Includes abstract. / Includes bibliographical references (p. 89-106). / Regular exercise protects individuals against developing insulin resistance and type II diabetes. This effect of exercise does not appear to be due to an improvement in the insulin signalling pathway but instead due to an increase in the content of the insulin-regulatable glucose transporter (GLUT4) in skeletal muscle (84). Understanding the mechanisms by which exercise increases GLUT4 levels in skeletal muscle may reveal targets for pharmaceuticals to treat insulin resistance and type II diabetes. Although in vitro binding assays have shown that GLUT4 expression during exercise is mediated by the binding of myocyte enhancer factor-2A (MEF2A) to its cis-element on the Glut4 promoter (122), this has not been demonstrated in vivo. Moreover, the mechanisms by which exercise increases MEF2A binding to the Glut4 promoter have not been fully characterised.

Background: The popularity of endurance running events has rapidly increased in recent years with more recreational runners entering the field. How recreational runners train is not well known. Understanding this and the relationship between training and performance in this group of runners is important for prescribing appropriate training to maximise performance and decrease the risk of injury. This forms the underlying theme throughout this thesis. Aim: The broad aims of this thesis were to better understand the ad libitum training habits of well-trained competitive recreational runners and to determine the relationships between performance, training load, and submaximal heart rate (HR) in this cohort. Methods: Five inter-related studies were performed to: 1) determine relationships between 56-km race performance and pacing (n = 7,327) in competitive recreational runners; 2) determine relationships between 56-km race performance, pacing, and training load in competitive recreational runners (n = 69); 3) determine the accuracy of GPS sport watches in measuring distance (n = 255); 4) develop a feasible and reliable submaximal running test, and 5) determine relationships between performance on a submaximal running test, training load, and submaximal HR in well-trained competitive recreational runners (n = 29). Main findings: A group of well-trained competitive recreational runners performed 44 ± 22 km/week (median ± IQR) in a six-month time frame while training ad libitum. This group had a wide range of inter-individual differences in training load performed even when considering participants who had the same relative marathon performance. The same group of well-trained competitive recreational runners maintained most of their training over a sixmonth period in a range of 0.81 – 1.14 for the acute: chronic workload ratio (ACWR). When the ACWR values reached > 1.50, it was mainly due to participation in endurance running races (> 21-km). When looking at relative weekly changes in training load, the maximum increase was 30% with only two participants having maximum increases of < 10%. The increases in load were predominantly short term (one to two weeks). Submaximal HR had a negative linear relationship with performance in 21% of the study participants. In those participants, poor performances were associated with a higher submaximal HR. Training load was only related to changes in performance in one participant. Conclusion: This thesis confirms that no single variable can provide the necessary information on how to adjust training load to maximise performance. Athletes, coaches, and sports scientists need to have a holistic view of stress exposure and how this affects the body. Although we can only speculate, when the participants had a poor performance it may have been due to factors such as lack of motivation, fatigue, mental stress, dehydration, and/or sleep deprivation. It is important for runners, coaches, and sports scientists to approach the training load – recovery balance as being unique for each athlete. Even in a homogenous group of well-trained competitive recreational runners, their ad libitum training load is widely varied and was not associated with performance or ability level. The balance should be adjusted over time based on the athlete’s symptoms.

