Barbell back squat:How do resistance bands affect muscle activation and knee kinematics?

ObjectivesThis study aimed to determine whether looped resistance bands affect knee kinematics and lower body muscle activation during the barbell back squat.MethodsTwenty-six healthy participants (13 female, 13 male) calculated their one repetition maximum (RM) prior to data collection. Each participant performed three squats at both 80% and 40% 1RM wearing a light resistance band, an extra-heavy resistance band and no resistance band.Vicon 3D motion analysis cameras were used to collect the kinematic data, and Delsys Trigno Lab wireless electromyography (EMG) system was used to measure vastus medialis, vastus lateralis, gluteus maximus, gluteus medius and biceps femoris muscle activity. Peak knee flexion angle, peak knee valgus angle and maximum tibial rotation values were examined. Peak EMG values were also analysed after being normalised and expressed as a percentage of maximum voluntary contraction (MVC).ResultsGluteus maximus (GM) activity is significantly increased when a resistance band is used during squatting. However, squatting with a resistance band is detrimental to knee kinematics as it leads to an increase in knee valgus angle and maximum tibial rotation angle. A direct correlation is recorded between an increase in resistance and an increase in these two angles.ConclusionsSquatting with resistance bands is likely to increase the risk of knee injury. Coaches and clinicians who already implement this technique are advised to remove resistance band squats from training and rehabilitation programmes. Further research evaluating the long-term effects of using resistance bands during the barbell back squat should be considered

Numerical Analysis of GDI Flash Boiling Sprays Using Different Fuels

[EN] Modeling the fuel injection process in modern gasoline direct injection engines plays a principal role in characterizing the in-cylinder mixture formation and subsequent combustion process. Flash boiling, which usually occurs when the fuel is injected into an ambient pressure below the saturation pressure of the liquid, is characterized by fast breakup and evaporation rates but could lead to undesired behaviors such as spray collapse, which significantly effects the mixture preparation. Four mono-component fuels have been used in this study with the aim of achieving various flashing behaviors utilizing the Spray G injector from the Engine Combustion Network (ECN). The numerical framework was based on a Lagrangian approach and was first validated for the baseline G1 condition. The model was compared with experimental vapor and liquid penetrations, axial gas velocity, droplet sizes and spray morphology and was then extended to the flash boiling condition for iso-octane, n-heptane, n-hexane, and n-pentane. A good agreement was achieved for most of the fuels in terms of spray development and shape, although the computed spray morphology of pentane was not able to capture the spray collapse. Overall, the adopted methodology is promising and can be used for engine combustion modeling with conventional and alternative fuels.This research was funded by Ministerio de Ciencia, Innovacion y Universidades grant number RTI2018-099706-B-I00 in the frame of the project Study of Primary Early Atomization using DNS and Optical Ultra-high resolution Techniques (SPREAD OUT). Additionally, the PhD student Rami Abboud has been funded by Ayudas para la formacion de profesorado universitario (FPU) program with reference FPU19/03838.Payri, R.; Marti-Aldaravi, P.; Abboud, R.; Bautista-Rodríguez, A. (2021). Numerical Analysis of GDI Flash Boiling Sprays Using Different Fuels. Energies. 14(18):1-23. https://doi.org/10.3390/en14185925123141

Immediate effect of kinesiology tape on ankle stability

BackgroundLateral ankle sprain is one of the most common musculoskeletal injuries, particularly among the sporting population. Due to such prevalence, many interventions have been tried to prevent initial, or further, ankle sprains. Current research shows that the use of traditional athletic tape can reduce the incidence of sprain recurrence, but this may be at a cost to athletic performance through restriction of motion. Kinesiology tape, which has become increasingly popular, is elastic in nature, and it is proposed by the manufacturers that it can correct ligament damage. Kinesiology tape, therefore, may be able to improve stability and reduce ankle sprain occurrence while overcoming the problems of traditional tape.AimTo assess the effect of kinesiology tape on ankle stability.Methods27 healthy individuals were recruited, and electromyography (EMG) measurements were recorded from the peroneus longus and tibialis anterior muscles. Recordings were taken from the muscles of the dominant leg during induced sudden ankle inversion perturbations using a custom-made tilting platform system. This was performed with and without using kinesiology tape and shoes, creating four different test conditions: barefoot(without tape), shoe(without tape), barefoot(with tape) and shoe(with tape). For each test condition, the peak muscle activity, average muscle activity and the muscle latency were calculated.ResultsNo significant difference (p>0.05) was found by using the kinesiology tape on any of the measured variables while the wearing of shoes significantly increased all the variables.ConclusionKinesiology tape has no effect on ankle stability and is unable to nullify the detrimental effects that shoes appear to have

