Jamie A. Harley

Motion analysis of match-play in elite U12 to U16 age-group soccer players

Abstract The aim of this study was to quantify the motion demands of match-play in elite U12 to U16 age-group soccer players. Altogether, 112 players from two professional soccer clubs at five age-group levels (U12–U16) were monitored during competitive matches (n = 14) using a 5 Hz non-differential global positioning system (NdGPS). Velocity thresholds were normalized for each age-group using the mean squad times for a flying 10 m sprint test as a reference point. Match performance was reported as total distance, high-intensity distance, very high-intensity distance, and sprint distance. Data were reported both in absolute (m) and relative (m · min−1) terms due to a rolling substitute policy. The U15 (1.35 ± 0.09 s) and U16 (1.31 ± 0.06 s) players were significantly quicker than the U12 (1.58 ± 0.10 s), U13 (1.52 ± 0.07 s), and U14 (1.51 ± 0.08 s) players in the flying 10 m sprint test (P < 0.001). The U16 age-group covered significantly more absolute total distance (U16 > U12, U13, U14), high-intensity distance (U16 > U12, U13, U14, U15), very high-intensity distance (U16 > U12, U13), and sprint distance (U16 > U12, U13) than their younger counterparts (P < 0.05). When the data are considered relative to match exposure, few differences are apparent. Training prescription for youth soccer players should consider the specific demands of competitive match-play in each age-group.

The Interchangeability of Global Positioning System and Semiautomated Video-Based Performance Data During Elite Soccer Match Play

Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and semiautomated video-based performance data during elite soccer match play. J Strength Cond Res 25(8): 2334-2336, 2011—In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone® [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; >4.0 m·s-1) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD (GPS: 1,755.4 ± 245.4 m; PZ: 1,631.3 ± 239.5 m; p < 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 ± 24.0 m; GPS: 20.3 ± 15.8 m; HIR: PZ, 368.1 ± 129.8 m; GPS: 317.0 ± 92.5 m; p < 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.

Physiological Response, Time–Motion Characteristics, and Reproducibility of Various Speed-Endurance Drills in Elite Youth Soccer Players: Small-Sided Games Versus Generic Running

PURPOSE To quantify the physiological responses, time-motion characteristics, and reproducibility of various speed-endurance-production (SEP) and speed-endurance-maintenance (SEM) drills. METHODS Sixteen elite male youth soccer players completed 4 drills: SEP 1 v 1 small-sided game (SSG), SEP running drill, SEM 2 v 2 SSG, and SEM running drill. Heart-rate response, blood lactate concentration, subjective rating of perceived exertion (RPE), and time-motion characteristics were recorded for each drill. RESULTS The SEP and SEM running drills elicited greater (P < .05) heart-rate responses, blood lactate concentrations, and RPE than the respective SSGs (ES 1.1-1.4 and 1.0-3.2). Players covered less (P < .01) total distance and high-intensity distance in the SEP and SEM SSGs than in the respective running drills (ES 6.0-22.1 and 3.0-18.4). Greater distances (P < .01) were covered in high to maximum acceleration/deceleration bands during the SEP and SEM SSGs than the respective running drills (ES 2.6-4.6 and 2.3-4.8). The SEP SSG and generic running protocols produced greater (P < .05) blood lactate concentrations than the respective SEM protocols (ES 1.2-1.7). Small to moderate test-retest variability was observed for heart-rate response (CV 0.9-1.9%), RPE (CV 2.9-5.7%), and blood lactate concentration (CV 9.9-14.4%); moderate to large test-retest variability was observed for high-intensity-running parameters (CV > 11.3%) and the majority of accelerations/deceleration distances (CV > 9.8%) for each drill. CONCLUSIONS The data demonstrate the potential to tax the anaerobic energy system to different extents using speed-endurance SSGs and that SSGs elicit greater acceleration/ deceleration load than generic running drills.

Examining the External Training Load of an English Premier League Football Team With Special Reference to Acceleration

Abstract Akenhead, R, Harley, J, and Tweddle, S. Examining the external training load of an English Premier League football team with special reference to acceleration. J Strength Cond Res 30(9): 2424–2432, 2016—Practitioners and coaches often use external training load variables such as distance run and the number of high-speed running (HSR) activities to quantify football training. However, an important component of the external load may be overlooked when acceleration activities are not considered. The aim of this study was to describe the within-microcycle distribution of external load, including acceleration, during in-season 1-game weeks in an elite football team. Global Positioning System technology was used to collect time-motion data from 12 representative 7-day microcycles across a competitive season (48 training days, 295 data sets). Training time, total distance (TD), high-speed running (HSR) distance (>5.8 m·s−1), sprint running distance (>6.7 m·s−1) and acceleration variables were recorded during each training session. Data were analysed for interday and interposition differences using mixed linear modeling. The distribution of external load was characterized by the second training day of the microcycle (5 days prematch) exhibiting the highest values for all variables of training load, with the fourth day (1 day prematch) exhibiting the lowest values. Central midfield players covered ∼8–16% greater TD than other positions excluding wide midfielders (p ⩽ 0.03, d = 0.2–0.4) and covered ∼17% greater distance accelerating 1–2 m·s−2 than central defenders (p = 0.03, d = 0.7). When expressed relative to training duration and TD, the magnitude of interday and interposition differences were markedly reduced (p = 0.03, d = 0.2–0.3). When managing the distribution of training load, practitioners should be aware of the intensity of training sessions and consider the density of external load within sessions.

A comparison of FA Premier League referee and player match work rates

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.

Motion characteristics of elite 12- to 16-year old soccer match-play

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.

The effect of prior training load on soccer referees’ physical match performances

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.