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Single-leg landings with or without subsequent jumping are frequently used to evaluate landing biomechanics. The purpose of this study was to investigate the effects of subsequent jumping on the external knee abduction moment and trunk and hip biomechanics during single-leg landing. Thirty young adult female participants performed a single-leg drop vertical jumping (SDVJ; landing with subsequent jumping) and single-leg drop landing (SDL; landing without subsequent jumping). Trunk, hip, and knee biomechanics were evaluated using a 3-dimensional motion analysis system. The peak knee abduction moment was significantly larger during SDVJ than during SDL (SDVJ 0.08 [0.10] N·m·kg−1·m−1, SDL 0.05 [0.10] N·m·kg−1·m−1, P =.002). The trunk lateral tilt and rotation angles toward the support-leg side and external hip abduction moment were significantly larger during SDVJ than during SDL (P <.05). The difference in the peak hip abduction moment between SDVJ and SDL predicted the difference in the peak knee abduction moment (P =.003, R2 =.252). Landing tasks with subsequent jumping would have advantages for evaluating trunk and hip control as well as knee abduction moment. In particular, evaluating hip abduction moment may be important because of its association with the knee abduction moment. [ABSTRACT FROM AUTHOR]

Objective To estimate the effect of airline travel restrictions on the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) importation. Methods We extracted passenger volume data for the entire global airline network, as well as the dates of the implementation of travel restrictions and the observation of the first case of coronavirus disease (COVID-19) in each country or territory, from publicly available sources. We calculated effective distance between every airport and the city of Wuhan, China. We modelled the risk of SARS-CoV-2 importation by estimating survival probability, expressing median time of importation as a function of effective distance. We calculated the relative change in importation risk under three different hypothetical scenarios that all resulted in different passenger volumes. Findings We identified 28 countries with imported cases of COVID-19 as at 26 February 2020. The arrival time of the virus at these countries ranged from 39 to 80 days since identification of the first case in Wuhan. Our analysis of relative change in risk indicated that strategies of reducing global passenger volume and imposing travel restrictions at a further 10 hub airports would be equally effective in reducing the risk of importation of SARS-CoV-2; however, this reduction is very limited with a close-to-zero median relative change in risk. Conclusion The hypothetical variations in observed travel restrictions were not sufficient to prevent the global spread of SARS-CoV-2; further research should also consider travel by land and sea. Our study highlights the importance of strengthening local capacities for disease monitoring and control. [phrase omitted] [phrase omitted] Objectif Evaluer les effets des restrictions de voyage par voie aerienne sur le risque d'importer le coronavirus 2 du syndrome respiratoire aigu severe (SARS-CoV-2). Methodes Nous avons preleve les donnees sur le volume de passagers pour l'ensemble du reseau aerien dans le monde, ainsi que les dates de mise en reuvre des restrictions de voyage et l'observation du premier cas de maladie a coronavirus (COVID-19) dans chaque pays ou territoire, a partir de sources accessibles au public. Nous avons calcule la distance reelle entre chaque aeroport et la ville de Wuhan, en Chine. Nous avons modelise le risque d'importation du SARS-CoV-2 en estimant sa probabilite de survie, la periode mediane d'importation etant exprimee en fonction de la distance reelle. Nous avons determine l'evolution relative du risque d'importation selon trois scenarios hypothetiques, qui ont tous debouche sur differents volumes de passagers. Resultats Nous avons identifie 28 pays ayant importe des cas de COVID-19 au 26 fevrier 2020. La date d'arrivee du virus dans ces pays s'est etalee sur une periode de 39 a 80 jours depuis la detection du premier cas a Wuhan. Notre analyse de l'evolution relative du risque a indique que les strategies de reduction du nombre global de passagers et de restriction des voyages dans 10 aeroports de premiere categorie auraient eu le meme niveau d'efficacite dans la diminution du risque d'importation du SARS-CoV-2. Neanmoins, cette diminution est tres limitee, avec une evolution relative mediane du risque proche de zero. Conclusion Les variations hypothetiques presentes dans les restrictions de voyage observees n'etaient pas suffisantes pour eviter la propagation du SARS-CoV-2 aux quatre coins de la planete. Les futures recherches a ce propos devraient egalement tenir compte des deplacements par voie terrestre et maritime. Notre etude souligne l'importance de renforcer les capacites locales de surveillance et de controle des maladies. [phrase omitted] Objetivo Estimar el efecto de las restricciones a los viajes en avion sobre el riesgo de importacion del coronavirus tipo 2 del sindrome respiratorio agudo grave (SARS-CoV-2). Metodos Se obtuvieron los datos sobre el volumen de pasajeros de toda la red global de aerolineas, asi como las fechas en las que se implementaron las restricciones de viaje y la observacion del primer caso de la enfermedad del coronavirus (COVID-19) en cada pais o territorio, a partir de fuentes a disposicion del publico. Se calculo la distancia efectiva entre cada aeropuerto y la ciudad de Wuhan, China. Se diseno un modelo del riesgo de importacion del SARS-CoV-2 al estimar la probabilidad de supervivencia, que indica el tiempo medio de importacion en funcion de la distancia efectiva. Se calculo el cambio relativo en el riesgo de importacion bajo tres escenarios hipoteticos diferentes que arrojaron valores distintos sobre el volumen de pasajeros. Resultados Se identificaron 28 paises con casos importados de la COVID-19 al 26 de febrero de 2020. El tiempo de llegada del virus a estos paises oscilo entre 39 y 80 dias desde la identificacion del primer caso en Wuhan. El analisis que se expone aqui sobre el cambio relativo del riesgo indico que las estrategias orientadas a reducir el volumen de pasajeros a nivel mundial y a imponer restricciones a los viajes en otros 10 aeropuertos centrales serian igualmente efectivas para reducir el riesgo de importacion del SARS-CoV-2; sin embargo, esta reduccion es muy limitada si se tiene en cuenta que el cambio relativo medio del riesgo es casi nulo. Conclusion Las variaciones hipoteticas de las restricciones de viaje que se observaron no fueron suficientes para impedir la propagacion global del SRAS-CoV-2; ademas, se deberia analizar la posibilidad de viajar por tierra y por mar en las investigaciones futuras. Este estudio destaca la importancia de fortalecer la capacidad local para monitorear y controlar la enfermedad., Introduction As of 25 May 2020, 347 697 deaths resulting from 5 392 654 laboratory-confirmed infectious cases of coronavirus disease (COVID-19) had been reported. (1,2) Global travel contributed to the [...]