Background: Rugby union is a high-intensity, intermittent sport, characterised by numerous contact events, such as rucks, mauls, scrums, and tackles. Specifically, the tackle is the most common action to occur during a rugby game. Subsequently, the tackle (tackler and ballcarrier) is responsible for the highest number of total injuries during a season. The most effective tackle technique is associated with a lower risk of injury than poorly executed tackles. Considering the prevalence of tackles, their propensity to cause injury, and the link between safety and proper tackle technique, a tool for assessing individual tackling and ball-carrying technique would be useful for rugby union researchers and practitioners. In particular, the assessment of tackling and ball-carrying technique would aid in monitoring adaptations to training, evaluating training programs and the prescription of training, assessing player qualities, and predicting performance and identifying future talent. Objectives: The primary objectives of this study were 1) to determine if undergoing videobased training would improve the agreement, reliability, and accuracy of raters using a subjective-rating measure to assess contact technique in rugby union, and 2) to establish if a self-selected viewing pace resulted in improved agreement, reliability, and criterion-validity over a real-time pace. Methods: Data were collected from 30 participants, with no prior experience in rugby union, who were randomly divided into training and non-training groups. After completing the training or non-training visits, all participants conducted tackling and ball-carrying technique assessments in 4 subsequent visits. Participants viewed video footage of players tackling and carrying the ball into contact during a full contact rugby drill on a laptop computer. Participants assessed tackling and ball-carrying technique using the standardised list of technical criteria. Technical proficiency scores were calculated out of 12 for tackling technique and out of 10 for ball-carrying technique, respectively. Agreement and reliability of the assessments were measured using the proportion of observed agreement (Po) and Kappa statistics (K). Criterion validity (accuracy) was measured using the proportion of observed agreement (Po) by comparing the raters’ assessments to a criterion. Between groups comparisons for technical proficiency scores and accuracy were done with hypothesis testing and effect sizes. Results: Over the real-time and self-selected paces, the training group produced 61-73% (K=0.24-0.38, Fair) and 63-73% (K=0.12-0.17, Poor) inter-rater agreement for tackling and ball-carrying technique, respectively. The non-training group produced 61-72% (K=0.26-0.38, Fair) and 59-71% (K=0.15-0.19, Poor) inter-rater agreement for tackling and ball-carrying technique, respectively. Including both real-time and self-selected paces, the within session intra-rater agreement for the training group ranged from 71-84% (K=0.43-0.65, Moderate-Substantial) and 74-83% (K=0.39-0.48, Moderate) for tackling and ball-carrying technique assessment, respectively. Then, the intra-rater agreement for the non-training group ranged from 68-83% (K=0.40-0.62, Fair-Moderate) and 67-84% (K=0.31-0.55, Fair-Moderate) for tackling and ball-carrying technique assessment, respectively. In terms of between session reliability, over the real-time and self-selected paces, the training group achieved intra-rater reliability that ranged from 74-83% (K=0.50-0.62, Moderate-Substantial) and 72-82% (K=0.35- 0.45, Fair-Moderate) for tackling and ball-carrying technique assessment, respectively. The non-training group achieved intra-rater reliability ranging from 72-82% (K=0.46-0.59, Moderate) and 69-81% (K=0.33-0.48, Fair-Moderate) for tackling and ball-carrying technique assessment, respectively. The technical proficiency scores between the groups displayed variation, and in some cases it was statistically significant. Compared to the criterion scores, the training group produced observed agreement of 68% and 67% for real-time pace and 74% and 72% for self-selected pace on tackling and ball-carrying technique assessment, respectively. The non-training group produced observed agreement of 66% and 67% for realtime pace and 74% and 73% for self-selected pace on tackling and ball-carrying technique assessment, respectively. Conclusion: Whether trained or untrained, the individual should be able to produce the same results if the footage is assessed within the same viewing period (agreement) or over two separate viewings (reliability). The tool is accurate for both groups when assessing at real- time or self-selected paces, with the latter being more accurate. However, it would appear that the tool is insufficiently robust when it comes to agreement between different raters. Future research should explore the inter-rater dynamics of assessing tackling and ball-carrying technique.

The primary objectives of this dissertation were to investigate the behavioural and neurophysiological factors related to overweight and obesity, as well as to weight loss maintenance versus weight relapse in a purposively sampled group of healthy South African women. The battery of investigations was designed to explore two central hypotheses: First, weight loss induces several behavioural compensations related to habitual eating behaviour and daily physical activity (PA) practices which facilitate the generation of a chronic positive energy balance, thereby increasing the risk of weight regain in reduced-overweight and reduced-obese women. Second, overweight and obese women as well as those at risk of undergoing relapse exhibit heightened indices of visual food cue-reactivity in various regions of the brain associated with obesogenic eating and reward-seeking tendencies. The novelty of this thesis lies in that we ascertained dietary, PA and psychobehavioural variables through both subjective accounts and objective measurement. Moreover, we employed electroencephalography to objectively evaluate high resolution temporal changes in visual food cue processing to test our second hypothesis. Overweight and obesity treatments focus, for the most part, on dietary- and/or exercise-centred interventions to facilitate weight loss. Our data suggest that certain interaction effects exist between the perception of environmental food cues and variables such as dietary restraint, habitual fat intake, body shape dissatisfaction and total body adiposity [Note: this thesis is embargoed until 30 November 2016]

Includes abstract. / Includes bibliographical references (p. [212]-228). / The aim of this dissertation was to investigate various systems affecting performance in skilled and less-skilled batsmen. These systems included kinetics, visual perception, psychophysiology and visual tracking. Individual chapter abstracts have been presented because of the multifaceted nature of this dissertation.

