P18. Backstroke Start Performance: The Impact of Using the Omega Backstroke Ledge

Background: FINA recently approved use of the “backstroke ledge” (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare starts performed on a flat wall to those performed with the OBL2, and to identify factors that contribute to better start performance. Methods: Ten elite backstroke swimmers performed three flat-wall and three OBL2 starts. Horizontal impulse, vertical impulse, takeoff velocity and takeoff angle were calculated from the force plate data. Entry distance, time to 10 m and start of hip and knee extension were recorded using digital video cameras. Results: We determined that starts performed with the OBL2 had a faster time to 10 m, less variability in vertical impulse and greater entry distance. Time to 10 m and head entry distance had a significant negative correlation. Starts with the OBL2 also had a trend toward lower resultant takeoff velocity, lower horizontal impulse and greater COM takeoff angle. Discussion and Conclusions: The OBL2 appears to provide a performance advantage by allowing an increased head entry distance, rather than larger impulse on the wall. Additional studies are needed to evaluate the factors that contribute to improved performance when using the OBL2. Coaches may consider head entry distance as a training target. Athletes should use the OBL2 in training and competition to ensure optimal start performance. Interdisciplinary Reflection: Concepts from physical and biological sciences are combined to explain the factors which affect backstroke start performance

Regulation of Balance After Spinning: A Comparison Between Figure Skaters and Controls

Introduction: The purpose of the present study was to compare the balance performance of control subjects and varsity figure skaters after spinning on a turntable for 6 seconds. It was hypothesized figure skaters would demonstrate better balance control after spinning. Methods: 9 female figure skaters and 9 female control subjects stood as still as possible for 15 seconds on a Kistler force plate during both a control condition and after spinning for 6 seconds on a turntable. Balance performance was quantified by the percentage of total time the center of pressure (CoP) was within a 5mm radius of the center of their base of support (BoS). Results: In the control condition, figure skaters and control participants did not have significantly different balance ability. In the post-spin condition, figure skaters were significantly better at maintaining their CoP within a smaller area. Conclusions: These results are valuable from a training and coaching perspective because they suggest that balance performance after spinning can be improved with training

Backstroke start performance: the impact of using the Omega OBL2 backstroke ledge

© 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group. FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras. Starts performed with the OBL2 had a 0.13 s lower time to 10 m, 2.5% less variability in time to 10 m and 0.14 m greater head entry distance. The OBL2 provides a performance advantage by allowing an increased head entry distance rather than larger horizontal impulse on the wall. This may be due to the swimmers assuming different body positions during the start manoeuvre. Additional studies are needed to evaluate factors that contribute to improved performance when using the OBL2. Swimmers should train with the OBL2 and use it in competition to ensure optimal start performance

Different Lower-Limb Setup Positions Do Not Consistently Change Backstroke Start Time to 10 m

Backstroke starts involve the athlete starting from a flexed position with their feet against the pool wall and then extending their ankles, knees, hips and back to push off; however, swimmers can start in different positions. The purpose of this study was to evaluate the performance impact of different knee extension angles in the setup position for a backstroke start. Ten backstroke swimmers completed maximum-effort starts in each of two setup positions: one with the knees maximally flexed, and one with the knees less flexed. The start handles and touchpad were instrumented with multi-axial force sensors. Activity of major hip and knee extensors was measured using surface electromyography. Body position in the sagittal plane was recorded using high-speed cameras. There was no overall difference in time to 10 m between the two conditions (p = 0.36, dz = 0.12), but some participants showed differences as large as 0.12 s in time to 10 m between start conditions. We observed that starts performed from a setup position with less knee flexion had an average 0.07 m greater head entry distance (p = 0.07, dz = 0.53), while starts from a setup position with maximal knee flexion had an average 0.2 m/s greater takeoff velocity (p = 0.02, dz = 0.78). Both head entry distance and takeoff velocity are related to start performance, suggesting each position may optimize different aspects of the backstroke start. Coaches should assess athletes individually to determine which position is optimal

Detection and Profiling of Human Coronavirus Immunoglobulins in Critically Ill Coronavirus Disease 2019 Patients

Objectives:. Coronavirus disease 2019 continues to spread worldwide with high levels of morbidity and mortality. We performed anticoronavirus immunoglobulin G profiling of critically ill coronavirus disease 2019 patients to better define their underlying humoral response. Design:. Blood was collected at predetermined ICU days to measure immunoglobulin G with a research multiplex assay against four severe acute respiratory syndrome coronavirus 2 proteins/subunits and against all six additionally known human coronaviruses. Setting:. Tertiary care ICU and academic laboratory. Subjects:. ICU patients suspected of being infected with severe acute respiratory syndrome coronavirus 2 had blood collected until either polymerase chain reaction testing was confirmed negative on ICU day 3 (coronavirus disease 2019 negative) or until death or discharge if the patient tested polymerase chain reaction positive (coronavirus disease 2019 positive). Interventions:. None MEASUREMENTS AND MAIN RESULTS:. Age- and sex-matched healthy controls and ICU patients who were either coronavirus disease 2019 positive or coronavirus disease 2019 negative were enrolled. Cohorts were well-balanced with the exception that coronavirus disease 2019 positive patients had greater body mass indexes, presented with bilateral pneumonias more frequently, and suffered lower Pao2:Fio2 ratios, when compared with coronavirus disease 2019 negative patients (p < 0.05). Mortality rate for coronavirus disease 2019 positive patients was 50%. On ICU days 1–3, anti–severe acute respiratory syndrome coronavirus 2 immunoglobulin G was significantly elevated in coronavirus disease 2019 positive patients, as compared to both healthy control subjects and coronavirus disease 2019 negative patients (p < 0.001). Weak severe acute respiratory syndrome coronavirus immunoglobulin G serologic responses were also detected, but not other coronavirus subtypes. The four anti–severe acute respiratory syndrome coronavirus 2 immunoglobulin G were maximal by ICU day 3, with all four anti–severe acute respiratory syndrome coronavirus 2 immunoglobulin G providing excellent diagnostic potential (severe acute respiratory syndrome coronavirus 2 Spike 1 protein immunoglobulin G, area under the curve 1.0, p < 0.0005; severe acute respiratory syndrome coronavirus receptor binding domain immunoglobulin G, area under the curve, 0.93–1.0; p ≤ 0.0001; severe acute respiratory syndrome coronavirus 2 Spike proteins immunoglobulin G, area under the curve, 1.0; p < 0.0001; severe acute respiratory syndrome coronavirus 2 Nucleocapsid protein immunoglobulin G area under the curve, 0.90–0.95; p ≤ 0.0003). Anti–severe acute respiratory syndrome coronavirus 2 immunoglobulin G increased and/or plateaued over 10 ICU days. Conclusions:. Critically ill coronavirus disease 2019 patients exhibited anti–severe acute respiratory syndrome coronavirus 2 immunoglobulin G, whereas serologic responses to non–severe acute respiratory syndrome coronavirus 2 antigens were weak or absent. Detection of human coronavirus immunoglobulin G against the different immunogenic structural proteins/subunits with multiplex assays may be useful for pathogen identification, patient cohorting, and guiding convalescent plasma therapy