The consideration of the end-point of exercise (teleoanticipation) may influence fatigue development. This study examined the effect of expected exercise duration on physiological and psychological variables. 20 male cyclists participated in a graded maximal aerobic cycling test and two 20 minute cycling bouts. Participants expected to cycle for 20 minutes for the first bout (20 MIN), and for 40 minutes for the second (40 MIN) VO, was higher at 2 minutes and lower at 17 minutes in the 40 MIN condition. RPE was lower throughout the 40 MIN condition. Following initial analyses, participants were separated into intensity groups based on whether they exercised above RER=l.00 at any time during either cycling bout. RPE was lower for 40 MIN in the lower intensity group only. Results suggest that teleoanticipation alters both physiological and psychological variables via separate mechanisms that may be intensity-dependent.

The purpose of this study was to determine if the ingestion of sodium citrate (CIT), and the subsequent expansion of plasma volume, would have a direct effect on thermoregulation and physiological function during a simulated 1-hour time trial (TT) under sever heat stress. Eight subjects, aged 24.9 years (SD + 4.4), were studied under the following three conditions: (1) High Sodium Citrate (HCIT; 0.2 g/kg sodium citrate), (2) Low Sodium Citrate (LCIT; 0.1 g/kg sodium citrate), and (3) Control (Gatorade). Blood samples, taken before and during exercise, were analyzed for hematocrit (Het), haemoglobin (Hb), bicarbonate (HCO3-), base excess (BE), pH, sodium (Na), potassium (K), and glucose (GLU). Rectal temperature (Tr) and skin temperature (Tsk) was also recorded. Heart rate and psychophysical strain were also measured throughout each TT. Plasma volume significantly increased by 7.1% after ingesting the HCIT compared to the other two trials. There were no differences in mean body temperature, physiological strain, cardiovascular strain or psychophysical perception. The ingestion of HCIT appears to improve cycling performance despite no difference in physiological measurements. HCIT reduced split times, better maintained power output over the TT. and improved time total cycling time.

Playing professional football is a high risk occupation. Injury rates among professional footballers are higher than those commonly found in other industries. Several Scandinavian studies have begun to document the long-term physical health problems, such as osteoarthritis (OA), that can beset ex-professional footballers. However, the experiences of ex-professional footballers playing and living in the United Kingdom (UK) have not received similar academic attention. Furthermore, no studies have investigated the impact that OA has on the quality of life of former players anywhere in the world. This thesis aimed to rectify a widespread and serious health problem among a cohort that has largely been neglected to date. In Phase I, 284 ex-professional footballers responded to a postal survey which aimed to establish the prevalence of injury and OA. In Phase II, 12 semi-structured interviews were conducted with ex-professional footballers from Phase I who had developed OA. The aim was to gain an in-depth understanding of how the condition impacted on their lives and how they coped. In Phase II, 101 ex-professional footballers, who were not involved in Phases I and II, responded to a cross-sectional postal survey, which investigated the relationships between pain, pain coping and psychological distress within the context of a stress and coping model. Career injury and surgery were common among respondents in Phase I and nearly half (49%) had subsequently developed OA in at least one joint. Pain was the most common problem for all respondents irrespective of OA diagnosis. Lack of mobility and work disability were other problems reported by respondents. Interviewees in Phase II described how they were encouraged to 'play hurt' during their career and to accept, minimise or ignore the threat of pain, injury and OA. It was some of these attributes which enabled respondents to 'live hurt' in the presence of chronic pain and disability in later life. In Phase II it was shown that psychological distress was not a serious problem for many respondents. However, several coping strategies (denial, emotional venting and upward comparison) were positively associated with pain and psychological distress, particularly for those participants in greater pain. Although OA and chronic pain are prevalent among ex-professional footballers in the UK, its impact upon psychological distress was not as great as reported in some other studies of persons which chronic disease and pain. Increased psychological distress was linked to greater pain and the use of several coping strategies (e.g. denial, emotional venting and upward comparison). However, given the cross-sectional design, it remains to be clarified whether coping predicts psychological distress or whether an increase in psychological distress precipitates more coping. Suggestions are proposed for a psychosocial intervention which would have an impact on pain coping and psychological distress among ex-professional footballers.