There appears to be an emerging phenotype of recreational runners who are overweight despite being regularly active. This conflicts with the common perception that exercise protects against weight-gain, and it may be caused by underlying insulin-resistance. Alternatively, recent research has brought attention to metabolically healthy obese (MHO) individuals, who have increased adiposity but no commonly associated metabolic abnormalities, such as insulin-resistance, hypertension, dyslipidaemia and systemic inflammation. This study aimed to determine whether overweight (OW, BMI ≥ 25 kg.m⁻²) female runners were at risk of developing metabolic pathology and compare the findings to lean (LN, BMI < 23 kg.m⁻²) counterparts. A secondary aim was to explore potential inherent or lifestyle factors that may have predisposed or contributed to weight-gain in OW runners. METHODS. Twenty (10 OW, 10 LN) female recreational runners (years of running experience 7.1 ± 4.4 OW; 8.0 ± 3.7 LN) matched for mean age (38.7 ± 4.6 OW; 37.7 ± 4.3 LN), current mileage in km.week⁻¹ (42.0 ± 10.9 OW; 44.5 ± 12.1 LN) and running calibre expressed as energy expenditure (kcal.min⁻¹) in their most recent half-marathon (9.0 ± 1.1 OW; 9.2 ± 1.1 LN) were recruited for this study. Body fat percentage (BF%) was determined using DXA. Participants completed questionnaires about health history, lifestyle and eating habits and validated questionnaires concerning recent sleep and stress. Their diet was recorded using 3-day diet records and analysed using the South African Food Data System (Medical Research Council of South Africa). Habitual sleep and physical activity were quantified using 7-day actigraphy (Actiwatch 2) and accelerometry (Actigraph GTX3+) respectively. Blood pressure and resting metabolic rate were measured after an overnight fast. Blood samples were analysed for cardio-metabolic parameters and an Oral Glucose Tolerance Test was performed for insulin-sensitivity. RESULTS. OW exhibited a greater body weight (74.4 ± 6.4 kg OW; 59.4 ± 7.8 kg LN, p < 0.001) but similar fat-free-mass (49.4 ± 5.6 kg OW; 45.4 ± 5.9 kg LN) to the LN group. OW had a higher BF% (32.1 ± 3.9 OW; 21.8 ± 3.9 LN, p < 0.0001), and systolic (118 ± 10 mmHg OW; 107 ± 5 mmHg LN, p < 0.05), but not diastolic (72 ± 6 mmHg OW; 68 ± 4 mmHg LN) blood pressure. There was no difference between groups in serum uric acid, alanine aminotransferase, % HbA1c, total cholesterol, HDL-cholesterol, triglycerides or free-fatty-acids. OW had higher levels of C-reactive protein (1.30 ± 0.97 mg.L⁻¹ OW; 0.59 ± 0.35 mg.L⁻¹ LN, p < 0.05), total cholesterol / HDL-cholesterol (2.70 ± 0.40 OW; 2.30 ± 0.42 LN, p < 0.05) and LDL-cholesterol (2.99 ± 0.65 mM OW; 2.43 ± 0.72 mM LN, p < 0.05), but these were within normal ranges. IDL-cholesterol constituted a significantly greater proportion of total cholesterol in OW compared to LN, but HDL- and LDL- cholesterol sub-fraction distributions were similar. Indices of hepatic (HOMA-IR, 1.06 ± 0.51 OW; 0.86 ± 0.24 LN), and whole-body (Matsuda, 7.84 ± 2.46 OW; 9.16 ± 2.28 LN) insulin-sensitivity were variable and similar between groups. Total area-under-the-curve of the OGTT insulin response tended to be higher in OW (p = 0.08). Two OW runners had insulin-resistance (Matsuda < 5); but no participants had the metabolic syndrome. RMR (kcal.kg FFM⁻¹.day⁻¹) was lower in OW (29.5 ± 2.1 OW; 31.6 ± 2.3 LN, p < 0.05), but there were no significant differences in lifestyle factors (diet, physical activity, sleep and stress). Total energy intake in kcal.day⁻¹ (1928 ± 354 OW; 2166 ± 489 LN) and % macronutrient composition as Protein/Fat/Carbohydrate/Alcohol (20/44/33/3 OW; 16/43/36/5 LN) were both similar between groups. OW and LN also exhibited similar activity in steps.day⁻¹ (10 742 ± 3552 OW; 12 073 ± 3273 LN) and percentage accelerometer wear-time spent in Sedentary/Light/Moderate-Vigorous physical activity (75/14/11 OW; 72/15/13 LN). Both groups attained circa 7 hours.night⁻¹ of sleep, with good sleep onset latency (7.3 ± 5.8 minutes OW; 5.8 ± 3.5 minutes LN) and sleep efficiency (91.6 ± 4.4% OW; 90.7 ± 2.8% LN), and they reported reduced to average levels of recent stress. DISCUSSION. OW runners presented with greater mean adiposity than LN counterparts, but the two groups were not as distinct as anticipated. OW runners did present with greater metabolic risk according to some traditional risk factors, including inflammation, systolic blood pressure, LDL-C and total cholesterol. However, the first three were within normal ranges and the clinical relevance of the latter is questionable. It was, therefore, concluded that on average the OW group was not