Ric Lovell | Western Sydney University (original) (raw)
Papers by Ric Lovell
European Journal of Sport Sciences, 2019
The aim of this study was to determine the in-season micro-cycle scheduling strategies used in pr... more The aim of this study was to determine the in-season micro-cycle scheduling strategies used in professional team sport with particular reference to the reasoning and perceptions that underpin current practice. An online survey was completed by 35 practitioners from professional collision (C; Australian rules football: n=9; rugby league: n=6; rugby union: n=2) and non-collision (NC; soccer; n= 18) sports. Respondents identified a common 48 h post-match recovery period, with few scheduling training stimuli during this period (NC: range: 0-17%; C: range: 0-47%). The majority (C: 78%; NC: 89%) of resistance training sessions were concurrent in nature, often delivering resistance training in the afternoon following field-based training (C: 72%; NC: 92%). NC practitioners were less satisfied with the maintenance of strength, power and hypertrophy (33-44%) versus C sports (59-76%), reflected by the lower frequency of prescription reported (C: 2.4 ± 0.6; NC: 1.5 ± 0.9; p = 0.003). Cold-water immersion following both matches and daily training was highly prevalent, as was the adoption of self-report tools to monitor recovery. The congested and concurrent nature of training prescription during the micro-cycle, together with the universal adoption of routine cold-water immersion warrants further investigation to inform evidence-based prescription and scheduling of training and recovery modalities in professional team sports.
Journal of Science and Medicine in Sports, 2019
Objectives: To examine the influence of maturation and its interaction with playing position upon... more Objectives: To examine the influence of maturation and its interaction with playing position upon physical match performances in U15 footballers from a national federation.
Design: Observational Study
Methods: 278 male outfield players competing in a national tournament were assessed for somatic maturity and match physical performances according to playing position. Stature, sitting height, and body mass were measured and entered into an algorithm to estimate the age at peak height velocity (APHV). Players match movements were recorded by Global Positioning System devices (10Hz), to determine peak speed, and total- (TD), low-speed running (LSR; ≤ 13.0 kmh-1), high-speed running (HSR; 13.1 - 16.0 kmh-1), very high-speed running (VHSR; 16.1 - 20.0 kmh-1) and sprint distances (SPR; > 20.0 kmh-1) expressed relative to match exposure (mmin-1).
Results: Linear-mixed models using log transformed response variables revealed a significant contribution of estimated APHV upon TD (1.01; 95% CI: 0.99-1.02 mmin-1; p < 0.001), HSR (1.05; 95% CI: 0.98-1.13 mmin-1; p < 0.001) and VHSR (1.07; 95% CI: 1.00-1.14 mmin-1; p = 0.047). An increase by one year in APHV was associated with an increase of 0.6, 5.4 and 6.9% in TD, HSR and VHSR respectively. No effects of APHV were observed for LSR, SPR, and peak speed. Further, no APHV effects were observed relative to players’ field position.
Conclusion
Later maturing players covered substantially more higher-intensity (HSR and VHSR) running in matches, irrespective of playing position. The greater match intensity of later maturing players may inform talent identification and athletic development processes within a national federation.
Journal of Science and Medicine in Sports, 2019
Objective: The study examined if three feasible strategies involving additional in-play cooling p... more Objective: The study examined if three feasible strategies involving additional in-play cooling periods attenuate the core (rectal) temperature rise during simulated football matches.
Design: Four counterbalanced experimental trials in an environmental chamber set to 35°C ambient temperature, 55% relative humidity, and 30°C WBGT.
Method: Twelve healthy well-trained football players completed a regular simulated match (REG), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption (COOLwater), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption and the application of an ice towel around the neck (COOLtowel), regular simulated match with an extended (+5 min; total of 20-min) half-time break (HTextended).
Results: The difference in rectal temperature change was significantly lower in the COOLwater (-0.25°C), COOLtowel (-0.28°C), and HTextended (-0.21°C) trials in comparison to the REG (all p<0.05). Exercising heart rate and session rating of perceived exertion was lower in the COOLwater (-13 bpm; -1.4 au), COOLtowel(-10 bpm; -1.3 au), and HTextended (-8 bpm; -0.9 au) trials in comparison to the REGtrial (all p<0.05). The cooling interventions did not significantly change skin temperature or thermal sensation in comparison to the REG (all p>0.05).
