Effects of different sprint training programs with ball on explosive, high-intensity and endurance-intensive performances in male young soccer players

This study compared the effects of different sprint ball-based training programs on fitness-related performances in youth soccer players. Forty male players (age: 15.2 ± 0.6 yrs) participated in a short-term (8 weeks) randomized parallel fully controlled training study, with pre-to-post measurements. Players were randomly assigned to 3 sprint ball-based training groups: training with combined sprint (performing linear and change of direction sprints; CST), or using linear sprint (LST), or performing sprint with change of direction (CODT) and to a control group (CONT). Pre- and post-training players completed a test battery involving linear sprinting (10 and 20 m, and flying 10 m), 505 test (COD), 15 m test with ball (CODB), countermovement jump test (CMJ test) and maximal oxygen consumption (VO2max). All physical performance’ variables improved after the training intervention (all p < 0.05; ES ≥ 0.2). No main effect of groups was observed in linear sprinting, CMJ and VO2max (p > 0.05; ES < 0.2). A training group main effect was found (p < 0.0001; ES = 0.50) for COD with CODT induced better performance than LST and CONT (all p <0.0001; ES > 0.8). Also, a training group main effect (p = 0.009; ES = 0.35) was found for CODB with CODT elicited better performance than LST and CONT (all p = 0.001; ES > 0.80). Our findings suggest that ball-based training programs were more effective to improve fitness levels in youth players during the in-season period and that CODT modality was more effective to improve COD and CODB performances.

Predicting change-of-direction performance in elite young badminton players: A multiple regression analysis on acceleration- and deceleration-related qualities

The aim of this study was to examine the interrelationships between direct (sprint and change-of-direction [COD] velocities) and indirect measures (COD-deficit [CODD], deceleration deficit [DD], and sprint momentum) of speed-related performances in young badminton players. Thirty young male badminton players (age: 16.8 ± 1.4 years; body-mass: 61.5 ± 7.9 kg; height: 170 ± 5.8 cm) performed a 20-m sprint followed by 505 COD tests, on the same day. A Pearson product moment test was applied to determine the relationships among variables. A multiple regression analysis was used to verify whether the combination of CODD and DD increased the capacity to predict COD performance. Large and significant relationships were observed between COD and linear sprint velocity and sprint momentum ( r ranging from 0.62 to 0.84; P < 0.05). COD velocity revealed a moderate significant ( r = −0.38) and a small non-significant ( r = 0.29) relationship with CODD and DD, respectively. The multiple regression model combining CODD and DD explained 44% of the variance in COD performance. In summary, young badminton players who sprint faster are equally faster in COD manoeuvres but present higher levels of CODD and DD. Coaches should be aware that faster badminton players may exhibit greater magnitudes of CODD-DD, thus requiring specific interventions to optimize the transition between high deceleration and (re) acceleration phases.

Disruptive Technology, Value Proposition, and Business Model Change Management in a Multi-Faceted SME

Disruptive technology, or disruptive innovation, is undeniably one of the most significant concepts to emerge from management theory in the last three decades. Both its theoretical and practical impact has been far reaching. Notwithstanding this stellar impact, it seems unlikely that a small hyper-conservative, risk-averse SME with limited management training in concepts that have little immediate return on investment would choose to embark upon a radical change of direction sparked by new technology and innovation. Using an interpretivist, inductive, approach based on interview material and personal observation, this chapter examines the realities of business strategy, how disruption is perceived, management decisions made, technologies introduced, and change management enacted in this family-run business. The chapter concludes that change perception and change management are related to efficiency and threat responses rather than disruption to business models or technology availability.

