Showing papers in "Journal of Sports Sciences in 2015"
TL;DR: The results of the present study showed that CMJ height can be easily, accurately and reliably evaluated using a specially developed iPhone 5 s app.
Abstract: The purpose of this investigation was to analyse the concurrent validity and reliability of an iPhone app (called: My Jump) for measuring vertical jump performance. Twenty recreationally active healthy men (age: 22.1 ± 3.6 years) completed five maximal countermovement jumps, which were evaluated using a force platform (time in the air method) and a specially designed iPhone app. My jump was developed to calculate the jump height from flight time using the high-speed video recording facility on the iPhone 5 s. Jump heights of the 100 jumps measured, for both devices, were compared using the intraclass correlation coefficient, Pearson product moment correlation coefficient (r), Cronbach’s alpha (α), coefficient of variation and Bland–Altman plots. There was almost perfect agreement between the force platform and My Jump for the countermovement jump height (intraclass correlation coefficient = 0.997, P < 0.001; Bland–Altman bias = 1.1 ± 0.5 cm, P < 0.001). In comparison with the force platform, My Ju...
286 citations
TL;DR: Information from the tactical modelling can provide a more thorough and objective match understanding to coaches and performance analysts for evaluating post-match performances and for scouting upcoming oppositions.
Abstract: Identifying match statistics that strongly contribute to winning in football matches is a very important step towards a more predictive and prescriptive performance analysis. The current study aime...
164 citations
TL;DR: The Omron pedometer seems to provide the most reliable and valid estimate of steps taken, as it was the best performer under lab-based conditions and provided comparable results to the YX in free-living.
Abstract: Activity monitors are frequently used to assess activity in many settings. But as technology advances, so do the mechanisms used to estimate activity causing a continuous need to validate newly developed monitors. The purpose of this study was to examine the step count validity of the Yamax Digiwalker SW-701 pedometer (YX), Omron HJ-720 T pedometer (OP), Polar Active accelerometer (PAC) and Actigraph gt3x+ accelerometer (AG) under controlled and free-living conditions. Participants completed five stages of treadmill walking (n = 43) and a subset of these completed a 3-day free-living wear period (n = 37). Manually counted (MC) steps provided a criterion measure for treadmill walking, whereas the comparative measure during free-living was the YX. During treadmill walking, the OP was the most accurate monitor across all speeds (±1.1% of MC steps), while the PAC underestimated steps by 6.7–16.0% per stage. During free-living, the OP and AG counted 97.5% and 98.5% of YX steps, respectively. The PAC ov...
133 citations
TL;DR: It is demonstrated that variation of physical performance in youth soccer players could be explained by a combination of both functional movement screen scores and maturation.
Abstract: The purpose of this study was to examine relationships between functional movement screen scores, maturation and physical performance in young soccer players. Thirty males (11–16 years) were assessed for maturation, functional movement screen scores and a range of physical performance tests (squat jump, reactive strength index protocol and reactive agility cut). Older players significantly outperformed younger participants in all tests (P < 0.05; effect sizes = 1.25–3.40). Deep overhead squat, in-line lunge, active straight leg raise and rotary stability test were significantly correlated to all performance tests. In-line lunge performance explained the greatest variance in reactive strength index (adjusted R2 = 47%) and reactive agility cut (adjusted R2 = 38%) performance, whilst maturation was the strongest predictor of squat jump performance (adjusted R2 = 46%). This study demonstrated that variation of physical performance in youth soccer players could be explained by a combination of both fun...
128 citations
TL;DR: It was found that GKs and DEFs were the tallest and heaviest compared with MFs and ATTs in all age groups, and inherent physical capacities might select players in or reject players from an attacking position from U15–U17.
Abstract: The present study aimed to investigate positional differences in 744 high-level soccer players, aged 8 to 18 years. Players were assigned to six age groups (U9–U19) and divided into four playing positions (goalkeeper (GK), defender (DEF), midfielder (MF) and attacker (ATT)). MANOVA and effect sizes were used to examine anthropometrical and functional characteristics between all positions in all age groups. The main findings of the study were that GKs and DEFs were the tallest and heaviest compared with MFs and ATTs in all age groups. Further, between U9–U15, no significant differences in functional characteristics were found, except for dribbling skill, which MFs performed the best. In the U17–U19 age groups, ATTs seemed to be the most explosive (with GKs), the fastest and the more agile field players. These results suggest that inherent physical capacities (i.e., speed, power, agility) might select players in or reject players from an attacking position, which is still possible from U15–U17. Appa...
