Effects of age and playing position on field-based physical fitness measures in adolescent female soccer players.

BACKGROUND: While numerous studies have explored age and playing position effects on fitness levels in male adolescent soccer players, research on female players in this context is lacking. The purpose of this study was to examine the effects of age and playing position on field-based physical fitness measures in adolescent female soccer players, with consideration for maturity. METHODS: This cross-sectional study involved 284 females aged 12.0-15.9 years. Participants performed the 20-m multi-stage fitness test (20MSFT) to assess estimated maximum oxygen uptake (VO2max), 10-m and 20-m sprints, 505 Test to evaluate change of direction speed (CODS), the medicine ball chest throw (MBCT) and countermovement vertical jump (CMVJ) to assess muscle power. For data analysis, participants were separated into age groups (12, 13, 14, and 15 years), and playing position (forward, midfielder, defender, and goalkeeper). Age at peak height velocity was considered a covariate to account for maturity status. RESULTS: Players aged 14 years demonstrated faster CODS compared to 15 years old (P=0.014), while superior MBCT performance was noted at both ages compared to younger ages (P<0.001). Goalkeepers exhibited lower VO2max than midfielders and defenders (P<0.05). Defenders and goalkeepers exhibited greater hip circumference and body mass compared to midfielders (P≤0.01), along with a larger waist circumference for defenders compared to midfielders (P=0.003). Age and position interactions were absent. When analyses were run without controlling for maturity, all results were the same except for CODS where no age effect was found. CONCLUSIONS: This study suggests that upper body power, and flexibility may be impacted by age and playing position in adolescent female soccer players, regardless of maturity status. The CODS appears to be influenced by age only when controlling for maturity.

Effects of Age and Playing Position on Field-Based Physical Fitness Measures in Adolescent Female Netball Players.

This cross-sectional study investigated the impact of age and playing position, controlling for maturity, on physical fitness indicators in 303 adolescent female netball players aged 12.0 to 15.9 years. Assessments included estimated maximal oxygen uptake (VO2max) via the 20 m shuttle run test, 10 m and 20 m sprints, change of direction speed (CODS) using the 505 test, and muscle power via the medicine ball chest throw (MBCT) and countermovement vertical jump (CMJ). Participants were grouped by age (12 to 15 years) and playing position (non-circle and circle players), with age at peak height velocity as a covariate for maturity. Results revealed that, at 15 years, CMJ height was greater than at 12 years and 13 years (p < 0.05, partial η2 = 0.048). MBCT distance increased across age groups (p < 0.01, partial η2 = 0.323). Age had no impact on sprints, VO2max, or CODS. Non-circle players outperformed circle players in the 10 m sprint (p = 0.042, partial η2 = 0.016) and 20 m sprints (p = 0.010, partial η2 = 0.025) and displayed higher VO2max (p < 0.001, partial η2 = 0.036). Circle players were taller (p = 0.046, partial η2 = 0.014) and heavier (p < 0.001, partial η2 = 0.040) than non-circle players. Playing positions showed no differences in CMJ and MBCT. In adolescent female netball players, only muscle power is influenced by age, while non-circle players exhibit superior aerobic fitness and speed compared to circle players. Coaches may be able to utilize the distinct age and playing position traits of adolescent netballers to inform player selection and design targeted training programs.

Is the use of the coefficient of variation a valid way to assess the swimming intra-cycle velocity fluctuation?

