Exercise participation is linked to mental health and wellbeing. However, we need to identify optimal settings for promoting exercise-associated wellbeing outcomes, and for promoting exercise adherence. The literature suggests environmental settings may be important. The aim of this thesis was to rigorously test influences of environmental settings on exercise-related wellbeing outcomes. These over-arching research questions guided the experimental chapters: (i) is there an optimal green exercise environment for promoting wellbeing? (ii) When exercise is controlled, are findings consistent with previously reported psychological outcomes? (iii) Do environmental settings influence social outcomes of exercise or intentions to repeat exercise behaviours? Via field-based sampling, Chapter 3 found large proportions of affective benefits were universally obtainable across four typical green exercise environments, and suggested that the processes component of green exercise warranted further investigation; however, this method lacked control. Chapter 4 used laboratory-based methodology to control exercise and isolate the visual environment; consistent with both theory and previous research, nature environments facilitated wellbeing-related attention restoration. However, this method did not provide an accurate multisensory experience, therefore lacking ecological validity. Chapter 5 investigated methodologies for controlling the exercise component, comparing wellbeing-related outcomes of indoor versus outdoor exercise. This was important because previous research had not rigorously controlled exercise, therefore potentially confounding its findings. Results for environment-related exercise differences and affective outcomes were inconclusive. Chapter 6 merged laboratory-based methods with the indoor versus outdoor exercise paradigm, ensuring control and ecological validity. Environmental setting did not influence perceived exertion or mood; green settings promoted attention restoration and social interaction; for green exercise, social interaction predicted exercise intentions. Green exercise promotes wellbeing improvements; environmental influences on affective outcomes may be contributed to by differences in exercise performed. Independent of exercise differences, green environments promote attention restoration and social interaction during exercise, which may in turn influence exercise intentions.

Application of GPS technology in elite level soccer is a growing area of research. This thesis comprises an examination of current practice in elite youth level soccer, and a critical examination of the potential applications in the PlayerLoadTM measure to quantify the biomechanical demands of match play. The thesis comprises four experimental studies that consider the development of monitoring biomechanical intensity in training and/or competitive matches. The first experimental study provides a critical examination of the biomechanical specificity of training drills relative to competitive match play. This study utilised the performance metrics as collated on a daily basis by the football club. Specifically, in relation to tri-axial accelerometry the measurement of PlayerLoad was restricted to total accumulated loading. Additional parameters related to distance and velocity parameters were also examined. ‘Small-Sided Games’ generated similar values to 90-min matches for PlayerLoad (standardised for duration) and total distance covered. However, these drills failed to provide a valid demand in terms of high-intensity running, which was most valid in ‘Movement Pattern’ drills. Drills described as ‘Possession’ and ‘Game-Related’ failed to match the mechanical demands of match play. The implications of these findings relate directly to the micro-design of the training week, and the monitoring of player performance. The correlation between PlayerLoad and distance covered was stronger in small-sided games (r=0.92) than in regulation 11 vs 11 match play (r=0.37), highlighting mechanical issues in the calculation of PlayerLoad. The smaller pitch size is likely to promote a greater frequency of speed and or directional change, and as such the summation principle applied to generate a “total” or 3- dimensional loading value is limited. 6 In the second experimental study the analysis of tri-axial accelerometry was extended to provide a uni-axial consideration of PlayerLoad. Biomechanically, this is analogous to analysing each force vector rather than the development of a “total” kinetic parameter based on a summation principle. This uni-axial analysis of mechanical loading was first applied to the influence of playing age via a comparison of the U16, U18 and U21 squads within the same club. The U16s performed the greatest total distance, primarily in the lower speed zones. Correlation between PlayerLoad and total distance ranged from r=0.26-0.56, for the three age groups, with evidence of higher coefficients in the U16 group. The U18s exhibited the greatest PlayerLoad, evident in each movement plane. Uni-axial analysis highlighted a higher contribution from medio-lateral loading in the U18s, indicative of greater lateral movement. This finding might also relate to the higher injury incidence observed in this U18 age group. The practical applications of this study relate to the transition of players through the academy structure and into senior football. The unique movement patterns identified by a uni-axial analysis of PlayerLoad highlights potential in the