Rony Ibrahim
@qu.edu.qa
Assistant Professor of Biomechanics at the department of physical education and sport science
Qatar University
EDUCATION
PhD in Biomechanics
RESEARCH INTERESTS
Biomechanics, Modelling, Simulation, Kinematics, Kinetics, electromyography, Sports, Exercise, Health
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Lina Majed, Rony Ibrahim, Merilyn Jean Lock, and Georges Jabbour
Frontiers Media SA
Walking is the most accessible and common type of physical activity. Exercising at one’s self-selected intensity could provide long-term benefits as compared to following prescribed intensities. The aim of this study was to simultaneously examine metabolic, perceptual, spatiotemporal and stability parameters at an absolute 3 km·h−1 speed range around the individual preferred walking speed (PWS). Thirty-four young sedentary adults (18 women) volunteered to walk at seven speeds relative to their PWS in 3-min trials interspaced with 3-min rest intervals. Results indicated a significant main effect of speed on all studied variables. While metabolic, perceptual and spatiotemporal values were sensitive to the smallest change in speed (i.e., 0.5 km·h−1), a significant increase in the rate of carbohydrate oxidation and decrease in %fat oxidation were only observed at speeds above PWS. Results also revealed significantly higher coefficients of variation for stride characteristics at speeds below PWS only. Moreover, analyses of best fit models showed a quadratic relationship between most variables and speed, with the exceptions of metabolic cost of transport, rating of perceived exertion and stride duration that changed exponentially with speed. PWS coincided with optimized mechanical efficiency, fuel oxidation and gait stability. This indicated that walking below PWS decreased both mechanical efficiency and stability of gait, while walking above PWS increased carbohydrate oxidation. Those factors seem to play an important role as determinants of PWS. We suggest that walking at PWS may provide benefits in terms of fat oxidation while optimizing gait stability.
Connor J.M. Holdback, Rony Ibrahim, David S. Haydon, Ross A. Pinder, Paul N. Grimshaw, and Richard M. Kelso
Human Kinetics
This research provides a review of seated shot put alongside new data from the Tokyo 2020 Paralympic Games with the aim to understand the latest trends in equipment within a recently established rule set and how key equipment variables may impact performance for athletes in different classifications. First, a review of the literature found that the throwing pole is a key equipment aid that is not well understood, in part due to limitations in testing design. New data from the 2020 Paralympic Games showed inconsistent trends for the use of the throwing pole among athletes, particularly in transitionary classes (F33–34 and F54–55). A two-way analysis of variance found a main effect of classification on performance (p < .001), as well as an interaction effect between pole use and classification on performance (p < .05). Notably, pole users are seen to perform better than non–pole users in Class F32 (p < .05).
Monoem Haddad, Zied Abbes, Rony Ibrahim, Zlatan Aganovic, Khalid Bibi, and Johnny Padulo
MDPI AG
Impaired balance is associated with an increased risk of lower extremity injuries. The purpose of this study was to investigate the relationship between age, anthropometric measurement, and asymmetry index (AI) in an adolescent high school population. Twenty-six male students (15 ± 1.0 years) were randomly selected. Body composition, measurements of vertical jump height using a countermovement jump test (CMJ), and dynamic single stance balance using the Y-balance test (YBT), were collected over 4 weeks. Hierarchical multiple linear regression analyses were used as dimension reduction techniques in four different blocks to determine valid predictors for AIs. In the first regression analysis, controlling for age, body mass, height, and body mass index (BMI), the regression coefficient (B = 0.383, 95% confidence interval [CI] [0.088, 0.679], p < 0.05) associated with body fat indicated that with each additional unit of body fat, the YBT AI increased by 0.383 units. In the second regression analysis, controlling for age, body mass, and BMI, the regression coefficients associated with height (B = −1.692, 95% CI [−3.115, −0.269], p < 0.05] and body fat percentage (B = 0.529, 95% CI [0.075, 0.983], p < 0.05) indicated that with each additional unit of height or body fat percentage, the CMJ AI decreased by 1.692 units and increased by 0.529 units. Grouping participants based on body fat percentage had a significant effect on the AIs (p < 0.05) of the CMJ and YBT. The AI of the CMJ was 15% higher, and that of the YBT was 7% higher in non-obese students than obese students. These findings contribute to the knowledge of the local community and the emerging body of literature on motor skills and competence related to weight in this population.
