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Mallo J.,Technical University of Madrid | Alexandre D.,OGC Nice | Alexandre D.,Tunisian Research Laboratory Sport Performance Optimisation
Journal of Sports Medicine and Physical Fitness | Year: 2012

Aim. The aim of this study was to examine injury incidence in professional football players according to the playing positions and with a special reference to training periodization. Methods. A Spanish professional team was followed prospectively for the 2007-08 and 2008-09 seasons and exposure times and time-loss injuries were individually recorded during all training sessions and matches. Heart rate was monitored in all training sessions. Results. A total of 114 injuries were registered during the study period (mean injury incidence: 6.6 injuries per 1000 hours). The frequency of injuries was not uniformly distributed by playing positions (P<0.001), as forwards and central defenders sustained the greatest number of injury episodes and the highest match absence. Ligament sprains and muscle strains accounted for 50% of all injuries and 62% of all match absences. The highest incidence of sprains was achieved during pre-season and the beginning of the competition period. The risk to sustain a muscular strain peaked at the beginning and in the final weeks of the competition period and was related (r=0.72; P<0.05) to mean heart rate during the training stage. Conclusion. The results suggest that there exists a difference of injury risk according to the period of the season and therefore, injury prevention strategies should be introduced from pre-season. Moreover, training workloads should be controlled to avoid increasing the risk of muscle strains. Source

Dellal A.,Olympique Lyonnais FC soccer | Dellal A.,Tunisian Research Laboratory Sport Performance Optimisation | Drust B.,Liverpool John Moores University | Lago-Penas C.,University of Vigo
International Journal of Sports Medicine | Year: 2012

The aim of the present study was to examine the physical and technical activity during different periods within small-sided soccer games (SSGs). 20 elite players completed 3 different SSGs (2-a-side, 3-a-side and 4-a-side games) in which the number of ball touches per individual possession was fixed at a maximum of 2. The duration and the pitch size of each SSG were strictly controlled (2 min, 3 min, 4 min, respectively; 1:75 m 2) with each period repeated 4 times (P1, P2, P3, P4). The physical and technical activities, heart rate responses, blood lactate concentration and rating of perceived exertion (RPE) were analysed. The results showed a decrease of high and very high-intensity activities (from 26.2% to 37.7%, P<0.001), an increase of blood lactate concentration (from + 28.0% to + 76.9%), RPE (from + 29.0% to + 32.8%), and heart rate responses (~ 6.6%), and a significant alteration of technical activities from P1 to P4 in each SSG. The greatest differences from P1 and P4 were observed for the 2-a-side game when compared to the 3-a-side and 4-a-side games (P<0.05) for each variable analysed. In conclusion, the variation of the player's activity throughout the periods indicates that the duration and number of exercise periods used within SSGs is an important variable in determining the training stimulus in soccer-specific training. Source

Behm D.G.,Memorial University of Newfoundland | Chaouachi A.,Tunisian Research Laboratory Sport Performance Optimisation
European Journal of Applied Physiology | Year: 2011

An objective of a warm-up prior to an athletic event is to optimize performance. Warm-ups are typically composed of a submaximal aerobic activity, stretching and a sport-specific activity. The stretching portion traditionally incorporated static stretching. However, there are a myriad of studies demonstrating static stretch-induced performance impairments. More recently, there are a substantial number of articles with no detrimental effects associated with prior static stretching. The lack of impairment may be related to a number of factors. These include static stretching that is of short duration (<90 s total) with a stretch intensity less than the point of discomfort. Other factors include the type of performance test measured and implemented on an elite athletic or trained middle aged population. Static stretching may actually provide benefits in some cases such as slower velocity eccentric contractions, and contractions of a more prolonged duration or stretch-shortening cycle. Dynamic stretching has been shown to either have no effect or may augment subsequent performance, especially if the duration of the dynamic stretching is prolonged. Static stretching used in a separate training session can provide health related range of motion benefits. Generally, a warm-up to minimize impairments and enhance performance should be composed of a submaximal intensity aerobic activity followed by large amplitude dynamic stretching and then completed with sport-specific dynamic activities. Sports that necessitate a high degree of static flexibility should use short duration static stretches with lower intensity stretches in a trained population to minimize the possibilities of impairments. © 2011 Springer-Verlag. Source