Epidemiology of Traumatic Posterior Hip Instability in the National Football League

Background: There is a paucity of literature regarding injury incidence, mechanism, and return to play in National Football League (NFL) players who have sustained traumatic posterior hip instability. Purpose: To describe the incidence of traumatic posterior hip instability and the rate of return to play in NFL players across 18 seasons. Study Design: Descriptive epidemiology study. Methods: We retrospectively assessed all traumatic posterior hip dislocations/subluxations that occurred during football-related activities in the NFL seasons from 2000 through 2017. Player demographics and injury data (injury mechanism, season of injury, treatment, days missed, and return to play time) were collected from all 32 NFL teams prospectively through a leaguewide electronic health record system. Descriptive statistics are presented. Results: Across the 18 NFL seasons, 16 posterior hip instability injuries in 14 players were reported, with a maximum incidence of 4 (25%) in 2013. Posterior hip instability was predominantly sustained by offensive players (64.3%), with tight ends being the most affected (31.3%). Half of the injuries occurred during the regular season, 43.8% in the preseason, and 6.2% in the offseason. Of all injuries, 37.5% were noncontact, while 56.3% involved contact (direct or indirect), and 6.2% were of unknown mechanism. Among noncontact injuries, 66.7% occurred during cutting and change of direction while sprinting. The time of return to full participation was documented for 11 of the 16 reported injuries (68.8%); among them, the mean time loss was 136.7 ± 83.8 days—143.3 ± 99.6 days if the player underwent surgery (n = 4) and 116.7 ± 76.2 days missed by players without surgery (n = 6)—the treatment modality was unknown in 1 player. Conclusion: Although the incidence of traumatic posterior hip instability during the study period was low, all injured athletes missed time from football activities and competitions. Injuries that required surgery led to more missed time than those that did not. Ongoing research to understand risk factors and mechanisms of this injury, in conjunction with improvements to prevention and rehabilitation protocols, is necessary to ensure the safety of professional American football players.

Effects of complex strength training with elastic band program on repeated change of direction in young female handball players: Randomized control trial

This study examined the effect of 10-week complex strength training with elastic band program on fitness components in young female handball players. Thirty-eight handball players aged 15.8 ± 0.2 years were randomly assigned to an experimental group or control group. The experimental group performed complex strength training with elastic band twice a week over 10 weeks, which included 8 workshops of progressing set length (number of sets) and band resistance for each specific exercise. Sessions were lasted approximately 35 min. The control group maintained regular in-season training. Tests included handgrip; back extensor; medicine ball throw; 30 m sprint times; Modified Illinois change-of-direction (Illinois-MT); four jump tests (squat jump, countermovement jump, countermovement jump with arms and five jump test; static (stork test) and dynamic (Y balance test) balance; and repeated sprint T-test. The experimental group enhanced all strength performance (handgrip right ( p < 0.001), handgrip left ( p < 0.001), back extensor strength ( p < 0.001) and medicine ball throw ( p < 0.001) compared to the controls); sprint performance (5 m ( p<0.001), 10 m ( p < 0.001), 20 m ( p < 0.001), and 30 m ( p < 0.001)); the change of direction (Illinois-MT ( p < 0.001)); jump performance (squat jump ( p < 0.001), countermovement jump ( p < 0.001), countermovement jump with arms ( p < 0.001), and five jump test ( p < 0.01)); and the repeated sprint T-test scores ( p<0.001in all scores). In contrast, no significant difference in both static and dynamic balance performance between experimental group and control group. Ten weeks of complex strength training with elastic band improve fitness components measures in young female handball players then habitual training.

Different change of direction tests assess different physical ability parameters: Principal component analysis of nine change of direction tests

Change of direction (CoD) ability is critical for the success of athletes in many sports. The purpose of this study was to perform a principal component analysis using 9 CoD tests in order to reveal possible subcomponents of CoD ability, which could aid practitioners in test selection. Male and female kinesiology students (n = 76) performed all CoD tests and a 30-m sprint test in a quasi-randomized, counterbalanced order. Three components for males and two components for females were extracted from principle component analysis (variance explained = 82.3 and 71.4%, respectively). It seems that the CoD test should be subdivided into at least two components: a) “pure CoD tests” (such as 505 test, T-test and 180° turn) and maneuverability tests (such as AFL run, Illinois test and Figure of Eight test). Considering that different factors seem to underlie CoD and maneuverability, our findings have important practical implications for training design. If hopping/jumping CoD is important for a given athlete, it should also be tested separately.

