedentary control animals.

The purpose of this study was to determine effects of diet composition and exercise on the loss and maintenance of loss of body weight and body fat; and the protection of muscle in obese subjects. Ten subjects who were members of the Ball State University (BSU) Adult Fitness Program and/or the BSU Weight Management Program, and who were at least 120 percent of ideal body weight, participated in the one-year study.Three-day diet records collected at four-month intervals were assessed using the Nutriplanner computer data base to determine energy and nutrient composition of subjects' diets. Measures of weight, triceps skinfolds (TSF), and arm circumference were collected at three-month intervals to assess changes in weight, arm fat area (AFA), and arm muscle area (AMA). Adherence to exercise was reported by participants.The findings of this study showed that obese subjects who consumed low-fat, high-carbohydrate diets while adhering to an exercise program lost, or tended to lose, more weight and arm fat area, while experiencing an increase in arm muscle area. Further studies in this area of research are needed to assess the effects of diet composition, exclusive of exercise, on changes in fat and muscle area. In addition, work is needed to develop more reliable means of assessing food intake over an extended period of time.