PURPOSE: To evaluate the effects of moderate normobaric hypoxia on the parameters of the work-time relationship during upper body exercise in women. METHODS: Thirteen recreationally active women (age: 22.7 ± 2.6 y; height: 167 ± 8.6 cm; weight: 66.4 ± 9.7 kg; body fat: 27.6 ± 5% body fat) completed a graded exercise test in both normobaric hypoxia (H; FiO2=~14%) and normoxia (N; FiO2=~20%) to exhaustion on an arm ergometer to determine V̇ O2peak and peak power output (PPO). Each participant completed four constant work-rate arm-cranking tests at 90-120% PPO in both environmental conditions. Linear regression was used to estimate CP and AWC via the work-time relationship during the constant work-rate tests. Paired samples t tests compared mean differences between V̇ O2peak, PPO, CP and AWC between conditions (N vs. H). Two-way (condition × intensity) repeated measures ANOVA was used to compare total work and time-to-exhaustion. RESULTS: H significantly reduced VO2peak (N: 1.73L/min ± .31L/min vs. H: 1.62L/min ± .27L/min, (p=.008) but had minimal effects on PPO (N: 78.08W±14.51W vs. H: 75.38W±13.46, p=.089), CP (N: 57.44W±18.89W vs. H: 56.01W±12.36W, p=.546), and AWC (N: 4.81kJ±1.01kJ vs. H: 4.56kJ±.91kJ, p=.510). No significant condition × intensity interactions were noted for total work or time-to-exhaustion (p > .05). CONCLUSIONS: Moderate normobaric hypoxia significantly reduced VO2peak but had minimal effects on CP and AWC using the work-time model.

Context: National Collegiate Athletic Association (NCAA) institutions are required to certify insurance coverage of medical expenses that result from athletically related injuries sustained while partaking in an NCAA event. This means that the student-athlete must be covered either by their parent’s/guardian’s insurance, their own personal insurance coverage, and/or the institution’s insurance program. Institutions assign this role to a variety of employees, including head athletic trainers (ATs), assistant ATs, athletic administrators, business managers, secretaries, or other institution employees. In 1994 Street, Yates, Lavery, and Lavery observed that the head AT was responsible for administering medical insurance/claims payment at 51% of the institutions studied. The tasks necessary to pay athletic medical claims require a lot of paperwork and can be very time consuming. Additionally, insurance rules and regulations are complicated. Anecdotally, ATs do not always feel well suited to perform these tasks. Objective: Investigate the ways that athletic associations/departments coordinate athletic medical claims and how often an AT is assigned to be the administrator who oversees policies and procedures related to athletic medical claims. Design: Cross sectional. Setting: Participants completed a web-based questionnaire. Patients or Other Participants: Responses from 184 (38%) ATs employed in collegiate settings (Division I 26.1%; Division II 28.8%, Division III 45.1%) were analyzed. Intervention: None. Main Outcome Measures: Demographics. Results: The mean number of full-time ATs on staff was 3.8 (n=97). The head AT was primarily responsible for the payment of athletic medical claims at 48.4% (n=89) of institutions and the assistant AT was responsible at 13.6% (n=25) of institutions. A non-AT was responsible at 38% (n=70). The mean hours spent on this task by head ATs (n=86) was 6.17 hours per week and the mean hours spent by assistant ATs (n=22) was 10.32 hours per week. Most respondents (62.0%, n=103) reported no formal training in athletic medical insurance claims payments whereas 20.5% (n=34) reported the individual responsible had had formal, with 17.5% (n=29) stating they were not sure what training the individual had received. When asked where they felt it was most appropriate to learn these concepts, respondents reported: within an accredited AT program curriculum (36% n=56), on the job training (34% n=52), or CEU event (30% n=46). Conclusions: It is clear that ATs at NCAA institutions are responsible for the administration of athletic medical claims. ATs are spending a large amount of time each week on medical claims, although most have no formal training. An AT may not be the most ideal individual to handle these medical claims; but if an AT is going to continue to be responsible for this task, AT programs should increase the emphasis of this content within the curriculum and CEU opportunities should be made available to ensure athletic medical claims are handled effectively.

