Breast volume is a key metric in breast surgery and there are a number of different methods which measure it. However, a lack of knowledge regarding a method's accuracy and comparability has made it difficult to establish a clinical standard. We have performed a systematic review of the literature to examine the various techniques for measurement of breast volume and to assess their accuracy and usefulness in clinical practice. Each of the fifteen studies we identified had more than ten live participants and assessed volume measurement accuracy using a gold-standard based on the volume, or mass, of a mastectomy specimen. Many of the studies from this review report large (>200 ml) uncertainty in breast volume and many fail to assess measurement accuracy using appropriate statistical tools. Of the methods assessed, MRI scanning consistently demonstrated the highest accuracy with three studies reporting errors lower than 10% for small (250 ml), medium (500 ml) and large (1000 ml) breasts. However, as a high-cost, non-routine assessment other methods may be more appropriate.

The tennis racket has developed since the origins of Lawn Tennis in the 1870s. This study investigated how the tennis racket developed from 1874 to 2017, using measurements and material classifications for 525 samples. Racket measurements covered geometric, inertial and dynamic properties, and the number of strings. Rackets predating 1970 were mainly wooden, and typically characterised by head areas below 0.05 m2, masses over 350 g and natural frequencies below 120 Hz. Rackets from the 1970s were made from wood, metal and fibre–polymer composites, with most postdating 1980 made from fibre–polymer composites with a larger head, lower mass and higher natural frequency than their predecessors. Principal component analysis was used to reduce the dimensionality of the number of variables. Principal component one (PCA1) accounted for 35% of the variance in the measured racket properties, and was found to be significantly affected by material. Head width was best correlated with principal component one (r = 0.897, p < 0.001), followed by head length (r = 0.841, p < 0.001) and natural frequency (r = 0.813, p < 0.001). Early rackets were constrained by the limitations of wood, and the move to composites, which began in the 1970s, allowed this observed increase in head size and natural frequency. As material development has been a major driver of racket design in the past, we propose that new materials and manufacturing techniques, like additively manufactured composites, could further improve the tennis racket. The measurement techniques described here can be used to monitor developments in racket design.

The performance characteristics of elite tennis match-play differ depending on court surface. However, the performance characteristics (e.g. aces, first serve points won, forced errors) most associated with success on different surfaces are currently unknown. With three weeks typically separating Roland Garros and Wimbledon, the transition from clay to grass courts, whereby players must adapt their game style between surfaces, is crucial to understand. Using the recently validated PWOL method, we analysed 984 singles matches across the 2016 and 2017 Roland Garros and Wimbledon tournaments, to identify the most important performance characteristics in clay and grass court tennis. Results revealed that points won of 0-4 shot rally length, first serve points won and baseline points won were most strongly associated with success for both sexes; serverelated performance characteristics (aces, double faults and average first serve speed) were among the least associated with success. Furthermore, winning short points (points of 0-4 shots) was more closely associated with success than winning medium-length (5-8 shots) and long points (9+ shots). To be representative of match-play, findings suggest that players should afford sufficient practise time to short rallies and point-ending strategies during the clay and grass court seasons, rather than over-emphasising long rallies.

Many biomechanical analyses rely on the availability of reliable body segment inertia parameter (BSIP) estimates. Current processes to obtain these estimates involve many time consuming manual measurements of the human body, used in conjunction with models or equations. While such methods have become the accepted standard they contain many inherent errors arising from manual measurement and significant assumptions made in the underlying data used to form the models and equations. Presented here is an alternative approach to obtaining reliable estimates of body segment inertia parameters through the use of the Microsoft Kinect sensor. A 3D scanning system was developed, comprising four Kinects aligned to a single global coordinate system using rigid body calibration and random sample consensus (RANSAC) optimisation. The system offers the advantage of obtaining BSIP estimates in a single scanning operation of around three seconds, much quicker than the circa thirty minutes of manual measurements required for existing BSIP estimation methods. The results obtained with the system show a mean error of 0.04% and a standard deviation of 2.11% in volumetric measurements of a torso manikin, suggesting comparable and in many cases, greater accuracy volumetric estimates than a commonly used geometric BSIP model. Further work is needed to extend this study to include a full range of BSIP measurements across more of the bodies segments and to include scanning of living human subjects. However, this initial study suggests great potential for a low cost system that can provide quick and accurate subject specific BSIP estimates.

There has been little three-dimensional (3D) analysis of the interaction of a tennis ball and racket during realistic play conditions. This paper is a descriptive study of elite players in practice conditions. The method used records racket and ball movement in 3D, intrudes minimally into the player's environment and has a high level of portability. Testing was performed using two Phantom V4.2 high speed video cameras operating at 1,000 frames per second. Racket movement was tracked using five reflective markers attached to the player's racket and the ball was tracked as a single point. The method allowed accurate measurement of ball and racket speeds, impact positions, and angular velocities of the racket in threedimensions. It was used at the 2006 Wimbledon qualifying tournament in practice conditions to record 106 shots from 16 internationally ranked players. The results obtained showed that all players aim to hit the node point on the racket face in a standard forehand drive. The average postimpact ball velocity of male players was 9.4% greater than that of female players at 33.9 m s -1 , post-impact ball spin was 22.3% higher at 1,480 rpm. These results could be used to confirm previous research into player movement and impact, or as a basis for future investigation into the interaction between the ball, racket and player.