A Comparison of Video and Accelerometer Based Approaches Applied to Performance Monitoring in Swimming.

The aim of this paper is to present a comparison of video- and sensor based studies of swimming performance. The video-based approach is reviewed and contrasted to the newer sensor-based technology, specifically accelerometers based upon Micro-Electro-Mechanical Systems (MEMS) technology. Results from previously published swim performance studies using both the video and sensor technologies are summarised and evaluated against the conventional theory that upper arm movements are of primary interest when quantifying free-style technique. The authors conclude that multiple sensor-based measurements of swimmers’ acceleration profiles have the potential to offer significant advances in coaching technique over the traditional video based approach

Technique utilisation and efficiency in competitive Brazilian Jiu-Jitsu matches at white and blue belts

Despite its increasing popularity, little is known about Brazilian Jiu- Jitsu and what makes a successful fighter. This work aims to start answering questions about the most used and successful techniques to allow development of coaching methods towards enhancing performance at lower belt levels. One-hundred and forty tournament fights were analysed. The most common takedown was guardpull with 94% success. Significantly more single leg takedowns were attempted for blue belts (BBs), compared to white belts (WBs) (p = 0.013). However, there was no significant difference in success (p = 0.150). WBs used three main guardpasses with 93% covering knee slice, knee pin and bullfighter. A greater variety of passes were witnessed at BB with 71% coming from these three passes. The four most commonly attempted guard sweeps were scissor sweep, back take, Xguard sweep and SitUp sweep all experiencing varying levels of success: 55% for the scissor sweep, 60% back take, 63% Xguard sweep and 38% for the sit up sweep. Of all the submissions attempted 34% were for arm bar, 21% triangle, 12% cross collar choke but there were almost an inverse relationship between use and success with the least used having higher success rates, demonstrating that variety in submissions could lead to greater chances of success

A randomised observational study of individualised variations in the start position of the Closed-Kinetic Chain Upper Extremity Stability Test

Objectives To assess the reliability, precision and differences between scores produced using the standard 36″” start position and 3 modified start positions of the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), towards normalisation to the individual. Design RCT of 4 conditions. Setting Clinical. Participants Thirty-four asymptomatic individuals. Main outcome measures Using an RCT method, variations in CKCUEST starting hand position were tested using hand spacing at standard 36″, 50% height, bi-acromial distance, and bi-acromial distance with reach to 36″. The average number of touches over 3 × 15 s maximal efforts were averaged. The intra-variation reliability, minimum detectable change (MDC) and differences to the standard 36″” start position were tested. Results The most reliable variation was the 50% height (ICC: 0.93) and with the smallest MDC (14%). 36″ results were second-most reliable (ICC: 0.90), with a low MDC (19%). Significant differences were found between bi-acromial and 50% height to the 36″” standard setup. Conclusions A setup position where the hand separation is 50% of the individual's height offers excellent repeated measures reliability and the smallest MDC, suggesting it is the most sensitive to change and is a recommendation to clinicians. Conversion calculations between start variations are presented

Assessing the Impact of Sensor Orientation on Accelerometer-Derived Angles: A Systematic Analysis and Proposed Error Reduction

Accelerometers have been widely used for motion analysis. The effect of initial sensor orientation (ISO) on the derived range of motion (ROM) is currently unexplored, limiting clarity in understanding error. This two-step study systematically explored the effect of ISO on the error of accelerometer-derived range of motion (ROM) and the effect of a proposed correction algorithm. Accelerometer data were used to compute peak and through-range ROM across a range of ISO and movement angular velocities up to 148° s−1 compared to an optoelectronic gold-standard. Step 1 demonstrated that error increased linearly with increasing ISO offsets and angular velocity. Average peak ROM RMSE at an ISO of 20° tilt and twist was 5.9° for sagittal motion, and for an ISO of 50° pitch and 20° twist, it was 7.5° for frontal plane ROM. Through-range RMSE demonstrated errors of 7–8° for similar ISOs. Predictive modeling estimated a 3.2° and 3.7° increase in peak and through-range sagittal plane error for every 10° increase in tilt and twist ISO. Step 2 demonstrated error reduction utilizing mathematical correction for ISO, resulting in <1° mean peak error and <1.2° mean through-range ROM error regardless of ISO. Accelerometers can be used to measure cardinal plane joint angles, but initial orientation is a source of error unless corrected