Chaabene H.,Higher Institute of Sports and Physical Education | Chaabene H.,Manouba University | Hachana Y.,Higher Institute of Sports and Physical Education | Hachana Y.,Manouba University | And 4 more authors.
Sports Medicine | Year: 2012

This review focuses on the most important physical and physiological characteristics of karate athletes from the available scientific research. It has been established that karates top-level performers require a high fitness level. Top-level male karate athletes are typified by low body fat and mesomorphic-ectomorphic somatotype characteristics. Studies dealing with body composition and somatotype of females are scarce. Aerobic capacity has been reported to play a major role in karate performance. It prevents fatigue during training and ensures the recovery processes during rest periods between two subsequent bouts of fighting activity within a fight and between two consecutive matches. It has been established that there is no significant difference between male and female kata (forms) and kumite (sparringcombat) athletes with regard to aerobic performance. Nevertheless, further studies are needed to support these findings. Concerning anaerobic performance, there is a difference in maximal power explored by the force-velocity test between national and international level karatekas (karate practitioners) but, for the maximum accumulated oxygen deficit test there is no difference between them. Muscle explosive power plays a vital role in a karatekas capacity for high-level performance. However, it has been revealed that vertical jump performance, maximal power and maximal velocity differed between national- and international-level karatekas. Moreover, it has been reported that karate performance relies more on muscle power at lower loads rather than higher ones. Thus, karates decisive actions are essentially dependent on muscle explosive power in both the upper and lower limbs. With regard to dynamic strength, limited research has been conducted. The maximal absolute bench press, half-squat one-repetition maximum and performance of isokinetic tasks differed significantly between highly competitive and novice male karatekas. Studies on female karate athletes do not exist. Concerning flexibility, which is important for the execution of high kicks and adequate range of action at high speeds, it has been demonstrated that karate athletes ranges of bilateral hip and knee flexion are greater compared with non-karate athletes. Finally, reaction time is a crucial element in karate because high-level performance is based essentially on explosive techniques. A significant difference in the choice reaction time between high-level and novice karatekas exists. Further research is needed concerning the physiological characteristics of female karatekas, the differences between kata and kumite athletes and variations based on weight categories. © 2012 Springer International Publishing AG. All rights reserved. Source

Dellal A.,University of Strasbourg | Dellal A.,Tunisian Research Laboratory Sport Performance Optimisation | Jannault R.,University Claude Bernard Lyon 1 | Lopez-Segovia M.,Research Section Soccer Federation of the Region of Murcia | Pialoux V.,University Claude Bernard Lyon 1
Journal of Human Kinetics | Year: 2011

The purpose of this study was to compare heart rate (HR) responses within and between small-sided games (SSG) training methods in elite young soccer players. Twenty-seven youth soccer players (age: 16.5 ± 0.5 years, height: 174.5 ± 5.5 cm, weight: 62.9 ± 8.3, velocity at maximal aerobic speed (MAS): 15.9 ± 0.9 km.h-1) performed 3 different SSG (2 vs. 2, 3 vs. 3, 4 vs. 4 without goalkeeper). In each SSG, HR was continuously measured and expressed as a mean percentage of HR reserve (%HRreserve). The mean %HRreserve calculated during the SSG was significantly lower during 4 vs. 4 (70.6 ± 5.9 %) compared to 2 vs. 2 (80.1 ± 3.6 %, p<0.001) and 3 vs. 3 (81.5 ± 4.3 %, p<0.001) SSG. Regardless of the time spent above 60, 65, 70, 75, 80, 85 and 90 % of HRreserve, 4 vs. 4 solicited lower percentage of time than 3 vs. 3 and 2 vs. 2. Intersubject coefficients of variation were significantly higher during 4 vs. 4 compared to 2 vs.2 and 3 vs. 3. The %HRreserve after 30s of recovery was significantly higher for 3 vs. 3 (70.6 ± 5.3 %) compared to 2 vs. 2 (65.2 ± 4.8 %, p<0.05) and 4 vs. 4 (61.6 ± 9.3 %, p<0.05). In conclusion, this study demonstrates that the physiological demands is higher during 2 vs. 2 and 3 vs. 3 compared to 4 vs. 4 in youth soccer players. This difference could be due to that young soccer players do not have the same technical ability and experience as adult players and thus, their activity during the 2 vs. 2 and 3 vs. 3 induces a greater physical demand due to their lack of experience. The age of the players could be linked with the physical demands within small-sided games. Source

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