at metabolic risk. Only two OW runners and no LN runners were insulin-resistant according to indices derived from the OGTT. These findings may primarily reflect the insulin-sensitising effects of regular exercise and the consequent fitness of the OW runners. Appetite-dysregulation is speculated to have played an integral role in their prior weight-gain. We did not identify any lifestyle discrepancies that could have explained this weight-gain. The cross-sectional nature of this study made it difficult to assess past behaviour during weight-gain, and inter-individual variation was considerable. In combination with the small sample size, these factors limited the generalisability of the results. Future exploration of the 'overweight-runner' phenotype is warranted to clarify the mechanisms of weight-gain in habitual runners and consequent lifestyle changes that may promote meaningful weight-loss.

Includes bibliographical references / Purpose: The predominant impairment to function following a total knee arthroplasty (TKA) is a distinctive reduction in quadriceps muscle strength. It has been suggested that eccentric rehabilitation may be more beneficial than traditional concentric only rehabilitation at improving muscle strength, physical functioning and quality of life in this population. The aim of this study was therefore to determine if an eccentric cycling ergometry rehabilitation intervention (a) was feasible in participant's early after TKA surgery (Study 1), (b) resulted in greater improvements in muscle strength and endurance, as well as muscle activity and muscle volume (Study 2) and, (c)resulted in greater knee functional ability, health related quality of life and physical activity levels (Study 3), when compared to an concentric cycling ergometry rehabilitation intervention. Finally, knee and hip kinematics, ground reaction force and muscle activity was described during the sit-to-stand transfer within this population (Study 4). Methods: Eighteen age- and sex-matched participants', three to nine month's post-TKA were recruited and randomly divided into either an eccentric or concentric cycling rehabilitation intervention. The participants were required to perform three exercise sessions a week, over a period of eight weeks. Isokinetic strength and muscle activity of the quadriceps and hamstring muscles, sit-to-stand motion capture analysis and knee functional ability and health related quality of life questionnaires (Knee Injury and Osteoarthritis Outcome Score, SF-36Health Survey and Tegner Activity Scale) were assessed pre and post- rehabilitation intervention. Data Analysis: Two-way repeated-measures analysis of variance were used to analyse the effects of time and the ECC and CON intervention groups and the group/time interaction for each of the dependent variables. Results: The eccentric rehabilitation intervention was well tolerated with regards to pain levels in participants' as early as three months post-TKA, the peak level of pain perceived per session, never exceeding a "mild" classification. The eccentric intervention resulted in greater power (P= 0.029) and work output (P ≤ 0.001) with a reduced overall heart rate (P= 0.014) ; moderate decreases in biceps femoris (BF) muscle activity (-3.2%) and increases in the lean thigh volume (+807.32) of the uninvolved limb; as well as improvements in the physical fun ctioning (+12.2%) and physical role functioning SF-36 scores (+22.2%) and the level of physical activity (+0.9) (Tegner activity scale). The concentric intervention resulted in decreases in vastus lateralis (VL) muscle activity (-8.17%) and work fatigue (-7.34%) and increases in the lean thigh volume (+677.49) and the hip abduction angle (+ 2.67°) (sit-to-stand) of the involved limb. Conclusion: The eccentric rehabilitation intervention is well tolerated with regards to pain and is characterised by significantly greater power output produced and work performed at significantly lower heart rates. Eccentric cycling ergometry matched in perceived exertion and duration, is associated with greater improvements in physical functioning outcome scores, physical activity level and knee flexion muscle efficiency during concentric contractions, when compared with concentric cycling ergometry. However, knee extensor muscle endurance and efficiency during concentric contractions, as well as muscle volume of the involved limb increased more significantly after concentric training in comparison to eccentric training, Further research is required to establish which training modality is the most feasible and effective in restoring knee function in participant's three months post-TKA.

