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Biomechanical Indicators of Jump Height Among Varied Techniques of Vertical Jump
Abdel-Rahman Ibrahim Akl,
Mohamed Mohamed Doma
Issue:
Volume 4, Issue 5, September 2016
Pages:
77-83
Received:
29 July 2016
Accepted:
5 August 2016
Published:
21 August 2016
Abstract: The purpose of the present study was to determine the biomechanical indicators of jump height among varied techniques of vertical jump and examine if the rate of force development is a valid indicator for vertical jump height or not. Fifteen male high level athletes participated in this study performed three techniques of the vertical jump. Motion data were recorded by a high-speed camera at a frequency of 250 Hz, video point v 2.5 2D motion analyses for kinematic variables, and force platform (MP4060®, Bertec Corporation, Columbus, OH, USA) which measured the ground reaction force at a sampling rate of 1000 Hz. The RFD was calculated as the Peak Force divided by the time taken to achieve the Peak Force, the integration was calculated by OriginPro 8.5 to calculate impulse and work. The results showed a significant difference between techniques in all analyzed variables, a positive significant correlation between vertical velocity, impulse, work, temporal variables with flight height, and the negative significant correlation between the rate of force development with flight height and jump techniques. In Conclusion, this results emphasized the importance of velocity, impulse, and work as indicators when evaluating the vertical jump.
Abstract: The purpose of the present study was to determine the biomechanical indicators of jump height among varied techniques of vertical jump and examine if the rate of force development is a valid indicator for vertical jump height or not. Fifteen male high level athletes participated in this study performed three techniques of the vertical jump. Motion ...
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Quantitative Analysis of Penalty Kicks and Yellow Card Referee Decisions in Soccer
Jimmy Tanamati Soares,
Lior Shamir
Issue:
Volume 4, Issue 5, September 2016
Pages:
84-89
Received:
1 August 2016
Accepted:
15 August 2016
Published:
29 August 2016
Abstract: Soccer referees are required to make instant decisions during the game under non-optimal conditions such as imperfect view of the incident and substantial pressure from the crowd, the teams, and the media. Some of the decisions can be subjective, such as a yellow card decision after a foul is called, where different referees might make different decisions. Here we perform quantitative analysis of factors related to the reputation of the team such as the team’s rank, budget, and crowd attendance in home games, and correlate these factors with referee decisions such as penalty kicks and yellow cards. The calls were normalized by dividing the number of yellow cards by the number of fouls, and the number of penalty kicks by the number of shot attempts from the penalty box. Application of the analysis to the four major soccer leagues shows that certain referee decisions have significant correlation with factors such as the team’s rank, budget, and audience in home games, while for other decisions the Pearson correlation is not statistically significant. For budget, or audience in home games. On the other hand, a significant Pearson correlation has been identified between the chance of a foul call to result in a yellow card and the rank or budget of the team in the Bundesliga. The strongest correlation has been observed between the chance of a tackle to result in a foul call, and the budget and rank of the team.
Abstract: Soccer referees are required to make instant decisions during the game under non-optimal conditions such as imperfect view of the incident and substantial pressure from the crowd, the teams, and the media. Some of the decisions can be subjective, such as a yellow card decision after a foul is called, where different referees might make different de...
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Effects of Resisted Sprint Training on Sprint Performance in High School Baseball Players
Yuta Sekine,
Junichi Okada
Issue:
Volume 4, Issue 5, September 2016
Pages:
90-97
Received:
4 August 2016
Accepted:
19 August 2016
Published:
7 September 2016
Abstract: Resisted sprint training (RST) affects sprint speed in the acceleration phase, but there is no research regarding this for in adolescents. This study investigated the effects of RST on sprint speed and ground reaction force (GRF) in high school baseball players. Subjects were assigned to the resisted sprint group (RSG, n=10, loading 20% body mass), or the normal sprint group (NSG, n=9, without loading) and trained three days per week for eight weeks. Sprint speed [0-5, 5-10, 10-15, 15-20 and 0-20 meters (m)] and GRF [peak propulsive/resultant force, (PFpro/ PFres); impulse, (I); and ratio of force applied onto the ground (RF)] measured at the right and left foot at the start, the first step of the left foot (L1st), 5 m and 10m were assessed before and after training. In the RSG, a significant interaction was found for sprint speed at 0-5 m (p=0.028) and increased after training (p<0.0001). The 15-20 m sprint speed increased significantly in the NSG after training (p=0.022). The 0-20 m sprint speed increased significantly in both groups after training (RSG, p=0.001; NSG, p=0.041). Significant interactions were found for PFpro (p=0.015) and RF (p=0.0002) at the L1st in the RSG. PFpro (p=0.005), PFres (p=0.038) and RF (p=0.0002) at L1st increased significantly in the RSG. RST increased sprint speed in the early part of the acceleration phase by improving force production but prevented the improvement of sprint speed over 15 m. Combining RST and sprint training without loading improved sprint speed in the acceleration phase.
Abstract: Resisted sprint training (RST) affects sprint speed in the acceleration phase, but there is no research regarding this for in adolescents. This study investigated the effects of RST on sprint speed and ground reaction force (GRF) in high school baseball players. Subjects were assigned to the resisted sprint group (RSG, n=10, loading 20% body mass),...
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