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  Access statistics : Table of Contents
   2015| July-December  | Volume 4 | Issue 2  
    Online since August 5, 2021

 
 
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ARTICLES
The Effects of Short-Duration Static Stretching of The Lower Extremities after Warm-Up Exercise on Endurance Running Performance
Kazuki Takizawa, Taichi Yamaguchi, Keisuke Shibata
July-December 2015, 4(2):37-49
Previous studies have shown that static stretching impairs running economy and endurance running performance. However, these studies have only examined the effects of long-duration static stretching, and the duration of the stretch is generally too long compared to the typical duration in actual practice. Hence, the purpose of this study is to investigate the effects of short-duration (20-second) static stretching of the lower extremities of athletes after a 15-minutes warm-up exercise on their endurance running performance. The subjects of this study comprise seven healthy, well-trained middle-distance or long-distance male runners (age: 21.3 ± 2.1 years, height: 170.3 ± 3.1 cm, weight: 60.0 ± 5.5 kg). Each subject ran on the treadmill at 90% VO2max until exhaustion after one of two warm-up procedures. The two warm-up procedures consist of 15-minute running at 70% VO2max (Warm-up), and 15-minute running at 70% VO2max and five static stretches of the lower extremities (Warm-up + static stretching). The running performance was evaluated based on the time to exhaustion. The results show that there are no significant differences in the time to exhaustion between the warm-up treatment (819.3 ± 230.6 s) and the warm-up and static stretching treatment (817.9 ± 213.7 s). The results suggest that endurance running performance is not affected by 20-second static stretches and there may be no need to carry out static stretches before endurance running if the duration is not too long.
[ABSTRACT]   Full text not available  [PDF]
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Psychological Profiles of Indonesian Elite Swimmers
Miftakhul Jannah, Olievia Prabandini Mulyana, Toho Cholik Muthohir
July-December 2015, 4(2):31-36
In Indonesia, sports psychology is one of the branches of psychology that plays a vital role in improving athletic performance and therefore, it is not confined within the boundaries of academic research. Even though a number of studies have been carried out in recent years on the psychological profiles of elite swimmers, there are only a few studies which provide empirical data on the psychological profiles of elite athletes. Owing to the importance of the relationship between the psychological characteristics and sports performance of athletes, the the objective of this study is to determine the psychological profiles of Indonesian elite swimmers. Two sets of factors are identified from a comprehensive literature review, namely motivational and emotional factors. However, based on the literature review, it is observed that the combination of motivational and emotional factors has not been investigated in most studies, particularly the relationship between these factors and the psychological characteristics of Indonesian elite swimmers. In this study, we identified the psychological characteristics of this specific group of athletes using personal interviews and focus group discussions with 14 Indonesian elite swimmers (comprising seven males and seven females) and eight coaches from the East Java Province. Based on the results, we conclude that that there are six psychological characteristics of Indonesian elite swimmers: (1) self-confidence, (2) optimism, (3) resilience, (4) hope, (5) emotional stability, and (6) motivation for achievement.
[ABSTRACT]   Full text not available  [PDF]
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Special Invited Paper: The Power of Cycling
Steve Stannard, Paul Macdermid, Matthew Miller, Phil Fink
July-December 2015, 4(2):1-8
One of the advantages of cycling exercise is that the rider is interfaced to a machine, and this exercise can be easily metered. Recent technological advances have made this metering easier and cheaper such that riders, sports scientists and coaches are able to record the external work done, and thus the net rate of mechanical work (power) during training and racing. Since external power is related to performance, the power requirements of competition can be observed and the training intensity can be prescribed. However, the ability to closely scrutinize power during training brings about a number of issues which need to be addressed. These issues include the accuracy and reliability of the meter, the relationship of the external work rate to the total physiological stress, and how training prescription through analysis by power may change the athlete-coach relationship.
