Consistency of Field-Based Measures of Neuromuscular Control Using Force Plate Diagnostics in Elite Male Youth Soccer Players

Consistency of field-based measures of neuromuscular control using force-plate diagnostics in elite male youth soccer players. J Strength Cond Res 30(12): 3304–3311, 2016—Deficits in neuromuscular control during movement patterns such as landing are suggested pathomechanics that underlie sport-related injury. A common mode of assessment is measurement of landing forces during jumping tasks; however, these measures have been used less frequently in male youth soccer players, and reliability data are sparse. The aim of this study was to examine the reliability of a field-based neuromuscular control screening battery using force-plate diagnostics in this cohort. Twenty-six pre–peak height velocity (PHV) and 25 post-PHV elite male youth soccer players completed a drop vertical jump (DVJ), single-leg 75% horizontal hop and stick (75%HOP), and single-leg countermovement jump (SLCMJ). Measures of peak landing vertical ground reaction force (pVGRF), time to stabilization, time to pVGRF, and pVGRF asymmetry were recorded. A test-retest design was used, and reliability statistics included change in mean, intraclass correlation coefficient, and coefficient of variation (CV). No significant differences in mean score were reported for any of the assessed variables between test sessions. In both groups, pVGRF and asymmetry during the 75%HOP and SLCMJ demonstrated largely acceptable reliability (CV ≤ 10%). Greater variability was evident in DVJ pVGRF and all other assessed variables, across the 3 protocols (CV range = 13.8–49.7%). Intraclass correlation coefficient values ranged from small to large and were generally higher in the post-PHV players. The results of this study suggest that pVGRF and asymmetry can be reliably assessed using a 75%HOP and SLCMJ in this cohort. These measures could be used to support a screening battery for elite male youth soccer players and for test-retest comparison

Psychological intervention program to control stress in youth soccer players

The influence on the psychological well-being of the players and their sports performance seems to be one of the keys to the current sports practice. The purpose of this study was to determine the effectiveness of a psychological intervention program for stress control in youth soccer players. A total sample of 19 male youth soccer players (age: 16.3 ± 0.99 years; years playing soccer: 10.89 ± 1.56 years) completed the current research. The Psychological Characteristics Questionnaire related to Sports Performance (CPRD) was used to assess stress factors related to sports competition. A program based on Cognitive-Behavioral Therapy was implemented during eight sessions of approximately 50 min each. A pre-post design was used and statistical differences between pre- and post-measures were checked through dependent sample t-tests. The results indicated that the post-test scores were higher than the pre-tests in "Influence of the Evaluation of Performance" and "Mental Skills" factors, which supposes a significant improvement of the stress management related to performance evaluation, as well as the use of psychological resources and techniques. In addition, the post-test scores were also higher in the "Stress Control" factor, although in this case the differences were not statistically significant. Practical indications deriving from the findings of this study can help youth soccer players to manage the stress of competition using a psychological training program

CAN SHORT BOUTS OF TECHNIQUE TRAINING IMPROVE SPRINT TECHNIQUE AND PERFORMANCE IN YOUTH SOCCER PLAYERS?

This study aimed to investigate whether a technique-oriented intervention would result in improvements in sprint running technique and sprint performance in youth soccer players. Fourteen youth soccer players with pelvis and trunk control issues were divided into intervention and control groups. The intervention group did three weekly 15 minute running technique-oriented training sessions over seven weeks while their counterparts continued with their usual training programme. Sprint performance and technique were assessed before and after the intervention with a Laveg device and two video cameras, respectively, during a 40-m maximal sprint test. The players of the intervention group showed improved control of the trunk and pelvis (p≤0.01) while no change was observed in the control group. Both groups showed a trend for improvement in sprint performance

Influence of oxygen uptake kinetics on physical performance in youth soccer

Purpose: To examine the relationship between oxygen uptake kinetics (VO2 kinetics) and physical measures associated with soccer match-play, within a group of highly trained youth soccer players. Methods: Seventeen highly trained youth soccer players (age: 13.3 ± 0.4 yr, self-assessed Tanner Stage: 3 ± 1) volunteered for the study. Players initially completed an incremental treadmill protocol to exhaustion, to establish gaseous exchange threshold (GET) and VO2max (59.1 ± 5.4 mL.kg-1.min-1). On subsequent visits players completed a step transition protocol from, rest–moderate intensity exercise, followed by an immediate transition from moderate–severe intensity exercise (moderate: 95%GET, severe: 60%∆), during which VO2 kinetics were determined. Physical soccer-based performance was assessed using a maximal Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1) and via GPS derived measures of physical soccer performance during soccer match-play, 3 2 x 20min, 11 v 11 matches, to gain measures of physical performance during soccer match-play. Results: Partial correlations revealed significant inverse relationships between the unloaded to moderate transition time constant (tau) and: Yo-Yo IR1 performance (r = -0.58, P = 0.02) and GPS variables (Total distance (TD): r = - 0.64, P = 0.007, High speed running (HSR): r = - 0.64, P = 0.008, High speed running efforts (HSReff): r = - 0.66, P = 0.005). Conclusion: Measures of VO2 kinetics are related to physical measures associated with soccer match-play and could potentially be used to distinguish between those of superior physical performance, within a group of highly-trained youth soccer players

