Jump ability is important in volleyball; therefore analysis of factors that influence jump performance is necessary to ensure maximal jump ability. Purpose: To analyze how strength characteristics associated with jumping are affected by percent body fat, lean body mass and free fat mass. Methods: Data from eleven female NCAA DI volleyball players as part of an ongoing athlete monitoring program collected from 2007-2010 was analyzed. Data was separated into weakest and strongest based on isometric peak force allometrically scaled. In all cases the weakest data corresponded to testing during the athletes first year at ETSU. Body composition was measured using air displacement plethsmography (BodPod). Maximum strength (isometric peak force – IPF) and strength characteristics (peak force -F@ 50ms, 90ms, and 250ms; rate of force development, 0-200ms –RFD) were measured with isometric mid-thigh pulls on a force plate, and countermovement jumps with 0, 11 and 20 kg . Allometric scaling of the different force values (IPFa, F@50a, F@90a, F@250a) was used to normalize differences in the body mass of the athletes (absolute force/ (body mass (kg0.67)). Pearson correlations were used to determine the relationship strengths. Results: In weaker test results, there are moderate and small inverse correlations between CMJ and PF (r=-0.34) and PFa (r= -0.19), and strong inverse correlations between CMJ and percent body fat (r=-0.67). In stronger test results there are small correlations between CMJ and PF (r=0.23), PFa (r= 0.26), and moderate inverse correlations between CMJ and percent body fat (r=-0.40). There is a significant change in jump ability and strength between both groups. Conclusion: As an athlete becomes stronger, there is a significant correlation between CMJ strength, PF, PFa, F250, and F250a. The relationship between CMJ and strength characteristics decreases as BF increases.

Exercise can have very beneficial effects on health and body satisfaction, but sometimes a negative body image gets in the way of exercising. Modern society holds certain beauty ideals in high regard, and these standards are often unattainable and unrealistic. These outside pressures to look a certain way can have a very negative effect on an individual’s body image, or the way that a person perceives his or her own appearance. There have been many studies done that have attempted to define the relationship between body image with exercise behaviors (Burger and Diony 2002, Hall and Pearson 2013). Some studies have shown that a negative body image is related with higher prevalence of exercise, while others have shown that a negative body image is a major barrier to participation in exercise at all (Berry, McHugh, and Pankratow 2013, Burger and Diony 2002, Gammage and Lamarche 2012, Hall and Pearson 2013). While the data from these studies has shown different relationships, there is an abundance of research on the topic. There is a lack of information, however, on the relationship between body image and exercise type. This study focused on this relationship in an attempt to determine if body image, positive or negative, had any effect on what type of exercise activities an individual chose to participate in. A total of 70 undergraduate college students were surveyed using a 9 question health and exercise questionnaire and a 6 question body image survey, written and published by Thomas Cash and previously utilized in other body image survey studies (Cash, et al. 2002). The data collected was analyzed using chi-square tests and a significant correlation between body image and exercise type, as well as body image and gender. Participants with a negative body image reported a preference for aerobic exercise while those with a positive body image preferred anaerobic exercise. The analysis also found that females were more likely to have a negative body image than males, which supports previous research trends (Burger and Diony 2002). This study only surveyed 70 individuals, and so the results can not necessarily be generalized to the entire population. Further research could include a larger sample size so as to find a more generalizable relationship between body image and exercise type.