115 citations
TL;DR: A systematic review of existing methods for biomechanical analysis of swimming performance using inertial and magnetic sensors indicated that inertial sensors are reliable tools for swimming biomechanicals analyses.
Abstract: The use of contemporary technology is widely recognised as a key tool for enhancing competitive performance in swimming. Video analysis is traditionally used by coaches to acquire reliable biomecha...
108 citations
TL;DR: It appears that minimalist footwear with lower heel heights and minimal shock absorption is more effective in replicating barefoot running.
Abstract: Despite the growing interest in minimalist shoes, no studies have compared the efficacy of different types of minimalist shoe models in reproducing barefoot running patterns and in eliciting biomec...
104 citations
TL;DR: The results presented herein indicate that the plyometric training-axis is decisive in determining neuromechanical training responses in high-level soccer players.
Abstract: The aim of this study was to investigate the effects of adding vertical/horizontal plyometrics to the soccer training routine on jumping and sprinting performance in U-20 soccer players. The vertical jumping group (VJG) performed countermovement jumps (CMJ), while the horizontal jumping group (HJG) executed horizontal jumps (HJ). Training interventions comprised 11 sessions, with volume varying between 32 and 60 jumps per session. The analysis of covariance revealed that CMJ height and peak force improved only in the VJG, and that HJ distance and peak force improved in both groups. Velocity in 20 m (VEL 20 m) did not improve in either group; however, velocity in 10 m (VEL 10 m) presented a moderate positive effect size (ES = 0.66) in the HJG, while the ES was large (1.63) for improvement in the 10-20 m acceleration in the VJG, and it was largely negative (-1.09) in the HJG. The transference effect coefficients (calculated by the equation: TEC = result gain (ES) in untrained exercise/result gain (ES) in trained exercise) between CMJ and VEL 20 m and ACC 10-20 m were 1.31 and 2.75, respectively. The TEC between HJ and VEL 10 m, VEL 20 m and ACC 0-10 m were 0.44, 0.17 and 0.44, respectively. The results presented herein indicate that the plyometric training-axis is decisive in determining neuromechanical training responses in high-level soccer players.
98 citations
TL;DR: GI symptoms are very common during ultramarathon running, and in particular, nausea is the most common complaint for finishers and non-finishers.
Abstract: This study examined the incidence, severity, and timing of gastrointestinal (GI) symptoms in finishers and non-finishers of the 161-km Western States Endurance Run. A total of 272 runners (71.0% of starters) completed a post-race questionnaire that assessed the incidence and severity (none = 0, mild = 1, moderate = 2, severe = 3, very severe = 4) of 12 upper (reflux/heartburn, belching, stomach bloating, stomach cramps/pain, nausea, vomiting) and lower (intestinal cramps/pain, flatulence, side ache/stitch, urge to defecate, loose stool/diarrhoea, intestinal bleeding/bloody faeces) GI symptoms experienced during each of four race segments. GI symptoms were experienced by most runners (96.0%). Flatulence (65.9% frequency, mean value 1.0, s = 0.6 severity), belching (61.3% frequency, mean value 1.0, s = 0.6 severity), and nausea (60.3% frequency, mean value 1.0, s = 0.7 severity) were the most common symptoms. Among race finishers, 43.9% reported that GI symptoms affected their race performance, with...
96 citations
TL;DR: The findings suggest that the learning benefits of an external focus and enhanced expectancies mediate learning through partially different mechanisms.