Placement of inertial measurement units in Racket Sports: Perceptions of coaches for IMU use during training and competition

While inertial measurement units (IMU) have become an integral part of sports performance analysis, upper body-mounted IMUs have been found to exhibit poor reliability in measuring lower-limb loading. In racket sports, IMUs have been placed in a number of positions on the upper body, lower body and racket in a research setting. A potential limitation to the concurrent use of multiple IMUs is that coaches may be reluctant to allow their athletes to wear the units during training and competition due to concerns that the units would interfere with athlete movement. This study seeks to understand the perceptions of racket sports coaches towards the use of IMUs in training and competition. A total of 58 racket sport coaches responded to a survey on the use of IMUs during training and competition. Based on the responses, 96.6% (56 out of 58) of coaches indicated that they would allow their athletes to wear IMUs in training, while 65.5% (38 out of 58) would allow their athletes to wear IMUs during competition. For use in training, 9 of the 14 suggested IMU placements received significant positive responses. However, none of the suggested IMU placements received significant positive responses for use during competition and 11 of the 14 received significant negative responses. This suggests that while coaches understand the benefits of collecting data from IMUs during competition. Despite this, for use in training, a number of upper and lower body-mounted IMUs placements have the potential to be part of regular monitoring in racket sports

Variability of extracorporeal cardiopulmonary resuscitation utilization for refractory adult out-of-hospital cardiac arrest: an international survey study.

Objective: A growing interest in extracorporeal cardiopulmonary resuscitation (ECPR) as a rescue strategy for refractory adult out-of-hospital cardiac arrest (OHCA) currently exists. This study aims to determine current standards of care and practice variation for ECPR patients in the USA and Korea. Methods: In December 2015, we surveyed centers from the Korean Hypothermia Network (KORHN) Investigators and the US National Post-Arrest Research Consortium (NPARC) on current targeted temperature management and ECPR practices. This project analyzes the subsection of questions addressing ECPR practices. We summarized survey. Results: Overall, 9 KORHN and 4 NPARC centers reported having ECPR programs and had complete survey data available. Two KORHN centers utilized extracorporeal membrane oxygenation only for postarrest circulatory support in patients with refractory shock and were excluded from further analysis. Centers with available ECPR generally saw a high volume of OHCA patients (10/11 centers care for \u3e75 OHCA a year). Location of, and providers trained for cannulation varied across centers. All centers in both countries (KORHN 7/7, NPARC 4/4) treated comatose ECPR patients with targeted temperature management. All NPARC centers and four of seven KORHN centers reported having a standardized hospital protocol for ECPR. Upper age cutoff for eligibility ranged from 60 to 75 years. No absolute contraindications were unanimous among centers. Conclusion: A wide variability in practice patterns exist between centers performing ECPR for refractory OHCA in the US and Korea. Standardized protocols and shared research databases might inform best practices, improve outcomes, and provide a foundation for prospective studies

Limb specific training magnitude and asymmetry measurement to discriminate between athletes with and without unilateral or bilateral lower limb injury history

Objectives: This study investigates the use of tibia-mounted inertial measurement units (IMUs) as an alternative to upper trunk-mounted IMUs for assessing lower limb training magnitudes and asymmetries in Badminton players. Design: Cross-Sectional Study. Setting: Youth athlete training environment. Participants: Thirty-three adolescent Badminton players, grouped based on injury history (non-injured ¼ 19, bilateral ¼ 6, unilateral ¼ 8). Main outcome measures: Players wore 1 upper trunk-mounted and 2 tibia-mounted IMUs during simulated match-play. Modified vector magnitudes were assessed to identify if the IMUs can discriminate between injury history groups to assess the device location sensitivity, determine to what extent players exhibit movement asymmetry within the sport, and explore if asymmetries exist within groups with injury history. Results: Upper trunk-mounted IMUs could not distinguish between injury history groups. Statistically significant asymmetries were observed in the non-injured group, however these were below the 10% threshold for clinical asymmetry. No significant asymmetries were observed in the bilaterally injured group, while statistically significant asymmetries were observed in the unilaterally injured group, which were above the 10% threshold for clinical asymmetry. Conclusion: These results suggest that direct limb specific IMU measurement offers a method to suitably assess training magnitudes and asymmetry within a sporting performance, rather than isolated non- sport specific testing