The effective prescription of resistance exercise for strength and power development has been a source of debate amongst practitioners and sport scientist alike. One of the key issues in this area relates to the training load that would best facilitate strength and power adaptation. Heavy loads (>60-70% 1RM) have been traditionally used for maximal strength development by facilitating changes in neural function (strength) and muscle size (hypertrophy). However, many studies have now found lighter load (>45%1RM) training equally effective in improving both strength and hypertrophy. Similarly, many studies have found heavy load training effective in enhancing various measures of power though lighter loads (e.g. 45% 1RM) are thought to maximise the mechanical power output of muscle. Realising that adaptation depends upon some interaction between the mechanical, hormonal and metabolic stimuli, examining these responses would enhance our understanding of the underlying determinants of strength and power, and thereby improve strength and conditioning practice. Therefore, the purpose of this study was to examine the mechanical, hormonal and metabolic responses to equal volume light and heavy loading schemes. Eleven males (mean 26.6 ± 6.7 years; mean 79.0 ± 8.1 kg) with a minimum of 12 months weight training experience each performed two exercises (Smith squat and supine squat) at a light (45% 1RM) and heavy (88% 1RM) intensity. The light scheme consisted of eight sets of six repetitions, with six sets of four repetitions performed in the heavy scheme. Rest periods of three and four minutes respectively were used. Saliva sampling was used to determine the hormonal (cortisol and testosterone) and metabolic (lactate) responses. Samples were collected at rest (pre-), immediately after the first exercise (mid-), at the conclusion of the second exercise (P0) and every 15 minutes thereafter for one hour (P15, P30, P45, P60). Mean values for all variables were analysed with a paired sample T-test. Chances that the true effects were substantial (% and qualitative) were also calculated. No significant (P>0.05) difference in total forces was found between schemes; however, the light scheme produced significantly greater total time under tension (36%), total work (37%) and total power output (115%). Total impulse (38%) was the only variable found to be greater in the heavy scheme. A decrease in testosterone (TST) was observed in the heavy scheme (-4 to -29%) with no significant changes found across the light scheme (1 to 12%). Cortisol decreased in the light (-6 to -30%) and heavy (-14 to -44%) schemes until P45. An increase in the TST/cortisol ratio was observed in both the light (17 to 49%) and heavy (2 to 44%) schemes. Both loading schemes resulted in similar increases in lactate (0.3 to 1.0nmol/l). Equating two schemes by volume resulted in differential responses, many of which favoured the lighter scheme in terms of mechanical, hormonal and metabolic outputs. These findings suggest that load or intensity employed may be not as important as initially proposed and that other factors (e.g. volume, technique) may explain the similar strength and hypertrophy adaptation reported in studies comparing light and heavy schemes.

The effective prescription of resistance exercise for strength and power development has been a source of debate amongst practitioners and sport scientist alike. One of the key issues in this area relates to the training load that would best facilitate strength and power adaptation. Heavy loads (>60-70% 1RM) have been traditionally used for maximal strength development by facilitating changes in neural function (strength) and muscle size (hypertrophy). However, many studies have now found lighter load (>45%1RM) training equally effective in improving both strength and hypertrophy. Similarly, many studies have found heavy load training effective in enhancing various measures of power though lighter loads (e.g. 45% 1RM) are thought to maximise the mechanical power output of muscle. Realising that adaptation depends upon some interaction between the mechanical, hormonal and metabolic stimuli, examining these responses would enhance our understanding of the underlying determinants of strength and power, and thereby improve strength and conditioning practice. Therefore, the purpose of this study was to examine the mechanical, hormonal and metabolic responses to equal volume light and heavy loading schemes. Eleven males (mean 26.6 ± 6.7 years; mean 79.0 ± 8.1 kg) with a minimum of 12 months weight training experience each performed two exercises (Smith squat and supine squat) at a light (45% 1RM) and heavy (88% 1RM) intensity. The light scheme consisted of eight sets of six repetitions, with six sets of four repetitions performed in the heavy scheme. Rest periods of three and four minutes respectively were used. Saliva sampling was used to determine the hormonal (cortisol and testosterone) and metabolic (lactate) responses. Samples were collected at rest (pre-), immediately after the first exercise (mid-), at the conclusion of the second exercise (P0) and every 15 minutes thereafter for one hour (P15, P30, P45, P60). Mean values for all variables were analysed with a paired sample T-test. Chances that the true effects were substantial (% and qualitative) were also calculated. No significant (P>0.05) difference in total forces was found between schemes; however, the light scheme produced significantly greater total time under tension (36%), total work (37%) and total power output (115%). Total impulse (38%) was the only variable found to be greater in the heavy scheme. A decrease in testosterone (TST) was observed in the heavy scheme (-4 to -29%) with no significant changes found across the light scheme (1 to 12%). Cortisol decreased in the light (-6 to -30%) and heavy (-14 to -44%) schemes until P45. An increase in the TST/cortisol ratio was observed in both the light (17 to 49%) and heavy (2 to 44%) schemes. Both loading schemes resulted in similar increases in lactate (0.3 to 1.0nmol/l). Equating two schemes by volume resulted in differential responses, many of which favoured the lighter scheme in terms of mechanical, hormonal and metabolic outputs. These findings suggest that load or intensity employed may be not as important as initially proposed and that other factors (e.g. volume, technique) may explain the similar strength and hypertrophy adaptation reported in studies comparing light and heavy schemes.