Learning processes play a major role in controlling intake of food. Through repeated experiences an animal acquires the ability to predict the postingestive effects of a particular food (i.e., of its nutrients and energy) from its sensory characteristics. What is unclear from the literature, however, is whether an animal can anticipate the duration of subsequent food deprivation from predictive sensory qualities of a food, and hence increase the amount eaten of that cueing food. Therefore, the aim of this work was to investigate the characteristics of this under-researched type of learning, i.e., anticipatory eating, using laboratory rats trained on two lengths of fasting (short: 2-3 h, long: 8-10 h). The main findings were as follows. 1) Anticipatory eating is learnt when a choice is given between protein- and carbohydrate-rich foods as well as on a single balanced test food. 2) The learnt extra intake of food is instrumental to preventing the return of hunger, removal of which negative reinforcement extinguishes the response. 3) The resulting return of hunger induces re-learning of anticipatory eating. 4) During the training sessions, learning of anticipatory eating competes with classical conditioning of sensory preference. Conditioning of preference is likely to be stronger with the shorter than with the longer length of fasting. Therefore, the difference between intakes before the long and the short fast at each trial is the summed result of these two mechanisms of acquired increase in intake. While preference conditioning usually reaches a maximum rapidly, depletion-avoidance increases for as long as has been tested, with interruptions of rapid self-extinction and re-learning, This self-extinction contributes to the homeostatic character of this learning. 5) High-fat maintenance diet attenuates the learning of anticipatory eating. Overall, the findings provided robust evidence that eating in rats can be controlled by instrumental learning reinforced by hunger. Accordingly, the design of an experiment on such instrumental control of eating in human subjects is proposed to conclude this thesis.

Memory function was examined in association with sex hormone levels in women. The results of the first study suggest that self-reports of memory problems were especially prevalent among women attending a menopause clinic compared to a nonpatient sample. In the following investigation, women given placebo after undergoing a bilateral oophorectomy showed decreases in memory performance, specifically on a paired-associate learning task, coincident with declines in estrogen levels. Significant improvements were found in estrogen-treated women pre- to postoperatively in the immediate recall of paragraphs, in association with supraphysiological estrogen levels. A final study on naturally-cycling women found a decline in visual memory performance during the menstrual compared to the luteal phase of the cycle. Visual memory scores were positively correlated with progesterone levels whereas paired-associate recall scores were positively associated with estradiol levels during the luteal phase. These results suggest that certain aspects of memory covary with changes in sex steroid levels in some women.

No description available.

The extent of denaturation and glycation of lysozyme and BSA with the application of high hydrostatic pressure (HHP) at 400 MPa at 30°C from 8 to 48 hours and focused microwave irradiation at 50°C under varying microwave power and from 10 to 60 minutes was investigated in the presence and absence of D-glucose. The HHP treatment caused 10 to 20% denaturation of lysozyme whereas microwave irradiation caused 20 to 40% denaturation, with more destruction to the lysozyme in the presence of glucose compared to the control. The extent of glycation was also higher with the high pressure samples, causing 60% glycation upon 8 hours of high pressure exposure, but decreasing to around 40% thereafter. Microwave irradiation brought about 40% glycation to the lysozyme samples upon 20 min of irradiation. BSA, on the other hand, was more susceptible to damage by high energy exposures. BSA samples were denatured to a greater extent compared to lysozyme, up to 80% upon the prolonged exposures, but in all treatments, glucose seemed to act as a protectant contrary to the case of lysozyme. The extent of glycation detected was also minimal, ranging from 8 to 20%. / The feasibility of analyzing glycated proteins using pyrolysis-GC/MS was also investigated. Taking advantage of the formation of a diagnostic marker---2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one---upon pyrolysis of glycated proteins, the intensity of this peak was used to correlate the extent of glycation. The intensity of this peak in the pyrograms of glycated lysozymes was found to increase linearly with increasing incubation times and subsequently with the sugar loads of the glycated lysozyme. In addition, using the pyrograms as unique fingerprints, the extent of structural changes between modified and unmodified proteins were also assessed.