OBJECTIVES: Swimming intra-cycle velocity fluctuation has often been assessed using the coefficient of variation, which requires a mathematical assumption of a positive linear relationship between the velocity mean and standard deviation. As this assumption has never been tested, the current study aimed to investigate the within-participant relationship between the mean and standard deviation of the intra-cycle velocity. DESIGN: Cross-sectional study. METHODS: The intra-trial mean and standard deviation of one stroke cycle centre of mass velocity (vCMmean and vCMSD, respectively) were obtained from 80 front crawl trials (10 participants × eight swimming speeds) using whole-body three-dimensional motion analysis. The linear mixed-effect model and intra-class correlation analysis were used to test the linear relationship between vCMmean and vCMSD (n = 80) and the absolute agreement between vCMmean and vCMSD relative to those during the fastest trial (n = 70). RESULTS: Neither the linear regression model (95 % confidence interval range of the fixed effect of vCMmean: -0.003-0.031) nor the intra-class correlation coefficient (ICC = 0.07; p = 0.26) verified linear relationships between vCMmean and vCMSD, which violated the background assumption of coefficient of variation calculation. CONCLUSIONS: When investigating the intra-cycle velocity fluctuation, the coefficient of variation should not be used alone. Researchers and practitioners should always interpret/report the obtained results together with the mean and standard deviation to avoid misleading conclusions and feedback because the coefficient of variation obtained from one cycle velocity data is likely biased by mean velocity.

"Selecting the right tool for the job" a narrative overview of experimental methods used to measure or estimate active and passive drag in competitive swimming.

Free-swimming performance depends strongly on the ability to develop propulsive force and minimise resistive drag. Therefore, estimating resistive drag (passive or active) may be important to understand how free-swimming performance can be improved. The purpose of this narrative overview was to describe and discuss experimental methods of measuring or estimating active and passive drag relevant to competitive swimming. Studies were identified using a mixed-model approach comprising a search of SCOPUS and Web of Science data bases, follow-up of relevant studies cited in manuscripts from the primary search, and additional studies identified by the co-authors based on their specific areas of fluid dynamics expertise. The utility and limitations of active and passive drag methods were critically discussed with reference to primary research domains in this field, 'swimmer morphology' and 'technique analysis'. This overview and the subsequent discussions provide implications for researchers when selecting an appropriate method to measure resistive forces (active or passive) relevant to improving performance in free-swimming.

Insights into the Uptake, Distribution, and Metabolism of 3-Isobutyl-2-hydroxypyrazine in Grapevine Using a Stable Isotope Tracer.

Methoxypyrazines (MPs) are potent aroma compounds that have been predominately studied in grape berries but can also be detected in other vine tissues. The synthesis of MPs in berries from hydroxypyrazines by VvOMT3 is well established, but the origin of MPs in vine tissues that have negligible VvOMT3 gene expression is unknown. This research gap was addressed through the application of stable isotope tracer 3-isobutyl-2-hydroxy-[2H2]-pyrazine (d2-IBHP) to the roots of Pinot Meunier L1 microvines and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) quantification of HPs from grapevine tissues following a novel solid-phase extraction method. Four weeks post-application, d2-IBHP and its O-methylated product 3-isobutyl-2-methoxy-[2H2]-pyrazine (d2-IBMP) were present in excised cane, berry, leaf, root, and rachis material. Translocation of d2-IBHP and d2-IBMP was investigated, but results were inconclusive. Nonetheless, knowledge that d2-IBHP, and potentially d2-IBMP, are translocated from roots to other vine organs, including the berries, could provide opportunities for controlling MP accumulation in grapevine tissues pertinent to winemaking.

Froude Efficiency and Velocity Fluctuation in Forearm-Amputee Front Crawl: Implications for Para Swimming Classification.

PURPOSE: The impact of physical impairment on Froude efficiency and intracyclic velocity fluctuation in Para swimmers is not well documented. Identification of differences in these variables between disabled and nondisabled swimmers could help develop a more objective system for assigning Para swimmers to classes for competition. This study quantifies Froude efficiency and intracyclic velocity fluctuation in unilateral forearm-amputee front crawl swimmers and evaluates associations between these variables and performance. METHODS: Ten unilateral forearm-amputee swimmers completed front crawl trials at 50- and 400-m pace; three-dimensional video analysis provided mass center, and wrist and stump velocities. Intracyclic velocity fluctuation was calculated as follows: 1) maximum-minimum mass center velocity, expressed as percent of mean velocity, and 2) coefficient of variation in mass center velocity. Froude efficiency was the ratio between mean swimming velocity and wrist plus stump velocity during each segment's respective 1) underwater phase and 2) propulsive underwater phase. RESULTS: Forearm amputees' intracyclic velocity fluctuation (400 m: 22% ± 7%, 50 m: 18% ± 5%) was similar to published values for nondisabled swimmers, whereas Froude efficiencies were lower. Froude efficiency was higher at 400-m (0.37 ± 0.04) than 50-m pace (0.35 ± 0.05; P < 0.05) and higher for the unaffected limb (400 m: 0.52 ± 0.03, 50 m: 0.54 ± 0.04) than the residual limb (400 m: 0.38 ± 0.03, 50 m 0.38 ± 0.02; P < 0.05). Neither intracyclic velocity fluctuation nor Froude efficiency was associated with swimming performance. CONCLUSIONS: Froude efficiency may be a valuable measure of activity limitation in swimmers with an upper limb deficiency and a useful metric for comparing swimmers with different types and severity of physical impairment.

