'Setting the Benchmark' Part 2: Contextualising the Physical Demands of Teams in the FIFA World Cup Qatar 2022

This study aimed to contextualise and benchmark the physical demands of teams in the FIFA World Cup Qatar 2022. With FIFA's official approval, all sixty-four games were analysed during the competition (n = 32 teams) using a multi-camera computerised tracking system. On average, teams during Qatar 2022 covered around 108.1 ± 3.6 km in total, with 9.0 ± 0.9 and 2.3 ± 0.3 km covered at the higher intensities (≥20.0 and ≥25.0 km · h-1), respectively. Compared to the FIFA World Cup Russia 2018, national teams in Qatar 2022 covered only 3% more total distance but 16-19% more distance at the higher intensities (P < 0.01; Effect Size [ES]: 0.9-2.0). When the data was adjusted based on the number of minutes played, tournament differences at the higher intensities were less pronounced (9-12%; P < 0.01; ES: 0.7-1.3). The United States, Canada, Saudi Arabia, Germany and IR Iran covered 19-34% more high-intensity distance than Argentina, Ecuador, Qatar, Poland and Costa Rica during the 2022 tournament (P < 0.01; ES: 3.2-3.5). Match-to-match variation of each team in Qatar 2022 revealed Ecuador and Uruguay were particularly consistent for the distances covered at higher intensities (Coefficient of Variation [CV]: 2-3%), whilst Japan demonstrated considerable variation (CV: 23-29%). Teams generally covered more total distance on a per-minute basis in the first versus the second half (P < 0.01; ES: 1.2), but no differences existed at higher intensities (P > 0.05; ES: 0.0-0.1). Correlations between the number of high-intensity runs and various phase of play events across all teams were strongest for defensive transitions and recoveries, in addition to progressions up the pitch and into the final third (r = 0.63-0.75; P < 0.01). The present findings provide valuable context into the contemporary team demands of international football. This information could be useful for practitioners to benchmark team performances and to potentially understand the myriad of factors impacting physical performances.

'Setting the Benchmark' Part 1: The Contextualised Physical Demands of Positional Roles in the FIFA World Cup Qatar 2022

This study aimed to contextualise and benchmark the positional role demands during the FIFA World Cup Qatar 2022. With FIFA's official approval, all sixty-four games were analysed during the competition (n=722) using a multi-camera computerised tracking system. During a typical FIFA World Cup Qatar 2022 match, defensive and central midfielders covered 8-19% more total distance than other positional roles (P<0.01; Effect Size [ES]: 0.8-2.5). The distances covered at higher intensities (≥20 and ≥25 km · h-1) were 16-92% and 36-138% higher for wide midfielders and wide forwards compared to central defenders, defensive and central midfielders as well as centre forwards (P<0.01; ES: 0.7-2.2 and ES: 0.6-1.4). Defensive and central midfielders covered a greater proportion of their distance at higher intensities (≥20 and ≥25 km · h-1) out-of-possession (71-83%; P<0.01; ES: 1.4-3.0), whilst attacking midfielders, wide and centre forwards more in-possession (55-68%; P<0.01; ES: 1.6-3.3). Nine out of the top ten sprint speeds attained at the tournament were from wide positional roles (35.3-35.7 km · h-1). All positional roles demonstrated a second half reduction in total distance covered compared to the first half (P<0.01; ES: 0.8-1.3). A decline between halves for the distances covered at higher intensities (≥20 and ≥25 km · h-1) were more evident in attacking midfielders, wide defenders and midfielders than for other positional roles (P<0.01; ES: 0.3-0.7). Defensive midfielders and centre forwards were found to have the highest coefficient of variation (CV: 30.9-35.9% and 67.7-67.8%) for the distances covered at higher intensities (≥20 and ≥25 km · h-1) compared to other positional roles. The current findings provide valuable contextual information about the contemporary positional demands of international football. This could be useful in the development and prescription of specific training regimes for national teams.

Transcranial direct current stimulation during a prolonged cognitive task: the effect on cognitive and shooting performances in professional female basketball players

The negative effect of prolonged cognitive demands on psychomotor skills in athletes has been demonstrated. Transcranial direct current stimulation (tDCS) could be used to mitigate this effect. This study examined the effects of tDCS over the left dorsolateral prefrontal cortex (DLPFC) during a 30-min inhibitory Stroop task on cognitive and shooting performances of professional female basketball players. Following a randomised, double-blinded, sham-controlled, cross-over design, players were assigned to receive anodal tDCS (a-tDCS, 2 mA for 20 min) or sham-tDCS in two different sessions. Data from 8 players were retained for analysis. Response Time decreased significantly over time (p < 0.001; partial η² = 0.44; no effect of condition, or condition vs. time interaction). No difference in mean accuracy and shooting performance was observed between tDCS conditions. The results suggest that a-tDCS exert no additional benefits in reducing the negative effects of prolonged cognitive demands on technical performance compared to sham (placebo).Practitioner summary: Prolonged cognitive demands can negatively affect the athletes' performance. We tested whether transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) could attenuate these effects on cognitive and shooting performance in professional female basketball players. However, tDCS did not exert any additional benefits compared to sham.Abbreviations: tDCS: transcranial direct current stimulation; a-tDCS: anodal transcranial direct current stimulation; PFC: prefrontal cortex; DLPFC: dorsolateral prefrontal cortex; PCT: prolonged cognitive task; TT: time trial; RT: response time; NASA-TLX: National Aeronautics and Space Administration Task Load Index; RPE: ratings of perceived exertion; CR-10 scale: category rating scale; EEG: electroencephalogram; AU: arbitrary units.