This thesis discussed the cardiovascular effects of the aqueous leaf extract and a fraction of the methanol extract of Leonotis leonurus, a plant commonly used in traditional medicine in South Africa for the treatment of hypertension and other cardiac problems. The cardiovascular effects was tested on anaesthetized normotensive male Wistar rats and isolated perfused rat hearts.

<p>The incidence of cardiovascular diseases, including hypertension, is on the increase worldwide. Medicinal plants played an important role in the treatment of hypertension for centuries. Very few scientific studies have, however, been done to validate the use of these phytotherapies. O africana is on of the many phytotherapies that has been use indigenously for years to treat hypertension. The objectives of this study were to determine the most effective does of O africana aqueous extract which will reduce blood pressure / to determine whether chronic administration of O africana can be used to prevent and treat hypertension / to determine whether O africana exert its effects by modulation of the renin-angiotensin system.</p>

This study was designed to determine the impact of glycerol hyperhydration, compared with a placebo hyperhydration, on the run performance during an Olympic distance triathlon. Ten competitive triathletes (mean peak oxygen consumption, VO2 peak = 65.5 ± 5.5 ml.kg.-1min-1) undertook two simulated Olympic Distance Triathlons in 31° C and 61% relative humidity. The trials were split into two work phases: a fixed workload phase comprising a 18-20 min swim and a 60 min cycle and, a self regulated time trial run over 10 kilometres conducted on a treadmill. One hundred and fifty min prior each trial, either a glycerol solution (1 g.kg.-1 body mass (BM) in a 4% carbohydrate – electrolyte drink) or a placebo of equal volume of the 4% carbohydrate-electrolyte solution was ingested over one hour. The total fluid intake in each trial was 23 ml.kg.-1 BM. A randomised, double blind, cross over design was used. Due to either 1) the arduous nature of the trials 2) the side effects associated with the ingestion of glycerol 3) or the combination of the two aforementioned reasons, only five of the 10 subjects completed the final 10 km self regulated time trial for both treatments. Only the data obtained from these five subjects were reported in this study. Glycerol ingestion expanded body water over the placebo by 154 ml (26%). At 60 and 90 min after the start of drinking, urine output was significantly higher with glycerol than placebo treatment (216.4, 366.4 ml vs 81.0, 242.0 ml, respectively) but significantly higher at 120 min in the placebo (421.6 ml vs 131.2 ml). There were no significant differences in heart rate and rectal temperature during the swim and cycle phases. However, there were significant increases in heart rate (at 5, 10, 15, 25 and 30 min) and rectal temperature (at 5, 20 and 30 min) during the 10 km run in the glycerol trial. The mean 10 km run time for the placebo trial was 40 min 21 sec (± 2.9 min) while the glycerol trial was 39 min 22 sec (± 2.0 min). The mean difference of 2.1% in finishing time between trials was not significant. Three of the five subjects in the glycerol trial improved their 10 km time by 7.0, 2.4 and 2.7%, respectively. The finishing time for one subject did not change for both trials while another subject had deteriorated by 2.3% in the glycerol trial. In the glycerol treatment, five subjects complained of bloating and nausea while only one subject complained of feeling unwell in the placebo treatment. Data from this study have shown that glycerol hyperhydration did not significantly improve performance while plasma volume expansion and subsequent lower rectal temperature and lower heart rates were not evident. The exact mechanisms of how glycerol hyperhydration can improve performance warrant further investigation. / Masters in Applied Science