Methoxypyrazine concentrations in the grape bunch rachis of Vitis vinifera L. Cv Shiraz: Influence of rootstock, region and light.

Vitis vinifera L. cv Shiraz appears unable to synthesise 3-alkyl-2-methoxypyrazines (MPs) in the berry, but can still produce significant concentrations in rachis. MPs are readily extracted from rachis during fermentation, producing Shiraz wines with uncharacteristic "green" flavours. Recently, rootstocks were shown to significantly alter MP concentrations in Cabernet Sauvignon rachis compared to own-rooted varieties, but whether Shiraz followed a similar trend required investigation. This study considered the effect of thirteen rootstocks on the concentrations of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) in the rachis of Shiraz bunches sampled during multiple vintages across several Australian growing regions. Although IBMP was the most abundant, all measured MP concentrations were significantly affected by vintage, rootstock, and region. In addition, vine vigour showed positive correlations with IBMP, which were attributed to changes in canopy coverage impacting rachis light exposure. This hypothesis was explored with light exclusion trials, which significantly increased rachis IBMP concentrations.

How Technique Modifications in Elite 100m Swimmers Might Improve Front Crawl Performances to Podium Levels: Swimming 'Chariots of Fire'.

In this paper ways in which performance in 100 m front crawl might be improved are explored. Researchers were identified as 'primary sources' to provide a rationale for how swimmers might improve their performance and to estimate the potential magnitude of improvement. The researchers selected as the primary sources were identified from an initial search of the Scopus and Web of Science data bases using keywords appropriate for the race phases including start, stroking, turn, and finish and their component sub-phases. Recent research was prioritised to ensure that the latest knowledge was considered. Based on an analogy drawn from the 'Chariots of Fire' movie, the hypothetical question was asked: how can we reduce the 100 m time by 0.5s of a swimmer who is already an elite performer? Estimates of potential improvement ranged from 0.013s for the reaction time in the start phase to 1.0s by optimising mid-pool kicking to minimise drag. It is concluded that even at the very elite level, fine-tuning to optimise performance in the different phases of the race could elevate an elite swimmer to podium level performance.

Is torso twist production the primary role of the torso muscles in front crawl swimming?

The torso muscles play important roles in longitudinal rotation between the upper and lower torso on land but demands on these muscles at different swimming speeds and their role in torso twist in front crawl remains unclear. We aimed to compare torso muscle activity at different front crawl speeds and to assess the relationships between torso muscle activity and torso twist. Three-dimensional kinematics and torso muscle EMG data were collected from 15 male swimmers during middle-distance and sprint front crawl. Internal oblique, external oblique, and rectus abdominis, but not erector spinae, activities were greater at sprint than middle-distance pace. Sprint swimmers are likely to benefit from focusing training on the abdominal muscles. Cross-correlation peak coefficients between muscle activity and torso twist occurred with 517-775 and 400-600 ms lag at middle-distance and sprint paces (respectively). These lags are beyond the torso muscle electromechanical delay (~220 ms) and are too long for these muscles to produce movement changes. Further, peak coefficients coincided with both positive and negative shifts, indicating that muscle activity did not always precede kinematic changes. The torso muscles are therefore likely to play a greater role in maintaining stability and controlling posture in front crawl than producing torso twist.

Differences in the rotational effect of buoyancy and trunk kinematics between front crawl and backstroke swimming.