Abstract: The authors examined the individual and combined influences of 2 factors that have been shown to benefit motor learning: an external focus of attention and enhanced performance expectancies. Another purpose of this study was to gain further insight into the mechanisms underlying these variables. In a factorial design, participants learning a novel motor skill (i.e., throwing with the non-dominant arm) were or were not given external focus instructions, and were or were not provided bogus positive social-comparative feedback to enhance their expectancies. This resulted in 4 groups: external focus, enhanced expectancy, external focus/enhanced expectancy and control. External focus instructions and enhanced expectancies had additive benefits for learning: the external focus/enhanced expectancy group demonstrated the greatest throwing accuracy on both retention and transfer tests, while the accuracy scores of the external focus and enhanced expectancy groups were lower, but higher than those of the control group. Furthermore, self-efficacy was increased by both external focus and enhanced expectancy, and predicted retention and transfer performance. Positive affect was heightened in the enhanced expectancy and external focus/enhanced expectancy groups after practice and predicted transfer performance. The findings suggest that the learning benefits of an external focus and enhanced expectancies mediate learning through partially different mechanisms.
96 citations
TL;DR: The results support the importance of frequent monitoring of recovery and stress parameters to lower the risk of injuries in professional football.
Abstract: Professional football is a contact sport with a high risk of injury. This study was designed to examine the contribution of stress and recovery variables as assessed with the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) to the risk of injury in professional football players. In a prospective, non-experimental cohort design, 22 professional football players in the highest German football league were observed over the course of 16 months. From January 2010 until April 2011, the players completed the RESTQ-Sport a total of 222 times in monthly intervals. In addition, injury data were assessed by the medical staff of the club. Overall, 34 traumatic injuries and 10 overuse injuries occurred. Most of the injuries were located in the lower limb (79.5%), and muscle and tendon injuries (43.2%) were the most frequently occurring injury type. In a generalised linear model, the stress-related scales Fatigue (OR 1.70, P = 0.007), Disturbed Breaks (OR 1.84, P = 0.047) and Injury (OR 1.77, P < 0.001) and the recovery-related scale Sleep Quality (OR 0.53, P = 0.010) significantly predicted injuries in the month after the assessment. These results support the importance of frequent monitoring of recovery and stress parameters to lower the risk of injuries in professional football.
TL;DR: Experience, position and time-trial performance impacted the relationship between external training load and s-RPE training load, suggesting that a given external training Load may result in different internal responses between athletes, potentially leaving individuals at risk of overtraining or failing to elicit positive adaptation.
Abstract: The relationship between external training load and session rating of perceived exertion (s-RPE) training load and the impact that playing experience, playing position and 2-km time-trial performance had on s-RPE training load were explored. From 39 Australian Football players, 6.9 ± 4.6 training sessions were analysed, resulting in 270 samples. Microtechnology devices provided external training load (distance, average speed, high-speed running distance, player load (PL) and player loadslow (PLslow)). The external training load measures had moderate to very large associations (r, 95% CI) with s-RPE training load, average speed (0.45, 0.35–0.54), high-speed running distance (0.51, 0.42–0.59), PLslow (0.80, 0.75–0.84), PL (0.86, 0.83–0.89) and distance (0.88, 0.85–0.90). Differences were described using effect sizes (d ±95% CL). When controlling for external training load, the 4- to 5-year players had higher s-RPE training load than the 0- to 1- (0.44 ± 0.33) and 2- to 3-year players (0.51 ± 0.30), ...
TL;DR: The present findings show that, similar to other tasks, the performance of form-based skills can be enhanced relatively easily by appropriate external focus instructions.
Abstract: The present study was designed to fill a gap in the literature on attentional focus and sports performance. Specifically, in contrast to most previous studies in which an external focus was directed at an implement, we used a gymnastics skill that did not involve the use of an implement. Furthermore, while most studies used only outcome measures of performance, we also assessed movement quality. Twelve-year-old gymnasts performed a maximum vertical jump with a 180-degree turn while airborne, with their hands crossing in front of their chest during the turn under three different focus conditions. Under the external focus condition, participants were asked to focus on the direction in which a tape marker, which was attached to their chest, was pointing after the turn. Under the internal focus condition, they were asked to focus on the direction in which their hands were pointing after the turn. Under the control condition, no focus instructions were given. The external focus condition resulted in both superior movement form and greater jump height than did the other two conditions, which produced comparable results. The present findings show that, similar to other tasks, the performance of form-based skills can be enhanced relatively easily by appropriate external focus instructions.
TL;DR: JS is more effective in reducing the ACC capacity over very short sprints while HS is moreeffective in improving squat jump performance, and both strategies improve ACC over longer distances.