Prolonged moderate intensity cycle exercise is associated with a gradual and progressive reduction in gross efficiency (GE). It was speculated that this loss of GE might reflect a reduction in maximal muscle function and result in a parallel decline in aerobic performance. The effect of prolonged moderate intensity cycle exercise on maximal muscle function and anaerobic performance has not been clearly established. This thesis examined the impact of 1-2 h of cycling exercise at 60-65% maximal aerobic power in well-trained cyclists on subsequent changes in aerobic and anaerobic performance, GE and maximal muscle function.

The current work is novel in that it investigated in vivo analysis of glucose metabolism during and following hypoxic exposure in type 2 diabetics. Using moderate levels of hypoxia, study one found that 60 min of resting hypoxic (Hy Rest) exposure reduced blood glucose concentrations in type 2 diabetics. Insulin sensitivity was also found to be significantly greater following hypoxic exposure when compared to the normoxic control. The second study showed that exercise under hypoxic (Hy Ex) conditions acutely reduced arterialised blood glucose concentrations. The total area under the curve for insulin was also significantly lower subsequent to an intravenously administered glucose load (IVGTT) in the 4 hr following Hy Ex versus normoxic exercise. The third study demonstrated that glucose disposal was acutely enhanced in exercise bouts lasting 60 and 40 min (of equal work) in hypoxia.

This thesis investigates the England Visually Impaired Cricket Team, whose squad members comprise sixteen men aged 18-54, and their lived experiences' of playing visually impaired cricket. This is the first piece of research to examine elite visually impaired cricket and the first to explicitly analyse the social dynamics of any visually impaired sports team. Through an embodied theoretical approach, that accounts for the corporeal experience of impairment alongside the role of social institutions and discourse in the high performance culture of modern disability sport, this thesis establishes the significant aspects of this previously unexamined research 'site', both on and off the pitch. This study consisted of ten months of ethnographic fieldwork using participant observation and semi-structured interviews shaped by a new method of recording and eliciting data. To capture the participants' sensorial experiences of playing visually impaired cricket, 'soundscape elicitation', the process of composing auditory 'tracks' of the players' participation and then using these recordings during semi-structured interviews to prompt sensorial discussions, was utilised. This original and innovative method was central to the production of previously unexamined knowledge and is a significant methodological advancement in the wider field of sensory studies. The findings present a number of original contributions to knowledge regarding 'sporting bodies', the sensorial experiences of sport, and the construction of identity through disability sport. The participants' embodied experiences of playing visually impaired cricket reveal an alternative way of 'being' in sport and physical activity. However, it is the inescapable ocularcentric value of 'sight' that inhibits the resistive potential of the game. Instead of the presumed empowering experience, elite visually impaired cricket is disempowering for many participants due to the irreversible relationship of blind cricket institutions with mainstream cricketing bodies. Furthermore, a 'hierarchy of sight' based upon the official sight classification process emerges that highly values those players with the highest sight classifications and marginalises the blind players. All of these factors inform visually impaired cricket players’ construction of their own identities. Although many players view visually impaired cricket as a way of demonstrating their 'normality', it actually accentuates the impairment that they are attempting to dissociate from and is one of the few social situations where they are 'outed' as disabled or blind.