Menstrual cycle phase and elite female soccer match-play: influence on various physical performance outputs

INTRODUCTION

The aim of the study was to investigate whether menstrual cycle phases influence the physical performance during soccer match-play.

METHODS

Fifteen elite female soccer players, with physiologically normal menstrual cycles, competed in matches over a four-month period. Physical performance was assessed via GPS and expressed as meters per minute, and separated into four individualised thresholds (low, high, very high and sprinting). Seventy-six complete individual match observations, 36 from the follicular and 40 from the luteal phase were recorded. The differences in physical match performance parameters between the cycle phases were evaluated using a mixed linear model.

RESULTS

The results of the current study indicate that very high-intensity running distance was significantly greater during the luteal phase compared to the follicular phase (5.90 ± 2.16 m^.min^-1 vs. 6.64 ± 2.72 m^.min^-1; p = 0.02). However, this finding was accompanied by large variations across matches (CV = 39.5%).

CONCLUSIONS

Overall, the results suggest that the menstrual cycle phase does not influence match physical performance of female soccer players to a significant degree. Therefore, at present, interventions or other methods of coping with menstrual cycle phase do not seem necessary on a group/team level to maximise competitive physical performance.

Physiological characteristics and acute fatigue associated with position-specific speed endurance soccer drills: production vs maintenance training

Objective: The study aimed to compare the physiological characteristics and acute fatigue associated with position-specific speed endurance production (SEP) and maintenance (SEM) soccer drills.Methods: Twenty male soccer players performed a position specific drill consisting of 8 exercise bouts each lasting ~30 s interspersed by 150 s (SEP) and 60 s (SEM) of passive recovery. A selection of players (n = 10) completed neuromuscular assessments pre and post drill.Results: Players covered greater high speed (12%), very high speed (49%) and sprint (218%) running distances in SEP (P < 0.05, ES: 0.51-0.80). SEP resulted in greater peak (7%) and average (10%) running speeds (P < 0.01, ES: 0.70-0.93). Mean and peak heart rate responses were greater in SEM (4-10%, P < 0.01, ES: 0.97-1.84) whilst blood lactate concentrations were higher following SEP (6%, P < 0.05, ES: 0.42). Reductions in vertical countermovement jump height were more pronounced immediately after SEP (2%, P < 0.05, ES: 0.36) but 24 h post SEM (4%, P < 0.05, ES: 0.52). Horizontal countermovement jump performance was reduced immediately post SEP and SEM (3-5%, P < 0.01, ES: 0.22-0.38) and 24 h post SEM (4%, ES: 0.32).Conclusion: The data demonstrate that position-specific SEP and SEM drills overload different physiological indices and induce small impairments in some neuromuscular measures.

Accumulative weekly load in a professional football team: with special reference to match playing time and game position

The aim of this study was to compare weekly accumulative load during the in-season competitive period by professional soccer players according to the amount of time played in official matches (90-min, >60-min, <60-min, and 0-min) regarding the players' position. Twenty-four professional outfield football players were monitored by GPS devices during training sessions and official matches and the accumulative weekly load were calculated for the following external load variables: total distance (TD; m), high speed running (HSR; >19.8 km·h-1), sprint meters (SPR; >25.2 km·h-1), high metabolic load distance (HMLD; >25.5 W·kg-1), number of accelerations (ACC; >3 m·s-2) and decelerations (DEC; <-3 m·s-2). This study revealed that players (as a whole o per demarcation) with more match playing time had a higher accumulative weekly load for most of the variables, but particularly at TD and HMLD (90-min and >60-min vs. <60-min and 0-min), HSR (90-min vs. <60-min and 0-min) and SPR (90-min vs. <60-min and 0-min). In addition, less positional variation was observed in relation to the competition requirements. This information would allow coaches to refine the required load with the objective of optimizing performance to soccer players.

Effect of Transcranial Direct Current Stimulation on Professional Female Soccer Players' Recovery Following Official Matches

This study investigated the effect of transcranial direct current stimulation (tDCS) combined with a recovery training session on the well-being and self-perceived recovery of professional female soccer players after official matches. Data from 13 world-class players were analyzed after participating in four official soccer matches of the first division of the Brazilian Women's Soccer Championship (7-, 10-, and 13-day intervals). We applied anodal tDCS (a-tDCS) over the left dorsolateral prefrontal cortex with 2 mA for 20 minutes (+F3/-F4 montage) the day after each match. Participants underwent two randomly ordered sessions of a-tDCS or sham. Players completed the Well-Being Questionnaire (WBQ) and the Total Quality Recovery (TQR) scale before each experimental condition and again the following morning. A two-way repeated-measures ANOVA showed a significant time x condition interaction on the WBQ (F_(1,11)=5.21; p=0.043; η_p²=0.32), but not on the TQR (F_(1,12) = 0.552; p = 0.47; η_p² = 0.044). There was a large effect size (ES) for a-tDCS for the WBQ score (ES = 1.02; 95%CI = 0.17;1.88), and there was a moderate WBQ score increase (ES = 0.53; 95%CI = -0.29;1.34) for the sham condition. We found similar increases in the TQR score for a-tDCS (ES = 1.50; 95%CI = 0.63-2.37) and the sham condition (ES = 1.36; 95%CI = 0.51-2.22). These results suggest that a-tDCS (+F3/-F4 montage) combined with a recovery training session may slightly improve perceived well-being beyond the level of improvement after only the recovery training session among world-class female soccer players. Prior to widely adopting this recovery approach, further study is needed with larger and more diverse samples, including for female teams of different performance levels.

