Analysing splash in competitive diving

Splash size is an important factor in competitive diving and is considered to have a large effect in final judged scores. The aim of this research was to develop a system to determine the splash size during different stages of the dive entry. One diver was recorded during a training session and their dives analysed using the developed system. Three splash metrics were calculated at time of complete entry and maximum splash: (1) width of splash, (2) height of splash and (3) size of splash. Results indicated that there was no relationship between the splash metrics at complete entry and time of maximum splash. This may have implications for the scoring of a dive if the judge is unable to distinguish between these two splash events

Kinetic and kinematic analysis of stamping impacts during simulated rucking in rugby union

Laceration injuries account for up to 23% of injuries in rugby union. They are frequently caused by studded footwear as a result of a player stamping onto another player during the ruck. Little is known about the kinetics and kinematics of rugby stamping impacts; current test methods assessing laceration injury risk of stud designs therefore lack informed test parameters. In this study, twelve participants stamped on an anthropomorphic test device in a one-on-one simulated ruck setting. Velocity and inclination angle of the foot prior to impact was determined from high-speed video footage. Total stamping force and individual stud force were measured using pressure sensors. Mean foot inbound velocity was 4.3 m ∙ s-1 (range 2.1 - 6.3 m ∙ s-1). Mean peak total force was 1246 N and mean peak stud force was 214 N. The total mean effective mass during stamping was 6.6 kg (range: 1.6 - 13.5 kg) and stud effective mass was 1.2 kg (range: 0.5 - 2.9 kg). These results provide representative test parameters for mechanical test devices designed to assess laceration injury risk of studded footwear for rugby union

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

Image based stroke-rate detection system for swim race analysis

Swim race analysis systems often rely on manual digitization of recorded videos to obtain performance related metrics such as stroke-rate, stroke-length or swim velocity. Using imageprocessing algorithms, a stroke tagging system has been developed that can be used in competitive swimming environments. Test images from video footage of a women’s 200 m medley race recorded at the 2012 Olympic Games, was segmented into regions of interest (ROI) consisting of individual lanes. Analysis of ROI indicated that the red component of the RGB color map corresponded well with the splash generated by the swimmer. Detected red values from the splash were filtered and a sine-fitting function applied; the frequency of which was used to estimate stroke-rate. Results were compared to manually identified parameters and demonstrated excellent agreement for all four disciplines. Future developments will look to improve the accuracy of the identification of swimmer position allowing swim velocity to be calculated

Understanding shoe-surface interactions in football

One of the key aims of modern football shoe manufacturers is to find the balance between developing a shoe that improves performance but also minimises the risk of injury. Traction properties of the outsole play an important part in reaching this balance; high levels of traction are necessary to enable players to accelerate and change direction without slipping, but excessive traction can lead to stud fixation, a potential cause of injuries. The ability to accurately measure and assess the traction properties is essential in the design of outsoles, but appropriate test parameters need to be used in order for the assessment to relate back to the intended use. The purpose of the study was to develop a method to identify how the shoe interacts with the surface during realistic football movements and then to use observations from data collected to recommend appropriate test parameters. A high-speed camera system was developed to capture the motion of the shoe in both a laboratory and natural turf environment. The cameras were calibrated using the checkerboard approach and filmed at 1000 Hz. Five markers positioned on the side of the shoe were tracked using a semi-automated algorithm developed using image processing techniques. Transposition matrices were used to identify the location of individual studs on the outsole of the shoe enabling the orientation, velocity and acceleration of the shoe to be calculated. Two data collection studies took place; firstly a single-participant study in the laboratory using a force-plate to relate kinematic results to kinetic information and secondly, a larger scale data collection outside on natural turf. Three movements representing scenarios requiring high levels of traction in football were assessed; acceleration, change in direction and braking. A representative trial for each movement was selected and full post-processing analysis was carried out. Information such as the orientation of the shoe on foot-strike, translation directions and centre of rotations during the transition phase and the number of studs in contact with the surface during push-off was obtained for each movement. The period at which the player was at greatest risk of slipping was identified for each movement. The motion of the shoe during this period was used to suggest appropriate test conditions for mechanical and computational traction testing methods. The influence of the shoe-surface interaction on outsole design was also considered; with the observed translation directions and centre of rotations being used to suggest a design aiming to enhance translational traction, but minimise rotational resistance

A method for characterizing high acceleration movements in small-sided football

Small sided football is the most popular area of adult football in the UK, with an estimated 1.5m adults playing every week. Matches are played on smaller pitches using different rules to the 11-a-side game; this results in less stoppage time and a higher volume of ball activity per player. Despite these established differences in playing style and the increase in participation, the types and frequencies of movements performed are not fully understood due to the time consuming nature of current notational analysis methods. Understanding movements is of particular interest to researchers and developers seeking task representative protocols and products for small sided football. The importance of movement type, specifically those with high horizontal plane accelerations, has been demonstrated by recent findings linking traction and shoe stiffness to injury and performance in a number of team sports. In this paper we introduce a new motion analysis technique that uses a combination of inertial sensors and manual notational analysis to describe high acceleration movements in a repeatable and more time effective manner than previously published. A recreational 5-a-side team (mean ± SD: age 17.8 ± 0.26 years, body height 1.77 ± 0.05 m, body mass 74.23 ± 16.25 kg) were observed during one season at a commercial football centre. Player mounted sensors were used to identify 1824 high acceleration movements from three players in seven matches. These movements were then classified using operational definitions adapted from notational analysis literature. This paper outlines a high acceleration movement analysis technique, provides normative high acceleration movement profiles for three individual 5-a-side players, and suggests comparisons to published 11-a-side data. These movement profiles provide a foundation for footwear researchers and product designers to re-align their current practice or products from the 11-a-side game to this more popular style of football