Perceived Fitness is a Stronger Predictor of Maximal Aerobic Speed Than Submaximal Fitness in Rugby Union Players

BACKGROUND: Monitoring athlete training effects in team sports requires a systematic approach, adopting frequently implementable methods and sensitive proxy outcome measures able to detect acute and chronic training effects. Consequently, the use of submaximal fitness tests (SMFT) in team sport settings has increased, likely given their time-efficient nature, ease of administration in-season, and strong physiological rationale in observing athlete responses to a standardised exercise stimulus. However, this process has primarily favoured objective measures over subjective athlete responses, and both approaches are yet to be assessed for their respective associations and predictive qualities with maximal test outcomes. AIM: The study evaluated the relationships and predictive qualities between field-based measures of perceived, submaximal and maximal aerobic fitness in a sample of rugby union players. METHODS: Using an observational, cross-sectional approach, 47 high-performance British university rugby union players (21.1 ± 1.2 years; 184.86 ± 7.28 cm; 97.82 ± 14.31 kg) rated their aerobic capacity using a newly modified rating of perceived fitness (RPF) scale, before completing a SMFT (shuttle based, continuous-fixed, 4 min running at 12 km·h-1), and a 1.2 km shuttle run test (1.2SRT) to assess maximal aerobic speed (MAS). Data were analysed using magnitude-based inferences (MBI). RESULTS: An almost certainly [large] positive association between RPF and MAS (r = 0.58; ±0.19) was revealed, with backs reporting a higher RPF (almost certainly [small] increase) and achieving a higher MAS (possibly [small] increase) during the 1.2SRT in comparison to forwards. A likely [small] negative association between SMFT exercise heart rate (HRex) and MAS (r = -0.25; ±0.23) and a possibly [small] negative relationship between RPF and HRex (r = -0.19; ±0.27) was also identified. Regression analysis revealed RPF as the strongest predictor of MAS (R2 = 0.33; SEE: 0.28) compared to SMFT HRex (R2 = 0.06; SEE: 0.35), and both variables combined (Adj. R2 = 0.29; SEE: 0.28), and RPF was shown to be a poor predictor of SMFT HRex as a measure of submaximal aerobic fitness (R2 = 0.04; SEE: 8.48). CONCLUSIONS: Athlete RPF show promising levels of content, face and construct domains of validity in the prediction of MAS measured using the 1.2SRT; however, further work is needed to assess other domains of validity, reliability and sensitivity. Whilst SMFT HRex shows good convergent validity with some field measures of aerobic capacity, HRex is poorly related to or predictive of MAS measured using the 1.2SRT. RPF in its form derived from this study is not well related to or predictive of proxy measures of submaximal cardiovascular/aerobic fitness such as SMFT HRex. The RPF scale used in this study could be a useful monitoring tool in team sports

THE INFLUENCE OF FOOTBALL INFLATION PRESSURE ON IMPACT FORCE AND HEAD ACCELERATIONS DURING FOOTBALL HEADING

The study investigated the effects of ball inflation pressure on head impact biomechanics. In a two-stage study, footballs with a range of ball inflation pressures (0.4 – 0.95 atm) were impacted into a force plate across a range of ball velocities. Next, 12 male players headed a reduced range of inflation pressures (0.4 & 0.54 atm) and ball velocities (5 & 8m/s) whilst instrumented with three-dimensional motion capture markers to assess linear and angular head accelerations. Results suggest that in isolation, a reduced inflation pressure reduces peak impact force across all velocities barring a low velocity of 4.6 m/s. In Vivo, findings suggest that inflation pressure has no effect on linear or angular head accelerations at any velocity, and ball velocity has no effect on linear accelerations. However, a ball velocity of 5 m/s could reduce angular accelerations by 180 rads/s2 (95% CI: 104 – 255 rads/s2)