The purpose of the present study was to investigate differences between front crawl and backstroke swimming in hydrodynamic (produced by swimmers) and buoyant torque around the transverse axis. Ten swimmers performed 50 m front crawl and backstroke at four selected velocities (same velocities for both techniques). All trials were recorded by four underwater and two above-water cameras to collect data for three-dimensional whole-body motion during one stroke cycle (defined as a period between two consecutive wrist entries to the water). The inverse dynamics approach was applied to obtain buoyant and hydrodynamic torque around the transverse axis. The differences between front crawl and backstroke techniques across four levels of velocity were assessed with a two-way repeated-measures ANOVA. There was a main effect of technique on the mean buoyant and hydrodynamic torque, with 30-40 % larger leg-raising buoyant torque and leg sinking hydrodynamic torque in front crawl than in backstroke (p ≤ 0.001). The time-series data revealed that the hydrodynamic leg-sinking torque had its peaks during the first half of the underwater upper-limb motion in front crawl, but that was not observed in backstroke, implying that the strategy of counterbalancing the buoyant torque is different between the techniques.

How do swimmers control their front crawl swimming velocity? Current knowledge and gaps from hydrodynamic perspectives.

The aim of this study was to review the literature on front crawl swimming biomechanics, focusing on propulsive and resistive forces at different swimming velocities. Recent studies show that the resistive force increases in proportion to the cube of the velocity, which implies that a proficient technique to miminise the resistive (and maximise the propulsive) force is particularly important in sprinters. To increase the velocity in races, swimmers increase their stroke frequency. However, experimental and simulation studies have revealed that there is a maximum frequency beyond which swimmers cannot further increase swimming velocity due to a change in the angle of attack of the hand that reduces its propulsive force. While the results of experimental and simulation studies are consistent regarding the effect of the arm actions on propulsion, the findings of investigations into the effect of the kicking motion are conflicting. Some studies have indicated a positive effect of kicking on propulsion at high swimming velocities while the others have yielded the opposite result. Therefore, this review contributes to knowledge of how the upper-limb propulsion can be optimised and indicates a need for further investigation to understand how the kicking action can be optimised in front crawl swimming.Abbreviations: C: Energy cost [kJ/m]; E: Metabolic power [W, kJ/s]; Fhand: Fluid resultant force exerted by the hand [N]; Ftotal: Total resultant force [N] (See Appendix A); Fnormal: The sum of the fluid forces acting on body segments toward directions perpendicular to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Ftangent: The sum of the fluid forces acting on body segments along the direction parallel to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Faddmass: The sum of the inertial force acting on the body segments due to the acceleration of a mass of water [N] (See Appendix A); Fbuoyant: The sum of the buoyant forces acting on the body segments [N] (See Appendix A); D: Fluid resistive force acting on a swimmer's body (active drag) [N]; T: Thrust (propulsive) force acting in the swimming direction in reaction to the swimmer's actions [N]; Thand: Thrust force produced in reaction to the actions of the hand [N]; Tupper_limb: Thrust force produced in reaction to the actions of the upper limbs [N]; Tlower_limb: Thrust force produced in reaction to the actions of the lower limbs [N]; Mbody: Whole-body mass of the swimmer [kg]; SF: Stroke frequency (stroke number per second) [Hz]; SL: Stroke length (distance travelled per stroke) [m]; v: Instantaneous centre of mass velocity of the swimmer [m/s]; V-: Mean of the instantaneous centre of mass velocities in the swimming direction over the period of the stroke cycle [m/s]; a: Centre of mass acceleration of the swimmer [m/s2]; V-hand: Mean of the instantaneous magnitudes of hand velocity over a period of time [m/s]; Wtot: Total mechanical power [W]; Wext: External mechanical power [W]; Wd: Drag power (mechanical power needed to overcome drag) [W, Nm/s]; α: Angle of attack of the palm plane with respect to the velocity vector of the hand [deg]; ηo: Overall efficiency [%]; ηp: Propelling efficiency [%]; MAD-system: Measuring Active Drag system; MRT method: Measuring Residual Thrust method.

Effect of torso morphology on maximum hydrodynamic resistance in front crawl swimming.