[ABSTRACT]   Full text not available  [PDF]
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Aerodynamic Study of a Modern Sepak Takraw Ball Using Smoke Flow Visualization Technique
Abdul Syakir Abdul Mubin, Norhafizan Ahmad
July-December 2015, 4(2):19-30
It has been shown in previous studies that the flight trajectories of sports balls are influenced by their aerodynamic characteristics. These aerodynamic characteristics are primarily dependent on the physical shape and surface texture of the balls. Even though sepak takraw is well established as a sport, little is known regarding the aerodynamic characteristics of the sepak takraw ball, which has a rather complex shape and surface texture. Hence, the main objective of this research is to investigate the aerodynamic characteristics (specifically the drag and lift coefficients) and flow features of a modern sepak takraw ball commercially available in the market by means of numerical simulations and wind tunnel experiments using the smoke flow visualization technique. The aerodynamic characteristics and flow features of the ball are determined for non-spinning conditions at a wind speed of 3 m/s. It is found that the drag coefficient and lift coefficient of the sepak takraw ball is 0.4868400 and -0.0130915, respectively. The images captured from the smoke flow visualization experiments reveal that the sepak takraw ball is in the subcritical flow regime at a wind speed of 3 m/s, which is the regime before the drag crisis. The laminar boundary layer separates from the upper and lower surfaces of the ball at points upstream of the equator of the ball, creating a large wake region downstream of the sepak takraw ball and resulting in high drag. This in turn, influences the trajectory of the sepak takraw ball in flight. The flow features observed from the smoke flow visualization experiments are representative of the flow during a sepak takraw game. Owing to the complexity of sepak takraw ball, it is recommended that the aerodynamic characteristics of the sepak takraw ball are investigated for spinning conditions in future studies.
[ABSTRACT]   Full text not available  [PDF]
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Investigation of The Head Impact Power of A Sepak Takraw Ball on Sepak Takraw Players
Iskandar Hasanuddin, Zahari Taha, Nukman Yusoff, Norhafizan Ahmad, Raja Ariffin Raja Ghazilla, Husni , Tuan Mohammad Yusoff Shah Tuan Ya
July-December 2015, 4(2):63-77
Sepak takraw is a traditional sport in Asia in which the players use various parts of their bodies to hit the ball, with the exception of their hands. Unlike other sports such as soccer, boxing, and rugby, it is observed that none of the studies in the literature have examined the injuries resulting from the impact of the sepak takraw ball on the players' heads during a game. This study was initiated following the incidents of the 24th SEA Games in Korat, Thailand, in year 2007, whereby a number of players from the Malaysian Sepak Takraw Association (PSM) had to withdraw themselves from the championship. These players suffered from headaches which were believed to be caused by the impact of the sepak takraw ball, considering the fact that heading is one of the basic movements used to hit the ball. Moreover, it is expected that the sepak takraw ball travels at high velocities during the game. Hence, the objective of this study is to investigate the impact of the sepak takraw ball and its corresponding level of head injury among sepak takraw players in Malaysia by means of numerical simulations and experiments. In order to achieve this objective, a model of the scalp, skull, cerebrospinal fluid and brain is first developed and simulations are then carried out using finite element analysis (FEA) software. The results show that the maximum speed of the sepak takraw ball before heading is 13.581 m/s while the maximum impact force on the head obtained from the simulations is 688.11 N. The maximum displacement and maximum linear acceleration of the brain's centre of gravity is found to be 0.0080 m and 1674.5 m/s2, respectively, while the head impact power (HIP) is determined to be 11.366 kW. According to Newman, Shewchenko, and Welbourne (2000), the probability of concussion is 39% and based on the results obtained in this study, it can be concluded that the players may suffer from mild traumatic brain injuries (MTBI) due to the high impact of the sepak takraw ball during heading. Hence, it is recommended that the players wear protective headbands to reduce the impact during heading and prevent the occurrence of MTBI in the long term.