INTRODUCTION. The LCHF diet produces major changes in whole-body substrate metabolism and energy stores such as reduced muscle and liver glycogen content, increased rates of fat oxidation and decreased rates of carbohydrate (CHO) oxidation. Despite reduced CHO availability, the rate of CHO oxidation that can be sustained during exercise in LCHF athletes is surprisingly high. The most probable source of this glucose is via the process of gluconeogenesis (GNG). However, endogenous glucose production (EGP) and GNG has not been studied during exercise in athletes on a LCHF diet. Therefore, the aim of this study was to determine if there are differences in EGP, GNG and glycogenolysis (GLY) during exercise in endurance-trained athletes who habitually eat either a mixed or LCHF diet. METHODS. Fourteen (7 LCHF, 7 Mix) endurance-trained male cyclists (VO₂max 61 ± 5 ml/kg/min LCHF; 6 3 ± 8 ml/kg/min Mix), matched for age (36 ± 6 y LCHF; 32 ± 5 y Mix), body composition (BMI 23.6 ± 1.8 LCHF; 23.4 ± 2.0 Mix) and relative peak power output (4.8 ± 0.4 W/kg LCHF; 5.0 ± 0.4 W/kg Mix), were recruited. Diets were analysed using the Automated Self-Administered 24-hour Recall (ASA24) analysis software. Participants cycled for 2 h at 55% of peak power output during which EGP was measured by infusion of [6,6- ²H₂ ]glucose, and fractional gluconeogenesis was measured by ingestion of ²H₂O. Blood samples were collected at regular intervals for isotope enrichment analysis. R ESULTS. Rates of GNG were similar during exercise in both the LCHF and mixed diet groups (2.8 ± 0.4 mg/kg/min LCHF; 2.5 ± 0.3 mg/kg/min Mix). The rates of GLY during exercise were significantly higher in the mixed diet group than the LCHF group (3.2 ± 0.7 mg/kg/min LCHF; 5.3 ± 0.9 mg/kg/min Mix) which resulted in significantly higher rates of EGP in the mixed diet group (6.0 ± 0.9 mg/kg/min LCHF; 7.8 ± 1.1 mg/kg/min Mix). There were significant differences in the mean fat oxidation rates (1.2 ± 0.2 g/min LCHF; 0.5 ± 0.2 g/min Mix) and CHO oxidation rates (1.3 ± 0.5 g/min LCHF; 3.1 ± 0.5 g/min Mix). Blood beta-hydroxbutyrate (βHB) concentrations were significantly higher in the LCHF group than in the mixed diet group throughout exercise but there were no differences in plasma glucose, plasma lactate, serum insulin or serum FFA concentrations. The diets of the two groups differed only in fat and CHO intake (%Protein / %Fat / %CHO: 21/72/7 LCHF; 16/33/51 Mix). DISCUSSION. Rates of fat oxidation and CHO oxidation were not associated with the rates of GNG. Apart from βHB, the precursor, substrate and insulin concentrations were remarkably similar in both groups and may have influenced GNG similarly in both groups. We conclude that rates of GNG are relatively stable across a broad range of habitual diets that can significantly alter substrate utilisation, and that dietary CHO modulates the rates of EGP via alterations in rates of GLY, both at rest and during exercise.