Georges Jabbour, Rony Ibrahim, and Nicola Bragazzi
Frontiers Media SA
This systematic review summarizes current evidence on the relation between preoperative physical activity (PA) levels with bariatric surgery (BS) outcomes and on the beneficial role of preoperative exercise/PA program among BS candidates. This systematic review suggests that candidate patients accumulating the preoperative PA level improved several BS outcomes. These improvements were reported mainly for anthropometric and cardiometabolic parameters and physical function. Observed improvements manifested during a distinct period of time in response to a wide variety of exercise programs. Evidence on the preoperative PA level as well as on preoperative exercise implementation on BS outcomes is advocated despite the small number of participants and lack of control. Thus, further studies are required to explore the most effective and suitable form of exercise prescription prior to BS while considering physical and psychological limitations of obese patients.
Rony Ibrahim, Vosse de Boode, Idsart Kingma, and Jaap H. van Dieën
Informa UK Limited
The goal of this study was to evaluate the technical and physical adaptations to a data-driven 12-weeks training programs that incorporated recent findings from biomechanical studies on the diving save. Three-dimensional kinematics and kinetics were collected and analysed from 11 goalkeepers diving to save high (190 cm) and low (30 cm) balls at three occasions: twice pre-training and once post-training. Intraclass correlation coefficients were found to be excellent (>.7) between the pre-training tests, and there were no learning effects between them. Three-way repeated measures ANOVAs were used to evaluate the effect of dive side, dive height and training programme (pre- vs post-training) on normalised dive time [s·m-1], average centre of mass (CoM) horizontal velocity [m·s-1] and total power [W] generated at contralateral and ipsilateral push-offs. Compared to pre-training, the post-training results revealed greater average CoM horizontal velocity (+.82 m·s-1, 95% CI = [.62, 1.02]) and power (+523 W, 95% CI = [313, 732]) at contralateral push-off. These adaptations caused a reduction in normalised dive time (- .008 s·m-1, 95% CI = [- .014, - .002]) at post-training compared to pre-training. This translates to 42 cm more goal area coverage in a penalty situation.
Rony Ibrahim, Idsart Kingma, Vosse de Boode, Gert S. Faber, and Jaap H. van Dieën
Frontiers Media SA
Identifying the optimal preparatory posture of football goalkeepers can be very relevant for improving goalkeepers' diving save performance, and coaching practices of technical and strength and conditioning coaches. This study aimed to analyse the effect of different starting stance widths and knee flexion angles on movement time, center of mass (CoM) trajectory and velocity in goalkeepers' diving saves. Ten elite goalkeepers performed dives from preferred (PT) and imposed postures, by altering knee angle (45, 75, and 90°) and stance width (50, 75, and 100% of leg length) independently, at the starting position. Repeated measures ANOVA showed a main effect of preparatory posture on dive time (p < 0.01). Pairwise comparisons showed that the fastest dive movement time was observed when goalkeepers started from a stance width of 75% (SW75). CoM traveled a larger distance between contralateral and ipsilateral peak ground reaction forces in SW75 than PT (p < 0.05). The goalkeepers were also more efficient in SW75, as a smaller countermovement and vertical velocity range were observed during high and low dives, respectively, from SW75 than PT (p < 0.05). Thus, diving from a position with wider stance width than the preferred one leads to shorter movement time, and a faster and more direct CoM trajectory toward the ball.
Rony Ibrahim, Idsart Kingma, Vosse A de Boode, Gert S. Faber, and Jaap H. van Dieën
Informa UK Limited
ABSTRACT Kinetics and full body kinematics were measured in ten elite goalkeepers diving to save high and low balls at both sides of the goal, aiming to investigate their starting position, linear and angular momentum, and legs' contribution to end-performance. Our results showed that goalkeepers adopted a starting position with a stance width of 33 ± 1% of leg length, knee flexion angle of 62 ± 18° and hip flexion angle of 63 ± 18°. The contralateral leg contributed more than the ipsilateral leg to COM velocity (p < 0.01), both for the horizontal (2.7 ± 0.1 m·s−1 versus 1.2 ± 0.1 m·s−1) and for the vertical component (3.1 ± 0.3 m·s−1 versus 0.4 ± 0.2 m·s−1). Peak horizontal and peak angular momenta were significantly larger (p < 0.01) for low dives than for high dives with a mean difference of 55 kg·m·s−1 and 9 kg·m2·s−1, respectively. In addition, peak vertical momentum was significantly larger (p < 0.01) for high dives with a mean difference between dive heights of 113 kg·m·s−1. Coaches need to highlight horizontal lateral skills and exercises (e.g. sideward push-off, sideward jumps), with emphasis on pushing-off with the contralateral leg, when training and assessing goalkeeper’s physical performance.
Rony Ibrahim, Gert S. Faber, Idsart Kingma, and Jaap H. van Dieën
Informa UK Limited
Abstract Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training.