[ABSTRACT]   Full text not available  [PDF]
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Comparative Efficacy of Imagery-Based Relaxation and Abbreviated Muscle Relaxation Training on The Reaction Ability of Netball Players
Srilekha Saha, Soumendra Saha, Nurfarrah Ezzaty Mohd Zahir, Foujia Huda
July-December 2015, 4(2):51-61
In this study, we investigated the benefits of differential psychotherapeutic intervention techniques on the modification of autonomic competence and its impact on the visual reaction ability of young competitive netball players. Thirty-six young female netball players with an age range of 18–24 years were recruited. Upon baseline evaluation of psychomotor (reaction time); physiological (resting heart-rate and VO2max) and psychobiological (Sc components: latency, amplitude and recovery time) indices, we categorised the subjects into three groups: Group I (control group in which the subjects did not receive any intervention), Group II (experimental group in which the subjects received abbreviated progressive muscle relaxation (APMR) training) and Group III (experimental group in which the subjects received imagery-based relaxation intervention (IRT) training). The subjects from the experimental groups (Group I and Group II) were subjected to their respective interventions (APMR and IRT) for 24 sessions following the protocol, viz., 20 min/day, 2 days/week for 12 weeks). After six weeks of intervention, we conducted mid-term evaluation on all of the aforementioned parameters that had been determined during baseline evaluation. Following this, intervention sessions were continued using the same protocol for six more weeks. At the end of twelfth week, we conducted post-intervention assessment on all psychological, psychomotor and psychobiological variables to verify the effect of training on the dependent measures. Based on the results, we found that there are improvements in various parameters during the mid-term evaluation and post-intervention analysis, which can be rationally attributed to the differential therapeutic interventions introduced to the subjects of the experimental groups. The results suggest that both of the intervention techniques facilitate in improving the reaction ability whereas our in-depth analysis clarifies that netball players with a relatively lower phasic Sc but with higher extent of amplitude, had faster recovery which will be highly beneficial since they are able to regulate their task-focus well enough to yield faster agile reaction performance.
[ABSTRACT]   Full text not available  [PDF]
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Does Power Output Vary Accordingly with High Load Resistance Training? A Comparative Study Between Bulk-Up and Strength-Up Resistance Training
Keisuke Shibata, Kazuki Takizawa, Masao Mizuno
July-December 2015, 4(2):7-14
The objective of this study is to investigate the effects of six weeks of high-intensity resistance training on the power output of 14 university basketball players. The subjects were randomly divided into two groups: a hypertrophy-oriented group (bulk-up) and a neuromuscular improvement oriented-group (strength-up). The bulk-up group performed three sets of squat exercises at 75% of 1RM with 10 repetitions and 1-minute rest period between sets. The strength-up group performed six sets of squat exercises at 90% of 1RM with four repetitions and 3-minute rest period between sets. Both groups performed the squat exercises twice a week over a period of six weeks. The one repetition maximum (1RM) and muscle power of the squat were measured before training (0-wk), after three weeks of training (3-wk), and after six weeks of training (6-wk). The thigh circumference of each subject was measured at 0-wk and 6-wk. It is found that the 1RM of the squat increases significantly after the training period for both groups, and the rate of improvement does not differ between the groups at 6-wk (bulk-up group: 13.1 ± 9.3%, strength-up group: 12.6 ± 6.3%). It is also found that there is a significant increase in the thigh circumference (p < 0.01) in the left leg for the bulk-up group. In contrast, there is a significant increase in the peak muscle power (POWmax) (p < 0.05) for the strength-up group. The rate of increase for POWmax is different even after three weeks of training (bulk-up group: -4.5 ± 9.6%, strength-up group: 13.9 ± 13.6%). The results suggest that the effects of resistance training on the power output and thigh circumference vary according to the training programme even if the total work load remains the same. It is recommended that strength-up resistance training is implemented to increase muscle power.
[ABSTRACT]   Full text not available  [PDF]
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