greater analysis of movement. This uni-axial analysis was extended in the third experimental study to further examine issues in the movement profile with a consideration of the influence of playing position on mechanical loading. Whilst not generalisable beyond this team and playing strategy, attackers covered the greatest (total and high speed) distance, whilst midfielders exhibited the greatest load across all movement planes. Correlation between PlayerLoad and total distance was position specific, forwards and midfielders recorded values of r=0.74 and r=0.16 respectively. Playing position categorising defenders, midfielders and attackers failed to identify the impact of positional width on the biomechanical demands of match play. The traditional grouping of playing units might therefore be considered in terms of individualising training programmes. The distinction between distance covered and PlayerLoad is consistent throughout the first three experimental studies, with a low correlation in part explained by the calculation used to 7 quantify PlayerLoad. In the final experimental study the PlayerLoad calculation is critically examined beyond the uni-axial nature of acceleration. Having previously examined the summation principle, the failure of the PlayerLoad calculation to consider magnitude of acceleration is examined. The instantaneous change in acceleration is not influenced by the magnitude of acceleration, and in the final study a novel iLoad parameter is introduced which is analogous to the iEMG parameter utilised widely in electromyography. This parameter considers the integral of the acceleration-time curve. Further, the sign principle is critically examined, with the PlayerLoad calculation negating all negative values and thus making all movements forward, to the right, and upward. By considering both positive and negative values the tri-axial accelerometer has the capacity to differentiate between medial and lateral movement for example, with clear implications for the monitoring of performance and injury risk. This novel biomechanical analysis was applied to an examination of fatigue during match play, which has implications for both performance and injury. Over 15min segments of match play, fatigue did not influence the anterio-posterior or medio-lateral loading but there was a significant decrease in vertical load. There was also evidence of movement asymmetry in each plane, favouring movements forward and to the left. Correlation between iLoad and total distance was r=0.19. In conclusion, the thesis evaluated PlayerLoad and critically discussed the mechanical specificity of training activities. Furthermore, use of uni-axial load highlighted differences in positional demands and the influence of age group on GPS variables. Critical evaluation of PlayerLoad calculation aimed to highlight the deficiency of tri-axial acceleration of the formula. Thus, iLoad further developed calculation to refine movement quality data to examine fatigue. By adopting principles analogous to kinetic analyses in force platform and electromyography, additional analysis parameters may be defined which provide greater depth 8 of information in movement quality. The implications in movement asymmetry also have implications for the monitoring of injury risk.

The purpose of this investigation was to examine impacts during running. The protocol used to fulfill this purpose consisted of subjects running at a constant velocity but altering their stride frequency. In the first of three studies, shock attenuation was investigated as a possible optimizing criteria. It was found that impacts and shock attenuation both increased as the stride frequency decreased. The result was that shock at the head changed very little across stride frequency conditions. Because oxygen consumption and shock attenuation both increased during the low stride frequency conditions, it was thought that increasing the attenuation of shock in the body may have an associated energy cost. The second study examined the locations of muscular energy absorption during the impact phase of the running cycle. A rigid body model was used to estimate energy absorbed during the impact phase of running. During the low stride frequency conditions, the magnitude of the velocities of the support leg and the rest of the body were greater during ground contact. This required greater energy absorption at the hip, knee and ankle joints. Muscles that cross the knee joint adjusted the most in response to increased shock. It was conjectured that the perpendicular distance from the line of action of the resultant ground reaction force to the knee joint center played a role in this increased energy absorption. The third study used a mass-spring-damper model to simulate the vertical ground reaction forces of a human runner as stride frequency was altered. The input parameters of the model were measured from the actual characteristics of the runners when possible. Spring stiffness values were selected by an optimizing routine. An upper mass-spring system was used to control the active portion of the ground reaction force. The stiffness of this spring showed a twofold increase as the subjects increased their stride frequency. A lower, mass-spring-damper system was used to control the impact portion of the ground reaction force. This stiffness value showed a trend opposite that of the upper spring. The lower spring apparently prevented the support leg from completely collapsing during the low frequency running.