The ability to perform well during the sprint start and early acceleration phases of sprint running is critical. Many forms of training interventions are utilised to give a sprinter a competitive edge over their opponents in these particular phases. Despite this fact, there has been limited research on the technical and power type training strategies appropriate to improve sprint kinematics and the associated sprint performance in the sprint start and early acceleration phases. PURPOSE: To determine the best sprint start and early acceleration phase kinematic determinants, investigate the effect that load has on the kinematics of the sprint start and early acceleration performance and to determine how various physical characteristics may influence both resisted and unresisted sprint running. METHODS: Ten male track sprinters (mean ± SD: age 20 ± 3 years; height 1.82 ± 0.06 m; weight 76.7 ± 7.9 kg; 100 m personal best: 10.87 + 0.36 s {10.37 - 11.42 s}) attended two testing sessions. The first session required the athletes to sprint twelve 10 m sprints from a block start under unresisted and resisted (10% & 20% body mass) sled conditions. The second session required each athlete to complete an anthropometric assessment (height, mass, 3 bone lengths, 2 bone widths) and a variety of vertical (squat jump, countermovement jump, continuous straight legged jump) and horizontal (single leg hop for distance, single leg triple hop for distance) jump tests (3 trials each). Centre of gravity, joint and segment kinematics were calculated from 2D analysis utilising a kinematic analysis system (Ariel Performance Analysis System, U.S.A.). Means and standard deviations are presented for kinematic and performance measures. Pearson's product-moment correlation coefficients were employed to establish relationships between sprint start (block) performance variables and 10 m sprint performance. A linear regression analysis was used to quantify the relationships between the dependent variables (start performance and 10 m sprint time) and selected kinematic independent variables. ANOVA's with repeated measures were used to determine if there was a significant interaction between the kinematics under the various loaded conditions. A stepwise multiple regression and linear regression analysis were used for the prediction of unresisted and resisted sprint times from anthropometrical and functional performance measures. RESULTS: Mean horizontal block acceleration was identified as the start performance variable with the strongest relationship to 10 m sprint time. The most significant kinematic predictors of mean horizontal block acceleration were a large horizontal block velocity, short start time, and low thigh angle of the front block leg with respect to the horizontal at block takeoff. Sprint time over 10 m was best predicted by a large mean horizontal block acceleration (sprint start performance), increased angle of the front arm shoulder at step takeoff, and increased angle of front upper arm at step takeoff. Sprint start kinematics significantly altered as a result of resisted sled towing were start time (increase) and push-off angle from the blocks (decrease). Step length, stance time and propulsion time significantly increased, whereas flight time and flight distance significantly decreased under loaded conditions. A load of 20% body mass was revealed to be the better training load to utilise during resisted sled sprinting, especially for athletes who performed faster than 2.10 s for a 10 m sprint from a block start. The countermovement jump exercise was a strong predictor of both 10 m and 100 m sprint time. The continuous straight legged jump test was revealed to be a good predictor of resisted sprints over 10m.CONCLUSION: Consideration should be given to the technical training aspects of sprint start performance and forceful arm movements during step takeoff for improving sprint start and early acceleration sprint performance from starting blocks. These technical training aspects should also be supplemented with resisted sled towing with a load of 20% body mass and countermovement jump training to improve sprint ability.

The phase of greatest acceleration (0-30 metres) during sprinting is thought to be critical for success in many sporting situations. Methods for improving acceleration phase performance are therefore an important area of study for conditioners and sports scientists. Typically a variety of resistance training techniques are used to improve strength and power of the lower limb musculature that is important to sprinting performance. One such technique is resisted sprinting which involves the use of apparatus such as weighted vests and sleds to provide movement specific overload to athletes. The purpose of this thesis was primarily, to compare sprint times, step variables and joint kinematics when sprinting with a vest loaded at 15% and 20% of the athlete's body mass and towing a sled with 15% and 20% of body mass. A secondary aim was to examine the effect of a six-week training program utilising resisted sprinting on acceleration phase performance in three athletes.In the first study, 20 semi-elite subjects performed five 30-metre sprints: one unloaded sprint, two sled sprints loaded at 15% of their body mass and 20% of their body mass, and two vest sprints with the same loads relative to body mass. Each sprint was videoed in the sagittal plane at five, 15 and 25 metres from the start of the 30-metre sprint and times were recorded at 10 and 30-metres using timing lights. Video data were digitised and the following step variables were calculated: step length, step frequency, stance phase duration and swing phase duration. Stance phase angles of the trunk, thigh, knee and ankle were also calculated. Step length, step frequency and swing phase duration during vest and sled sprinting were found to decrease significantly (P<0.05) when compared to unloaded sprinting values. Stance phase duration during vest and sled sprinting increased compared to unloaded sprinting values (P<0.05). Additionally, sled towing displayed significantly greater (P<0.05) trunk flexion at foot strike and toe-off, and significantly greater (P<0.05) knee flexion at foot strike than both the unloaded and vest sprinting conditions. Sled towing also induced significantly greater thigh extension at toe-off compared to the vest conditions (P<0.05). Thus the addition of load to the athlete via vest sprinting and sled towing may influence performance in different ways, and hence the objective of the athlete should be considered when choosing which of these techniques to use.In the second study, a single subject research design was utilised to assess whether sled towing and vest sprinting resulted in changes in performance over a six-week period of training. In this study, three subjects trained twice a week for six weeks using resisted sprinting. Subjects were randomly assigned to sled training, vest training or combination training (one training session a week with each apparatus). Subjects were tested at baseline, after three weeks of training and after six weeks of training for 10 and 30-metre sprint times and selected step variables (step length, step frequency and stance phase duration). Data analysis involved both visual analysis of graphed data and statistical analysis using the two standard deviation band method. The combination training subject improved performance over both 10 and 30 metres. Step variable data were inconclusive regarding the mechanisms behind these improvements. Neither sled towing nor vest sprinting resulted in significant improvements in performance. The results indicated that the use of both training apparatus in unison may be required in order to improve performance during the acceleration phase of sprinting.