Effect of tDCS on well-being and autonomic function in professional male players after official soccer matches

This study aimed to examine the effect of transcranial direct current stimulation (tDCS) used as a recovery strategy, on heart rate (HR) measures and perceived well-being in 12 male professional soccer players. tDCS was applied in the days after official matches targeting the left dorsolateral prefrontal cortex (DLPFC) with 2 mA for 20 min (F3-F4 montage). Participants were randomly assigned to anodal tDCS (a-tDCS) or sham tDCS sessions. Players completed the Well-Being Questionnaire (WBQ) and performed the Submaximal Running Test (SRT) before and after tDCS. HR during exercise (HRex) was determined during the last 30 s of SRT. HR recovery (HRR) was recorded at 60 s after SRT. The HRR index was calculated from the absolute difference between HRex and HRR. A significant increase was observed for WBQ (effect of time; p<0.001; η_p²=0.417) with no effect for condition or interaction. A decrease in HRR (p = 0.014; η_p²=0.241), and an increase in HRR index were observed (p = 0.045; η_p²=0.168), with no effect for condition or interaction. No change for HRex was evident (p>0.05). These results suggest that a-tDCS over the DLPFC may have a positive effect on enhancing well-being and parasympathetic autonomic markers, which opens up a possibility for testing tDCS as a promising recovery-enhancing strategy targeting the brain in soccer players. The findings suggest that brain areas related to emotional and autonomic control might be involved in these changes with a possible interaction effect of tDCS by placebo-related effects, but more research is needed to verify this effect.

Are There Differences in Elite Youth Soccer Player Work Rate Profiles in Congested vs. Regular Match Schedules?

ABSTRACT

Zanetti, V, Carling, C, Aoki, MS, Bradley, PS, and Moreira, A. Are there differences in elite youth soccer player work rate profiles in congested vs. regular match schedules? J Strength Cond Res 35(2): 473-480, 2021-Official international tournaments in which youth soccer players participate can involve very congested schedules. Yet, no information regarding physical and technical match performance during congested vs. regular (noncongested) cycles is available. In this study, accelerations, decelerations, mean metabolic power (MP), and technical performance (offensive and defensive variables) were compared across very congested match (VCM; 10 international matches played over 3 successive days, including 2 days with 2 consecutive matches separated by a 4- to 5-hour interval) and 10 regular (noncongested match [NCM]) match periods in elite male Under 15 (U15, n = 11) and Under 17 (U17, n = 13) soccer players. Players wore a 15-Hz Global Positioning System unit with a 100-Hz triaxial accelerometer. The session rating of perceived exertion (RPE) were assessed 30 minutes after match. Results showed a higher number of accelerations per minute observed in VCM vs. NCM (U15; 2.27 ± 0.35 vs. 2.12 ± 0.23; effect size [ES] = 0.49; U17; 2.27 ± 0.41 vs. 2.01 ± 0.31; ES = 0.69). Decelerations per minute were higher during VCM (U15; 1.99 ± 0.27 vs. 1.84 ± 0.25; ES = 0.55; and U17; 1.98 ± 0.35 vs. 1.80 ± 0.27; ES = 0.56). Mean MP was higher in the VCM (U15; 0.42 ± 0.06 vs. 0.37 ± 0.02; ES = 1.08; U17; 0.46 ± 0.03 vs. 0.30 ± 0.03; ES = 1.94). Technical actions per minute were higher in the VCM for U17 (ES = 1.60 and 1.37, for offensive and defensive performance, respectively) but lower (during VCM) for U15 (ES = 3.59 and 0.28, for offensive and defensive performance). U15 reported a higher session RPE in the VCM (7.9 ± 0.5 AUs vs. 6.9 ± 0.5 AUs). The findings suggest that running activity in these youth players was unaffected overall in tournaments with congested schedules, and that the intensity of match-play was actually greater than in regular match schedules.