The purpose of this research was to determine consequences of repeated impacts during running. Part I. This study investigated midsole hardness influences on mechanics and hematology during a prolonged downhill run. Twenty-four males ran downhill (−12%, 3.4 m·s−1, 30 minutes) wearing soft, medium or hard midsoles (40, 55, or 70 Shore A). Mean peak tibial acceleration (PTA) was calculated every five minutes. Plasma free hemoglobin (PfHb), hemoglobin (Hb), hematocrit (Hct), and creatine kinase (CK) were analyzed pre- and post-exercise. PTA was initially less (p < 0.05) and tended to be less (p = 0.057) In the soft versus the hard group. Hemolysis and muscle damage resulted. Hard midsoles increased shock and may prolong hemolysis and increase muscle damage. Part II. This study investigated impact shock attenuation, joint kinematics, muscle activation and oxygen consumption during a prolonged run. Ten males ran downhill (−12% grade, 3.4 m·s−1 , 30 minutes). Accelerometers sampled shock data. Joint kinematics and oxygen cost (O2) were collected. Electromyography data (EMG) were collected from six muscles. Shock magnitude, high frequency power and attenuation remained constant. Joint geometry was modified while peak joint velocities increased (p < 0.05). EMG timing was altered (p < 0.05; gluteus maximus, tibialis anterior and gastrocnemius). EMG activation increased (p < 0.05; rectus femoris, vastus lateralis) and O2 increased (p < 0.05). Shock may have remained constant by modifying joint geometry, increasing peak joint velocities, varying muscle timing, and increasing muscle activation and energy cost. Part III. This study investigated midsole hardness and surface stiffness influences on impact shock, joint kinematics, muscle activation and oxygen cost. Twelve males ran in six conditions, combinations of midsole hardness (40 and 70 Shore A) and surface stiffness (100 kN·m −1, 200 kN·m−1, 350 kN·m −1). Accelerometers sampled shock data. Joint kinematics and O2 were collected. EMG was collected from six muscles. Shock magnitude, the power of high frequencies, and attenuation increased (p < 0.05) with surface stiffness regardless of midsole. Peak joint velocities increased (p < 0.05) with increasing surface stiffness while O2 decreased (p < 0.05). Muscle activation levels decreased (p < 0.05; gluteus maximus, biceps femoris and gastrocnemius). Shock was attenuated by increasing peak joint velocities without a concomitant increase in energy cost or muscle activation.

A person's ability to see an object clearly is based on both the optical characteristics of their eyes and their ability to keep their eyes oriented toward the target. The ability to accomplish the latter can be compromised by self-motion if adequate compensation for the movement is not provided. The goal of the research presented here is to measure subjects' visual acuity during gaze tasks performed while walking. In addition, the effects of body movements on the gaze goals will be quantified using a measure of head fixation distance (HFD). By defining the distance between the subject and a point in space where minimal ocular compensation would be required, HFD provides a goal-relative measure that captures the integrated contributions from all non-ocular body movements. In Study I, subjects walked on a treadmill at 1.8 m/s and fixed their gaze on visual targets placed in front of them at 0.5 and 4 meters. During the "far" target condition, visual acuity was not different between standing and walking. Shorter HFDs during the "near" condition indicate changes in the coordinative relationships of non-ocular body movements. Although these changes appear to facilitate gaze stabilization by reducing the amplitude of the required eye movements, subjects' acuity was compromised while viewing the "near" target during locomotion. In Study II, treadmill speeds from 1.0 to 1.8 m/s were used to investigate the effects of walking velocity on gaze stabilization of the "near" target. Vertical HFD indicated that head pitch was compensating for more of the vertical trunk translation as walking velocity increased, yet visual acuity became progressively worse. In Study III, the "far" target condition from Study I was repeated to investigate visual acuity and vertical HFD at a sub-step timescale. The vertical HFD was shown to vary within the step-cycle and when compared to an assessment made mid-way between heelstrikes, visual acuity was shown to be compromised immediately following heel contact. The results from these experiments indicate that non-ocular mechanisms contribute to gaze stabilization while walking and provide evidence that ocular control is likely more complex than that provided by simple fixed-gain responses to vestibular stimulation.