Skeletal muscle damage can lead to cell death and the subsequent release of intracellular molecules. To investigate whether molecules from skeletal muscle can interact with the heart, the Langendorff isolated heart preparation was used to assess cardiac function, while NF-κB and AP-1 activation were assessed by EMSA to observe inflammatory status. Hearts were perfused for 75 min with 1 μg/ml of either soleus, white gastrocnemius (WG), or heat stressed white gastrocnemius (HSWG) skeletal muscle homogenate and a decreased LVDP, +dP/dt and –dP/dt were observed when compared to untreated (control) hearts. Greater early and late decreases in cardiac function were observed in hearts treated with HSWG and soleus muscle homogenates, respectively. No alterations in NF-κB or AP-1 activation were detected. These data suggests the contents of skeletal muscle are capable of interacting with the heart and altering contractile function in a fibre type specific manner, possibly related to muscle HSP content.

Skeletal muscle damage can lead to cell death and the subsequent release of intracellular molecules. To investigate whether molecules from skeletal muscle can interact with the heart, the Langendorff isolated heart preparation was used to assess cardiac function, while NF-κB and AP-1 activation were assessed by EMSA to observe inflammatory status. Hearts were perfused for 75 min with 1 μg/ml of either soleus, white gastrocnemius (WG), or heat stressed white gastrocnemius (HSWG) skeletal muscle homogenate and a decreased LVDP, +dP/dt and –dP/dt were observed when compared to untreated (control) hearts. Greater early and late decreases in cardiac function were observed in hearts treated with HSWG and soleus muscle homogenates, respectively. No alterations in NF-κB or AP-1 activation were detected. These data suggests the contents of skeletal muscle are capable of interacting with the heart and altering contractile function in a fibre type specific manner, possibly related to muscle HSP content.

The ability to perform well during the sprint start and early acceleration phases of sprint running is critical. Many forms of training interventions are utilised to give a sprinter a competitive edge over their opponents in these particular phases. Despite this fact, there has been limited research on the technical and power type training strategies appropriate to improve sprint kinematics and the associated sprint performance in the sprint start and early acceleration phases. PURPOSE: To determine the best sprint start and early acceleration phase kinematic determinants, investigate the effect that load has on the kinematics of the sprint start and early acceleration performance and to determine how various physical characteristics may influence both resisted and unresisted sprint running. METHODS: Ten male track sprinters (mean ± SD: age 20 ± 3 years; height 1.82 ± 0.06 m; weight 76.7 ± 7.9 kg; 100 m personal best: 10.87 + 0.36 s {10.37 - 11.42 s}) attended two testing sessions. The first session required the athletes to sprint twelve 10 m sprints from a block start under unresisted and resisted (10% & 20% body mass) sled conditions. The second session required each athlete to complete an anthropometric assessment (height, mass, 3 bone lengths, 2 bone widths) and a variety of vertical (squat jump, countermovement jump, continuous straight legged jump) and horizontal (single leg hop for distance, single leg triple hop for distance) jump tests (3 trials each). Centre of gravity, joint and segment kinematics were calculated from 2D analysis utilising a kinematic analysis system (Ariel Performance Analysis System, U.S.A.). Means and standard deviations are presented for kinematic and performance measures. Pearson's product-moment correlation coefficients were employed to establish relationships between sprint start (block) performance variables and 10 m sprint performance. A linear regression analysis was used to quantify the relationships between the dependent variables (start performance and 10 m sprint time) and selected kinematic independent variables. ANOVA's with repeated measures were used to determine if there was a significant interaction between the kinematics under the various loaded conditions. A stepwise multiple regression and linear regression analysis were used for the prediction of unresisted and resisted sprint times from anthropometrical and functional performance measures. RESULTS: Mean horizontal block acceleration was identified as the start performance variable with the strongest relationship to 10 m sprint time. The most significant kinematic predictors of mean horizontal block acceleration were a large horizontal block velocity, short start time, and low thigh angle of the front block leg with respect to the horizontal at block takeoff. Sprint time over 10 m was best predicted by a large mean horizontal block acceleration (sprint start performance), increased angle of the front arm shoulder at step takeoff, and increased angle of front upper arm at step takeoff. Sprint start kinematics significantly altered as a result of resisted sled towing were start time (increase) and push-off angle from the blocks (decrease). Step length, stance time and propulsion time significantly increased, whereas flight time and flight distance significantly decreased under loaded conditions. A load of 20% body mass was revealed to be the better training load to utilise during resisted sled sprinting, especially for athletes who performed faster than 2.10 s for a 10 m sprint from a block start. The countermovement jump exercise was a strong predictor of both 10 m and 100 m sprint time. The continuous straight legged jump test was revealed to be a good predictor of resisted sprints over 10m.CONCLUSION: Consideration should be given to the technical training aspects of sprint start performance and forceful arm movements during step takeoff for improving sprint start and early acceleration sprint performance from starting blocks. These technical training aspects should also be supplemented with resisted sled towing with a load of 20% body mass and countermovement jump training to improve sprint ability.