EVALUATION OF A TIME-FREQUENCY LOW-PASS FILTER METHOD FOR ASSESSING KNEE JOINT MOMENTS AND ACL INJURY RISK

Time-frequency low-pass filters may enable more precise assessment of knee joint kinetics and help identify athletes at risk of ACL injury. The aim of this study was thus to evaluate use of a fractional Fourier filter (FrFF) for estimating knee joint moments during unanticipated sidestepping. 3D kinematic and GRF data were collected from 11 team sports athletes performing 45° cutting manoeuvres and knee moments were derived in five different low-pass filter conditions. The FrFF produced peak abduction moments similar to ‘unmatched’ Butterworth low-pass filter conditions (0.7 – 1.2 Nm/Kg) and larger than the ‘matched’ conditions (0.1 – 0.5 Nm/Kg). This preliminary evidence suggests time-frequency filters can help researchers identify athletes at risk from sustaining ACL injury

The nature and scale of container packing and unpacking facilities on the South Durban Basin (SDB).

Thesis (M.T.R.P.)-University of KwaZulu-Natal, Durban, 2008.No abstract available

MEMS 411: ARLISS Canister Vehicle

To design, build, and test an autonomous canister vehicle to compete in the ARLISS competition. Design must autonomously drive to a given set of GPS coordinates, record and store GPS data during operation, survive a parachute drop, and traverse rough, uneven terrain

P4_1 The 'Fatman'

In this paper we investigated the feasibility of the M42 `Fat Man' by considering the recoil felt on a person when firing the $5.5$ kg projectile. It was found that a muzzle velocity of $v = 32.1$ms$^{-1}$ is required to fire the projectile $105$ m when air resistance was taken into account. To achieve this muzzle velocity a pressure of $P = 16.1$x$10^6$ Pa is required in the pneumatic firing system. It was found that the recoil of the system is $p = 188.1$ kgms$^{-1}$. The M42 `Fat Man' was determined to be a feasible weapon system

STPA-SafeSec: Safety and Security Analysis for Cyber-Physical Systems

AbstractCyber-physical systems tightly integrate physical processes and information and communication technologies. As today's critical infrastructures, e.g., the power grid or water distribution networks, are complex cyber-physical systems, ensuring their safety and security becomes of paramount importance. Traditional safety analysis methods, such as HAZOP, are ill-suited to assess these systems. Furthermore, cybersecurity vulnerabilities are often not considered critical, because their effects on the physical processes are not fully understood. In this work, we present STPA-SafeSec, a novel analysis methodology for both safety and security. Its results show the dependencies between cybersecurity vulnerabilities and system safety. Using this information, the most effective mitigation strategies to ensure safety and security of the system can be readily identified. We apply STPA-SafeSec to a use case in the power grid domain, and highlight its benefits

Cultural pillages of the leisure class? : consuming expressions of identity.

Thesis (M.A.)-University of KwaZulu-Natal, 2011.Society ‘obscures itself’ by presenting a world that is self-contained and logical (Barthes, 1973) – a world underpinned by a transparency of its underlying systems of meaning. This formulation maps the theoretical location of the dissertation, by which an investigation into tourism, as an economic and political expression of contemporary culture, occurs. More specifically, the dissertation addresses the type of tourism that bisects narratives of history and of cultures – that popularly described under the label of cultural tourism. Thus it employs an array of critical tourism and cultural theory, to offer an exposition on how best to understand the articulation of meaning in the consumption of ‘place’, formations of heritage and Otherness. The study also explores the epistemological nature/agendas of the so-called ‘Image of Africa’ and the ‘Absolute Other’, and how these are recycled in the parameters of modernity. Using a genealogical approach to studying discursive formations articulating some kind of Zulu Otherness, the dissertation grounds these conventions of identity predominantly in the symbolic practice of a colonial Western society. This exposes the arbitrary, constructed nature by which contemporary society governs itself. Methodologically, the research applies participant observation and semiotic analyses, predominantly in the cultural/filmic village of Shakaland, near Eshowe, KwaZulu-Natal, to explore how the constructions of identity manifest and are negotiated and consumed in the activity of this tourism