Soccer-Specific Reactive Repeated-Sprint Ability in Elite Youth Soccer Players: Maturation Trends and Association With Various Physical Performance Tests

Di Mascio, M, Ade, J, Musham, C, Girard, O, and Bradley, PS. Soccer-specific reactive repeated-sprint ability in elite youth soccer players: maturation trends and association with various physical performance tests. J Strength Cond Res 34(12): 3538-3545, 2020-Repeated-sprint ability is an important physical prerequisite for competitive soccer and deviates for players in various stages of growth and development. Thus, this study investigated reactive repeated-sprint ability in elite youth soccer players in relation to maturation (age at peak height velocity) and its association with performance of other physical tests. Elite male youth players from an English Premier League academy (U12, n = 8; U13, n = 11; U14, n = 15; U15, n = 6; U16, n = 10; and U18, n = 13) completed the reactive repeated-sprint test (RRST; 8 × 30-m sprints with 30-second active recovery), and other physical tests including the Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2), arrowhead agility test, countermovement jump test with arms (CMJA), in addition to 10- and 20-m straight-line sprints. Reactive repeated-sprint test (RRST) performance (total time across 8 sprints) progressively improved from U12 to U16 (p < 0.01; effect size [ES]: 1.0-1.9), yet with no differences found between U16 and U18. No between-group differences in RRST performance were evident after accounting for age at peak height velocity (p > 0.05; ES: <0.3). Correlation magnitudes between performance on the RRST and other tests were trivial to moderate for the Yo-Yo IR2 (r = -0.15 to 0.42), moderate to very large for the arrowhead agility test (r = 0.48-0.90), moderate to large for CMJA (r = -0.43 to 0.66), and trivial to large for 10- and 20-m sprints (r = 0.05-0.61). The RRST was sensitive at tracking maturation trends in elite youth players, although performance improvements were not as marked from 15 to 16 years of age. RRST performance correlates with several physical qualities decisive for competitive soccer (agility, speed, power, and aerobic endurance).

Quantification of a Professional Football Team's External Load Using a Microcycle Structure

Martín-García, A, Gómez Díaz, A, Bradley, PS, Morera, F, and Casamichana, D. Quantification of a professional football team's external load using a microcycle structure. J Strength Cond Res 32(12): 3520-3527, 2018-The aims of this study were to (a) determine the external load of a football team across playing position and relative to competition for a structured microcycle and (b) examine the loading and variation the day after competition for players with or without game time. Training and match data were obtained from 24 professional football players who belonging to the reserve squad of a Spanish La Liga club during the 2015/16 season using global positioning technology (n = 37 matches and n = 42 training weeks). Training load data were analyzed with respect to the number of days before or after a match (match day [MD] minus or plus). Training load metrics declined as competition approached (MD-4 > MD-3 > MD-2 > MD-1; p < 0.05; effect sizes [ES]: 0.4-3.1). On the day after competition, players without game time demonstrated greater load in a compensatory session (MD + 1C) that replicated competition compared with a recovery session (MD + 1R) completed by players with game time (MD + 1C > MD + 1R; p < 0.05; ES: 1.4-1.6). Acceleration and deceleration metrics during training exceeded 50% of that performed in competition for MD + 1C (80-86%), MD-4 (71-72%), MD-3 (62-69%), and MD-2 (56-61%). Full backs performed more high-speed running and sprint distance than other positions at MD-3 and MD-4 (p < 0.05; ES: 0.8-1.7). The coefficient of variation for weekly training sessions ranged from ∼40% for MD-3 and MD-4 to ∼80% for MD + 1R. The data demonstrate that the external load of a structured microcycle varied substantially based on the players training day and position. This information could be useful for applied sports scientists when trying to systematically manage load, particularly compensatory conditioning for players without game time.

Influence of the Varied Pitch Shape on Soccer Players Physiological Responses and Time-Motion Characteristics During Small-Sided Games

The aim of this study was to investigate the effect of pitch shape modifications on heart rate responses and time-motion characteristics in soccer players during 5-a-side small-sided games (SSGs). Players completed four different SSG dimensions: (1) short narrow pitch (SN; 40 × 25 m), (2) short wide pitch (SW; 66 × 25 m), (3) long narrow pitch (LN; 40 × 50 m), and (4) long wide pitch (LW; 66 × 50 m). Twenty amateur soccer players (age: 21 ± 5 yr; stature: 176.8 ± 1.9 cm; body mass: 72.7 ± 3.7 kg) were monitored using a heart rate monitor and a 10 Hz GPS device. Mean maximum heart rate (%HR_max), rating of perceived exertion (RPE), peak running speed, total distance covered (TD), distance covered in four speed categories, number of moderate and high accelerations (Ac), decelerations (Dc), changes of direction (COD) and player load were recorded. Increasing the pitch length had a greater effect compared to increasing the pitch width especially on RPE (3.8, 6.3, 4.9 and 6.6 AU to SN, LN, SW and LW, respectively) and time-motion characteristics such as TD (101, 127, 108 and 131 m·min^-1 to SN, LN, SW and LW, respectively), peak speed (4.8, 6.1, 5.2 and 6.2 m·s^-1 to SN, LN, SW and LW, respectively), and the number of accelerations, decelerations, and changes of direction. The data demonstrates that increasing the length rather than the width of 5-a-side SSG has a greater impact on players' responses in terms of increasing workloads.