The aim of this study was to determine the influence of torso morphology on maximum instantaneous hydrodynamic resistance in front crawl swimming. Outlines of the torso in the frontal and anteroposterior planes were calculated from photographic images to determine continuous form gradients (m/m) for the anterior, posterior and lateral aspects of the torso. Torso cross-sectional areas at each vertical sample (0.001 m) were used to calculate maximal rate of change in cross-sectional area (m2/m) in the chest-waist and waist-hip segments. During the non-propulsive hand phase in middle-long distance front crawl, kicking propulsion is negligible and therefore the net force is equal to the drag. Drag coefficients were calculated at the instant of maximum horizontal deceleration of centre of mass during the non-propulsive hand phase of 400 m pace front crawl. Maximal rate of change in cross-sectional area (r = 0.44, p = 0.014) and posterior form gradient (r = 0.50, p = 0.006) of the waist-hip torso segment had moderate positive correlations with the maximal drag coefficient. A regression model including these variables explained 41% of the variance (p = 0.001). Indentation at the waist and curvature of the buttocks may result in greater drag force and influence swimming performance.

The Effectiveness of Coaching the Australian Recommended Fundamental Overarm Throwing Skill Criteria for Less-Skilled Adolescents.

Purpose: The aim of this study was to investigate the effects of coaching the Australian recommended fundamental overarm throwing skill criteria for less-skilled adolescents on movement competency using three-dimensional (3D) motion analysis. Methods: Less-skilled non-sports-active and skilled sports-active pupils were assigned to FMS Group (n = 97) and Sports Group (n = 129), respectively. Demographic, anthropometric, whole-body kinematic (discrete and time-series angular displacement and angular velocity data), motor coordination (segmental sequencing) and motor performance (maximum ball release speed) were analyzed. Baseline data were compared using independent T-tests and Chi-Square tests; interaction effects were assessed using repeated-measure ANOVAs. Changes in time-series kinematic data were analyzed by comparing the areas enclosed by the 95% confidence intervals. Results:There was merely a modest improvement in motor competency for the less-skilled pupils. The FMS group significantly acquired 13/75 discrete kinematic variables (p < .01) and four movement patterns but not motor coordination (p = .469) and motor performance (p = .756). Prior to the intervention, the pupils acquired 4/7 recommended skill criteria. The descriptions of another three criteria were not appropriate with no improvement in motor coordination and performance. Two new skills were identified and improved after the FMS intervention. Conclusions: The recommended skill criteria for children were not developmentally and age-appropriate for early adolescents. The use of quantitative 3D motion data provided a more precise and developmentally applicable fundamental overarm throwing criteria than content validated skill criteria. The recommended skill criteria should be modified to facilitate teachers and coaches for effective education.

Effects of Age and Sex on Aerobic Fitness, Sprint Performance, and Change of Direction Speed in High School Athletes.

ABSTRACT: Hackett, DA, He, W, Fleeton, JRM, Orr, R, and Sanders, RH. Effects of age and sex on aerobic fitness, sprint performance, and change of direction speed in high school athletes. J Strength Cond Res 37(5): 325-331, 2023-The purpose of this study was to examine the effects of sex and age on aerobic fitness, sprinting performance, and change of direction speed (CODS) in high school athletes, with consideration for maturity. This cross-sectional study involved 2,132 adolescents (1,415 male and 717 female athletes) aged 12.0-15.9 years. Assessment of aerobic fitness using the 20-m multistage fitness test (20MSFT) and 20-m sprint and CODS using the 505 test was performed. For the analysis of data, subjects were separated into 4 age groups: U/13 years, U/14 years, U/15 years, and U/16 years. Estimated age at peak height velocity was a covariate in the data analysis to control for maturity status. Compared with female athletes, male athletes had superior performances at all age groups in 10-m sprint ( p < 0.001, effect size [ES] = >-0.44), 20-m sprint ( p < 0.001, ES = >-0.55), and 505 test ( p < 0.001, ES = >-0.41). Female athletes performed better than male athletes in 20MSFT at U/13 ( p < 0.01, ES = -0.22); however, male athletes had better performances at U/15 ( p < 0.01, ES = 0.27) and U/16 ( p < 0.001, ES = 0.67). At each consecutive age group, male athletes improve their performances in 20MSFT and sprints and at U/14 and U/16 in the 505 test ( p < 0.001, ES > -0.37). Female athletes showed no improvement in the 20MSFT and 505 test between U/13-U/16 but showed improved sprint performance at U/15 compared with U/13 and at U/16 compared with U/14 ( p < 0.05). This study shows that adolescent male athletes perform consistently better than female athletes in running-related field-based tests and display continuous improvements across age groups.

