The goal of this study was to access the possibility that a vigorous physical regimen is suppressive to the immune system and that conditioning to the exercise minimizes the immune suppression. The following groups of fifteen rats each were used: (i) control rats. (ii) rats exposed to one bout of swimming for two to three hours (exercise-stressed), and (iii) rats which were conditioned to the exercise by swimming two hours daily for two months (exercise-conditioned).FINDINGS1. Exercise-stressed rats were immune suppressed as compared to control rats. In contrast, exercise-conditioned rats were only slightly immune suppressed.2. The immune reactivity of spleen cells from exercise-stressed rats and from exercise-conditioned rats was restored by the addition of indomethacin, a prostaglandin synthesis inhibitor.3. Exercise-stressed rat spleen cells were more sensitive to the immune suppressive effectsPGE than were the control or excercise-conditioned rat spleen cells.4. The nonadherent spleen cells from both exercise-stressed and exercise-conditioned rats were immune suppressive as compared to control rat nonadherent spleen cells. However, immune stimulatory activity was prominent in the nonadherent spleen cells from the excercise-conditioned rats. Immune stimulatory activity was negligible in the adherent spleen cell fractions from exercise-stressed rats.CONCLUSIONSThe results of this study showed that, extreme physical exercise was immune suppressive while conditioning to the exercise minimized the suppression.The immune suppression in the exercise-stressed rats resulted from an increased sensitivity to the immunosuppressive effects of PGE and from immune suppressor activity of nonadherent lymphoid cells. The minimal extent of immune suppression in the exercise-conditioned rats resulted from a reduced sensitivity to immune suppression by PGE and from immune stimulatory activity of adherent macrophages.

The purpose of this investigation was to examine the seasonal change in the nutritional protein status of adolescent wrestlers who lost weight for competition. Additionally, this study determined if changes in plasma proteins and amino acids could be prevented through nutritional education and dietary supplementation. Twenty-seven adolescent wrestlers (14.8-18.1 yr) were divided into two groups for study during a three month period. One group received a nutritional education and supplement program, the other group served as a control. Height, weight, percent body fat, and free fat weight were measured during wrestling season. Venous blood samples were drawn and analyzed for essential (E) and nonessential (NE) plasma amino acids, hemoglobin (Hb), hematocrit (Hct), retinol-binding protein (RBP), prealbumin (PA), albumin (AL), and blood urea nitrogen (BUN). Four, 4-day dietary records taken during the season were analyzed for protein, carbohydrate, fat, and total calories. The results demonstrated that weight, percent body fat, and fat free weight decreased significantly during the experimental period (p<0.001), with no significant differences between treatment and control groups. The blood RBP and PA decreased significantly during the experimental period (p<0.01), whereas AL didNot change. Most of the amino acids did not show significant decreases during the experimental period whereas the total essential amino acids showed a decreasing trend (p<0.05), the total nonessential amino acids did not change. The subjects' average caloric intake showed significant decreases during the experimental period (p<0.001). The wrestlers failed to meet the RDA for energy and protein intake. It was concluded that nutritional status of adolescent wrestlers appears to be diminished as a result of weight loss during the season. / Human Performance Laboratory

The purpose of this investigation was to determine the influence of post exercise carbohydrate (CHO) intake on the rate of muscle glycogen restorage after high intensity weight resistance exercise in untrained subjects. In a cross over design, eight male subjects performed sets (mean= 8.8) of 6 single leg knee extensions at 70% of one repletion max until 50% of full knee extension was no longer possible. Total force application was equated between trials using a strain gauge interfaced to a computer. Post exercise supplementation was administered at 0 and 1 hrs consisting of either a 23% CHO solution (1.5g•kg-1•hr-1) or an equal volume of water (H20). Total force production, pre-exercise muscle glycogen content, and degree of depletion (-40.6 and -44.3 mmol•kg-1) were not significantly different between H2O and CHO trials, respectively. During the initial 2 hrs recovery, the CHO trial had a significantly greater rate of muscle glycogen resynthesis as compared to the H2O trial. In the final 4 hrs of recovery no difference in repletion rates were observed. The glycogen content (mmol•kg-1 w.w.) and rates of restorage (mmol•kg-1 w.w.) during the recovery period were (mean + SE):TrialPost2 Hr6 HrRate (0-2 hrs)H2O101.3+ 13.1105.1+ 13.1105.5+ 13.01.3+ 2.2CHO91.7+ 11.8117.6+ 16.5123.4+ 15.1 *12.9+ 4.0*significance between trials, p <0.01Only the CHO supplementation trial restored pre-exercise muscle glycogen content after 6 hrs. The spectrophotometric analysis of glycogen stained muscle sections (PAS) indicated no difference between trials in the pre and post glycogen content for Type I and II fibers. The change in absorbance, when these samples were combined demonstrate greater glycogenolysis in the Type II (0.284 + 0.58) as compared to Type I (0.014 ± 0.076). During the recovery period, the change in absorbance supports greater glycogenesis in the Type II ( 0.096 + 0.060) when compared to no observed change in absorbance in the Type I fibers.Supported by a grant from Ross Laboratories. / Human Performance Laboratory

