THE RELIABILITY OF TRUNK SEGMENT INERTIAL PARAMETER ESTIMATES MADE FROM GEOMETRIC MODELS

The purpose of this study was to examine the reliability with which trunk segment inertial parameters could be estimated using a geometric modelling technique. Repeat width and depth measurements were obtained from eight male participants by two examiners. This enabled trunk inertial parameters to be estimated using a geometric model similar to that defined by Yeadon (1990). The majority of these parameters were estimated with acceptable inter-examiner and intra-examiner reliability, this was determined by an intraclass correlation value greater than 0.7. The lowest reliability was obtained for the shoulders segment which can be difficult to model due to its irregular shape. If shoulder segment inertial parameters are to be considered in a given analysis, the use of repeat measures is recommended as a way to improve reliability

Proportioning of self-compacting concrete – the UCL method

This document sets out a procedure of the proportioning of self-compacting concrete (SCC) mixes which is suitable for use by an experienced concrete technologist who may not be familiar with SCC. It requires access to a laboratory with reasonable range of equipment for standard testing of fresh concrete, but not containing techniques for more sophisticated testing, such as mortar or concrete rheology. It is based on work carried out in a succession of studies at UCL

Programming and supervision of resistance training leads to positive effects on strength and body composition: results from two randomised trials of community fitness programmes

Background: Many sedentary adults have high body fat along with low fitness, strength, and lean body mass (LBM) which are associated with poor health independently of body mass. Physical activity can aid in prevention, management, and treatment of numerous chronic conditions. The potential efficacy of resistance training (RT) in modifying risk factors for cardiovascular and metabolic disease is clear. However, RT is under researched in public health. We report community-based studies of RT in sedentary (Study 1), and overweight and pre-diabetic (Study 2) populations. Trial Design: Study 1: A semi-randomised trial design. Study 2: A randomised wait-list controlled trial. Methods: Study 1 (48-weeks): Participants choosing either a fitness centre approach, and randomised to structured-exercise (STRUC, n=107), or free/unstructured gym use (FREE, n=110), or not, and randomised to physical-activity-counselling (PAC, n=71) or a measurement only comparator (CONT, n=76). Study 2 (12-weeks): Patients were randomly assigned to; traditional-supervised-exercise (STRUC, n=30), physical-activity-counselling (PAC, n=23), either combined (COMB, n=39), or a wait-list comparator (CONT, n=54). Outcomes for both were BF mass (kg), LBM (kg), BF percentage (%), and strength. Results: Study 1: One-way ANCOVA revealed significant between group effects for BF% and LBM, but not for BF mass or strength. Post hoc paired comparisons revealed significantly greater change in LBM for the STRUC group compared with the CONT group. Within group changes using 95%CIs revealed significant changes only in the STRUC group for both BF% (-4.1 to -0.9%) and LBM (0.1 to 4.5 kg), and in FREE (8.2 to 28.5 kg) and STRUC (5.9 to 26.0 kg) for strength. Study 2: One-way ANCOVA did not reveal significant between group effects for strength, BF%, BF mass, or LBM. For strength, 95%CIs revealed significant within group changes for the STRUC (2.4 to 14.1 kg) and COMB (3.7 to 15.0 kg) groups. Conclusion: Strength increased in both studies across all RT treatments compared to controls, yet significant improvements in both strength and body-composition occurred only in programmed and/or supervised RT. As general increases in physical activity have limited impact upon body-composition, public health practitioners should structure interventions to include progressive RT. Keywords: Resistance Training, Body Composition, Exercise Treatment, Health Status

Optimal fall indicators for slip induced falls on a cross-slope

Abstract: Slip induced falls are among the most common cause of major occupational injuries in the UK as well as being a major public health concern in the elderly population. This study aimed to determine the optimal fall indicators for fall detection models which could be used to reduce the detrimental consequences of falls. A total of 264 kinematic variables covering three dimensional full body model translation and rotational measures were analysed during normal walking, successful recovery from slips and falls on a cross-slope. Large effect sizes were found for three kinematic variables which were able to distinguish falls from normal walking and successful recovery. Further work should consider other types of daily living activities as results show that the optimal kinematic fall indicators can vary considerably between movement types

Validation and uncertainty of inverse dynamics analysis applied to high acceleration movements.