Repeated-Sprint Sequences During Female Soccer Matches Using Fixed and Individual Speed Thresholds

Nakamura, FY, Pereira, LA, Loturco, I, Rosseti, M, Moura, FA, and Bradley, PS. Repeated-sprint sequences during female soccer matches using fixed and individual speed thresholds. J Strength Cond Res 31(7): 1802-1810, 2017-The main objective of this study was to characterize the occurrence of single sprint and repeated-sprint sequences (RSS) during elite female soccer matches, using fixed (20 km·h) and individually based speed thresholds (>90% of the mean speed from a 20-m sprint test). Eleven elite female soccer players from the same team participated in the study. All players performed a 20-m linear sprint test, and were assessed in up to 10 official matches using Global Positioning System technology. Magnitude-based inferences were used to test for meaningful differences. Results revealed that irrespective of adopting fixed or individual speed thresholds, female players produced only a few RSS during matches (2.3 ± 2.4 sequences using the fixed threshold and 3.3 ± 3.0 sequences using the individually based threshold), with most sequences composing of just 2 sprints. Additionally, central defenders performed fewer sprints (10.2 ± 4.1) than other positions (fullbacks: 28.1 ± 5.5; midfielders: 21.9 ± 10.5; forwards: 31.9 ± 11.1; with the differences being likely to almost certainly associated with effect sizes ranging from 1.65 to 2.72), and sprinting ability declined in the second half. The data do not support the notion that RSS occurs frequently during soccer matches in female players, irrespective of using fixed or individual speed thresholds to define sprint occurrence. However, repeated-sprint ability development cannot be ruled out from soccer training programs because of its association with match-related performance.

Skeletal muscle and performance adaptations to high-intensity training in elite male soccer players: speed endurance runs versus small-sided game training

Purpose

To examine the skeletal muscle and performance responses across two different exercise training modalities which are highly applied in soccer training.

Methods

Using an RCT design, 39 well-trained male soccer players were randomized into either a speed endurance training (SET; n = 21) or a small-sided game group (SSG; n = 18). Over 4 weeks, thrice weekly, SET performed 6–10 × 30-s all-out runs with 3-min recovery, while SSG completed 2 × 7–9-min small-sided games with 2-min recovery. Muscle biopsies were obtained from m. vastus lateralis pre and post intervention and were subsequently analysed for metabolic enzyme activity and muscle protein expression. Moreover, the Yo–Yo Intermittent Recovery level 2 test (Yo–Yo IR2) was performed.

Results

Muscle CS maximal activity increased (P < 0.05) by 18% in SET only, demonstrating larger (P < 0.05) improvement than SSG, while HAD activity increased (P < 0.05) by 24% in both groups. Na⁺–K⁺ ATPase α₁ subunit protein expression increased (P < 0.05) in SET and SSG (19 and 37%, respectively), while MCT4 protein expression rose (P < 0.05) by 30 and 61% in SET and SSG, respectively. SOD2 protein expression increased (P < 0.05) by 28 and 37% in SET and SSG, respectively, while GLUT-4 protein expression increased (P < 0.05) by 40% in SSG only. Finally, SET displayed 39% greater improvement (P < 0.05) in Yo–Yo IR2 performance than SSG.

Conclusion

Speed endurance training improved muscle oxidative capacity and exercise performance more pronouncedly than small-sided game training, but comparable responses were in muscle ion transporters and antioxidative capacity in well-trained male soccer players.

Monitoring Training Loads in Professional Basketball Players Engaged in a Periodized Training Program

Aoki, MS, Ronda, LT, Marcelino, PR, Drago, G, Carling, C, Bradley, PS, and Moreira, A. Monitoring training loads in professional basketball players engaged in a periodized training program. J Strength Cond Res 31(2): 348-358, 2017-The aim of this study was to investigate the dynamics of external training load (eTL) and internal training load (iTL) during seasonal periods, and examine the effect of a periodized training program on physical performance in professional basketball players. Repeated measures for 9 players (28 ± 6 years; 199 ± 8 cm; 101 ± 12 kg) were collected from 45 training sessions, over a 6-week preseason phase and a 5-week in-season phase. Physical tests were conducted at baseline (T1), week 4 (T2), and week 9 (T3). Differences in means are presented as % ± confident limits. A very likely difference was observed during in-season compared with preseason for the eTL variables (measured by multivariable monitoring device), mechanical load (13.5 ± 8.8) and peak acceleration (11.0 ± 11.2), respectively. Regarding iTL responses, a very large decrement in TRIMP (most likely difference, -20.6 ± 3.8) and in session rating of perceived exertion training load (very likely difference, -14.2 ± 9.0) was detected from preseason to in-season. Physical performance improved from T1 to T3 for Yo-Yo intermittent recovery test 1 (62.2 ± 34.3, effect size [ES] > 1.2); countermovement jump (8.8 ± 6.1, ES > 0.6); and squat jump (14.8 ± 10.2, ES > 0.8). Heart rate (HR; %HRpeak) exercise responses during a submaximal running test decreased from T1 to T3 (3.2 ± 4.3, ES < 0.6), as well as the HR recovery after the test (14.7 ± 8.8, ES > 1.2). These results provide valuable information to coaches about training loads and physical performance across different seasonal periods. The data demonstrate that both eTL and iTL measures should be monitored in association with physical tests, to provide a comprehensive understanding of the training process.

Temporal Changes in Technical and Physical Performances During a Small-Sided Game in Elite Youth Soccer Players

Background

There have been claims that small-sided games (SSG) may generate an appropriate environment to develop youth players’ technical performance associated to game-related problem solving. However, the temporal change in technical performance parameters of youth players during SSG is still unknown.

Objectives

The aim of this study was to examine temporal changes in technical and physical performances during a small-sided game (SSG) in elite soccer players.