Abstract: The purpose of this study was to test which specific type of exercise (i.e., jump squat (JS) or half-squat (HS)) is more effective at maintaining speed and power abilities throughout a preseason in soccer players. Twenty-three male soccer players were randomly allocated into two groups: JS and HS. The mean propulsive power, vertical jumping ability, and sprinting performance were evaluated before and after 4 weeks of a preseason period. The optimum power loads for the JS and HS exercises were assessed and were used as load-references. The soccer players performed 10 power oriented training sessions in total. Both JS and HS maintained power in JS and speed abilities (P > 0.05, for main effects and interaction effect) as indicated by ANCOVA. Both groups demonstrated reduced power during HS (ES = −0.76 vs. −0.78, for JS and HS, respectively); both groups improved acceleration (ACC) from 5 to 10 m (ES = 0.52). JS was more effective at reducing the ACC decrements over 0–5 m (ES = −0.38 vs. −0.58, for J...
TL;DR: Future investigations should examine sleep during three stages of competition (i.e. before, during and after competition) to help coaches develop a greater understanding of how sleep changes during different phases of competition and enable them to plan post-competition training programmes to ensure appropriate rest and recovery is obtained.
Abstract: Good sleep is critical for optimising recovery and athletic performance. Yet, few studies have investigated how athletes sleep before and during competition. The aim of this study was to determine whether such sleep is poorer than that before a usual training day. Twenty-one male endurance cyclists’ (age: 19.9 ± 1.7 years) sleep/wake behaviour was assessed using wrist activity monitors for 11 nights, including a six-night baseline training phase, three nights before competition and two nights during competition. Cyclists had less sleep on the night before competition (6.5 ± 0.9 h) and during the first night of competition (6.8 ± 0.8 h) than at baseline (7.4 ± 0.6 h). Cyclists also went to bed and woke up earlier during competition than at baseline. Competition schedules and competition itself can disrupt the sleep/wake behaviour of athletes during competition. Future investigations should examine sleep during three stages of competition (i.e. before, during and after competition). This will help c...
TL;DR: The highest movement regularity found in 4- and 5-a-side identified these formats as more adequate to promote team-related emergent and self-organised behaviours.
Abstract: The aim of this study was to compare footballers’ movement behaviour during 2-, 3-, 4- and 5-a-side small-sided games. Ten young professional players (age = 18.0 ± 0.67 years) participated in 3 bouts of each small-sided games for 6 min with 1 min of active rest between bouts. Positional data were collected using GPS system units and used to calculate the following variables: team centroid, distance between each player and own and opponent team centroids and distance between centroids. Approximate entropy was used to identify the time series regularity for each variable. The distance to own team centroid increased with the number of players (effect sizes from moderate to perfect). The results from the distance to the opponent’s centroid exhibited a similar trend. The distance between centroids decreased from 2- to the 4-a-side, but then increased in 5-a-side. A higher number of players were associated with lower approximate entropy values, suggesting higher positional organisation in small-sided ga...
TL;DR: Regular conduction of the “FIFA 11+” did not prevent injuries in veteran footballers under real training and competition circumstances and the lack of preventive effects is likely due to the too low overall frequency of training sessions.
Abstract: The warm-up programme “FIFA 11+” has been shown to reduce football injuries in different populations, but so far veteran players have not been investigated. Due to differences in age, skill level and gender, a simple transfer of these results to veteran football is not recommended. The purpose of this study was to investigate the preventive effects of the “FIFA 11+” in veteran football players.Twenty veteran football teams were recruited for a prospective 9-month (1 season) cluster-randomised trial. The intervention group (INT, n = 146; 45 ± 8 years) performed the “FIFA 11+” at the beginning of each training session, while the control group (CON, n = 119; 43 ± 6 years) followed its regular training routine. Player exposure hours and injuries were recorded according to an international consensus statement.No significant difference was found between INT and CON in overall injury incidence (incidence rate ratio [IRR]: 0.91 [0.64–1.48]; P = 0.89). Only severe injuries reached statistical significance ...
TL;DR: Results showed no differences in the physical performance, although players’ spent more time synchronised during the non-congested fixtures compared to congested fixtures, and tactical performance seems to be affected by fixtures distribution.
