Variability and control in springboard diving

Elite springboard divers typically make very precise and reproducible movements when they perform the same dive many times. However, variability is always present in both technique and outcome. While it is desirable to have low outcome variability this may necessitate real-time adjustments which result in increased technique variability from trial to trial. The aim of the present research was to determine whether feedback control adjustment is used during (a) the hurdle takeoff, (b) the dive takeoff, and (c) the dive flight phase. 15 forward pike dives and 15 forward 2½ somersault pike dives, performed by an international diver, were video recorded at 250 Hz and manually digitised followed by DLT reconstruction of joint centre locations. Orientation angle and joint angles were calculated and fitted with quintic splines to give angular velocities. Foot placements, mass centre location and velocity were determined along with angular momentum about the mass centre. In the hurdle takeoff no adjustment was made to reduce the variability in the foot location at hurdle landing. In the dive takeoff phase an angle-driven simulation model was used to determine the expected variation in mass centre velocity and angular momentum at the instant of takeoff arising from the variation in velocity and angular momentum at touchdown. The simulated variation at the instant of takeoff was greater than the variation in the recorded performances indicating that some adjustment had been made during the takeoff phase. In the flight phase an angle-driven simulation model was used to determine the expected variation in orientation angle at water entry arising from the variation in velocity and angular momentum at takeoff. The variation in the orientation angle at entry obtained from the simulations was greater than the variability in the actual performances, indicating that the diver had used feedback control adjustments in the flight phase to reduce his performance outcome variability. The variation in the angular momentum at takeoff was reflected in the average hip angle in flight, indicating that the hip angle was adjusted to be larger to compensate when the initial angular momentum was greater. The use of feedback control adjustments found in this study demonstrated that variability has a functional role in human movement

A hybrid method of GRA and DEA for evaluating and selecting efficient suppliers plus a novel ranking method for grey numbers

Purpose: Evaluation and selection of efficient suppliers is one of the key issues in supply chain management which depends on wide range of qualitative and quantitative criteria. The aim of this research is to develop a mathematical model for evaluating and selecting efficient suppliers when faced with supply and demand uncertainties. Design/methodology/approach: In this research Grey Relational Analysis (GRA) and Data Envelopment Analysis (DEA) are used to evaluate and select efficient suppliers under uncertainties. Furthermore, a novel ranking method is introduced for the units that their efficiencies are obtained in the form of interval grey numbers. Findings: The study indicates that the proposed model in addition to providing satisfactory and acceptable results avoids time-consuming computations and consequently reduces the solution time. To name another advantage of the proposed model, we can point out that it enables us to make decision based on different levels of risk. Originality/value: The paper presents a mathematical model for evaluating and selecting efficient suppliers in a stochastic environment so that companies can use in order to make better decisions.Peer Reviewe

FACTORS INFLUENCING VARIATION IN DIVE HEIGHT IN 1M SPRINGBOARD DIVING

The aim of this study was to determine the factors contributing to variation in dive height in performing a 1m springboard dive. 15 performances of a forward dive pike by an international diver were recorded using high speed video (250 Hz) and were digitised manually. The relationships between variables at hurdle landing, during board contact and dive height were determined. Hip extension during board contact accounted for 77% of the variance in dive height

ADJUSTMENT IN THE FLIGHT PHASE OF 1M SPRINGBOARD FORWARD PIKE DIVES

The aim of this study was to investigate the variability in 1m springboard forward pike dives (101B). Variability of body orientation angle at takeoff and water entry together with joint angle time histories of 15 forward pike dives, performed by an international diver, were determined using video analysis. A computer simulation model was used to investigate the effects of initial conditions variability and flight phase configuration variability on outcome (orientation at entry) variability. It was found that the variation in the simulated orientation at entry arising from variability in the initial conditions was greater than the actual variation. This indicates that the diver used feedback correction to make adjustments during flight to reduce the variability of his entry angle

Functional variability in the flight phase of one metre springboard forward dives

In springboard diving, low variability in takeoff conditions and in the somersault orientation angle at water entry is to be expected since consistency and accuracy are necessary for a good dive. A diver's adjustment of body configuration during flight may be a deliberate compensation for variations in takeoff conditions, leading to increased joint angle variability and decreased entry angle variability. The aim of this research was to investigate the extent to which a diver pre-plans the aerial phase and then makes adjustments in flight to control the entry angle in one metre springboard forward dives. Performances of 15 forward pike dives and 15 forward 2½ somersault pike dives, performed by an international diver were video recorded at 250 Hz. Joint centres during flight were digitized and their spatial coordinates were subsequently reconstructed using the Direct Linear Transformation in order to determine orientation and configuration angles. A computer simulation model was used to investigate the effects of variability in takeoff conditions and configuration variability in flight on the variability of the orientation angle at water entry. The amount of variation in the somersault orientation angle at entry as determined using simulations based on the variability in the takeoff conditions was four times greater than the variation in the recorded performances. It was concluded that the diver used open loop control for the first half of the flight phase and subsequently used feedforward and feedback control to make timing adjustments of hip and arm angles to reduce the variability of his entry orientation angle

