A holistic investigation of amateur batters performance responses to a century protocol: a focused cognitive perspective
- Authors: Goble, David
- Date: 2017
- Subjects: Cricket -- Batting -- Physiological aspects , Cricket players -- Physiology , Cricket players -- Health and hygiene , Cognition -- Testing , Neurophysiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/40725 , vital:25020
- Description: No cognitive study has implemented an exercise modality that requires both physical effort and cognitive control, therefore, the effects of such exercise are unknown. Additionally, no studies have investigated how prolonged batting impacts cognitive functioning nor how physical responses and cognitive functioning are related while batting. At intensities of 6070 percent heart rate maximum, acute and prolonged bouts of physical activity have been shown to improve cognitive functioning. At higher intensities, the beneficial effects are minimal and in some cases performance is impaired. Therefore, the aim of this investigation was to determine how prolonged intermittent batting (a task that requires high muscular and cardiovascular loads but also continuous cognitive control) affects cognitive, physiological, physical and biophysical responses in amateur batters. Further aims included to test the reliability of the method employed in assessing these responses. To answer this question, the investigation was separated into three studies: phase 1 (a large-scale pilot) and phase 2 and 3 (a repeated measures test-retest hypothesis). In each phase, batters completed the 30 over BATEX simulation, which replicated the demands of scoring a one-day international century. To establish physiological, physical and perceptual strain; heart rate, sprint times and perceived exertion data were collected each over. Changes in body mass over time were compared to determine the effects of fluid loss on cognitive performance. Before, during and after the simulation, psychomotor function, visual attention, working memory, visual learning and memory as well as executive functions were assessed (CogState brief test battery). During cognitive assessments, heart rate and heart rate variability parameters were sampled so that autonomic modulation of the heart could be determined. The methodological differences between phase 1 and phase 2 and 3, were (respectively); the frequency of cognitive assessments (five vs. three), the samples used (15 schoolboy vs. 16 academy batters), hydration protocols (250ml of Energade vs. water ad libitum) and a singular change in a physical dependent variable (batting accuracy vs. vertical jump). In schoolboy and academy batters, the prolonged batting simulation placed significant strain on the cardiovascular and muscular subsystems; increasing heart rate (p<0.01), decreasing body mass (p<0.01) and deteriorating sprint performance (p<0.01) over time. In each sample, batters’ perceived exertion increased significantly (p<0.01) and exertion was highest in the final over of the protocol. Interestingly, the changes in cardiovascular and muscular responses were larger in schoolboy batters. While the cognitive performance decrements over time were not significant in academy batters (p>0.05; d<0.2), the magnitude of impairment in psychomotor function (p>0.05; d = 0.37), visual attention (p>0.05; d = 0.56), working memory (p>0.05; d = 0.61) and executive function (p>0.05; d = 0.58) was larger in schoolboy batters. In both samples, the simulation altered the modulation of heart rate significantly. Heart rate variability decreased linearly with time spent batting (p<0.01; d>0.8). During cognitive assessments, heart rate variability increased with time-on-task, where responses were significantly higher (p<0.05) in the last task of the battery compared to the first. Importantly, the results of the retest phase were the same as in the test phase and only two condition effects were observed; (i) heart rate (retest lower: p<0.04;d = 0.39), (ii) body mass (retest lower: p<0.03;d = 0.09). A task-related condition effect in heart rate variability (PNN30) was also observed (retest higher: p<0.03; d = not calculated). Resultantly, the test-retest reliability of phase 2 and 3 was high. The results indicate that prolonged intermittent batting at an intensity of 64-77 %HRmax impaired cognitive functioning in amateur batters. However, the cardiovascular and muscular strain induced by prolonged intermittent batting and its effects on cognitive functioning are mediated by intrinsic and extrinsic factors (age, training status, playing experience and hydration). Therefore, while prolonged batting has similar effects on cognitive functioning as acute bouts of physical activity, they do not share the same relationship. The author hypothesises that the continuous cognitive component inherent in prolonged batting mitigates the beneficial effects of physical activity, as demonstrated previously. Future research is needed to elucidate this relationship. Additionally, player experience affects the way in which batters regulate performance while batting; which also affects the rate of and magnitude of impairment during batting. Finally, the methodological limitations of this study provide direction for future research into batting.
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Strength training and cardiovascular risk post-menses, with particular emphasis on the plasma lipoproteins: a controlled trial
- Authors: Viljoen, Janet Erica
- Date: 2014
- Subjects: Weight training for women -- Physiological aspects , Exercise for women -- Physiological aspects , Middle-aged women -- Health and hygiene , Cardiovascular system -- Diseases , Hypercholesteremia , Blood lipoproteins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5155 , http://hdl.handle.net/10962/d1013578
- Description: Introduction: Cardiovascular disease affects a greater proportion of females than it does males, and is responsible for an estimated 52 percent of female deaths per annum, globally. Due to the loss of oestrogen associated with the menopause, post-menopausal females are at elevated risk for hypercholesterolaemia which is a primary risk factor for cardiovascular disease. It has not yet been conclusively established whether resistance training can be used to ameliorate hypercholesterolaemia. Aim: This randomized controlled trial investigated what effect 12 weeks of progressive resistance training would have on plasma lipoproteins in a sample of post-menopausal females. Methods: Caucasian women (n=30 intervention and n=18 control) between the ages of 55 and 65 years who were not taking hormone replacement therapy were recruited. Participants did not smoke, were sedentary, were not taking any form of cholesterol-lowering medication, had at least one cholesterol abnormality at baseline but were otherwise healthy and able to participate in a strength training programme. Following extensive medical pre-screening, information dissemination and voluntary consent, the sample was divided into two groups. The exercise sample undertook 12 weeks of resistance training on five days of the week. The control group received no intervention. Measurements were obtained at baseline and every four weeks thereafter and included measures of strength, biochemistry (oestradiol, testosterone, full blood lipid profile, glycated haemoglobin and sex hormone binding globulin), anthropometry, morphology and self-reports (dietary intake, energy expenditure and the profile of mood states questionnaire). Results: There was no change to low density lipoprotein cholesterol, high density lipoprotein cholesterol, triglyceride content or total cholesterol as a result of the intervention. Back, chest and leg strength increased significantly (p<0.01) (increases of 51 percent, 35 percent and 43 percent respectively from baseline); waist circumference dropped (p<0.01) by 5 percent overall and diastolic blood pressure decreased significantly (-9 percent, p<0.01) in the exercise cohort but no change was noted in the matched control. Dietary intake, energy expenditure and body mass remained unchanged in both samples. Morphology (sum of skinfolds, estimated body fat content and girth measures) did not change and nor did other biochemical measures (HbA1c and sex hormone binding globulin) or hormone levels (oestradiol and testosterone). Despite the lack of overall change, an important finding was noted in individual results where a clear indication of ‘responders’ and ‘non-responders’ emerged. Conclusion: Overall mean results suggest that 12 weeks resistance training undertaken five days of the week was ineffective in reducing hypercholesterolaemia in this sample. Despite there being no identifying characteristics determined in this sample, evidence of responders and non-responders to the intervention indicates that reliance on mean data may not be sufficient when analysing data from exercise interventions. Therefore, while progressive resistance training had a positive effect on strength, waist circumference and diastolic blood pressure, it did not positively influence the plasma lipoproteins in this cohort of post-menopausal women. , Maiden name: Kelly, Janet Erica
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