Conclusion: All three cooling interventions attenuated core body thermal strain during simulated matches. The laboratory-based study supports the use of brief in-play cooling periods as a means to attenuate the rise in core temperature during matches in hot and humid conditions.
Science and Medicine in Football, 2018
Objectives: This study aims to develop generic velocity thresholds for the analysis of external l... more Objectives: This study aims to develop generic velocity thresholds for the analysis of external load data collected in international women’s football matches.
Methods: Doppler-derived recordings of instantaneous velocity and acceleration were collected (10 Hz GPS) from 27 international female football players during 52 international matches between 2012 and 2015. Data were examined with k-means, Gaussian mixture model (GMM), and Spectral Clustering methods to identify four velocity zones, in each completed half of match-play (277 observations). Spectral Clustering was also performed with 4 different smoothing parameters ( values of 0, 0.001, 0.01, and 0.1). Linear-mixed modelling was used to determine generic squad thresholds, accounting for the within-subject variation.
Results: k-means and GMM generated low transition velocities, which had limited logical validity and deemed not fit for purpose. Spectral Clustering with a value of 0.1 derived thresholds that differed from the various methods adopted in existing literature and industry practice, yet providing a rigorous, acceptable, and feasible determination of velocity thresholds.
Conclusion: Velocities of 3.46 (12.5 km h−1), 5.29 (19.0 km h−1), and 6.26 m s−1 (22.5 km h−1) are recommended as entry criteria into high, very-high velocity, and sprinting locomotor categories, respectively, for the purpose of external load assessments in elite women’s football.
IJSPP, 2018
Purpose: This study assessed the utility of force-time characteristics from the Isometric mid-thi... more Purpose:
This study assessed the utility of force-time characteristics from the Isometric mid-thigh pull (IMTP) as a measure of neuromuscular function (NF) following elite level Australian Rules Football (ARF) matches. It was hypothesized that rate characteristics of force development would demonstrate a different response magnitude and recovery time-course compared to peak force measurements.
Methods:
Force-time characteristics of the IMTP (peak force, 0-50ms rate of force development [RFD], 100-200ms RFD) were collected at 48 h (G+2), 72 h (G+3) and 96 h (G+4) following three competitive ARF matches.
Results:
Meaningful reductions (>75% of the smallest worthwhile change) were observed at G+2, G+3 & G+4 for RFD 0-50ms (-25.8, -17.5 & -16.9%), and at G+2 & G+3 for RFD 100-200ms (-15.7 & -11.7%). No meaningful reductions were observed for peak force at any time point (G+2: -4.0; G+3: -3.9; G+4: -2.7%). Higher week-to-week variation was observed for RFD 0-50ms (G+2: 17.1; G+3: 27.2; G+4: 19.3%) versus both RFD 100-200ms (G+2: 11.3; G+3: 11.5; G+4: 7.2%) and peak force (G+2: 4.8; G+3: 4.4; G+4: 8.4%).
Conclusion:
These findings highlight the potential use of rate characteristics from the IMTP as measures of NF in elite sport settings, and in particular RFD 100-200ms due to its higher reliability. Interestingly, peak force collected from the IMTP was not meaningfully supressed at any time point following elite ARF match-play. This may suggest that rate characteristics from IMTP may provide a more sensitive and valuable insight regarding NF recovery kinetics than peak measures.
There were 1041 time loss injuries recorded during 52127h of exposure resulting in an injury 15 i... more There were 1041 time loss injuries recorded during 52127h of exposure resulting in an injury 15 incidence rate of 20 injuries/1000h (95% Confidence Interval [CI]: 15.9-23.3). The injury 16 burden (days lost to injury relative to exposure) was 228 days lost/1000h. Muscle and ligament 17 injuries were the most prevalent (41% and 26%) and incurred the highest injury burden (83 18 and 80 days lost/1000h, respectively). The most common injuries were observed at the thigh 19 (22%) and ankle (17%), with hamstring (13%) the highest reported muscle injury. The profile 20 of injury severity was: mild – 35%; minor – 29%; moderate – 28% and severe – 8%. Recurrent 21 injuries accounted for 20% of all injuries.