ADJUSTMENT IN THE TAKEOFF PHASE OF 1-M SPRINGBOARD FORWARD DIVES

The aim of this study was to investigate whether any adjustment is made during the board contact phase of 1-m springboard forward dives. Variability of body orientation angle at landing from hurdle (touchdown) and at takeoff together with joint angle time histories of 15 forward pike dive takeoffs, performed by an international diver, were determined using video analysis. A computer simulation model of a diver and springboard was used to determine the effects of perturbations of initial conditions on takeoff variability. The variation at takeoff obtained in the simulation outcome was much greater than in the actual performance, indicating that the diver made adjustments during the board contact phase. The diver varied his body configuration during the board recoil phase to adjust his body orientation, leading to low variability at takeoff

Attenuated cardiovascular reactivity is related to higher anxiety and fatigue symptoms in truck drivers

ACKNOWLEDGEMENTS The authors would like to thank all the truck drivers who participated in this study. The data presented in this paper were collected as part of the baseline measures from the “Structured Health Intervention For Truckers (SHIFT)” randomized controlled trial, which is funded by the NIHR Public Health Research Programme (reference: NIHR PHR 15/190/42). SAC, JAK, AS and NJP are supported by the NIHR Leicester Biomedical Research Centre—Lifestyle theme. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. The first author (AG) has received funding for their PhD Studentship from the Colt Foundation (reference: JD/618). The Colt Foundation had no role in study design; election, synthesis, and interpretation of data; writing of the report; or the decision to submit the manuscript for publicationPeer reviewedPublisher PD

Time in Nature Associated with Decreased Fatigue in UK Truck Drivers

Funding: The data presented in this paper were collected as part of the ‘Structured Health Interven- tion For Truckers (SHIFT)’ randomised controlled trial. This research was funded by the National Institute for Health Research (NIHR) Public Health Research Programme (reference: NIHR PHR 15/190/42). Funding Acquisition, S.A.C., J.A.K., V.V-M. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Acknowledgments: SAC: JAK, AS and NJP are supported by the NIHR Leicester Biomedical Re- search Centre—Lifestyle theme. AG has received funding for their PhD Studentship from the Colt Foundation (reference: JD/618).Peer reviewedPublisher PD

The structured health intervention for truckers (SHIFT) cluster randomised controlled trial : a mixed methods process evaluation

Funding This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme (reference: NIHR PHR 15/190/42). The study was also supported by the NIHR Leicester Biomedical Research Centre which is a partnership between University Hospitals of Leicester NHS Trust, Loughborough University, and the University of Leicester. Laura Gray is supported by the National Institute for Health Research (NIHR) Applied Research Collaboration East Midlands (ARC EM). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Funding to cover intervention costs (Fitbits, cab workout equipment) was provided by the Higher Education Innovation Fund, via the Loughborough University Enterprise Projects Group. The Colt Foundation provided funding for a PhD Studentship, awarded to Amber Guest (reference: JD/618), which covered Amber’s time and contributions to this project. None of the funding bodies had any role in study design; election, synthesis, and interpretation of data; writing of the report; or the decision to submit the manuscript for publication. Acknowledgements We gratefully acknowledge the support provided by senior Health and Safety personnel and Transport Managers at our partner logistics company in facilitating this research. We also thank all participants for taking part. We are grateful to the independent members of the Trial Steering Committee for their continued support and advice throughout the trial: Dr. Derrick Bennett, Prof Emma McIntosh, Prof Petra Wark and Mr. Paul Gardiner.Peer reviewedPublisher PD

Drivers with and without Obesity Respond Differently to a Multi-Component Health Intervention in Heavy Goods Vehicle Drivers

Funding This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme (reference: NIHR PHR 15/190/42). The study was also supported by the NIHR Leicester Biomedical Research Centre which is a partnership between University Hospitals of Leicester NHS Trust, Loughborough University and the University of Leicester. Laura Gray is supported by the National Institute for Health Research (NIHR) Applied Research Collaboration East Midlands (ARC EM). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Funding to cover the intervention costs (Fitbits and cab workout equipment) was provided by the Higher Education Innovation Fund, via the Loughborough University Enterprise Projects Group. The Colt Foundation provided funding for a PhD Studentship, awarded to Amber Guest (reference: JD/618), which covered Amber’s time and contributions to this project. The funders played no role in study design, data collection, data analysis, data interpretation or in the preparation of this manuscript.Peer reviewedPublisher PD