There is great concern over human exposure following the application of pesticides for the management of turf environments. This concern is expected and germane given the level and frequency of pesticide use, the extent of activities and time spent on turfgrass, and the exposure potential for infants, children, and adults alike. Much effort has been expended in the determination of applicator exposure issues and the means to mitigate problematic exposure situations before and during application of pesticides. However, there are potential exposure concerns for all who enter turfgrass areas following pesticide applications. The present research emphasizes dosimetry (measuring pesticide residues on cotton suits, gloves, and air samplers worn by golfers) and biomonitoring (measuring pesticide metabolites in urine of golfers) in conjunction with environmental monitoring to determine transfer and penetration factors. The direct and simultaneous determination of dosimetry and biomonitoring data provides a novel and complete database on how much pesticide is transferred from the treated turf to the golfer during the play of a round of golf, where transfer takes place, and subsequently how much pesticide is actually absorbed. Dermal exposure was determined to be the dominant exposure pathway to golfers. Exposure estimates based on a 1 h re-entry interval following full-course and full-rate applications of chlorpyrifos, carbaryl, and cyfluthrin are substantially below current US EPA acute Reference Dose (Rfd) values, indicating safe exposures. These already low exposures were successfully mitigated using several management strategies.

Running overuse injuries are typically associated with excessive pronation of the foot during stance. Excessive pronation may impose stress on the extrinsic muscles of the foot leading to injury. Therefore, the purpose of these studies were to examine the roles of these muscles when an external perturbation was employed in the form of varus, neutral, and valgus-wedged shoes. It was hypothesized that running in the valgus shoes would increase eversion (approximating pronation), the net inversion joint moment, activation of the invertor muscles, and the force in these muscles. The first experiment was designed to investigate the kinematic and kinetic responses to running at 3.6 m/s in the varus, neutral, and valgus shoes. This study also reported the EMG profiles of these muscles. The valgus shoes increased maximum eversion and the peak inversion joint moment. The calculation of joint work also demonstrated that there was greater energy absorption in the frontal plane while running in the valgus shoes. This indirectly suggests that the muscles involved in controlling pronation of the foot absorbed more energy when eversion increased, which could be related to injury potential. No significant differences were observed for EMG. Therefore, the increased joint moment may be due to passive mechanisms. The second experiment further investigated the activation of the extrinsic foot muscles using both EMG and functional fMRI during treadmill running. Generally, the activations patterns did not agree with the hypothesis that increased pronation would lead to increased muscle activity. The third study compared joint moments calculated in the frontal plane with joint moments calculated about an estimate of the subtalar joint. This study demonstrated that frontal plane kinetics might give an inaccurate portrayal of the muscular contributions to controlling foot motion. The fourth study developed a musculoskeletal model to estimate the force in each of the extrinsic foot muscles. The model established that the soleus was a substantial contributor to inversion of the foot, along with the tibialis posterior. Also, the valgus shoe increased energy absorption in the soleus tendon. These data may establish a direct link between “excessive” pronation and injuries such as medial tibial stress syndrome.