There is no abstract available for this dissertation. / Human Performance Laboratory

Skeletal muscle glycogenolysis was investigated in eight subjects during both high (HI) (70% 1 RM) and low (LO) intensity (35% 1 RM) leg extension weight-resistance exercise. Total force application to the machine lever arm was determined and equated between trials via a strain gauge and computer interfaced system. After the sixth set, muscle glycogen degradation was similar in the HI and LO trials (46.9 ± 6.6 and 46.6 ± 6.0 mmol•kg-1 wet wt, respectively), with the LO trial characterized by almost double the repetitions (6.0 and 12.7 ± 1.1) and half the peak concentric torque per repetition (24.2 ± 1.0 and 12.4 ± 0.5). After the sixth set, muscle lactate accumulation was also similar (13.8 ± 0.7 and 16.7 ± 4.2 mmol•kg-1 wet wt for HI and LO trials, respectively). After two hours of passive recovery with no feedings, muscle glycogen storage during the HI and LO trials was 22.2 (±6.8) and 14.2 (±2.5) mmol•kg-1 wet wt, respectively These values represented glycogen synthesis rates of 11.1 (±3.4) and 7.1 (±1.3) mmol•kg-1 •hr-1 , and occurred without significant increases in blood glucose relative to resting concentrations. Optical absorbance measurement of PAS stained muscle sections revealed no differences in the glycogen content of fast (FT) and slow twitch (ST) fibers between trials. When data from each trial were combined, declines in absorbance were larger in FT than ST fibers after the sixth set (0.356 ± 0.048) than in slow twitch fibers (0.222 ± 0.039, p < 0.05). The increase in absorbanceduring the two hour recovery was also larger in FT than ST fibers (0.119 ± 0.024 and 0.055 ± 0.024, p < 0.05). When total force application was constant, muscle glycogenolysis was the same regardless of the intensity of resistance exercise. Glycogenolysis was greater in fast twitch fibers, as was glycogen storage during the immediate post-exercise recovery. The relatively high rate of glycogen synthesis after exercise may be evidence of glycogenesis from intramuscular metabolites. / Human Performance Laboratory

No description available.

This thesis explores the coarticulatory effects of English /l/ and /r/, examining their articulatory basis, acoustic manifestation and perceptual relevance. It demonstrates that there are perceptually relevant coarticulatory differences associated with the distinction between /l/ and /r/. Two perceptual experiments, an articulatory experiment and a modelling study were conducted. Both perceptual experiments used a modified gating technique. The first experiment demonstrates that the coarticulatory effects of /l/ and /r/ on surrounding vowels and consonants can sometimes be used by listeners to identify an HI or /r/ which has been deleted and replaced by noise. The second perceptual experiment shows that the cues for an /r/ are more perceptually salient than those for an /l/. The articulatory experiment used simultaneous electromagnetic articulography, electropalatography and acoustic recordings to investigate the coarticulatory effects of /l/ and /r/. In /r/ contexts, relative to /l/ contexts, raising and retraction of the tongue, lip rounding and lowering of F₃ were found, up to two syllables preceding and following the /r/. The extent of this coarticulatory effect is far greater than commonly acknowledged in the coarticulation literature. Phonetic and phonological theories fail to predict or account for effects of this extent. The theory that coarticulation can be modelled as overlap of articulatory gestures was tested in a modelling study. A subset of the articulatory data was modelled numerically using dynamical descriptions of articulatory gestures from an approach developed at Haskins Laboratories. The modelling showed that longdistance coarticulatory effects could not be adequately accounted for by gestural overlap alone. Feature-spreading models, such as Keating's window model of coarticulation, are also unable to account for these effects adequately. The results of this thesis pose a challenge to current phonetic and phonological theory, as they show that coarticulatory effects have greater extent than commonly recognised.

