INFLUENCE OF BODY SEGMENT INERTIA PARAMETERS ON UNCERTAINTIES IN JOINT SPECIFIC POWER DURING SPRINT CYCLING: A MONTE CARLO SIMULATION

Joint-specific power analyses are important in the assessment of cycling biomechanics but they contain uncertainties due to errors in input parameters. The aim of the study was to investigate the effect of uncertainty in body segment parameters on joint-specific powers during maximal sprint cycling, using a Monte Carlo analysis. Joint powers were estimated using standard inverse dynamics techniques, with body segment parameters and uncertainty in these inputs defined using reference data. Monte Carlo simulations (10,000 iterations) were performed for pedal cycles at 120 rpm and 160 rpm. The analysis highlighted practically relevant uncertainties in peak hip joint power at racespecific pedalling rates caused by uncertainty in body segment parameters

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

A novel method to find the neutral position of the breast

Breast pain affects up to 70% of the female population. It is believed that stretching of the breast tissue causes discomfort and that by placing the breast into a position in which the tissue is neither in compression or tension (termed neutral position) will eliminate breast pain. The purpose of the study was to find a simple method that could be used to determine the location of the neutral position. One participant with a breast size of 34C performed three activities. The breast and torso movement were tracked using four retroreflective markers. The results suggest that the counter-movement jump was the most appropriate method as it forced the breast to oscillate from tension in the upper-side of the breast to tension in the under-side of the breast. The neutral position was found to be -129 ± 6 mm below the suprasternal notch, which was located 14 mm above the resting height of the breast. It was concluded that the first role of a bra is to lift the breast above the static position to cause more symmetrical oscillations about the neutral position

ASSESSING TENNIS PLAYER INTERACTIONS WITH TENNIS COURTS

Different types of tennis injury have been associated with play on different court surfaces and current knowledge of tennis player and court interactions is limited. This paper provides a brief overview of tennis injury incidence, player movements and the biomechanics of slips. The discussion proposes a new direction for assessing tennis player-surface interactions and outlines current work. It is envisaged that current work will contribute to the understanding of tennis player-surface interactions and be of practical use in the future regulation of tennis courts

USING A WIRELESS INERTIAL SENSOR TO MEASURE TIBIAL SHOCK DURING RUNNING: AGREEMENT WITH A SKIN MOUNTED SENSOR

Monitoring and feedback of tibial shock using wireless skin mounted sensors could reduce the risk of injury in runners. The purpose of this study was to assess the agreement between a wireless sensor and a skin mounted accelerometer in measuring peak tibial acceleration during running. A skin mounted laboratory standard accelerometer was mounted to a wireless inertial sensor and attached to the tibia. Peak positive tibial accelerations of 13 participants were compared at 2.5 ms-1, 3.5 ms-1 and 4.5 ms-1. Intraclass correlation coefficient demonstrated good agreement. Limits of agreement showed accuracy to within 1.2 – 1.65 g. The inertial sensor can be used as a tool to measure peak tibial accelerations during running for the purpose of real-time feedback in a gait training system

How shape-based anthropometry can complement traditional anthropometric techniques: a cross-sectional study

Abstract: Manual anthropometrics are used extensively in medical practice and epidemiological studies to assess an individual's health. However, traditional techniques reduce the complicated shape of human bodies to a series of simple size measurements and derived health indices, such as the body mass index (BMI), the waist-hip-ratio (WHR) and waist-by-height0.5 ratio (WHT.5R). Three-dimensional (3D) imaging systems capture detailed and accurate measures of external human form and have the potential to surpass traditional measures in health applications. The aim of this study was to investigate how shape measurement can complement existing anthropometric techniques in the assessment of human form. Geometric morphometric methods and principal components analysis were used to extract independent, scale-invariant features of torso shape from 3D scans of 43 male participants. Linear regression analyses were conducted to determine whether novel shape measures can complement anthropometric indices when estimating waist skinfold thickness measures. Anthropometric indices currently used in practice explained up to 52.2% of variance in waist skinfold thickness, while a combined regression model using WHT.5R and shape measures explained 76.5% of variation. Measures of body shape provide additional information regarding external human form and can complement traditional measures currently used in anthropometric practice to estimate central adiposity

Effect of hurdling step strategy on the kinematics of the block start.

Athletes use either a seven-step or eight-step strategy to reach the first hurdle in the 110 m hurdle event. This study investigated the effect of step strategy on the start position, the block exit and the first four approach steps. Two-dimensional video data were collected in the sagittal plane from 12 male sprinters, grouped as seven-step (n = 6) or eight-step (n = 6) strategists. Mean block spacing was 0.08 m further apart, block contact time 0.06s longer, first step 0.25 m longer and first ground contact 0.03s longer for seven-step athletes compared with eight-step athletes. There was also a greater vertical displacement of the centre of mass (CoM) (0.04 m) for the seven-step athletes compared with the eight-step athletes. Additionally, the front hip mean angular acceleration was 197°/s2 slower for the seven-step athletes than the eight-step athletes. There was limited difference between groups for mean horizontal velocity at the moment of block exit (0.14 m/s). These technical alterations provide an important first insight into start kinematics. The findings of this study identify the position in the starting blocks, and the key parameters which pertain to the initial phases for a successful seven-step approach strategy to be employed