The purpose of this dissertation was to assess the relationship between body mass (M$\rm\sb{B})$ and endurance cycling performance. Four experiments were designed to describe the relationship between a dependent variable (Y) and M$\rm\sb{B}$ using multiple log-linear regression analysis procedures. Each analysis was used to conclude that Y changed proportionally with M$\rm\sb{B}$ raised to the power of b (i.e. $\rm Y\propto M\sbsp{B}{b}),$ where b is the M$\rm\sb{B}$ exponent. Experiment I utilized a preexisting data set from subjects aged 20-79 years to determine that peak oxygen uptake (VO$\sb{2PEAK}$) scaled with M$\rm\sb{B}$ to the 0.75 (95% CI: 0.651-0.862) power in a heterogeneous population and 0.65 (0.530-0.775) power in a homogeneous population. These findings were shown to be consistent with predictions from the theory of geometry similarity (TGS). Experiment II evaluated how net VO$\sb2$ (VO$\rm\sb{2(NET)})$ scaled with M$\rm\sb{B}$ as well as the combined mass (M$\rm\sb{C})$ of the cyclist and bicycle and M$\rm\sb{B}$ during uphill treadmill bicycling. It was concluded that VO$\rm\sb{2(NET)}\propto M\sbsp{C}{1.0}$ due to gravitational resistance, while VO$\rm\sb{2(NET)}\propto M\sbsp{B}{0.89}$ because the cyclists' bicycles were relatively lighter for heavier cyclists. Experiment III determined that the scaling relationship between projected frontal area (A$\rm\sb{p})$ and body mass. Both body A$\rm\sb{p}$ (A$\rm\sb{p}$ for cyclist's body) and total A$\rm\sb{p}$ (A$\rm\sb{p}$ for cyclist's body and bicycle) scaled with M$\rm\sb{B}$ to powers significantly lower (0.408 (95% CI: 0.299-0.517) and 0.463 (0.262-0.663), respectively) than the 0.67 power predicted for area measurements by the TGS. This indicates that larger cyclists should experience less aerodynamic drag relative to their body mass than smaller cyclists at a constant ground speed. Lastly, results from Experiments I-III were combined with data from the literature to derive and validate a generalized allometric model (GAM) of endurance cycling performance in Experiment IV. The GAM equated the metabolic power supply and external power demands of time-trial cycling performance in a mathematical model expressed exclusively in terms of M$\rm\sb{B}$ differences. The model results appeared consistent with anecdotal observations and valid when compared to actual time-trial data. The results of this dissertation support the use of M$\rm\sb{B}$ scaling as a tool for better understanding of body mass as a determinant of human performance.

Introduction: Black African populations present with low insulin sensitivity (SI) and hyperinsulinemia, the latter due to high insulin secretion and reduced clearance. In addition, they exhibit lower levels of central and ectopic fat, compared to their white counterparts, contradicting the known correlates of SI typically reported in white populations. Moreover, in black African women hyperinsulinemia is in excess of the level needed to compensate for low SI, with a corresponding high disposition index (DI), a marker of insulin response that accounts for the level of SI. Further, obese, black African women have a high risk for type 2 diabetes (T2D), but the correlates of hyperinsulinemia have not been fully elucidated, especially the role of ectopic fat and body fat distribution. Exercise training is beneficial to improve SI and DI, however, whether these effects are mediated by changes in ectopic fat in skeletal muscle, liver and pancreatic depots is unknown. Accordingly, exercise training can be used as a model to assess the correlates of hyperinsulinemia and SI in cohorts at high risk for developing T2D, such as obese black African women. This thesis therefore aims to describe the correlates of hyperinsulinemia and SI and to evaluate the effect of exercise training on these components with emphasis on the role of body fat distribution and ectopic fat in mediating these changes. Methods: Firstly, a cross-sectional analysis of 45 obese (BMI 30-40 kg/m2 ) black South African women (age 20-35 years) without T2D was conducted. Thereafter the women were block randomized into an exercise training (n=23) or no exercise (control, n=22) group. The exercise training group participated in a 12-week combined aerobic and resistance training programme (40-60 min session, 4 days/week) supervised by a biokineticist. Pre and post-intervention testing included assessment of acute insulin response to glucose (AIRg), SI, DI (AIRg x SI), insulin secretion rate (ISR), hepatic insulin extraction (HIE) and peripheral insulin clearance (CLp) (frequently sampled intravenous glucose tolerance test); body fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat and abdominal subcutaneous (aSAT) and visceral adipose tissue (VAT) (magnetic resonance imaging); intramyocellular (IMCL) and extramyocellular fat content (EMCL) (magnetic resonance spectroscopy). Results: The baseline results showed that a high DI was associated with low VAT (r0.565, p< 0.001), pancreatic fat, soleus IMCL and EMCL with VAT explaining most of the variance in DI (32%). SI