Prefrontal cortex is frequently linked to dual-task gait performance; however, its precise role is unknown. The purpose of this thesis was to examine the role of prefrontal cortex in the control of dual-task gait. Using transcranial direct stimulation (tDCS) to alter prefrontal cortex activity, the influence of prefrontal cortex on dual-task gait performance and the corticospinal system was examined across four experiential studies using the guided activation framework of prefrontal cortex function (Miller and Cohen, 2001). The first study examined the role of cognitive task type and walking speed on stride time variability and trunk range of motion during dual-task walking. Results revealed the greatest dual-task cost on gait occurred when walking at a slow speed whilst simultaneously performing a serial subtraction task, compared to performance of a working memory task, providing a rationale for the use of this paradigm in later studies. The second study examined the effect of prefrontal tDCS on dual-task gait performance during both normal and slow walking. Anodal tDCS reduced the dualtask cost on both gait and cognitive task performance, and these effects were not dependent on walking speed. These results indicating that prefrontal tDCS may alter the allocation of cognitive control across tasks during dual-task gait, in accordance with established models of prefrontal cortex function. The third study examined the effect of prefrontal tDCS on corticospinal excitability and working memory performance. Results revealed that cathodal tDCS reduced corticospinal excitability. However, there was no effect of tDCS on working memory performance. Because prefrontal tDCS altered the activity in remote motor networks, these results indicated a possible mechanism by which prefrontal cortex exerts control over gait performance. In addition, because this study failed to replicate previous reports of working memory improvement following tDCS, these results also suggested a degree of inter-individual variability in response to tDCS. The final study examined the influence of walking modality and task difficulty on the effects of prefrontal tDCS on dual-task gait performance. tDCS altered the allocation of cognitive control during over-ground dual-task gait performance, and 3 these effects were mediated by task difficulty. In contrast to the second study, there was no effect of tDCS on treadmill dual-task gait. A secondary aim of the final study was to examine whether cognitive and walking task performance were coordinated. Results revealed that participants articulated answers during the initial swing phase of the gait cycle more frequently than other phases, indicating a degree of coordination between the performance of these tasks. Overall the finding of this thesis indicate that prefrontal cortex is involved in the allocation of cognitive control processes during dual-task walking, in accordance with the guided activation and flexible hub accounts of frontal cortex function (Miller and Cohen, 2001; Cole et al., 2013). These findings may have implications for the design and validation of strategies aimed at improving the cognitive control of gait.

Background: Long distance road running is continually growing as competitive and recreational sport, globally. Despite its popularity, a high burden of incidence of injury exists among runners. Previous research has focussed on specific injuries, whereas others have investigated isolated risk factors that may contribute to running related injuries. The purpose of the study is to determine possible internal and external screening variables that may predict the incidence of running-related injuries in general. Methods: Forty one recreational runners participated in an observational study over the course of 12 weeks. Screening assessments consisted of injury history, training history, and anthropometric measurements. Functional and performance assessments included the Foot Posture Index (FPI), the Functional Movement Screen (FMS), vertical jump, single leg hop and sit-and-reach tests. Participants were monitored over a period of 12 weeks by completing a weekly online logbook regarding their training and possible incidence of injury. Monitoring was terminated after 12 weeks of observation. Differences between injured and non-injured runners were determined using Independent -T-tests for mean differences, or Mann-Whitney U Test for distributional differences (non-parametric data). Binomial Logistic regression models were used to determine the influence of internal, external functional and external behavioural factors on the risk for running injury, respectively. Results: The total group revealed a cumulative incidence of injury of 63% over the 12 weeks of observation. There was no gender difference between incidences of injuries over the 12 week observation training period (OTP). Injured runners achieved a higher total FMS score (median = 16, Interquartile Range = 3) compared to uninjured runners (median = 15, Interquartile range = 3; p = 0.006). Binomial logistic regression models of external functional (FMS, Vertical Jump, Sit-and-Reach scores) factors [X² (3) = 9.764, p = 0.021] were statistically significant. Only the FMS score contributed significantly to the incidence of injury (p = 0.013) of the three external functional factors in the Regression Model. Discussion and Conclusion: The study adds to current evidence that the assessment of the Functional Movement Screen is important in predicting injury, however, the present study shows that a higher score obtained during the FMS increase your odds to sustain an injury. The study is in contrast with the body of evidence that the incidence of previous injury is the strongest predictor of the incidence of a current injury. The study concluded that the Functional Movement Screen is a useful screening tool to determine a long distance runner's risk for running-related injuries and should be included in health-injury risk assessments of recreational runners.