The relationships between maturation and anthropometric and physical performance characteristics ... more The relationships between maturation and anthropometric and physical performance characteristics are dynamic and often asynchronous; confounding the capability to accurately evaluate performance during adolescence. This study aimed to (i) examine the influence of chronological age (CA) and somatic maturation (YPHV) upon anthropometric and physical performance parameters, and (ii) identify the transition/change time-points in these relationships using segmental regression. N=969 soccer players (8-18 years of age) completed anthropometric and physical test assessments, including a counter-movement jump (CMJ), agility T-test, 10 and 20m sprints, and multi-stage fitness test (MSFT). When modelled against CA and YPHV, results identified time-point phases with increased rates of stature (CA - 7.5, YPHV - 8.6 cm·year-1 at 10.7-15.2 years or -3.2 to +0.8 YPHV) and body mass gain (CA - 7.1, YPHV - 7.5 kg·year-1 at 11.9-16.1 years or -1.6 to +4.0 YPHV); followed by gain reductions. Increased rates of sprint performance development (31-43% gains) occurred at 11.8-15.8 CA or -1.8 to +1.2 YPHV; with gains subsiding thereafter. CMJ, T-test, and MSFT gains appeared relatively linear with no change in developmental rate apparent. Developmental tempos did again however subside at circa (CMJ and T-Test) to post-PHV (MSFT). Based on our sample and analysis, periods of increased developmental rates (stature, mass, sprint) were apparent alongside progressive gains for other physical measures, before all subsided at particular age and maturation time-points. Findings highlight dynamic asynchronous development of players, physical attributes, and the need to account for the influence of maturation on athletic performance until post-PHV.
Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle i... more Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle in Soccer is challenged by recovery and tapering phases. This study profiled muscle damage, neuromuscular performance, and perceptual responses to a lower-limb eccentric-based IPP administered 1 (MD+1) versus 3 days (MD+3) post-match. 18 semi-professional players were monitored daily during 3 in-season 6-day micro-cycles, including weekly competitive fixtures. Capillary creatine kinase concentration (CK), posterior lower limb isometric peak force (PF), counter-movement jump (CMJ) performance, and muscle soreness were assessed 24 h prior to match-day (baseline), and every 24 h up to 120 h post-match. The IPP consisted of lunges, single stiff leg dead-lifts, single leg-squats and Nordic hamstring exercises. Performing the IPP on MD+1 attenuated the decline in CK normally observed following match-play (CON: 142%; MD+3: 166%; small differences). When IPP was delivered on MD+3, CK was higher versus CON and MD+1 trials on both MD+4 (MD+3: 260%; CON: 146%; MD+1: 151%; moderate differences) and MD+5 (MD+3: 209%; CON: 125%; MD+1: 127%; small differences). Soreness ratings were not exacerbated when the IPP was delivered on MD+1, but when prescribed on MD+3, hamstring soreness ratings remained higher on MD+4 and MD+5 (small differences). No between trial differences were observed for PF and CMJ. Administering the IPP in the middle of the micro-cycle (MD+3) increased measures of muscle damage and soreness, which remained elevated on the day prior to the next match (MD+5). Accordingly, IPP should be scheduled early in the micro-cycle, to avoid compromising preparation for the following match.
The purpose of this study was to examine the utility of 10Hz GPS technology to determine peak spe... more The purpose of this study was to examine the utility of 10Hz GPS technology to determine peak speed (PS) during both field-testing assessments and tracking during football matches. 23 semi-professional football players wore GPS devices during 14 pre-season (non-competitive; n=6) and in-season (competitive; n=8) fixtures (GPSMatch), and also during 40-m maximal sprint assessments (GPSSprint) measured concurrently via timing gates at 10-m intervals. A large agreement (r = 0.84; 90% CI: 0.70-0.92) and trivial bias (-0.30 km.h-1; 90% CI: -0.61 to 0.01 km.h-1) was observed for PS determined via GPSSprint versus timing gates in sprint testing. Absolute PS was faster in matches (31.4 ± 1.5 km.h-1) versus timing gate (+0.80; 90% CI: 0.13-1.47 km.h-1; likely small effect) and GPSSprint (+1.14; 90% CI: 0.47-1.81 km.h-1; likely moderate effect), irrespective of positional role and stage of the season. These data question the relevance of sprint testing in football, and suggest that peak speed can be determined from GPS tracking data collected over a series of matches.