was inversely associated with VAT (rho -0.417, p=0.007) and AIRg was inversely and HIE was positively associated with VAT-aSAT ratio (rho - 0.345, p=0.029 and rho 0.510, p=0.011, respectively). DI was positively associated with CLp (rho 0.528, p=0.006), while its components (SI and AIRg) were not. Results from the intervention showed that exercise training increased DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) x103 arbitrary units, p=0.028), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l) -1 min -1 , p=0.005) and VO2peak (mean ± standard deviation: 24.9±2.42 to 27.6±3.39 ml/kg/min, p< 0.001), with no changes in control group. Exercise training decreased body weight (84.1±8.7 to 83.3±.9.7 kg, p=0.038) and gynoid fat mass (18.5±1.7 to 18.2±1.6%, p< 0.001). AIRg, ISR, HIE, CLp, aSAT, VAT and ectopic fat were unchanged after exercise training. However, the control group increased body weight and aSAT. The increase in SI and DI were not associated with changes in body composition, body fat distribution or ectopic fat. Conclusion: Novel results from our cross-sectional analysis showed that, in obese black South African women, DI was positively associated with peripheral insulin clearance, probably due to higher SI of peripheral tissue. Moreover, the most important correlate of a high DI was low VAT independent of ectopic fat accumulation in other sites. Further, we showed that low AIRg and high HIE correlated with a high VAT-aSAT ratio, while low SI was associated with high VAT. These associations require further exploration to determine direction of causality. Findings from our exercise intervention study extend on previous research by showing that moderate-to-high intensity combined aerobic and resistance exercise training increased SI and improved cardiovascular fitness, but insulin secretion, hepatic insulin clearance, ectopic and central fat depots did not change. Our results suggest that hyperinsulinemia may not occur solely as a compensatory mechanism for low SI and that ectopic and central fat might not be the primary correlates of insulin resistance in this cohort. Rather, intrinsic factors within muscle and adipose tissue may be putative mediators for observed improvements in the metabolic outcomes but will require further elucidation. Further research is required to confirm the causal role of VAT on low DI and to determine whether a long-term exercise training program and/or a low carbohydrate/glycemic index diet will reduce AIRg in those with hyperinsulinemia.

Short-term exercise training reduces insulin resistance and improves insulin action. The purpose of this research was to examine how short-term training, defined as 5–10 consecutive days of exercise, reduces insulin resistance. A preliminary study investigated the effects of short-term exercise training on substrate utilization during exercise to explore the relationship of fuel selection and insulin action. The primary study examined the role of energy balance in mediating improved insulin action following short-term exercise training and how that affected risk factors for type 2 diabetes and cardiovascular disease. Prior to this study, the importance of generating a caloric deficit was unclear. Replacing the energy expended during exercise to prevent negative energy balance might oppose the insulin-sensitizing effects of exercise. The purpose of this study was to establish the role of negative energy balance in mediating improved insulin action after short-term exercise training. Design. Previously sedentary, overweight/obese subjects were randomly placed in an energy balance group, in which energy expended during exercise was promptly replaced (BAL, n = 8) or in a caloric deficit group in which the energy was not replaced (NEG, n = 8). The groups were similar at baseline in age, BMI, trunk fat, lean mass, VO2 peak and insulin resistance. Training consisted of 6 consecutive days of treadmill walking (60–65% VO2 peak) to expend ∼500 kcals (duration = 62 ± 6.5 min/d). Insulin action pre- and post-training was measured by glucose rate of disappearance per unit insulin. Results. As designed, daily energy expenditure increased by ∼500 kcal/d during training in each group (NEG = 469 ± 45, BAL = 521 ± 48). Insulin action increased 40% in NEG (p = 0.032) but was unchanged in BAL (−8.4%, p = 0.107). Suppression of hepatic glucose production during the glucose infusion increased significantly only in NEG (+30.2 ± 9.5%, p = 0.037) but not in BAL (−10.0 ± 7.4%, p = 0.417). Mean changes in fasting plasma insulin, leptin, triglycerides, adiponectin and C-reactive protein tracked charges in insulin action but only changes in leptin were statistically significant. Conclusions. Short-term exercise training without energy replacement significantly reduced insulin resistance. Feeding back the 500 kcal of energy expended during exercise negated the effect of training. These findings suggest that subtle changes in energy balance that precede measurable fat loss play a key role in mediating the beneficial effects of exercise on whole-body insulin action.