Concussion management is changing. Recent years have marked a sea change, with the former rest-is-best approach being supplanted by an exercise-is-medicine mindset. Despite this, important questions remain unanswered in the pediatric exercise-concussion literature. The overarching aim of this thesis was to examine the effects of exercise on outcomes beyond concussion symptoms, and build our understanding of the relationship between pediatric concussion and physical activity. Four studies were performed to this end. First, per a systematic review, we found that randomized trials on the effects of exercise on neuroimaging and cognitive outcomes remain limited. Studies suggest that exercise may improve brain structure and function post-concussion, while data with respect to cognitive outcome were mixed. Second, we provided the first evidence that the functional neuropathology of pediatric concussion differs by sex at 1 month post-injury, with females demonstrating impairment not observed in males. Namely, only females with concussion showed patterns of both hyper-connectivity (between the lateral pre-frontal cortex & inferior frontal gyrus, lateral pre-frontal cortex & lateral occipital cortex, and the posterior cingulate cortex & cerebellum; all p-corrected <0.05) and hypo-connectivity (between the anterior cingulate cortex & precuneus, anterior cingulate cortex & cingulate gyrus, and posterior cingulate cortex & paracingulate gyrus; all p-corrected <0.05). Third, we provided the first accelerometer-based characterization of physical activity and sedentary time in children with concussion in comparison to 1:1 matched healthy controls. Relative to healthy controls, children with concussion were more sedentary, with a mean difference [MD] of 38.3 minutes/day (95% confidence interval [CI] 11.2 to 65.4, p<0.01), and they also performed less light (MD -19.5 minutes/day, CI -5.3 to -33.7, p<0.01), moderate (MD -9.8 minutes/day, CI -5.7 to -13.8, p<0.001) and vigorous physical activity (MD -12.0, CI -6.9 to -17.2, p<0.001); greater physical activity deficits were observed in females with concussion. Fourth, per the first study to employ both accelerometry and functional neuroimaging in pediatric concussion, we found that intra-network connectivity of the default mode network was associated with subsequent accelerometer-measured light (F(2, 11) = 7.053, p = 0.011, Ra2 = 0.562; β = 0.469), moderate (F(2, 11) = 6.159, p = 0.016, Ra2 = 0.528; β = 0.725), and vigorous (F(2, 11) = 10.855, p = 0.002, Ra2 = 0.664; β = 0.792) physical activity. This study provides the insight into a potential link between brain activity and physical activity in pediatric concussion. The next wave of exercise and physical activity research in concussion needs to move beyond symptom studies, employ sex-specific analyses, understand the impact of exercise on brain function, and consider interventions that increase habitual physical activity. Doing so is necessary for exercise to become medicine for concussion patients. / Thesis / Doctor of Philosophy (PhD) / Until a few years ago, the advice children received after a concussion (or mild brain injury) was to rest until they no longer had symptoms. But the way concussions are being treated is changing. Scientists have found that exercising soon after a concussion can lessen symptoms. It is no longer thought that rest-is-best. Instead, it is now believed that exercise-is-medicine. But there are still important questions about the role of exercise after a concussion that have not been answered. The four studies in this thesis had the goal of answering some of those questions. In the first study, we found that while exercise improves symptoms after a concussion, we know less about how it impacts the brain and our ability to think. From the second study, we learned that a concussion impacts the brains of boys and girls in different ways, and that girls may have longer lasting brain changes after a concussion than boys. Our third study showed that after a concussion, girls take part in less physical activity than boys throughout the day. The fourth study suggests that there may be a link between brain activity and physical activity in children with a concussion. This thesis adds to our knowledge of the role of exercise in concussion. It also raises some important questions that should be answered by new studies in the near future.