This study aimed to determine the measurement accuracy of triaxial accelerometers to determine ve... more This study aimed to determine the measurement accuracy of triaxial accelerometers to determine vertical stiffness (Kvert) during overground running, and to examine the influence of device location. Seventeen healthy adults wore two triaxial accelerometers (positioned between scapulae and at lumbar spine) during a 2 min continuous 20 m shuttle run (12 km⋅h-1), which was repeated 7-d later. Accelerometer-derived Kvert data was compared to that calculated from corresponding force-plate ground contacts (criterion measure). Moderate correlations (r=0.65-0.66) between the accelerometer and criterion measure were identified, irrespective of unit location. However, accelerometer-determined Kvert had questionable reliability in both positions (ICC=0.70-0.71). These results suggest caution be taken when utilizing accelerometer-derived Kvert during over-ground running.
This study examined the utility of a range of approaches used to develop player-dependent speed z... more This study examined the utility of a range of approaches used to develop player-dependent speed zones in time-motion analysis (TMA), in determining the dose-response (internal load) of daily football training. Daily external (10Hz GPS) and internal load (heart rate metrics, ratings of perceived exertion [RPE], wellness ratings) measures were tracked for 22 International women’s football players during a 21-day training camp. High-speed (HSR) and very high speed running (VHSR) were determined according to arbitrary speed thresholds, as well as using a range of different individualization approaches that included the velocities corresponding to the heart rate deflection point, maximal aerobic speed, YYIR1 performance, and maximal sprint speed (MSS). Within-player correlations between the TMA approaches versus internal load measures quantified the dose-response to training. Correlations between HSR and VHSR vs. RPE were large (r = 0.53-0.67), with the exception of VHSR for the MSS technique (moderate; r = 0.44). HSR was very-largely associated with heart rate indices (r = 0.72-0.78), again with the exception of MSS (large; r = 0.60-0.67). Using a range of different fitness characteristics to individualise speed thresholds did not enhance the dose-response determination to daily fluctuations in external load, and was worsened with MSS per se.
Science and Football Vii, 2015
Journal of Science and Medicine in Sport, 2015
The principle aim of the current study was to examine within-match patterns of locomotor efficien... more The principle aim of the current study was to examine within-match patterns of locomotor efficiency in professional soccer, determined as the ratio between tri-axial accelerometer data (PlayerLoad™) and locomotor activities. Between match variability and determinants of PlayerLoad™ during match play were also assessed. A single cohort, observational study. Tri-axial accelerometer data (PlayerLoad™) was recorded during 86 competitive soccer matches in 63 English championship players (574 match observations). Accelerometer data accumulated (PlayerLoad Vector Magnitude [PLVM]) from the individual-component planes of PlayerLoad™ (anterior-posterior PlayerLoad™ [PLAP], medial-lateral PlayerLoad™ [PLML] and vertical PlayerLoad™ [PLV]), together with locomotor activity (Total Distance Covered [TDC]) were determined in 15-min segments. Locomotor efficiency was calculated using the ratio of PLVM and TDC (PlayerLoad™ per metre). The proportion of variance explaining the within-match trends in PLVM, PLAP, APML, APv, and TDC was determined owing to matches, individual players, and positional role. PLVM, PLAP, APML, APv and TDC reduced after the initial 15-min match period (p=0.001; η(2)=0.22-0.43, large effects). PL:TDC increased in the last 15min of each half (p=0.001; η(2)=0.25, large effect). The variance in PLVM during soccer match-play was explained by individual players (63.9%; p=0.001) and between-match variation (21.6%; p=0.001), but not positional role (14.1%; p=0.364). Locomotor efficiency is lower during the latter stages of each half of competitive soccer match-play, a trend synonymous with observations of increased injury incidence and fatigue in these periods. Locomotor efficiency may be a valuable metric to identify fatigue and heightened injury risk during soccer training and match-play.