Effects of contrast strength training with elastic band program on sprint, jump, strength, balance and repeated change of direction in young female handball players

Maximal strength, power and his derivates (sprint, change of direction repeatedly and jump) are considered as major determinants of success in elite handball players. Contrast strength training with elastic band (CSTEB) program is form of resistance training, and may play an important method of training to improve this quality. This study examined the effects of 10-week contrast strength training with elastic band (CSTEB) program on physical performance in young female handball players. Thirty participants (age: 15.7 ± 0.3 years; body mass: 63.7 ± 3.7 kg; body height: 166.8 ± 3.8 cm; body fat: 26.9 ± 3.4; and Maturity-offset: 2.9 ± 0.3 years) were randomly assigned between experimental group (EG; n = 15) and control group (CG; n = 15). Two-way analyses of variance (group × time) were assessed for handgrip; back extensor; medicine ball throw; 30-m sprint times; Modified Illinois change-of-direction (Illinois-MT); four jump tests [(squat jump (SJ), countermovement jump (CMJ), countermovement jump with arms (CMJA) and five jump test (5JT)]; static (stork) and dynamic (Y balance) balance tests; and repeated sprint T-test (RSTT). The EG enhanced all strength performance [handgrip right, handgrip left, back extensor strength and medicine ball throw (p < 0.001)] compared to CG. The EG enhanced all sprint performance. The EG also improved performance in the Illinois-MT. All jump performance improved significantly [SJ (p = 0.007), CMJ (p = 0.001) and CMJA (p = 0.001)] except 5JT in the EG. Of the same, 3 of 4 repeated sprint T-test scores [RSTT-Best-Time, RSTT-Mean-Time and RSTT-Total-Time] increased significantly in the EG relative to the CG. Conversely, there were no significant changes in balance performance between groups. It is concluded that 10-weeks of CSTEB improved physical performance (strength, sprint, change of direction, jump, and repeated change of direction) measures in young female handball players.

Motion estimation in vehicular environments based on Bayesian dynamic networks

The cornerstone to achieve the development of autonomous ground driving with the lowest possible risk of collision in real traffic environments is the movement estimation obstacle. Predicting trajectories of multiple obstacles in dynamic traffic scenarios is a major challenge, especially when different types of obstacles such as vehicles and pedestrians are involved. According to the issues mentioned, in this work a novel method based on Bayesian dynamic networks is proposed to infer the paths of interest objects (IO). Environmental information is obtained through stereo video, the direction vectors of multiple obstacles are computed and the trajectories with the highest probability of occurrence and the possibility of collision are highlighted. The proposed approach was evaluated using test environments considering different road layouts and multiple obstacles in real-world traffic scenarios. A comparison of the results obtained against the ground truth of the paths taken by each detected IO is performed. According to experimental results, the proposed method obtains a prediction rate of 75% for the change of direction taking into consideration the risk of collision. The importance of the proposal is that it does not obviate the risk of collision in contrast with related work.

A Sudden Turnaround: The Pro-Han Immigration Policy in Manchuria and Its Abrupt Abrogation in Early Qing Era

For most of Qing domination over China, the Manchu rulers strictly controlled or even prohibited migration of Chinese people to the dynasty’s Motherland (long xing zhi di 龍興之地). Only two brief phases are an exception, namely the mid Shunzhi to early Kangxi and Yongzheng periods. During the former, in 1653, a “Regulation for the repopulation and land reclamation of Liaodong” was promulgated, establishing alluring incentives for whoever managed to move a hundred or more people to the region east of the Liao river. Only fifteen years later, when the maneuver had just started to produce some results, the Qing court abolished it. In the long term, such a change of direction appears perfectly normal, considering that later on most of the lands would be assigned to the Eight Banners and the state would have striven to keep the Chinese out. Nevertheless, in the short term, the decision seemed to come out of the blue. An interesting debate on what might have determined the turnabout began in the early twentieth century, and some most recent contributions have been published in the 2000s; yet none of the thesis proposed so far is fully convincing. On the basis of sources that have not yet been taken into account, this paper further investigates into the matter and aims at demonstrating that the concerns which compelled the rulers to officially oppose immigration in the following decades already existed in the very first years of Kangxi reign.