Associations among hip motions, knee abduction and internal rotation motion during a drop vertical jump (DVJ), which increases the risk of anterior cruciate ligament injury, remain unclear. The purpose of this study was to examine associations among knee abduction, internal rotation and hip joint motions during a DVJ. Fifty-seven young female participants performed a DVJ from a 30-cm height. Hip and knee kinematics and kinetics were analysed using a three-dimensional motion analysis system and force plates. Multiple regression analysis showed that peak knee abduction angle was negatively associated with knee internal rotation and hip internal rotation excursions from initial contact (IC) to peak knee flexion, and positively associated with peak knee abduction moment (R2 = 0.465, P< 0.001). Peak knee internal rotation angle was negatively associated with the hip flexion excursion from IC to peak knee flexion and peak hip adduction moment (R2 = 0.194, P= 0.001). In addition, hip internal rotation excursion was negatively associated with knee abduction and internal rotation excursion from IC to 50 ms after IC. To avoid a large knee abduction and internal rotation motion during jump-landing training, it might be beneficial to provide landing instructions to avoid a large hip external rotation motion. [ABSTRACT FROM AUTHOR]

within 50 milliseconds of initial contact, but are limited by imprecise timing and nondirect data acquisition. The objective of this study was to precisely quantify the timing associated with ligament strain during simulated landing and injury events. The hypotheses tested were that the timing of peak strain following initial contact would differ between ligaments and that peak strain timing would be independent of the injury-risk profile emulated during simulated landing. A mechanical impact simulator was used to perform landing simulations based on various injury-risk profiles that were applied to each specimen in a block-randomized order. The ACL and medial collateral ligament were instrumented with strain gauges that recorded continuously. The data from 35 lower-extremity specimens were included for analysis. Analysis of variance and Kruskal--Wallis tests were used to determine the differences between timing and profiles. The mean time to peak strain was 53 (24) milliseconds for the ACL and 58 (35) milliseconds for the medial collateral ligament. The time to peak ACL strain ranged from 48 to 61 milliseconds, but the timing differences were not significant between profiles. Strain timing was independent of injury-risk profile. Noncontact ACL injuries are expected to occur between 0 and 61 milliseconds after initial contact. Both ligaments reached peak strain within the same time frame. [ABSTRACT FROM AUTHOR]