Duncanwebb4441

When cyclists ride off the saddle, their center of mass (CoM) appears to go through a rhythmic vertical oscillation during each crank cycle. Just like in walking and running, the pattern of CoM movement may have a significant impact on the mechanical power that needs to be generated and dissipated by muscle. Purpose To date, neither the CoM movement strategies during non-seated cycling, nor the limb mechanics that allow this phenomenon to occur, have been quantified. Methods Here we estimate how much power can be contributed by a rider's CoM at each instant during the crank cycle by combining a kinematic and kinetic approach to measure CoM movement and joint powers of fifteen participants riding in a non-seated posture at three individualised power outputs (10%, 30%, and 50% of peak maximal power) and two different cadences (70 rpm and 120 rpm). Results The peak-to-peak amplitude of vertical CoM displacement increased significantly with power output and with decreasing cadence. Accordingly, the greatest peak-to-peak amplitude of CoM displacement (0.06 ± 0.01 m) and change in total mechanical energy (0.54 ± 0.12 J·kg) occurred under the combination of high-power output and low cadence. At the same combination of high-power output and low cadence, we found that the peak rate of CoM energy loss (3.87 ± 0.93 W·kg) was equal to 18% of the peak crank power. Conclusion Consequently, it appears that for a given power output, changes in CoM energy contribute to peak instantaneous power output at the crank, thus reducing the required muscular contribution. These findings suggest that rise and fall of a rider's CoM acts as a mechanical amplifier during non-seated cycling, which has important implications for both rider and bicycle performance.Introduction This study aimed to explore the relationship between elite rugby union match and post-match sleep architecture and to investigate the effects of a high-heat capacity mattress (MAT) and a whole-body cryotherapy session (WBC) on post-match sleep architecture. Methods Nineteen elite male U23 rugby union players performed in three official matches, followed by three experimental conditions, in a randomized order MAT, WBC, and no intervention (CONT). Match load was evaluated using global positioning system (GPS) trackers and video analyses. Sleep architecture was assessed by polysomnography (PSG). Core body temperature (CBT) and mattress surface temperature were monitored during sleep. Linear mixed-effects models were conducted to assess the effects of each experimental condition on sleep, with match load variables as covariates. Results A lower wake after sleep onset (β = -10.5 min, p less then 0.01) and higher rapid-eye-movement sleep proportion (β = +2.8%, p less then 0.05) were reported for MAT compared with CONT. Moreover, a lower mean CBT (β = -0.135°C, p less then 0.001) and mean mattress surface temperature (β = -2.736°C, p less then 0.001) during sleep were observed for MAT compared CONT. Whole-body cryotherapy did not affect nocturnal CBT nor interfere with sleep architecture. For every 100-m increase in high-speed running distance, a higher slow-wave sleep (SWS; β = +1.1%, p = 0.05) and lower light sleep proportion (β = -1.2%, p less then 0.05) proportion were observed. Conversely, for every 10 supplementary collisions, a lower SWS (β = -1.9, p = 0.09) and higher light sleep (β = +2.9%, p less then 0.001) proportion were observed. Conclusion MAT use had a positive effect on sleep architecture after an elite rugby union match, potentially through a more efficient nocturnal heat transfer.Purpose Confounding due to poor health is a concern in accelerometer-based studies of physical activity and health, but detailed investigations of this source of bias are lacking. Methods US adults (n=4,840) from NHANES (2003-2006) wore an accelerometer for 1 to 7 days (mean=5.7 days) and were followed for mortality through 2015. Logistic regression was used to examine odds ratios between poor health (chronic conditions, self-reported health, mobility limitations, frailty) and low physical activity levels; Cox models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (95%CI) for mortality associations for a one hour/day increase in moderate-to-vigorous physical activity using two commonly used cut-points (MVPA760, MVPA2020). Modeling scenarios with shorter and longer follow-up time, increasing adjustment for poor health, by age-group, and after excluding early years of follow-up were used to assess bias. Results Over a mean of 10.1 years of follow-up, 1,165 deaths occurred. Poor health was associated with low MVPA760 levels and increased mortality risk. In fully adjusted MVPA760 models HR were 26% stronger comparing 0-4 yrs (HR=0.46) to 0-12 yrs of follow-up (HR=0.62), particularly in older adults (65+ years). Increasing statistical adjustment for poor health attenuated MVPA760 associations by 13-15%, and exclusion of the first two years of follow-up had limited effects. Comparable results were obtained with the MVPA2020 cut-point. Conclusion We did not find evidence that confounding by health status resulted in entirely spurious MVPA-mortality associations, however, potential bias was appreciable in modeling scenarios involving shorter follow-up ( less then 6 years), older adults, and with more limited statistical adjustment for poor health. The strength of MVPA-mortality associations in studies reflecting these scenarios should be interpreted cautiously.Introduction Critical speed (CS) represents the highest intensity at which a physiological steady state may be reached. The aim of this study was to evaluate whether estimations of CS obtained from raw training data can predict performance and pacing in marathons. Methods We investigated running activities logged into an online