Abstract: The aim of this study was to examine the physical and tactical performances of a professional football team under congested and non-congested fixture periods. Six home matches of an English professional football team were analysed during competitive season (3 matches distancing three days from the previous fixture and 3 matches distancing six or more days from the previous fixture). Players’ physical performances were measured by the total distance covered and distance covered at different speed categories. Tactical performances were measured by the percentage of time of players’ movement synchronisation of lateral and longitudinal displacements. This variable was calculated considering all the possible pairs of outfield players, for the overall match and at different speed categories. Results showed no differences in the physical performance, although players’ spent more time synchronised during the non-congested fixtures compared to congested fixtures, both for lateral (41.26% to 38.51%, ES: −0....
TL;DR: The results may suggest that the front squat may be preferred to the back squat for knee extensor development and for preventing possible lumbar injuries during maximum loading.
Abstract: The aim of this study was to compare the musculature activity and kinematics of knee and hip joints during front and back squat with maximal loading. Two-dimensional kinematical data were collected and electromyographic activities of vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus and erector spinae were measured while participants (n = 12, 21.2 ± 1.9 years old) were completing front and back squat exercises with maximum loading. Paired sample t-test was used for comparisons between two techniques. Results showed that the electromyographic activity of vastus medialis was found to be greater in the front squat compared to the back squat during the ascending phase (P < 0.05, d = 0.62; 95% CI, −15.0/−4.17) and the whole manoeuvre (P < 0.05, d = 0.41; 95% CI, −12.8/−0.43), while semitendinosus (P < 0.05, d = −0.79; 95% CI, 0.62/20.59) electromyographic activity was greater in the back squat during the ascending phase. Compared to the front squat versi...
TL;DR: A single dose of l-citrulline or watermelon juice as a pre-exercise supplement appears to be ineffective in improving exercise performance; however, greater doses of l and watermelon Juice have been shown to be safe and are currently left unexamined.
Abstract: Citrulline has been proposed as an ergogenic aid, leading to an interest in watermelon given its high citrulline concentration. The aim of this study was to determine the effects of a single, pre-exercise dose of l-citrulline, watermelon juice, or a placebo on the total maximum number of repetitions completed over 5 sets, time to exhaustion, maximal oxygen consumption (VO2max), anaerobic threshold, and flow-mediated vasodilation. A randomised double-blind within-participants study design was used to examine these effects among 22 participants (n = 11 males). Supplementation included either a 7.5% sucrose drink containing 6 g of l-citrulline, 710 mL of watermelon juice (~1.0 g citrulline), or a 7.5% sucrose placebo drink. Supplementation was administered 1 or 2 h before exercise testing to investigate a timing effect. There was no significant effect between the three supplements for the total number of repetitions, time to exhaustion, VO2max, anaerobic threshold, or flow-mediated vasodilation. Ther...
TL;DR: The afternoon training is more effective than morning or evening sessions for weightlifters, and coaches and weight lifters should be advised to schedule their training session in the afternoon hour.
Abstract: The aim of this study was to investigate the performance of an Olympic-Weightlifting session training at three times of the day on the performance related to biochemical responses. Nine weightlifters (21 ± 0.5 years) performed, in randomised order, on three Olympic-Weightlifting training (snatch, clean and jerk) sessions (08:00 a.m., 02:00 p. m., 06:00 p. m.). Blood samples were collected: before, 3 min and 48 h after each training session. Haematological parameters and markers of muscle injury were assessed. Resting oral temperature and rating of perceived exertion (RPE) were also assessed during each session. ANOVA showed that the performance was better (P < 0.001) at 02:00 p. m. with a less RPE (P < 0.01) compared to the morning and the evening sessions while there was higher (P < 0.05) oral temperature at 06:00 p. m. versus 08:00 a.m. and 02:00 p. m. Muscle damage changed immediately (without significant effect after 48 h) after the training sessions with lower values in the evening compared...
TL;DR: Differences in lean mass were also reflective of higher lean tissue mass in all regions, for example, upper limbs/lower limbs and trunk.