European Journal of Sport Sciences, 2019
The aim of this study was to determine the in-season micro-cycle scheduling strategies used in pr... more The aim of this study was to determine the in-season micro-cycle scheduling strategies used in professional team sport with particular reference to the reasoning and perceptions that underpin current practice. An online survey was completed by 35 practitioners from professional collision (C; Australian rules football: n=9; rugby league: n=6; rugby union: n=2) and non-collision (NC; soccer; n= 18) sports. Respondents identified a common 48 h post-match recovery period, with few scheduling training stimuli during this period (NC: range: 0-17%; C: range: 0-47%). The majority (C: 78%; NC: 89%) of resistance training sessions were concurrent in nature, often delivering resistance training in the afternoon following field-based training (C: 72%; NC: 92%). NC practitioners were less satisfied with the maintenance of strength, power and hypertrophy (33-44%) versus C sports (59-76%), reflected by the lower frequency of prescription reported (C: 2.4 ± 0.6; NC: 1.5 ± 0.9; p = 0.003). Cold-water immersion following both matches and daily training was highly prevalent, as was the adoption of self-report tools to monitor recovery. The congested and concurrent nature of training prescription during the micro-cycle, together with the universal adoption of routine cold-water immersion warrants further investigation to inform evidence-based prescription and scheduling of training and recovery modalities in professional team sports.
Journal of Science and Medicine in Sports, 2019
Objectives: To examine the influence of maturation and its interaction with playing position upon... more Objectives: To examine the influence of maturation and its interaction with playing position upon physical match performances in U15 footballers from a national federation.
Design: Observational Study
Methods: 278 male outfield players competing in a national tournament were assessed for somatic maturity and match physical performances according to playing position. Stature, sitting height, and body mass were measured and entered into an algorithm to estimate the age at peak height velocity (APHV). Players match movements were recorded by Global Positioning System devices (10Hz), to determine peak speed, and total- (TD), low-speed running (LSR; ≤ 13.0 kmh-1), high-speed running (HSR; 13.1 - 16.0 kmh-1), very high-speed running (VHSR; 16.1 - 20.0 kmh-1) and sprint distances (SPR; > 20.0 kmh-1) expressed relative to match exposure (mmin-1).
Results: Linear-mixed models using log transformed response variables revealed a significant contribution of estimated APHV upon TD (1.01; 95% CI: 0.99-1.02 mmin-1; p < 0.001), HSR (1.05; 95% CI: 0.98-1.13 mmin-1; p < 0.001) and VHSR (1.07; 95% CI: 1.00-1.14 mmin-1; p = 0.047). An increase by one year in APHV was associated with an increase of 0.6, 5.4 and 6.9% in TD, HSR and VHSR respectively. No effects of APHV were observed for LSR, SPR, and peak speed. Further, no APHV effects were observed relative to players’ field position.
Conclusion
Later maturing players covered substantially more higher-intensity (HSR and VHSR) running in matches, irrespective of playing position. The greater match intensity of later maturing players may inform talent identification and athletic development processes within a national federation.
Journal of Science and Medicine in Sports, 2019
Objective: The study examined if three feasible strategies involving additional in-play cooling p... more Objective: The study examined if three feasible strategies involving additional in-play cooling periods attenuate the core (rectal) temperature rise during simulated football matches.
Design: Four counterbalanced experimental trials in an environmental chamber set to 35°C ambient temperature, 55% relative humidity, and 30°C WBGT.
Method: Twelve healthy well-trained football players completed a regular simulated match (REG), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption (COOLwater), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption and the application of an ice towel around the neck (COOLtowel), regular simulated match with an extended (+5 min; total of 20-min) half-time break (HTextended).
Results: The difference in rectal temperature change was significantly lower in the COOLwater (-0.25°C), COOLtowel (-0.28°C), and HTextended (-0.21°C) trials in comparison to the REG (all p<0.05). Exercising heart rate and session rating of perceived exertion was lower in the COOLwater (-13 bpm; -1.4 au), COOLtowel(-10 bpm; -1.3 au), and HTextended (-8 bpm; -0.9 au) trials in comparison to the REGtrial (all p<0.05). The cooling interventions did not significantly change skin temperature or thermal sensation in comparison to the REG (all p>0.05).