fitness platform by >25,000 runners prior to big-city marathons. Each activity contained time, distance, and elevation every 100 m. We computed grade-adjusted pacing and the fastest pace recorded for a set of target distances (400, 800, 1000, 1500, 3000, 5000 m). CS was determined as the slope of the distance-time relationship using all combinations of, at least, three target distances. Results The relationship between distance and time was linear, irrespective of the target distances used (pooled mean ± standard deviation R = 0.9999±0.0001). The estimated values of CS from all models were not different (3.74±0.08 m·s), and all models correlated with marathon performance (R = 0.672±0.036, error = 8.01±0.51%). CS from the model including 400, 800 and 5000 m best predicted performance (R = 0.695, error = 7.67%), and was used in further analysis. Runners completed the marathon at 84.8±13.6% CS, with faster runners competing at speeds closer to CS (93.0% CS for 150 min marathon times vs. 78.9% CS for 360 min marathon times). Runners who completed the first half of the marathon at >94% of their CS, and particularly faster than CS, were more likely slowdown by more than 25% in the second half of race. Conclusion This study suggests that estimations of CS from raw training data can successfully predict marathon performance and provide useful pacing information.Objectives Fatalities due to being left in motor vehicles is an important cause of pediatric mortality. Few studies in the medical literature focus on this topic. This study aims to describe the circumstances surrounding these deaths, to determine their geographic distribution, and to evaluate the legal consequences for those responsible. Methods This is a retrospective cohort study of individuals ≤14 years old who died of heatstroke after being left in motor vehicles from 1990 through 2016 using a database provided by KidsAndCars.org. Seliciclib supplier Descriptive data and specified outcomes regarding victims and responsible individuals were recorded. Results Of the 541 cases included for analysis, 528 fatalities involved a single victim and 26 fatalities involved 2 or more victims left in a vehicle. Of all fatalities, 54.4% were male and the mean age was 16.4 (±13.7) months. The responsible individual(s) unknowingly left the victim(s) in the vehicle in 78.2% of cases and knowingly left the victim(s) in 16.6% of cases. A single individual was responsible for leaving the victim(s) in 88.9% of cases. The cases were noted in 45 of 50 states and most commonly occurred in Texas (15%), Florida (12%), and California (7%). Criminal charges against the responsible individual(s) occurred in 58.2% of cases. Conclusions Pediatric fatalities due to being left in motor vehicles most commonly occur when a caregiver leaves a child unknowingly in a home parking area. These fatalities occur most often in Texas, Florida, and California. Responsible individuals are frequently charged with a crime.Objectives This study aimed to evaluate patients who presented to the pediatric emergency department with an apparent life-threatening event (ALTE) to (1) determine if these patients would meet the criteria for brief resolved unexplained event (BRUE), a new term coined by the American Academy of Pediatrics in May, 2016; (2) risk stratify these patients to determine if they meet the BRUE low-risk criteria; and (3) evaluate outcomes of patients meeting the criteria for BRUE. Methods We conducted a retrospective chart review of patients who presented to a large urban academic center pediatric emergency department with an ALTE from January 2013 to May 2015 (before the publication of the BRUE guideline). Children ≤12 months of age were identified by the International Classification of Diseases, Ninth/Tenth Revision. Two physician reviews were performed to determine if patients met the ALTE diagnostic criteria. Data were then extracted from these charts to complete objectives. link2 Results Seventy-eight patients met the diagnostic criteria for ALTE. Only 1 of those patients met the diagnostic criteria for BRUE, but not for low-risk BRUE. This patient underwent an extensive inpatient evaluation and was eventually discharged after monitoring with a benign diagnosis. Most patients did not meet the criteria for BRUE because the event was not unexplained. Conclusions Only 1 patient who presented to the ED with ALTE met the criteria for BRUE, and this patient did not meet the low-risk criteria. This study corroborates previous research on BRUE and continues to highlight the importance of conducting a thorough history and physical examination on all patients presenting to the ED with concerning events.Objective To review outcomes of stapes surgery in patients with concurrent otosclerosis and superior semicircular canal dehiscence. Study design Retrospective case series. Setting Tertiary referral center. Patients Patients with concurrent otosclerosis and superior canal dehiscence, confirmed by computed tomography (CT) imaging. Intervention(s) Stapes surgery for conductive hearing loss. link3 Main outcome measure(s) Postoperative air-bone gap (ABG), as well as the number of patients in whom surgery was deemed successful (postoperative ABG less then 10 dB HL). Results Five patients with superior canal dehiscence and concomitant otosclerosis who underwent surgical repair were identified. Mean preoperative ABG was 29.0 ± 6.4 dB HL. Mean postoperative ABG was 13.0 ± 13 dB HL. Three patients (60%) had a successful outcome, defined as postoperative ABG less than 10. One patient experienced unmasking of superior canal dehiscence vestibular symptoms. Conclusions Patients with concurrent otosclerosis and superior canal dehiscence appear to have a lower likelihood of successful hearing restoration following stapes surgery.