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  • Author: Mohammadtaghi Khorasani x
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Mohammadtaghi Amiri-Khorasani, Noor Osman and Ashril Yusof

Kinematics Analysis: Number of Trials Necessary to Achieve Performance Stability during Soccer Instep Kicking

The purpose of this study was to investigate the stability of kinematics responses related to stretch shortening cycle (SSC) during 10 consecutive soccer instep kicks. The kicking motions of dominant legs were captured from five experienced adult male soccer players (body height: 184.60 ± 4.49 cm; body mass: 80 ± 4.24 kg; age: 25.60 ± 1.14 years) using a three-dimensional infra-red high speed camera at 200 Hz. Some important kinematic parameters include eccentric angular velocity (AVe), concentric angular velocity (AVc), duration of eccentric (Te), and duration of concentric (Tc) at forward and impact phases selected to analyses. The AVe result of the sixth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p ≤ 0.001). The AVc result of the fifth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p ≤ 0.001). The Te result of the fourth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p ≤ 0.011). The Tc result of the fifth kick, relative to the first kick, was significantly lower when compared to the other kicks (p ≤ 0.029). We concluded that 5 consecutive kicks are adequate to achieve high kinematic responses related to SSC.

Open access

Mohammadtaghi Khorasani, Noor Osman and Ashril Yusof

Biomechanical Responds of Instep Kick between Different Positions in Professional Soccer Players

The purpose of this study was to investigate some selected biomechanical characteristics of lower extremity between professional soccer defenders, midfielders and strikers. The kicking motions of dominant legs were captured from fifteen Olympic professional soccer players; (height: 181.93 ± 7.03 cm; mass: 70.73 ± 10.85 kg; age: 20.8 ± 0.77 years), volunteered to participate in this study, using four digital video cameras. There were significant differences between midfielders and defenders in (1) lower leg angular velocity (p ≤ 0.001), (2) thigh angular velocity (p ≤ 0.001), (3) lower leg net moment (p ≤ 0.001), (4) thigh net moment (p ≤ 0.001), and (5) ball velocity (p ≤ 0.012). There were significant differences between midfielders and strikers in lower leg net moment (p ≤ 0.001). There were significant differences between strikers and defenders in; (1) lower leg angular velocity (p ≤ 0.001), (2) thigh angular velocity (p ≤ 0.001), (3) lower leg net moment (p ≤ 0.001), (4) thigh net moment (p ≤ 0.001), and (5) ball velocity (p ≤ 0.024). In conclusion, midfielders can perform soccer instep kicking strongly and faster than defenders and there is, however, no significant difference between midfielders and strikers, but midfielders' ball velocity is higher than strikers' ball velocity.

Open access

Mohammadtaghi Amiri-Khorasani, Noor Osman and Ashril Yusof

Electromyography Assessments of the Vastus Medialis Muscle during Soccer Instep Kicking between Dynamic and Static Stretching

The purpose of this study was to examine the effects of static and dynamic stretching within a pre-exercise warm-up on vastus medialis muscle activity during instep kicking and ball velocity in soccer players. The kicking motions of dominant legs were captured from using six synchronized high-speed infra-red cameras at 200 Hz and Electromyography at 100 Hz. There was significant difference in vastus medialis activity after dynamic stretching relative to no stretching condition (0.12 ± 0.06 mV) versus static stretching relative to no stretching condition (-0.21 ± 0.10 mV) with p < 0.001). In addition, there was also a significant difference in ball velocity after dynamic stretching relative to no stretching condition (4.53 ± 2.10 m/s) versus static stretching relative to no stretching condition (-1.48 ± 2.43 m/s) with p < 0.003. We concluded that dynamic stretching during the warm-up, as compared to static stretching, is probably more effective as preparation for optimal muscle activity and finally have high ball velocity which is required in soccer.

Open access

Mohammadtaghi Amiri-Khorasani and Eleftherios Kellis

Abstract

The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. -1.45%, p < 0.001), RF (37.5% vs. -8.33%, p < 0.001), VM (12% vs. - 12%, p < 0.018), and VL EMG activity (20% vs. -6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching.

Restricted access

Mohammadtaghi Amiri-Khorasani, Julio Calleja-Gonzalez and Mansooreh Mogharabi-Manzari

Abstract

The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up, on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height: 177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49 years) was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min stretching program (except for the no-stretching protocol), and 2 min rest periods, followed by the 10 and 20 m sprint test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic stretching compared with static, combined, and no-stretching protocols. There were also significant differences between the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more force for a faster execution.