Conclusion: All three cooling interventions attenuated core body thermal strain during simulated matches. The laboratory-based study supports the use of brief in-play cooling periods as a means to attenuate the rise in core temperature during matches in hot and humid conditions.
Science and Medicine in Football, 2018
Objectives: This study aims to develop generic velocity thresholds for the analysis of external l... more Objectives: This study aims to develop generic velocity thresholds for the analysis of external load data collected in international women’s football matches.
Methods: Doppler-derived recordings of instantaneous velocity and acceleration were collected (10 Hz GPS) from 27 international female football players during 52 international matches between 2012 and 2015. Data were examined with k-means, Gaussian mixture model (GMM), and Spectral Clustering methods to identify four velocity zones, in each completed half of match-play (277 observations). Spectral Clustering was also performed with 4 different smoothing parameters ( values of 0, 0.001, 0.01, and 0.1). Linear-mixed modelling was used to determine generic squad thresholds, accounting for the within-subject variation.
Results: k-means and GMM generated low transition velocities, which had limited logical validity and deemed not fit for purpose. Spectral Clustering with a value of 0.1 derived thresholds that differed from the various methods adopted in existing literature and industry practice, yet providing a rigorous, acceptable, and feasible determination of velocity thresholds.
Conclusion: Velocities of 3.46 (12.5 km h−1), 5.29 (19.0 km h−1), and 6.26 m s−1 (22.5 km h−1) are recommended as entry criteria into high, very-high velocity, and sprinting locomotor categories, respectively, for the purpose of external load assessments in elite women’s football.
IJSPP, 2018
Purpose: This study assessed the utility of force-time characteristics from the Isometric mid-thi... more Purpose:
This study assessed the utility of force-time characteristics from the Isometric mid-thigh pull (IMTP) as a measure of neuromuscular function (NF) following elite level Australian Rules Football (ARF) matches. It was hypothesized that rate characteristics of force development would demonstrate a different response magnitude and recovery time-course compared to peak force measurements.
Methods:
Force-time characteristics of the IMTP (peak force, 0-50ms rate of force development [RFD], 100-200ms RFD) were collected at 48 h (G+2), 72 h (G+3) and 96 h (G+4) following three competitive ARF matches.
Results:
Meaningful reductions (>75% of the smallest worthwhile change) were observed at G+2, G+3 & G+4 for RFD 0-50ms (-25.8, -17.5 & -16.9%), and at G+2 & G+3 for RFD 100-200ms (-15.7 & -11.7%). No meaningful reductions were observed for peak force at any time point (G+2: -4.0; G+3: -3.9; G+4: -2.7%). Higher week-to-week variation was observed for RFD 0-50ms (G+2: 17.1; G+3: 27.2; G+4: 19.3%) versus both RFD 100-200ms (G+2: 11.3; G+3: 11.5; G+4: 7.2%) and peak force (G+2: 4.8; G+3: 4.4; G+4: 8.4%).
Conclusion:
These findings highlight the potential use of rate characteristics from the IMTP as measures of NF in elite sport settings, and in particular RFD 100-200ms due to its higher reliability. Interestingly, peak force collected from the IMTP was not meaningfully supressed at any time point following elite ARF match-play. This may suggest that rate characteristics from IMTP may provide a more sensitive and valuable insight regarding NF recovery kinetics than peak measures.
There were 1041 time loss injuries recorded during 52127h of exposure resulting in an injury 15 i... more There were 1041 time loss injuries recorded during 52127h of exposure resulting in an injury 15 incidence rate of 20 injuries/1000h (95% Confidence Interval [CI]: 15.9-23.3). The injury 16 burden (days lost to injury relative to exposure) was 228 days lost/1000h. Muscle and ligament 17 injuries were the most prevalent (41% and 26%) and incurred the highest injury burden (83 18 and 80 days lost/1000h, respectively). The most common injuries were observed at the thigh 19 (22%) and ankle (17%), with hamstring (13%) the highest reported muscle injury. The profile 20 of injury severity was: mild – 35%; minor – 29%; moderate – 28% and severe – 8%. Recurrent 21 injuries accounted for 20% of all injuries.
