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1
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Biomechanical Responds of Instep Kick between Different Positions in Professional Soccer Players

100%
Khorasani M., Osman N., Yusof A.
Journal of Human Kinetics
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2009
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vol. 22
21-27
EN
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.
2
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Electromyography Assessments of the Vastus Medialis Muscle during Soccer Instep Kicking between Dynamic and Static Stretching

100%
Amiri-Khorasani M., Osman N., Yusof A.
Journal of Human Kinetics
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2010
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vol. 24
35-42
EN
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.
3
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Bilateral and Unilateral Asymmetries of Isokinetic Strength and Flexibility in Male Young Professional Soccer Players

100%
Daneshjoo A., Rahnama N., Mokhtar A. H., Yusof A.
Journal of Human Kinetics
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2013
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vol. 36
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issue 1
45-53
EN
This study investigated bilateral and unilateral asymmetries of strength and flexibility in male young professional soccer players. Thirty-six soccer players (age: 18.9 ± 1.4 years) participated in this study. A Biodex Isokinetic Dynamometer was used to assess the hamstring and quadriceps strength at selected speeds of 60°/s, 180°/s and 300°/s. Hip joint flexibility was measured using a goniometer. No difference was observed in conventional strength ratio, dynamic control ratio and fast/slow speed ratio between the dominant and non-dominant legs (p>0.05). All but one of the players (97.2%) had musculoskeletal abnormality (bilateral imbalance > 10%) in one or more specific muscle groups. The dominant leg had greater hip joint flexibility compared with the non-dominant leg (108.8 ± 10.7° versus 104.6 ± 9.8°, respectively). The findings support the hypothesis that physical performance and movement pattern experienced during soccer playing may negatively change the balance of strength in both legs (bilateral strength balance), but not on the same leg of the young male professional soccer players. The results can be helpful for trainers and coaches to decide whether the players need to improve their balance and strength which in turn may prevent injury. It is suggested that in professional soccer training, quadriceps and hamstrings muscle strength, as well as hip joint flexibility should not be overlooked.
4
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Effectiveness of Injury Prevention Programs on Developing Quadriceps and Hamstrings Strength of Young Male Professional Soccer Players

100%
Daneshjoo A., Rahnama N., Mokhtar A. H., Yusof A.
Journal of Human Kinetics
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2013
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vol. 39
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issue 1
115-125
EN
Muscular strength is an important factor which is crucial for performance and injury prevention in most sports. The purpose of this study was to evaluate the effects of the FIFA’s Medical Assessment and Research Centre 11+ and HarmoKnee injury prevention programs on knee strength of young professional male soccer players. Thirty-six soccer players (age: 18.9 ± 1.4 years) were divided equally into three groups; the 11+, HarmoKnee and control groups. The programs were performed for 24 sessions. Hamstring and quadriceps strength was measured using the Biodex System 3 at 30°, 60° and 90° of knee flexion. The 11+ increased quadriceps strength in the dominant leg by 19.7% and 47.8% at 60°and 90° knee flexion, respectively, and in the non-dominant leg by 16%, 35.3% and 78.1 % at 30°, 60° and 90° knee flexion, respectively. The HarmoKnee group, however, showed increased quadriceps strength only at 90° i.e., by 85.7% in the dominant leg and 73.8% in the non-dominant leg. As for hamstring strength, only the 11+ group demonstrated an increment by 24.8% and 19.8% at 30° and 60° knee flexion in the dominant leg, and in the nondominant leg, by 28.7% and 13.7% at 30° and 60° knee flexion, respectively. In conclusion, both warm-up programs improve quadriceps strength. The 11+ demonstrated improvement in hamstring strength while the HarmoKnee program did not indicate any improvement. We suggest adding eccentric hamstring components such as Nordic hamstring exercise to the HarmoKnee program in order to enhance hamstring strength.
5
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Kinematics Analysis: Number of Trials Necessary to Achieve Performance Stability during Soccer Instep Kicking

100%
Amiri-Khorasani M., Osman N., Yusof A.
Journal of Human Kinetics
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2010
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vol. 23
15-19
EN
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.
6
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Stability Ball Training on Lower Back Strength has Greater Effect in Untrained Female Compared to Male

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Sukalinggam C., Sukalinggam G., Kasim F., Yusof A.
Journal of Human Kinetics
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2012
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vol. 33
133-141
EN
The purpose of this study was to evaluate the effectiveness of short-term stability ball (SB) training on males and females by comparing the strength changes produced in the core muscles. Forty-two previously untrained subjects, mean age = 23.62 ± 2.89 years were matched by their maximum strength (back strength: male = 190-200 kg, female = 45-50 kg and abdominal strength: male = 110-120 kg, female = 35-40 kg 1RM) and randomly placed in either one of these 3 groups; unstable SB group (n = 14), stable floor group (n = 14) and control group (n = 14) who did no exercise. SB training showed greatest improvement (p < 0.001) in back and abdominal strength (25.79 % and 29.51 % respectively), compared with the gain in floor training (FT) back and abdominal strength (10.28 % and 8.47 % respectively). Untrained female subjects achieved a higher percentage of improvement in strength compared to males in both back and abdominal muscles, and this is most evident in the SB training group. It is apparent that performing core training exercises on unstable surfaces stressed the musculature, possibly activating the neuro-adaptive mechanisms that led to the early phase gains in strength.
7
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Electromyographic Activity and Applied Load During High Intensity Elastic Resistance and Nautilus Machine Exercises

88%
Aboodarda S., Shariff M., Muhamed A., Ibrahim F., Yusof A.
Journal of Human Kinetics
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2011
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vol. 30
5-12
EN
This study was designed to quantify and compare Electromyographic activity (EMG) and applied load in quadriceps muscle within performing high intensity knee extension exercises by Elastic Resistance (ER) and Nautilus Machine (NM). Sixteen male and female subjects (22.4 ± 4.7 yrs) completed 8 RM seated knee extension by NM, elastic tubing with original length (E0) and elastic tubing with 30% decrement of original length (E30). The mean value of EMG and external force were calculated and synchronized across various segments of motion for the three modes of training. The results demonstrated that in the early concentric and late eccentric segments of contraction, NM elicited significantly higher muscle activation than both E30 and E0 (p < 0.05). However, in the mid-concentric and mid-eccentric as well as late concentric and early eccentric segments no significant differences were observed between NM and E30. These findings supported the approach that developing external recoil of force in ER device by reducing 30% of initial length of elastic material can offer similar neuromuscular activation compared with NM. On this basis, E30 can be suggested as an affordable and non-gym based exercise device which has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of athletes.
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