Abstract: Professional soccer players from the first team (1st team, n = 27), under twenty-one (U21, n = 21) and under eighteen (U18, n = 35) squads of an English Premier League soccer team were assessed for whole body and regional estimates of body composition using dual-energy X-ray absorptiometry (DXA). Per cent body fat was lower in 1st team (10.0 ± 1.6) compared with both U21 (11.6 ± 2.5, P = 0.02) and U18 (11.4 ± 2.6, P = 0.01) players. However, this difference was not due to variations (P = 0.23) in fat mass between squads (7.8 ± 1.6 v 8.8 ± 2.1 v 8.2 ± 2.4 kg, respectively) but rather the presence of more lean mass in 1st team (66.9 ± 7.1 kg, P < 0.01) and U21 (64.6 ± 6.5 kg, P = 0.02) compared with U18 (60.6 ± 6.3 kg) players. Accordingly, fat mass index was not different (P = 0.138) between squads, whereas lean mass index was greater (P < 0.01) in 1st team players (20.0 ± 1.1 kg · m−2) compared with U18 players (18.8 ± 1.4 kg · m−2). Differences in lean mass were also reflective of higher lean tis...
TL;DR: The best men and women largely maintained their split speeds between 5 km and 15 km, whereas slower athletes had decreased speeds from 5 km onwards, and those athletes who ran with the same competitors throughout sped up most during the finish.
Abstract: The aim of this study was to describe the pacing profiles and packing behaviour of athletes competing in the IAAF World Half Marathon Championships. Finishing and split times were collated for 491 men and 347 women across six championships. The mean speeds for each intermediate 5 km and end 1.1 km segments were calculated, and athletes grouped according to finishing time. The best men and women largely maintained their split speeds between 5 km and 15 km, whereas slower athletes had decreased speeds from 5 km onwards. Athletes were also classified by the type of packing behaviour in which they engaged. Those who ran in packs throughout the race had smaller decreases in pace than those who did not, or who managed to do so only to 5 km. While some athletes' reduced speeds from 15 to 20 km might have been caused by fatigue, it was also possibly a tactic to aid a fast finish that was particularly beneficial to medallists. Those athletes who ran with the same competitors throughout sped up most during the finish. Athletes are advised to identify rivals likely to have similar abilities and ambitions and run with them as part of their pre-race strategy.
TL;DR: The present findings show an imbalance between stress and recovery in English elite youth players even when players experience lower training exposure than stipulated by the EPPP.
Abstract: The 2011 English Elite Player Performance Plan (EPPP) stipulates training volumes that could put elite youth players at high risk of non-functional overreaching. The aim of the study was to assess player perceptions of well-being and physical performance to these high training loads. Fourteen academy football players (mean ± SD: age 17 ± 1 years; stature 179 ± 6 cm; body mass 70.8 ± 8.6 kg, at pre-season) completed a perception of well-being questionnaire 1–4 times per week throughout each training block (pre-season, in-season 1, 2, 3). Physical performance tests were carried out at the end of each training block. Increases in training exposure (P < 0.05; = 0.52) and moderate to large deteriorations in perceptions of well-being (motivation, sleep quality, recovery, appetite, fatigue, stress, muscle soreness P < 0.05; = 0.30–0.53) were evident as the season progressed. A moderate decrease in 30 m sprint performance (P < 0.05; = 0.48), a large improvement in Yo-Yo intermittent recovery test performa...
TL;DR: The results point to the importance of favourable patterns of motivational variables in the form of specific types, for medium-term performance development among promising football talents, and thus provide valuable clues for the selection and promotion of those.
Abstract: Psychological characteristics are crucial to identifying talents, which is why these are being incorporated in today’s multidimensional talent models. In addition to multidimensionality, talent studies are increasingly drawing on holistic theories of development, leading to the use of person-oriented approaches. The present study adopts such an approach by looking at the influence that motivational characteristics have on the development of performance, in a person-oriented way. For this purpose, it looks at how the constructs achievement motive, achievement goal orientation and self-determination interact with one another, what patterns they form and how these patterns are linked to subsequent sports success. Ninety-seven top young football players were questioned twice. Another year later, it was enquired which of these players had been selected for the U15 national team. At both measuring points, four patterns were identified, which displayed a high degree of structural and individual stability...
TL;DR: Satisfactory psychometric properties for the diagnostics are an important prerequisite for a scientifically sound rating of players’ actual motor performance and for the future examination of the prognostic validity for success in adulthood.