The relationships between maturation and anthropometric and physical performance characteristics ... more The relationships between maturation and anthropometric and physical performance characteristics are dynamic and often asynchronous; confounding the capability to accurately evaluate performance during adolescence. This study aimed to (i) examine the influence of chronological age (CA) and somatic maturation (YPHV) upon anthropometric and physical performance parameters, and (ii) identify the transition/change time-points in these relationships using segmental regression. N=969 soccer players (8-18 years of age) completed anthropometric and physical test assessments, including a counter-movement jump (CMJ), agility T-test, 10 and 20m sprints, and multi-stage fitness test (MSFT). When modelled against CA and YPHV, results identified time-point phases with increased rates of stature (CA - 7.5, YPHV - 8.6 cm·year-1 at 10.7-15.2 years or -3.2 to +0.8 YPHV) and body mass gain (CA - 7.1, YPHV - 7.5 kg·year-1 at 11.9-16.1 years or -1.6 to +4.0 YPHV); followed by gain reductions. Increased rates of sprint performance development (31-43% gains) occurred at 11.8-15.8 CA or -1.8 to +1.2 YPHV; with gains subsiding thereafter. CMJ, T-test, and MSFT gains appeared relatively linear with no change in developmental rate apparent. Developmental tempos did again however subside at circa (CMJ and T-Test) to post-PHV (MSFT). Based on our sample and analysis, periods of increased developmental rates (stature, mass, sprint) were apparent alongside progressive gains for other physical measures, before all subsided at particular age and maturation time-points. Findings highlight dynamic asynchronous development of players, physical attributes, and the need to account for the influence of maturation on athletic performance until post-PHV.
Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle i... more Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle in Soccer is challenged by recovery and tapering phases. This study profiled muscle damage, neuromuscular performance, and perceptual responses to a lower-limb eccentric-based IPP administered 1 (MD+1) versus 3 days (MD+3) post-match. 18 semi-professional players were monitored daily during 3 in-season 6-day micro-cycles, including weekly competitive fixtures. Capillary creatine kinase concentration (CK), posterior lower limb isometric peak force (PF), counter-movement jump (CMJ) performance, and muscle soreness were assessed 24 h prior to match-day (baseline), and every 24 h up to 120 h post-match. The IPP consisted of lunges, single stiff leg dead-lifts, single leg-squats and Nordic hamstring exercises. Performing the IPP on MD+1 attenuated the decline in CK normally observed following match-play (CON: 142%; MD+3: 166%; small differences). When IPP was delivered on MD+3, CK was higher versus CON and MD+1 trials on both MD+4 (MD+3: 260%; CON: 146%; MD+1: 151%; moderate differences) and MD+5 (MD+3: 209%; CON: 125%; MD+1: 127%; small differences). Soreness ratings were not exacerbated when the IPP was delivered on MD+1, but when prescribed on MD+3, hamstring soreness ratings remained higher on MD+4 and MD+5 (small differences). No between trial differences were observed for PF and CMJ. Administering the IPP in the middle of the micro-cycle (MD+3) increased measures of muscle damage and soreness, which remained elevated on the day prior to the next match (MD+5). Accordingly, IPP should be scheduled early in the micro-cycle, to avoid compromising preparation for the following match.
The purpose of this study was to examine the utility of 10Hz GPS technology to determine peak spe... more The purpose of this study was to examine the utility of 10Hz GPS technology to determine peak speed (PS) during both field-testing assessments and tracking during football matches. 23 semi-professional football players wore GPS devices during 14 pre-season (non-competitive; n=6) and in-season (competitive; n=8) fixtures (GPSMatch), and also during 40-m maximal sprint assessments (GPSSprint) measured concurrently via timing gates at 10-m intervals. A large agreement (r = 0.84; 90% CI: 0.70-0.92) and trivial bias (-0.30 km.h-1; 90% CI: -0.61 to 0.01 km.h-1) was observed for PS determined via GPSSprint versus timing gates in sprint testing. Absolute PS was faster in matches (31.4 ± 1.5 km.h-1) versus timing gate (+0.80; 90% CI: 0.13-1.47 km.h-1; likely small effect) and GPSSprint (+1.14; 90% CI: 0.47-1.81 km.h-1; likely moderate effect), irrespective of positional role and stage of the season. These data question the relevance of sprint testing in football, and suggest that peak speed can be determined from GPS tracking data collected over a series of matches.