This thesis is motivated by the lack of knowledge of the uncertainty in the estimation of joint forces and moments derived through inverse dynamics analysis. Previous studies have shown uncertainty bounds can be substantial during slow, simple movements such as gait or lifting however little is known about the uncertainty in inverse dynamics solutions applied to high acceleration, open chain, complex tasks. A three dimensional full body model was used to provide a mechanical basis for evaluating joint forces and moments during the golf swing. Eight male skilled golfers were used; kinematic data was recorded using the Polhemus LIBERTY, an electromagnetic tracker system, using 12 sensors attached to the body with a specially designed jacket. Force plates were used to measure ground reaction forces.Validation of the derived joint forces and moments is problematic since no 'gold standard' is available for comparison. A comparison of the measured with the estimated ground reaction forces, as well as a comparison of the moments at the T8/T9 intervertebral joint that results from bottom up and top down mechanical analysis provided an initial measure of validity. The high acceleration, complex nature of the golf swing resulted in a reduced validity compared to previous studies concerned with lifting, fast trunk rotations and slow speed golf swings. The residuals between the measured and predicted GRF were greatest during the downswing. Similarly, the residuals between the joint reaction forces and moments at the upper trunk joint measured using a top down and bottom up mechanical analysis were greatest during the downswing, exemplified by an increase in joint moment RMS differences of 30.9 Nm, 24.4 Nm and 25.2 Nm for lateral bending, axial rotation and flexion-extension respectively. It was shown that for open chain movements, through periods of high acceleration, inverse dynamics solutions can be subject to errors which have the capacity to significantly affect the interpretation of resultant joint moments depending on whether a top down or bottom up mechanical analysis is used. Top down-bottom up comparisons do not account for two sources of error; the joint centre location and the anatomical coordinate system of the joint where the two models meet. A further drawback associated with these validation methods is that nothing can be learnt about the individual sources of error and how they contribute to the total residual error.A consideration of how errors in measured variables propagate through inverse dynamics equations to produce uncertainties associated with the result was necessary. To analyse this, the Taylor Series Method for error propagation was used. Inaccuracies in body segment parameters, kinematics and external force measurement were determined experimentally. Soft tissue artefact and joint centre location errors were extracted from the literature. Inaccuracies in variables were assumed to be random and uncorrelated and results were representative of the upper bound uncertainty. Uncertainty in joint moment estimations was greatest for downswing where segments were moving with the greatest acceleration. The magnitude of the uncertainty was substantial and ranged from 6-339% of the peak joint moment magnitude.Inaccuracies in proximal moment arms and centre of mass accelerations had the most influence on the joint moment uncertainty and this uncertainty had the capability to alter the timing of peak joint moments by as much as 560ms. The results were critical to the interpretation of inverse dynamics derived joint forces and moments for high acceleration, open chain motions

Death by effectiveness:Exercise as medicine caught in the efficacy trap!

Sport and Exercise Medicine (SEM) has had a good run. For a while it was the low-cost magic bullet. With efficacy demonstrated in study after study, the conclusion was clear: ‘Exercise is Medicine’, a potential public health panacea. Sadly, the early promise waned. While we continue to be bombarded by original research and reviews extoling the efficacy of exercise, there is an apparent dearth of evidence of its effectiveness. This fact is highlighted in 2014 reports from the UK Government1 and Public Health England.

A formative review of physical activity interventions for minority ethnic populations in England

Background: Physical activity (PA) levels are lower among some UK minority ethnic groups than the majority White British population. Barriers to participation have been examined and a variety of tailored interventions have emerged. This study documents the characteristics and logic of local adaptations; a vital first step in evaluating such innovations. Methods: 58 PA interventions from an English PA dataset were examined to establish the characteristics of programmes focussed on minority ethnic populations. From these 58, three case studies were examined to reveal the nature of tailoring and the logic underpinning it; employing documentary analysis and qualitative interviews. Results: Interventions typically aimed to improve both health and social outcomes, were largely publically and charitably funded and sought to engage the most inactive groups. Tailoring was based on six principles including using community resources to promote the intervention and accommodating varying degrees of cultural identification. Additionally, tailoring interventions were intended to build capacity for sustainability. Conclusions: PA interventions tailored to the needs of minority ethnic groups reflect their largely disadvantaged position in society and focus on addressing inactivity. Tailoring PA with the six principles in mind could be used as a useful framework for developing, designing and evaluating interventions for minority ethnic populations