Methods

Sixty elite youth players (age 14.8 ± 0.2 yr; stature 177 ± 5 cm; body mass 66.2 ± 4.7 kg) completed a 5 v 5 SSG using two repetitions of 8 minutes interspersed by 3 minutes of passive recovery. To evaluate temporal changes in performance, the data were analysed across 4 minutes quarters. Physical performance parameters included the total distance covered (TDC), the frequency of sprints (>18 km•h^-1), accelerations and decelerations (> 2.0 m•s^-2 and - 2.0 m•s^-2), metabolic power (W•kg^-1), training impulse (TRIMP), TDC: TRIMP, number of impacts, and body load. Technical performance parameters included goal attempts, total number of tackles, tackles and interceptions, total number of passes, and passes effectiveness.

Results

All physical performance parameters decreased from the first to the last quarter with notable declines in TDC, metabolic power and the frequency of sprints, accelerations and decelerations (P < 0.05; moderate to very large ES: 1.08 - 3.30). However, technical performance parameters did not vary across quarters (P > 0.05; trivial ES for 1st v 4th quarters: 0.15 - 0.33).

Conclusions

The data demonstrate that technical performance is maintained despite substantial declines in physical performance during a SSG in elite youth players. This finding may have implications for designing SSG’s for elite youth players to ensure physical, technical and tactical capabilities are optimized. Modifications in player number, pitch dimensions, rules, coach encouragement, for instance, should be included taking into account the main aim of a given session and then focused on overloading physical or technical elements.

High-intensity efforts in elite soccer matches and associated movement patterns, technical skills and tactical actions. Information for position-specific training drills

This study aimed to translate movement patterns, technical skills and tactical actions associated with high-intensity efforts into metrics that could potentially be used to construct position-specific conditioning drills. A total of 20 individual English Premier League players' high-intensity running profiles were observed multiple times (n = 100) using a computerised tracking system. Data were analysed using a novel high-intensity movement programme across five positions (centre back [CB], full-back [FB], central midfielder [CM], wide midfielder [WM] and centre forward [CF]). High-intensity efforts in contact with the ball and the average speed of efforts were greater in WMs than CBs, CMs and CFs (effect sizes [ES]: 0.9-2.1, P < 0.05). WMs produced more repeated efforts than CBs and CMs (ES: 0.6-1.3, P < 0.05). In possession, WMs executed more tricks post effort than CBs and CMs (ES: 1.2-1.3, P < 0.01). FBs and WMs performed more crosses post effort than other positions (ES: 1.1-2.0, P < 0.01). Out of possession, CFs completed more efforts closing down the opposition (ES: 1.4-5.0, P < 0.01) but less tracking opposition runners than other positions (ES: 1.5-1.8, P < 0.01). CFs performed more arc runs before efforts compared to CBs, FBs and WMs (ES: 0.9-1.4, P < 0.05), however, CBs completed more 0-90° turns compared to FBs, CMs and WMs (ES: 0.9-1.1, P < 0.01). The data demonstrate unique high-intensity trends in and out of possession that could assist practitioners when devising position-specific drills.

The quantification of game-induced muscle fatigue in amputee soccer players

BACKGROUND

This study quantified the degree of game-induced muscular fatigue in amputee soccer players.

METHODS

Thirty-three male amputee soccer players performed muscular tests (Push Up Test [PUT], Countermovement Jump Test [CMJ] and medicine-ball throw [MBT]) before and after a competitive match. Five players served as a control group. The rating of perceived exertion was recorded after each battery.

RESULTS

Control group demonstrated no differences between the two testing batteries (P>0.05, effect size [ES]: 0.1-0.4). However, match group illustrated markedly lower performances for PUT (-17%, P<0.01, ES: 0.9) with less pronounced declines in MBT (-8%, P<0.01, ES: 0.7) and CMJ (-5%, P<0.01, ES: 0.3) compared to pre-match values. The rating of perceived exertion were higher after the match compared to baseline values (+60%, P<0.01, ES: 2.4).

CONCLUSIONS

The data demonstrate that the fatigue experienced after amputee soccer matches causes impairments in muscular performance and this could be different to able-bodied players.

The Yo-Yo IE2 test: physiological response for untrained men versus trained soccer players

PURPOSE

This study aimed to examine the physical capacity and physiological response to the Yo-Yo Intermittent Endurance level 2 test (IE2) for untrained individuals (UTR) and trained male soccer players (TR) and to investigate the determinants of intense intermittent exercise performance.

METHODS

Thirty-four healthy UTR males and 15 age-matched TR performed a maximal incremental treadmill test and a Yo-Yo IE2 test. Muscle biopsies and blood samples were obtained, and heart rate (HR) was measured before, during, and after tests.