This study aimed to determine the measurement accuracy of triaxial accelerometers to determine ve... more This study aimed to determine the measurement accuracy of triaxial accelerometers to determine vertical stiffness (Kvert) during overground running, and to examine the influence of device location. Seventeen healthy adults wore two triaxial accelerometers (positioned between scapulae and at lumbar spine) during a 2 min continuous 20 m shuttle run (12 km⋅h-1), which was repeated 7-d later. Accelerometer-derived Kvert data was compared to that calculated from corresponding force-plate ground contacts (criterion measure). Moderate correlations (r=0.65-0.66) between the accelerometer and criterion measure were identified, irrespective of unit location. However, accelerometer-determined Kvert had questionable reliability in both positions (ICC=0.70-0.71). These results suggest caution be taken when utilizing accelerometer-derived Kvert during over-ground running.
This study examined the utility of a range of approaches used to develop player-dependent speed z... more This study examined the utility of a range of approaches used to develop player-dependent speed zones in time-motion analysis (TMA), in determining the dose-response (internal load) of daily football training. Daily external (10Hz GPS) and internal load (heart rate metrics, ratings of perceived exertion [RPE], wellness ratings) measures were tracked for 22 International women’s football players during a 21-day training camp. High-speed (HSR) and very high speed running (VHSR) were determined according to arbitrary speed thresholds, as well as using a range of different individualization approaches that included the velocities corresponding to the heart rate deflection point, maximal aerobic speed, YYIR1 performance, and maximal sprint speed (MSS). Within-player correlations between the TMA approaches versus internal load measures quantified the dose-response to training. Correlations between HSR and VHSR vs. RPE were large (r = 0.53-0.67), with the exception of VHSR for the MSS technique (moderate; r = 0.44). HSR was very-largely associated with heart rate indices (r = 0.72-0.78), again with the exception of MSS (large; r = 0.60-0.67). Using a range of different fitness characteristics to individualise speed thresholds did not enhance the dose-response determination to daily fluctuations in external load, and was worsened with MSS per se.
Science and Football Vii, 2015
Journal of Science and Medicine in Sport, 2015
The principle aim of the current study was to examine within-match patterns of locomotor efficien... more The principle aim of the current study was to examine within-match patterns of locomotor efficiency in professional soccer, determined as the ratio between tri-axial accelerometer data (PlayerLoad™) and locomotor activities. Between match variability and determinants of PlayerLoad™ during match play were also assessed. A single cohort, observational study. Tri-axial accelerometer data (PlayerLoad™) was recorded during 86 competitive soccer matches in 63 English championship players (574 match observations). Accelerometer data accumulated (PlayerLoad Vector Magnitude [PLVM]) from the individual-component planes of PlayerLoad™ (anterior-posterior PlayerLoad™ [PLAP], medial-lateral PlayerLoad™ [PLML] and vertical PlayerLoad™ [PLV]), together with locomotor activity (Total Distance Covered [TDC]) were determined in 15-min segments. Locomotor efficiency was calculated using the ratio of PLVM and TDC (PlayerLoad™ per metre). The proportion of variance explaining the within-match trends in PLVM, PLAP, APML, APv, and TDC was determined owing to matches, individual players, and positional role. PLVM, PLAP, APML, APv and TDC reduced after the initial 15-min match period (p=0.001; η(2)=0.22-0.43, large effects). PL:TDC increased in the last 15min of each half (p=0.001; η(2)=0.25, large effect). The variance in PLVM during soccer match-play was explained by individual players (63.9%; p=0.001) and between-match variation (21.6%; p=0.001), but not positional role (14.1%; p=0.364). Locomotor efficiency is lower during the latter stages of each half of competitive soccer match-play, a trend synonymous with observations of increased injury incidence and fatigue in these periods. Locomotor efficiency may be a valuable metric to identify fatigue and heightened injury risk during soccer training and match-play.