GENDER DIFFERENCES IN TIBIAL ACCELERATION IN PRE-SEASON YOUTH SOCCER PLAYERS

In soccer, the players need to be able to change direction quickly, meaning the players need the ability to rapidly accelerate and decelerate. Females at a young age have a higher risk of sustaining injuries that can be caused by rapidly accelerating compared to males. The purpose was to investigate the gender differences in acceleration in youth soccer players. 30 youth soccer players engaged in the following drills: a jog, the M drill, 5-10-5 drill, and a single leg triple jump. This data was collected using inertial measurement units. The peak accelerations in the M drill on the left side was the only statistically significant drill (p=0.006, females: 590.9 ± 275.9 m/s2, males: 882.1 ± 263.4 m/s2). There is support to add load management strategies to current training programs and that individualized programs may be the most effective

Reliability, familiarization effect, and comparisons between a predetermined and a self-determined isometric-squat testing protocol

Purpose: This study examined the interday reliability of a predetermined and a self-determined isometric-squat test among youth soccer players. Familiarization effects were evaluated to determine the minimum number of trials necessary to obtain consistent outputs. Finally, differences between protocols were evaluated.Methods: Thirty-one youth soccer players (mean [SD] age: 13.2 [1.0] y; body mass: 54.1 [3.4] kg; stature: 166.3 [11.2] cm; percentage of estimated adult height: 92.6% [3.6%]) from a top-tier professional academy completed 4 experimental sessions for each protocol: familiarization 1, familiarization 2, test, and retest sessions. Peak force; relative peak force; impulse from 0 to 50 milliseconds, 0 to 100 milliseconds, 0 to 150 milliseconds, and 0 to 200 milliseconds; and rate of force development from 0 to 50 milliseconds, 0 to 100 milliseconds, 0 to 150 milliseconds, and 0 to 200 milliseconds were measured. Results: Both protocols displayed acceptable (intraclass correlation coefficient >=.75 and coefficient of variation ≤10%) reliability statistics for all metrics apart from rate of force development of any time epoch. Differences were found between familiarization 2 and both test and retest sessions for peak force (P = .034 and .021, respectively) and relative peak force (P = .035 and .005, respectively) across both protocols. Conclusions: The isometric-squat test is a reliable test among youth soccer players. Two familiarization sessions seem to be sufficient to ensure data stabilization. Outputs between the self-determined and predetermined are comparable; however, the latter seems preferable due to improved testing time efficiency

The impact of verbal encouragement during the repeated agility speed training on internal intensity, mood state, and physical enjoyment in youth soccer players

OBJECTIVE Verbal encouragement (VE) can be used by coaches to boost morale and commitment during training exercises. This investigation aimed to study the impacts of VE given by coaches on the physiological aspects, players' internal intensity, mood, and perceived enjoyment of youth soccer players during repeated agility speed training (RAS). METHODS A total of 17 male youth soccer players (mean ± SD; age: 13.8 ± 0.4 years; body mass: 59.1 ± 6.7 kg; height: 170.0 ± 6.2 cm; training experience: 5.1 ± 0.7 years) participated, in a randomized order, in two experimental training sessions that consisted of a RAS (i.e., the Illinois course) either with VE (RAS-E) or without VE (RAS-NE), with a 7-day interval between the testing sessions. Heart rate (HR) was registered throughout the exercise. The rating of perceived exertion, blood lactate concentration [La], and perceived enjoyment were measured after each training session. The mood state was recorded before and after each protocol. RESULTS HR mean (Cohen's coefficient d = 0.45, small), %HRmax (d = 0.37, small), HR peak (d = 0.66, moderate), [La] (d = 0.56, small), and the PACES score (d = 2.8, very large) were higher in RAS-E compared to RAS-NE (all, P < 0.001). Compared to the RAS-E trial, the RAS-NE trial showed higher fatigue (P < 0.01), tension (P < 0.05), anger (0.05), total mood score (P < 0.001), and lower vigor (P < 0.001). CONCLUSION Coaches may use VE during RAS to improve psychophysiological responses, mood state, and perceived enjoyment in youth soccer players

Seasonal Changes in Physical Qualities of Elite Youth Soccer Players according to Maturity Status: Comparisons with Aged Matched Controls.

Purpose: Longitudinal studies assessing the seasonal development of strength, speed and power qualities are limited in youth soccer players. The purpose of this study was to evaluate the seasonal changes in the physical development of elite youth soccer players across Pre-, Circa- and Post-Peak Height Velocity (PHV), against a similar age and maturity matched control groups. Methods: One-hundred and twelve male elite youth soccer players (Pre-PHV n = 55; Circa-PHV n = 21; Post-PHV n = 36) and 38 controls consisting of non-elite active participants (Pre-PHV n = 18; Circa-PHV n = 10; Post-PHV n = 10) all undertook isometric mid-thigh pull strength, 10–30 m sprints, change of direction speed (CODs) and countermovement jump (CMJ) tests pre- and post-season. Results: The elite Circa-PHV improved greater than the control group for all physical qualities between pre- and post-season. The elite Pre-PHV improved greater in sprints, CODs, CMJ jump height and strength while the elite Post-PHV group improved more in CODs and strength than their respective control groups. Conclusion: Findings suggest that systematic academy soccer training enhances the development of physical qualities in youth soccer players but maturity status may impact upon such adaptations