مدى توافر أبعاد التوجه الإستراتيجي في القطاع المصرفي

هدفت هذه الدِّراسة إلى تحديد مدى توافر أبعاد التوجه الإستراتيجي: التوجه الريادي، التوجه نحو العملاء، التوجه نحو التكنولوجيا في فروع المصارف التجارية الخاصة في الساحل السوري, اعتمد الباحث في هذه الدراسة على المنهج الوصفي، الذي يقوم على وصف الظاهرة وصفا دقيقا وتحليلها للإجابة على أهداف الدراسة ومناقشة فرضياتها. أما بالنسبة لطرائق البحث تم تطوير استبانة من خلال اطلاع الباحث على الأدبيات المنشورة كأداة لجمع البيانات الأولية, وتمّ توزيع الدرجات على بنود الاستبانة وفقاً لمقياس ليكرت الخماسي, وقاد تمثلت عينة البحث بـــ110 مفردة من كادر العاملين في المصارف، ومن ثمَّ أجرى دراسة ميدانيَّة بغرض بيان هذه العلاقة. وقد خلصت الدِّراسة إلى إن إدارة المصارف لا تتقبل ولا تنفذ الأفكار التي لم يتم التفكير فيها مسبقاً، وليس لدى المصارف  استعداداً لتحمل المخاطرة من جراء تقديم خدمات جديدة ، وإن المصارف لا تقوم باستطلاع آراء العملاء لمعرفة رضاهم عن الخدمات المقدمة، وبلغ متوسّط إجابات أفراد العيّنة لمتغيّر التوجه نحو المنافسين2.984 ، وهو يدلّ على عدم توافر بعد التوجه نحو المنافسين كأحد أبعاد التوجه الإستراتيجي في القطاع المصرف

Volar plating:functional recovery of the pronator quadratus

PURPOSE: The pronator quadratus (PQ) is reflected in the surgical approach to the distal radius. This study explores the functional strength of PQ, 12 months after volar plating without repair of PQ. METHODS: A total of 135 patients were identified from our prospectively collected database. All volunteers had grip strength and pronation power tested in the treated and contralateral forearms at 45, 90 and 135 degrees of elbow flexion using a custom-built torque measuring device and hydraulic hand dynamometer to evaluate forearm pronation. RESULTS: Twenty-seven participants were included in the study. No significant difference was identified in mean peak pronation torque between the volar plated and non-treated forearms. Pronation strength was identified as being independent of angle of elbow flexion. Grip strength was correlated with forearm pronation showing no significant difference between groups. CONCLUSIONS: Our results suggest adequate long-term (15–32 months) functional recovery of the pronator quadratus after volar plating. LEVEL OF EVIDENCE: III

Effect of ball position on the risk of injury to the lower limb joints during the hockey sweep pass in women

ObjectivesThis study aimed to determine if ball position influences the risk of lower limb non-contact injury in hockey sweep pass. It also aimed to determine a ball position that minimises excessive strain placed on the lower limb joints of the lead leg during the sweep pass.MethodsA cohort of 18 female hockey-playing volunteers (age: 19.7±1.5 years; height: 165.5±5.4 cm; body mass: 66.4±7.0 kg) were recruited. Participants performed the sweep pass using three different ball positions: in front, in line with, and behind the heel of the lead (left) foot.Motion analysis and force plate data were collected. Moments and angles in all three planes of motion for the three main lower limb joints were then calculated using Vicon software. Results were statistically analysed using SPSS software.ResultsSignificant differences (p<0.05) were found between the three tested ball positions for the mean maximum angles and moments, and mean ranges of motion produced at the lead three main lower limb joints. Positioning the ball in line with the heel of the lead foot resulted in the lowest moments and angles when compared with the other two ball positions.ConclusionsThe results indicate that positioning the ball in line with the heel of the lead foot is recommended to minimise the risk of injury to the lower limb joints during the hockey sweep pass. It is hoped that these findings will result in this position being implemented by players new to hockey or those returning to the sport following injury