RESULTS

UTR had a 67% lower (P < 0.01) Yo-Yo IE2 performance (665 ± 271 vs 2027 ± 298 m; effect size (ES), 4.8), 34% lower V˙O2max (P < 0.01), and 19% lower resting muscle glycogen (P < 0.05) than those of TR. Blood lactate concentration and HR during the first 560 m of the Yo-Yo IE2 test were higher (P < 0.01) in UTR than those in TR (560 m, 7.4 ± 2.8 vs 2.4 ± 0.8 mM; ES, 1.7-2.8; 188 ± 11 vs 173 ± 8 bpm; ES, 0.9-1.5), with no differences at exhaustion. Time >95% HRmax was lower (P < 0.01) in UTR than that in TR (1.0 ± 1.1 vs 6.3 ± 2.9 min; ES, 3.1). Mean rates of muscle creatine phosphate utilization (16.5 ± 9.5 vs 4.3 ± 2.7 mmol·kg d.w·min), muscle lactate accumulation (16.8 ± 9.1 vs 4.2 ± 2.9 mmol·kg d.w.·min), and glycogen breakdown (29.6 ± 14.2 vs 7.7 ± 5.4 mmol·kg d.w.·min) were fourfold higher (P < 0.01; ES, 1.4-1.7) in UTR than those in TR. For UTR, correlations (P < 0.01) were observed between Yo-Yo IE2 performance and V˙O2max (r = 0.77), incremental treadmill test performance (r = 0.79), and muscle citrate synthase activity (r = 0.57) but not for TR (r = -0.12 to 0.50; P > 0.05).

CONCLUSIONS

The Yo-Yo IE2 test was shown to possess high construct validity by showing large differences in performance, HR, and anaerobic metabolism between UTR and TR. In addition, V˙O2max seemed to be important for intermittent exercise performance in UTR but not for TR.

Positional interchanges influence the physical and technical match performance variables of elite soccer players

Positional variation in match performance is well established in elite soccer but no information exists on players switching positions. This study investigated the influence of elite players interchanging from one position to another on physical and technical match performance. Data were collected from multiple English Premier League (EPL) seasons using a computerised tracking system. After adhering to stringent inclusion criteria, players were examined across several interchanges: central-defender to fullback (CD-FB, n = 11, 312 observations), central-midfielder to wide-midfielder (CM-WM, n = 7, 171 observations), wide-midfielder to central-midfielder (WM-CM, n = 7, 197 observations) and attacker to wide-midfielder (AT-WM, n = 4, 81 observations). Players interchanging from CD-FB covered markedly more high-intensity running and sprinting distance (effect size [ES]: -1.56 and -1.26), lost more possessions but made more final third entries (ES: -1.23 and -1.55). Interchanging from CM-WM and WM-CM resulted in trivial to moderate differences in both physical (ES: -0.14-0.59 and -0.21-0.39) and technical performances (ES: -0.48-0.64 and -0.36-0.54). Players interchanging from AT-WM demonstrated a moderate difference in high-intensity running without possession (ES: -0.98) and moderate-to-large differences in the number of clearances, tackles and possessions won (ES: -0.77, -1.16 and -1.41). The data demonstrate that the physical and technical demands vary greatly from one interchange to another but utility players seem able to adapt to these positional switches.

Tier-specific evolution of match performance characteristics in the English Premier League: it's getting tougher at the top

This study investigated the evolution of physical and technical performances in the English Premier League (EPL), with special reference to league ranking. Match performance observations (n = 14,700) were collected using a multiple-camera computerised tracking system across seven consecutive EPL seasons (2006-07 to 2012-13). Final league rankings were classified into Tiers: (A) 1st-4th ranking (n = 2519), (B) 5th-8th ranking (n = 2965), (C) 9th-14th ranking (n = 4448) and (D) 15th-20th ranking (n = 4768). Teams in Tier B demonstrated moderate increases in high-intensity running distance while in ball possession from the 2006-07 to 2012-13 season (P < 0.001; effect size [ES]: 0.68), with Tiers A, C and D producing less pronounced increases across the same period (P < 0.005; ES: 0.26, 0.41 and 0.33, respectively). Large increases in sprint distance were observed from the 2006-07 to 2012-13 season for Tier B (P < 0.001; ES: 1.21), while only moderate increases were evident for Tiers A, C and D (P < 0.001; ES: 0.75, 0.97 and 0.84, respectively). Tier B demonstrated large increases in the number of passes performed and received in 2012-13 compared to 2006-07 (P < 0.001; ES: 1.32-1.53) with small-to-moderate increases in Tier A (P < 0.001; ES: 0.30-0.38), Tier C (P < 0.001; ES: 0.46-0.54) and Tier D (P < 0.001; ES: 0.69-0.87). The demarcation line between 4th (bottom of Tier A) and 5th ranking (top of Tier B) in the 2006-07 season was 8 points, but this decreased to just a single point in the 2012-13 season. The data demonstrate that physical and technical performances have evolved more in Tier B than any other Tier in the EPL and could indicate a narrowing of the performance gap between the top two Tiers.