This thesis is concerned with the role of 'central command' in cardiorespiratory control during exercise and the peripheral autonomic modulation of cardiac excitability. Chapter One reviews the background to the work in the thesis. The cardiorespiratory and autonomic changes occurring during exercise and the ways in which they are brought about are discussed. This is followed by a review of some pathological changes in autonomic activity and the ways in which they might be arrhythmogenic. Chapter Two details the experimental techniques used in the thesis and discusses their theoretical background. Chapter Three studies the cardiorespiratory responses to imagination of exercise under hypnosis. This results in hyperventilation, hypocapnia and an increase in heart rate. In contrast, no cardiorespiratory changes are seen when the same protocol is repeated in the awake state. The response to imagined exercise under hypnosis is not affected by maintaining isocapnia. A powerful drive to breathe arising from higher centres, that is independent of peripheral muscular feedback, is elicited when 'exercise' is imagined under hypnosis. Chapter Four investigates the neural correlates of imagined exercise under hypnosis using positron emission tomography to see if they are the same as those classically implicated in 'central command' during exercise. Activation of 'motor' areas occurs, including the supplementary motor area, primary motor cortex for breathing, premotor area, thalamus, basal ganglia and cerebellum. The insular cortex, right dorsolateral prefrontal cortex and posterior parietal cortices are also activated. These activations are similar to those previously reported during actual exercise, but occur in the absence of peripheral feedback that accompanies actual exercise and may therefore reflect 'central command'. Chapter Five studies the responses to altered perception of work rate during actual exercise using hypnotic suggestions. If exercising hypnotised subjects are told that the work rate has increased (when it hasn't), they hyperventilate, become hypocapnic and heart rate increases, suggesting a partial uncoupling of 'central command' from peripheral feedback. Chapter Six investigates the cardiovascular effects of electrical stimulation of the thalamus and midbrain in awake man to determine the role of subcortical areas in cardiovascular control. High-frequency stimulation of the thalamus, subthalamic nucleus and substantia nigra results in increases in heart rate and blood pressure, whereas stimulation of the globus pallidus has no effect. In patients with implanted stimulating electrodes, chronic high-frequency electrical stimulation does not affect baroreflex sensitivity, heart rate variability or blood pressure variability. Chapter Seven characterises the cardiac electrophysiological consequences of sympathetic imbalance using multi-electrode array mapping techniques in the pig heart in vivo. A novel potential arrythmogenic mechanism of noradrenaline is also investigated in two in vitro preparations. Chapter Eight presents a brief summary of the findings in the thesis and discusses future research directions.

This thesis explores the effects of movement on various face processing tasks. In Experiments One to Four, unfamiliar face recognition was investigated using identical numbers of frames in the learning phase; these were viewed as a series of static images, or in moving sequences (using computer animation). There was no additional benefit from studying the moving sequences, but signal detection measurements showed an advantage for using dynamic sequences at test. In Experiments Five and Six, moving and static images of unfamiliar faces were matched for expression or identity. Without prior study, movement only helped in matching the expression. It was proposed that motion provided more effective access to a stored representation of an emotional expression. Brief familiarisation with the faces led to an advantage for dynamic presentations in referring to a stored representation of identity as well as expression. Experiments Seven to Nine explored the suggestion that motion is beneficial when accessinga pre-existingd escription. Significantly more famous faces were recognised in inverted and negated formats when shown in dynamic clips, compared with recognition using static images. This benefit may be through detecting idiosyncratic gesture patterns at test, or extracting spatial and temporal relationships which overlapped the stored kinematic details. Finally, unfamiliar faces were studied as moving or static images; recognition was tested under dynamic or fixed conditions using inverted or negated formats. As there was no difference between moving and static study phases, it was unlikely that idiosyncratic gesture patterns were being detected, so the significant advantage for motion at test seemed due to an overlap with the stored description. However, complex interactions were found, and participants demonstrated bias when viewing motion at test. Future work utilising dynamic image-manipulated displays needs to be undertaken before we fully understand the processing of facial movement.

A series of experiments are described which explore the relationship between biomechanical properties and the control of jaw movement in speech. This relationship is documented using kinematic analyses in conjunction with a mathematical model of jaw motion and direct measures of jaw stiffness. / In the first experiment, empirical and modeling studies were carried out to examine whether the nervous system compensates for naturally occurring forces acting on the jaw during speech. As subjects walk or run, loads to the jaw vary with the direction and magnitude of head acceleration. While these loads are large enough to produce a measurable effect on jaw kinematics, variation in jaw position during locomotion is shown to be substantially reduced when locomotion is combined with speech. This reduction in jaw motion is consistent with the idea that in speech, the control of jaw movement is adjusted to offset the effects of head acceleration. Results of simulation studies using a physiologically realistic model of the jaw provide further evidence that subjects compensate for the effects of self-generated loads by adjusting neural control signals. / A second experiment explores the idea that a principle mechanical property of the jaw---its spring-like behavior, or stiffness---might influence patterns of kinematic variation in speech movements. A robotic device was used to deliver mechanical perturbations to the jaw in order to quantify stiffness in the mid-sagittal plane. The observed stiffness patterns were non-uniform, with higher stiffness in the protrusion-retraction direction. Consistent with the idea that kinematic patterns reflect directional asymmetries in stiffness, a detailed relationship between jaw kinematic variability and stiffness was observed---kinematic variability was consistently higher under conditions in which jaw stiffness was low. Modeling studies suggested that the pattern of jaw stiffness is significantly determined by jaw geometrical properties and muscle force generating abilities. / A third experiment examines the extent to which subjects are able to alter the three-dimensional pattern of jaw stiffness in a task-dependent manner. Destabilizing loads were applied to the jaw in order to disrupt the ability of subjects to maintain a static jaw posture. Subjects adapted by increasing jaw stiffness in a manner that depended on the magnitude and, to a more limited extent, direction of the destabilizing load. The results support the idea that stiffness properties can be controlled in the jaw, and thus may play a role in regulating mechanical interactions in the orofacial system.