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.

The high prevalence of running related injury, particularly in novice runners has prompted the investigation into interventions to mitigate the risk of injury. This dissertation set out to investigate the effects of a progressive 12-week running intervention in novice runners wearing footwear with reduced cushioning. The aim was to understand how intrinsic characteristics of novice runners, namely body composition, strength and flexibility, influence running biomechanics and ultimately injury outcome, and whether footwear structure effects this relationship. Prior to the intervention, participants were assigned to wearing footwear with reduced cushioning (RC) or footwear with traditional cushioning (TC). Three-dimensional running biomechanics were collected during over ground running at 3.0 meters per second in their prescribed footwear. Other measured variables included lower limb strength, by means of an isokinetic dynamometer, lower limb flexibility, full body composition by means of Duel Energy X-Ray Absorptiometry and lower leg bone oedema by means of magnetic resonance imaging. Throughout the intervention, pain or discomfort was assessed. All variables were reassessed after the intervention. The programme used in this thesis resulted in a 11.1 % prevalence of injury, which is considerably lower than other studies. No differences in injury incidence, bone oedema or pain or discomfort prevalence were found between footwear groups, however the RC group experienced pain or discomfort more frequently. Footwear with reduced cushioning was found to promote kinematic strategies, including a lower foot strike angle (FSA), more flexed knee angle at foot strike and reduced knee range of motion during stance phase to compensate for the lack of cushioning. Whilst most novice runners adopted a rear foot strike pattern throughout the intervention, the RC group were four times more likely to reduce FSA. Intrinsic characteristics of novice runners may not be indicative of injury, however the intervention resulted in changes to these variables. These included improvements in movement-specific strength, increased passive hip flexor flexibility and weight loss. Footwear had no effect on these variables. Greater mass characteristics resulted in kinematic adaptations in the knee. This dissertation highlighted the importance of a conservative training structure to mitigate injury risk in novice runners. Additionally, footwear has limited effect on injury risk and thus should not be prescribed to promote biomechanical change, but rather to compliment a runner's current biomechanics and intrinsic characteristics.

Background: Developing tackle and ruck technique is important to improve performance in matches and reduce the risk of injury. Little is known regarding valid tools to assess tackle and ruck technique in rugby union. The aims of this thesis were (1) to assess the validity and representativeness of the contact assessment tool, and (2) to identify factors which may affect the degree to which contact technique developed in training transfers to matches. Methods: Tackle, ball-carry and ruck technique of players competing at different levels of play were assessed in a two-on-two training drill using standardised technical criteria. Technique scores between levels of play were compared to assess the validity of the contact assessment tool, and contact technique scores assessed in training and matches were compared to assess the representativeness of the tool. Physical qualities and questionnaire data on the importance of technique to improve performance and reduce injuries were compared to contact technique scores assessed in training, to determine the effect of physical conditioning and player's knowledge on contact technique proficiency. Finally, tackle and ruck technique scores assessed in training and matches were compared to measures of match performance and contact related injuries. Results: Senior players scored significantly higher in the tackle, ball-carrier and ruck assessment than academy 1st and 2nd level players, demonstrating the good construct validity of the assessment tool. Contact technique scores were associated with performance outcomes in training and in matches, although technique scores in matches were lower than technique scores in training. There were no significant relationships between player's knowledge of the importance of contact technique and their contact technique proficiency. There were moderate to large associations between various physical qualities and tackle, ball-carry and ruck technique scores assessed in training. Players with better contact technique in matches performed better in matches, however, there were no meaningful correlations between contact technique in training and match performance or match related contact injuries. Conclusions: These findings demonstrate the validity of a tool to assess contact technique in rugby union with good representative learning design, however progressing the drill into less structured environments is recommended to further improve the representativeness of the assessment environment. Furthermore, the findings highlight the importance of contact skill training and physical conditioning to ensure skills developed in training are transferred to match performance.