PREDICTING ACTIVE FOOT CONTACT IN THE ACCELERATION PHASE OF ATHLETIC SPRINTING THROUGH ACCELEROMETER MEASUREMENTS

Active foot contact (absence of a braking impulse) during the acceleration phase of athletic sprinting is associated with the motion of the foot before touchdown (TD). Since the identification of braking impulses through force plate measurements is cost-expensive, the aim of this study was to develop a machine learning algorithm to predict active foot contact occurrences based on ankle-mounted accelerometer measurements. Ten recreationally active athletes (three females, seven males) performed 30 sprint-block-starts each, which were used as input to the machine learning model. Model performance was assessed by the AUC for both validation (AUC = 0.96) and testing (AUC = 0.94). It is therefore possible to predict active foot contact occurrence by a machine learning algorithm solely based on ankle-mounted accelerometer measurement data

JOINT SPECIFIC MECHANICAL POWER DURING VERTICAL JUMPS OF ELITE BOBSLEIGH ATHLETES

The purpose of the study was to quantify jumping mechanics of elite male bobsleigh athletes (N=10; 28?3 yrs; 193?5 cm; 99?8 kg) performing two different kinds of vertical jumps (squat and countermovement). Kinetics and kinematics were measured with two force platforms (one per leg, 1080 Hz) and eight high-speed infrared cameras sampled at 120 Hz. Detection of the joint specific mechanical power generation pattern between legs and across athletes was realized via inverse-dynamic calculation. The results show an average jumping height of about 50 cm, which is associated with average body mass of almost 100 kg. An average joint specific contribution of mechanical power generation during squad and countermovement jumps could be determined close to one third per joint (hip, knee, ankle)

DIFFERENCES BETWEEN TAKE-OFF BEHAVIOR DURING VERTICAL JUMPS AND TWO ARTISTIC ELEMENTS

The present study analysed the possible application of vertical jumps as a diagnostic tool for the acrobatic elements backward somersault (6s) and Menichelli (MEN). Therefore, 14 female gymnasts of the German national squad performed dassical vertical jumps (CMJ, SJ, DJ), backward somersaults and Menichellis during a diagnostic camp at the German Research Centre of Elite Sport (momentum). Kinematic and kinetic parameters were captured by a 30-motion capture system and two force plates. Take off velocities of the CMJ and backward somersault showed significant correlations (r=0.86). Besides possible predictions for take4ff velocity of BS performing CMJ, findings did not address execution of MEN. Concerning training purposes, vertical jumping does not affect performance characteristics of acrobatic elements

DETERMINANTS OF ACCELERATION PERFORMANCE IN ELITE FEMALE SPRINTERS

The purpose of this study was to explore the determinants of performance in the early acceleration phase (first four meters) in nine elite female sprinters. Acceleration performance was quantified using a modified version of the normalized average horizontal block power. Ground reaction forces were collected using an instrumented starting block and three force plates. In addition, full body kinematics were captured using an optoelectronic motion capture system. The results indicate that a starting technique facilitating a horizontal push-off direction and force application with short contact times is beneficial for starting performance. This might be achieved through a greater forward lean of the body. Previously proposed beneficial effects of an active touchdown of the foot could not be confirmed in the present study

JOINT WORK OF THE TAKE-OFF LEG DURING ELITE HIGH JUMP

The purpose of the study was to evaluate kinematics and kinetics in elite high jumpers and to estimate joint work of the lower extremity with a custom-modified full-body model. Motions of seven male athletes (personal best 2.24 ± 0.06 m) during jumping were filmed with 19 Infrared-Highspeed-Cameras and ground reaction forces were captured with a force plate. The results show that knee joint energy absorption is twice as much as at the ankle joint (p 0.05) in energy generation between the knee and ankle joint, but the ankle joint generates more energy than it absorbs (p < 0.05). The problem-solving approach to raise the center of mass to 2.10 m was different between the jumpers

Sprint start kinetics of amputee and non-amputee sprinters

The purpose of this study was to explore the relationship between the forces applied to the starting blocks and the start performances (SPs) of amputee sprinters (ASs) and non-amputee sprinters (NASs). SPs of 154 male and female NASs (100-m personal records [PRs], 9.58–14.00 s) and 7 male ASs (3 unilateral above knee, 3 unilateral below knee, 1 bilateral below knee; 100 m PRs, 11.70–12.70 s) with running specific prostheses (RSPs) were analysed during full-effort sprint starts using instrumented starting blocks that measured the applied forces in 3D. Using the NAS dataset and a combination of factor analysis and multiple regression techniques, we explored the relationship between force characteristics and SP (quantified by normalized average horizontal block power). Start kinetics were subsequently compared between ASs and NASs who were matched based on their absolute 100 m PR and their 100 m PR relative to the world record in their starting class. In NASs, 86% of the variance in SP was shared with five latent factors on which measured parameters related to force application to the rear and front blocks and the respective push-off directions in the sagittal plane of motion were loaded. Mediolateral force application had little influence on SP. The SP of ASs was significantly reduced compared to that of NASs matched on the basis of relative 100-m PR (−33.8%; d = 2.11, p < 0.001), while a non-significant performance reduction was observed when absolute 100-m PRs were used (−17.7%; d = 0.79, p = 0.09). These results are at least partially explained by the fact that force application to the rear block was clearly impaired in the affected legs of ASs

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase&nbsp;1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation&nbsp;disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age&nbsp; 6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score&nbsp; 652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc&nbsp;= 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N&nbsp;= 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in&nbsp;Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in&nbsp;Asia&nbsp;and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701