Jumping asymmetries are associated with speed, change of direction speed, and jump performance in elite academy soccer players. J Strength Cond Res 35(7): 1841-1847, 2021-The aim of this study was to establish interlimb asymmetries across different age groups in elite academy male soccer players and to examine any relationships between asymmetry and measures of physical performance. Fifty-one players from an English Premier League soccer academy were split into under-23 (n = 21), under-18 (n = 14), and under-16 (n = 16) groups and performed bilateral and unilateral countermovement jumps, 5-, 10-, and 20-m sprints, and a 505 change of direction speed tests. All tests showed low variability (coefficient of variation # 2.5%) and good to excellent reliability (intraclass correlation coefficient = 0.80-0.99). A 1-way analysis of variance showed that the under-23 group was significantly faster than the under-16 group during the 20-m sprint (2.90 vs. 2.98 s; p = 0.02; effect size = 0.94). No other significant differences were present between groups. Interlimb asymmetry was quantified from the single-leg countermovement jump, and no significant differences in the magnitude of asymmetry were present between groups. However, multiple significant correlations were present in each age group between asymmetry and physical performance tests, all of which were indicative of reduced athletic performance. Results from this study show that although interlimb asymmetry scores are comparable across age groups in elite academy soccer players, differences as low as 5% are associated with reduced physical performance during jumping, sprinting, and change of direction speed tasks. This study suggests the importance of monitoring jump height asymmetries in elite academy soccer players.

Bio-banded competition has been introduced to address the variation in physical maturity within soccer. To date, no research has investigated the effect of bio-banded competition relative to chronological competition. The current study investigated the effect of bio-banding upon physical and technical performance in elite youth soccer athletes. Twenty-five male soccer athletes (11–15 years) from an English Premier League soccer academy participated in bio-banded and chronological competition, with physical and technical performance data collected for each athlete. Athletes were between 85–90% of predicted adult stature, and sub-divided into early, on-time and late developers. For early developers, significantly more short passes, significantly less dribbles and a higher rating of perceived exertion (RPE) were evident during bio-banded competition compared to chronological competition (p < 0.05). Significantly more short passes and dribbles, and significantly fewer long passes were seen for on-time developers during bio-banded competition (p < 0.05). For late developers, significantly more tackles, and significantly fewer long passes were evident during bio-banded competition (p < 0.05). No significant differences in physical performance were identified between competition formats. Results demonstrated that bio-banded competition changed the technical demand placed upon athletes compared to chronological competition, without reducing the physical demands. Bio-banded competition can be prescribed to athletes of differing maturation groups dependent upon their specific developmental needs.

Eye movements are highly correlated with motor intentions and are often retained by patients with serious motor deficiencies. Despite this, eye tracking is not widely used as control interface for movement in impaired patients due to poor signal interpretation and lack of control flexibility. We propose that tracking the gaze position in 3D rather than 2D provides a considerably richer signal for human machine interfaces by allowing direct interaction with the environment rather than via computer displays. We demonstrate here that by using mass-produced video-game hardware, it is possible to produce an ultra-low-cost binocular eye-tracker with comparable performance to commercial systems, yet 800 times cheaper. Our head-mounted system has 30 USD material costs and operates at over 120 Hz sampling rate with a 0.5-1 degree of visual angle resolution. We perform 2D and 3D gaze estimation, controlling a real-time volumetric cursor essential for driving complex user interfaces. Our approach yields an information throughput of 43 bits s(-1), more than ten times that of invasive and semi-invasive brain-machine interfaces (BMIs) that are vastly more expensive. Unlike many BMIs our system yields effective real-time closed loop control of devices (10 ms latency), after just ten minutes of training, which we demonstrate through a novel BMI benchmark--the control of the video arcade game 'Pong'.

Physical demands of soccer competition vary between playing positions. Previous research investigated total, and high-speed distances, with limited research into acceleration demands of competition. Research investigating speed and acceleration demands have utilised arbitrary thresholds, overlooking the individual nature of athlete locomotion. The current investigation was the first utilising individual speed and acceleration thresholds, investigating the relative intensity of activities. Relationship between match outcome and physical outputs were also investigated. GPS data from 44 professional matches was collected using 10-Hz GPS and 100-Hz accelerometer devices. 343 observations were divided by playing position, and match result, with differences in GPS metrics analysed. Central midfielders produced the highest total distances, and moderateintensity acceleration distances (p<0.01). Wide defenders and attackers produced the highest very highspeed running, sprinting, and high-intensity acceleration distances (p<0.01). Central defenders produced the lowest values for all metrics (p<0.01). No significant differences were found between GPS metrics for differing match outcomes (p>0.05). In addition to differing tactical and technical roles, soccer playing positions have specific physical demands associated. Current results allow overload of individual training intensities relative to competition. No relationships were evident between GPS metrics and match outcome, suggesting soccer success is the result of superior technical and tactical strategies.

Soccer training games are popular training modalities, allowing technical, tactical, and physical aspects to be trained simultaneously. Small (SSGs), medium (MSGs) and large training games (LSGs) elicit differing physical demands. To date, no research has investigated physical and perceived demands of training games upon soccer playing positions relative to competitive demands. Additionally, previous research has referenced average competitive intensities, ignoring peak demands of competition. The current aim was to investigate the effect of training game formats upon average and peak physical outputs produced by soccer playing positions. Physical and perceptual data from twenty-two competitive matches and thirty-nine training game sessions was collected for forty-six U23 professional players using 10-Hz GPS and 100-Hz accelerometer devices (MinimaxX version 4.0; Catapult Innovations, Melbourne, Australia). Data analysed included GPS derived distance, speed, acceleration, deceleration, and RPE. Two-way between subjects ANOVAs were used to compare average and peak GPS metrics, and RPE, between training games and competition for playing positions. Despite eliciting significantly higher average total distances compared to competition (p<0.01), LSGs produced significantly lower peak total distances relative to competition (p<0.01). For very high-speed running and sprinting, LSGs elicited similar average intensities to competition, however peak intensities were significantly lower than competition (p<0.01). MSGs and LSGs produced significantly higher average and peak moderate-intensity explosive distances than competition (p<0.01). Results indicate the importance of analyzing relative to peak competitive demands, instead of focusing solely upon average demands. The study demonstrates specific game formats can overload the competitive demands of playing positions, and provide an individualized training stimulus.