The FIFA 11+ Kids Injury Prevention Program Reduces Injury Rates Among Male Children Soccer Players: A Clustered Randomized Controlled Trial.

BACKGROUND: The Fédération Internationale de Football Association (FIFA) 11+ Kids is an exercise-based injury prevention program developed by an international group of experts to prevent injuries among child soccer players. HYPOTHESIS: It was hypothesized that the FIFA 11+ Kids program would be more effective than performing a typical warm-up regimen in reducing overall injuries among soccer players aged 7 to 13 years. STUDY DESIGN: A clustered randomized controlled trial. LEVEL OF EVIDENCE: Level 1. METHODS: A total of 94 boys' soccer teams, including 780 players, were randomly allocated into an experimental or control group. Complete datasets were collected from 45 teams (377 players) and 43 teams (363 players) in the experimental and control groups, respectively. The experimental group underwent the FIFA 11+ Kids program as a warm-up during training sessions and matches at least twice a week, and the control group continued performing their usual warm-ups. Participants were prospectively followed during 1 season (6 months). The primary outcomes included the incidence of overall and recurrent injuries and their mechanism and severity. The secondary outcome was the rate of compliance with the intervention program. RESULTS: A total of 43 injuries were reported in the experimental group in 50,120 hours of exposure (0.85 injuries/1000 exposure hours). A total of 86 injuries were reported in the control group in 42,616 hours of exposure (2.01 injuries/1000 exposure hours). The injury risk ratio was 0.43 (0.29-0.61), suggesting that the experimental group experienced 57% fewer injuries than those in the control group. CONCLUSION: The FIFA 11+ Kids program reduced overall injury rates in children playing soccer more than the usual warm-ups. CLINICAL RELEVANCE: The results of this study provide evidence for children's coaches to consider including the FIFA 11+ Kids program in their warm-up regimen. Such a program may prevent injury risk and decrease absenteeism and injury-related financial burdens.

Injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament injury: a systematic review of cluster randomised trials.

QUESTION: Do injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament (ACL) injuries in sport? DESIGN: Systematic review of (cluster) randomised trials with meta-analysis. PARTICIPANTS: Sporting participants of any age, sex or competition level. INTERVENTIONS: The experimental intervention was an injury prevention program that included plyometric exercises. The control intervention was the usual warm-up program, which did not include plyometric exercises. OUTCOME MEASURES: Exposure-based ACL injury rates. RESULTS: The initial search yielded 7,302 articles, of which nine met the inclusion criteria. All nine articles reported cluster randomised trials, providing data on 14,394 participants. The pooled results showed that injury prevention programs that include plyometric exercises reduce the risk of ACL injury by 60% per 1,000 hours of exposure compared with the control group, with an injury risk ratio (IRR) of 0.40 (95% CI 0.26 to 0.63). Data from subgroups of these trials estimated that this preventative effect may be stronger in males (IRR 0.21, 95% CI 0.07 to 0.62) and weaker in females (IRR 0.51, 95% CI 0.30 to 0.87), albeit with less precise estimates. Subgroup analysis also suggested a stronger effect on non-contact ACL injuries (IRR 0.34, 95% CI 0.18 to 0.65), whereas the effect on contact ACL injuries remained uncertain (IRR 0.59, 95% CI 0.15 to 2.30). CONCLUSIONS: Injury prevention programs that incorporate plyometric exercises substantially decrease the risk of ACL injuries more than warm-up programs that do not include plyometric exercises. The preventive effect appears to be stronger among males and in the prevention of ACL injuries that do not involve contact with another player. PROSPERO CRD42020196982.