Includes abstract. / Includes bibliographical references (p. 325-399). / The aim of this study was to investigate the effects of exercise-induced muscle damage caused by a 90 km ultramarathon on submaximal oxygen consumption and stride length. The experimental group consisted of 11 male runners (39.7 ± 9.3 years) competing in a 90 km ultramarathon. Ten male runners (41.0 ± 10.8 years) who did not run the 90 km ultramarathon formed the control group. Maximum oxygen consumption and peak treadmill running speed were measured two weeks before the ultramarathon. Daily measurements of muscle pain and plasma creatine kinase (CK) activity were recorded for seven days after the ultramarathon. Muscle pain, plasma CK activity, and blood lactate concentrations were recorded before, and oxygen consumption, respiratory exchange ratio (RER), heart rate, rate of perceived exertion (RPE), and stride length were all measured during a 15-minute submaximal treadmill test seven days before the ultramarathon, and on days 4, 7, 14, 21, and 28 after the ultramarathon. Peak blood lactate concentrations were determined 3 minutes after the completion of each treadmill test. Plasma CK activity and muscle pain remained significantly elevated in the experimental group for two days (p &lt; 0.00002) and four days (p &lt; 0.02) respectively after the ultramarathon. There was a significant increase in the post-submaximal treadmill test blood lactate concentrations, compared to pre-test values for each day (p &lt; 0.00001). Submaximal oxygen consumption was significantly reduced in the experimental group for up to 28 days (p &lt; 0.0004), and stride length was significantly reduced for 14 days (p &lt; 0.05) after the ultramarathon. Furthermore, in the experimental group RER was significantly increased for up to seven days (p &lt; 0.05), and RPE was significantly increased for up to four days (p &lt; 0.04) after the ultramarathon. In conclusion, the decreased submaximal oxygen consumption following the ultramarathon may be interpreted as a positive training adaptation. However, other responses to the ultramarathon were not compatible with improved running performance. Furthermore, symptoms other than pain should be used to define the recovery period after an ultramarathon race.

Obesity and physical inactivity are established key risk factors in the development of skeletal muscle insulin-resistance and type II diabetes in human and domestic animal populations. Wild animals are similarly exposed to these risk factors as a result of captivity. This study aimed at describing the skeletal muscle properties of captive lions (Panthera leo) who present with obesity and are physically inactive, with a group of free roaming wild lions. Skeletal muscle biopsies were collected from the Triceps brachii and analysed for fibre type composition, fibre size, and maximum oxidative (citrate synthase (CS), 3-hydroxyacyl CoA dehydrogenase (3HAD) and glycolytic (phosphofructokinase (PFK) and lactate dehydrogenase (LDH) enzyme capacities. The type IIA fibres were the predominant fibre type in both the wild (48%) and captive (44%) lions. No significant differences were evident in the overall fibre type composition between groups, although a trend towards less type I (28% vs 36%) and more type IIX (28% vs 16%) fibres in the captive group were observed. The captive lions displayed significantly larger cross-sectional areas (CSA) of the type I (5847μm² vs 3318 μm²) and IIA fibres (8344μm² vs 4360μm²) with no difference evident in the CSA of the IIX fibres. Relationships were observed between body mass and the CSAs of type I (r = 0.68, P = 0.0002) and IIA (r = 0.44; P = 0.03) fibres. Metabolically, the captive lions displayed higher flux through the glycolytic pathway as represented by their higher PFK activities (551 ± 287 vs. 338 ± 123 μmol/min/g protein, P < 0.05). In contrast, their CS activities (11 ± 3 vs. 14 ± 2 μmol/min/g protein) were lower than free roaming lions, suggesting lower oxidative capacity. No differences in LDH and 3HAD activities were observed between the two groups. Relationships were observed between 3HAD activity and MHC IIx fibre content (r = -0.43, P = 0.001), 3HAD activity and MHC I content (r = 0.55, P = 0.001). A positive correlation was observed between CS activity and MHC I content (r = 0.35, P = 0.009). In light of previous research, the data collected from this project follows that observed in exercise training models, where a sedentary lifestyle decreases oxidative capacity of muscle and increases type II fibre content. However, due to the low sample size in the free roaming wild lion group, interpretation of the data is difficult. Therefore, future research must strive to increase the sample number of the free roaming group.