Abstract: The utilisation of motor performance tests for talent identification in youth sports is discussed intensively in talent research. This article examines the reliability, differential stability and validity of the motor diagnostics conducted nationwide by the German football talent identification and development programme and provides reference values for a standardised interpretation of the diagnostics results. Highly selected players (the top 4% of their age groups, U12–U15) took part in the diagnostics at 17 measurement points between spring 2004 and spring 2012 (N = 68,158). The heterogeneous test battery measured speed abilities and football-specific technical skills (sprint, agility, dribbling, ball control, shooting, juggling). For all measurement points, the overall score and the speed tests showed high internal consistency, high test–retest reliability and satisfying differential stability. The diagnostics demonstrated satisfying factorial-related validity with plausible and stable loadings...
TL;DR: Results suggest that team expertise starts with the establishment of team cohesion, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties.
Abstract: A nomological network on team dynamics in sports consisting of a multiframework perspective is introduced and tested The aim was to explore the interrelationship among cohesion, team mental models (TMMs), collective efficacy (CE) and perceived performance potential (PPP) Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study They responded to surveys on team cohesion, TMMs, CE and PPP Results are congruent with the theoretical conceptualisation of a parsimonious view of team dynamics in sports Specifically, cohesion was found to be an exogenous variable predicting both TMMs and CE beliefs TMMs and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams’ season record From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological root
TL;DR: Findings suggest international rugby sevens forwards and backs experience similar match demands while overall match demands remain consistent across tournament rounds.
Abstract: The purpose of this study was to quantify the global match demands of international rugby sevens and to compare the match demands of forwards and backs, and between tournament rounds. To assess the match demands, global positioning system (GPS) and video analysis were collected from 27 international rugby sevens players from the same team across an entire International Rugby Board Sevens World Series season. Differences in running demands and match activities between forwards and backs were mostly trivial and small (ES = 0.05–0.84) while differences in running demands and match activities between Pool and Cup rounds were trivial (ES = 0.001–0.12). Cup round matches showed an increase in long-duration ball-in-play sequences (proportion ratio 0.46). These findings suggest international rugby sevens forwards and backs experience similar match demands while overall match demands remain consistent across tournament rounds.
TL;DR: It is revealed that non-Elite players compare unfavourably to top-elite international European players in many anthropometric and performance characteristics, and differ in a few characteristics compared to elite European club team players.
Abstract: In order to maximise the potential for success, developing nations need to produce superior systems to identify and develop talent, which requires comprehensive and up-to-date values on elite players. This study examined the anthropometric and physical characteristics of youth female team handball players (16.07 ± 1.30 years) in non-elite (n = 47), elite (n = 37) and top-elite players (n = 29). Anthropometric profiling included sum of eight skinfolds, body mass, stature, girths, breadths and somatotype. Performance tests included 20 m sprint, counter-movement jump, throwing velocity, repeated shuttle sprint and jump ability test, and Yo-Yo Intermittent Recovery Test Level 1. Youth top-elite players had greater body mass, lean mass, stature, limb girths and breadths than elite and non-elite players, while only stature and flexed arm were higher in elite compared to non-elite players (all P 0.05). Top-elite performed b...
TL;DR: It is suggested that optimising the scaling of net height may be as critical as other task constraints, such as racquet length or court-size, as it leads to a more engaging learning environment for experienced children.
Abstract: The influence of scaling court-size and net height on children’s tennis performance was examined. Sixteen boys (9.7 ± 0.5 years) had to perform a 30-min match in four different conditions, where court-size and/or net height were scaled by using a scaling ratio based on the differences in temporal demands between the children and the adult game. These 30-min matches were analysed using Tennis Analyst (FairPlay Ltd., Jindalee, QLD, Australia) software to determine typical tennis match performance characteristics. Children hit more winners, more forced errors, played more volleys, struck more shots from a comfortable height and played in a more forward court position when the net was scaled. Scaling both the court and net lead to a faster children’s game, more closely approximating what is typical of the adult game. The differences between the typical tennis performance variables recorded suggested that scaling the net led to a more aggressive way of playing. Further, children enjoyed playing on the ...