Impact of maximal strength training on countermovement jump phase characteristics in athletes with cerebral palsy.

Analysis of the countermovement jump (CMJ) force-time curve phases provides insight into athlete neuromuscular function and methods by which jump height improves in response to training. A CMJ phase analysis and the dynamic strength index (DSI) have yet to be explored in athletes with cerebral palsy (CP). This study aimed to address this knowledge gap. Eleven state- to international-level athletes with CP completed a pre-post maximal strength training intervention with waitlist control. CMJ was assessed via force plate pre/post baseline and after the 12-week intervention. Following the intervention, CMJ height, takeoff velocity, and concentric phase peak and mean force, impulse and mean acceleration improved significantly (p = 0.006-0.001). No changes were observed in any eccentric braking phase variable (p = 0.79-0.13), while DSI lowered (p = 0.03). In athletes with CP, strength training increased CMJ concentric phase peak and mean force and impulse, increasing velocity and acceleration and therefore jump height. DSI lowered due to moderate and small increases in isometric mid-thigh pull and CMJ peak force, respectively. Unlike in non-disabled athletes, strength training did not alter any eccentric phase variable; therefore, other modalities may be required to further optimize jumping performance in athletes with CP.

Segmental sequencing of the upper body segments in unconstrained maximum overarm throws: An implication for coaching.

Overarm throwing is an essential fundamental movement skill (FMS). Competency in throwing is critical to encourage physical activity throughout lifespan. However, the segmental sequencing characteristics of skilled throwing to achieve maximum ball release speed are unclear. Further, the standard instructions for segmental sequencing in coaching manuals are anecdotal and not based on scientific evidence. Therefore, the aim of this study was to establish the critical features of upper-body sequencing in skilled throwing for maximum speed. This would enable revised instructions for coaching throwing based on scientific evidence. The three-dimensional kinematics of 144 right-handed unconstrained maximum overarm throws were captured and analyzed. The quartiles of participants with the fastest and lowest ball release speed, normalized by height, were defined as the Skilled Group and Less Skilled Group, respectively. Paired t-tests were used to determine the differences in times of successive events within groups and independent t-tests for between-group differences in temporal space between events for all sequences. A characteristic segmental sequence of each group was defined as a sequence with significant within-group differences in two successive events (p < 0.001), while a critical segmental sequence was defined as a sequence with significant differences in temporal space both within groups and between groups (p < 0.001). The Skilled Group had six characteristic sequences, while two were found for the Less Skilled Group, summarized in the conceptual model. A single critical sequence of non-throwing arm elbow extension prior to shoulder extension was found. Five evidence-based instructions were recommended to add to the Australian FMS instruction manual.

Injury prevention programs that include balance training exercises reduce ankle injury rates among soccer players: a systematic review.

QUESTION: What is the effect of injury prevention programs that include balance training exercises on the incidence of ankle injuries among soccer players? DESIGN: Systematic review of randomised trials with meta-analysis. PARTICIPANTS: Soccer players of any age, sex or competition level. INTERVENTIONS: The experimental intervention was an injury prevention program that included balance training exercises. The control intervention was the soccer team's usual warm-up program. OUTCOME MEASURES: Exposure-based ankle injury rates. RESULTS: Nine articles met the inclusion criteria. The pooled results of injury prevention programs that included balance training exercises among 4,959 soccer players showed a 36% reduction in ankle injury per 1,000 hours of exposure compared to the control group with an injury risk ratio (IRR) of 0.64 (95% CI 0.54 to 0.77). The pooled results of the Fédération Internationale de Football Association (FIFA) injury prevention programs caused a 37% reduction in ankle injury (IRR 0.63, 95% CI 0.48 to 0.84) and balance-training exercises alone cause a 42% reduction in ankle injury (IRR 0.58, 95% CI 0.41 to 0.84). CONCLUSIONS: This meta-analysis demonstrates that balance exercises alone or as part of an injury prevention program decrease the risk of ankle injuries. PROSPERO CRD42017054450.