Relationships between field performance tests in high-level soccer players

To reduce athlete testing time, the aim of this study was to investigate the relationship between the Yo-Yo intermittent recovery test levels 1 (IR1) and 2 (IR2) performances, maximal sprinting speed (10, 20, and 35 m), repeated sprint ability (RSA; 7 × 35 m), and submaximal heart rates (HRs) after 2 and 4 minutes of the Yo-Yo IR tests by testing 57 high-level soccer players. All players played regularly in one of 3 highest levels of Norwegian soccer and were tested during 3 sessions on 3 consecutive days. Large correlations were observed between Yo-Yo IR1 and IR2 test performances (r = 0.753, p ≤ 0.05). Small and moderate correlations were found between 20- and 35-m sprinting speed and Yo-Yo IR1 performance (r = -0.289 and -0.321, respectively, p ≤ 0.05), whereas 35-m sprinting speed correlated moderately to Yo-Yo IR2 performance (r = -0.371, p ≤ 0.05). Repeated sprint ability at 10, 20, and 35 m all showed moderate to large correlations to Yo-Yo IR1 performance (r = -0.337 to -0.573, p ≤ 0.05). Repeated sprint ability at 20 m (r = -0.348, p ≤ 0.05) and 35 m (r = -0.552, p ≤ 0.01) correlated moderately and largely to Yo-Yo IR2 performance. In addition, moderate and large correlations were found between submaximal Yo-Yo IR1 HRs after 2 (r = -0.483, p ≤ 0.01) and 4 minutes (r = -0.655, p ≤ 0.01) and Yo-Yo IR1 performance, and 2 minutes Yo-Yo IR2 HR and Yo-Yo IR2 performance (r = -0.530, p ≤ 0.01). Intraclass correlation measures of submaximal HR after 2 and 4 minutes of Yo-Yo IR1 test and after 2 minutes of the Yo-Yo IR2 were 0.92 (coefficient of variation [CV] = 4.1%, n = 33), 0.93 (CV = 3.8%, n = 33), and 0.72 (CV = 2.9%, n = 10). Adjusted ordinary least square (OLS) regressions revealed associations (p ≤ 0.05) between sprint speed at 20 and 35 m and Yo-Yo IR1 test performance, but only between 35 m and IR2 test performance (p ≤ 0.05). Further, OLS showed that RSA at 35 m was related to both levels of the Yo-Yo IR test (p ≤ 0.01), and that submaximal HRs after 2 and 4 minutes were independently associated with Yo-Yo IR1 and IR2 performances (p ≤ 0.01). In conclusion, Yo-Yo IR1 and 2 test performances, as well as sprint and RSA performances, correlated very largely, and it may therefore be considered using only one of the Yo-Yo tests and a RSA test, in a general soccer-specific field test protocol. The submaximal HR measures during Yo-Yo tests are reproducible and may be used for frequent, time-efficient, and nonexhaustive testing of intermittent exercise capacity of high-level soccer players.

Evolution of match performance parameters for various playing positions in the English Premier League

This study aimed to investigate position-specific evolution of physical and technical performance parameters in the English Premier League (EPL). Match performance observations (n=14700) were collected using a multiple-camera computerized tracking system across seven seasons (2006-07 to 2012-13). Data were analyzed relative to five playing positions: central defenders (n=3792), full backs (n=3420), central midfielders (n=3200), wide midfielders (n=2136) and attackers (n=2152). High-intensity running distance increased in the final season versus the first season in all playing positions (p<.05, ES: 0.9-1.3) with full backs displaying the greatest increase (∼36% higher in 2012-13). Similar trends were observed for sprint distance with full backs demonstrating the most pronounced increase across the seven seasons (36-63%, p<.001, ES: 0.8-1.3). Central players (central defenders and midfielders) illustrated the most pronounced increases in total passes and pass success rate (p<.05, ES: 0.7-0.9) whilst wide players (full backs and wide midfielders) demonstrated only small-moderate increases in total passes and pass success rate (p<.05, ES: 0.6-0.8). The data demonstrates that evolving tactics in the EPL have impacted on the physical demands of wide players and the technical requirements of central players. These findings could be used for talent identification or position-specific physical and technical training.

The evolution of physical and technical performance parameters in the English Premier League

This study examined the evolution of physical and technical soccer performance across a 7-season period in the English Premier League. Match performance observations (n=14 700) were analysed for emergent trends. Total distance covered during a match was ~2% lower in 2006-07 compared to 2012-13. Across 7 seasons, high-intensity running distance and actions increased by ~30% (890±299 vs. 1 151±337 m, p<0.001; ES: 0.82) and ~50% (118±36 vs. 176±46, p<0.001; ES: 1.41), respectively. Sprint distance and number of sprints increased by ~35% (232±114 vs. 350±139 m, p<0.001; ES: 0.93) and ~85% (31±14 vs. 57±20, p<0.001; ES: 1.46), respectively. Mean sprint distance was shorter in 2012-13 compared to 2006-07 (5.9±0.8 vs. 6.9±1.3 m, p<0.001; ES: 0.91), with the proportion of explosive sprints increasing (34±11 vs. 47±9%, p<0.001; ES: 1.31). Players performed more passes (35±17 vs. 25±13, p<0.001; ES: 0.66) and successful passes (83±10% vs. 76±13%, p<0.001; ES: 0.60) in 2012-13 compared to 2006-07. Whereas the number of short and medium passes increased across time (p<0.001; ES>0.6), the number of long passes varied little (p<0.001; ES: 0.11). This data demonstrates evolution of physical and technical parameters in the English Premier League, and could be used to aid talent identification, training and conditioning preparation.

Evaluation of the most intense high-intensity running period in English FA premier league soccer matches

The aim of this study was to examine the most intense period of high-intensity running during elite soccer matches. Elite players (n = 100) were analyzed using a multicamera computerized tracking system. High-intensity running (speed >19.8 km·h) in 5-min periods were quantified during matches. High-intensity running was performed for approximately 3% of total time, but this doubled (F[1,99] = 9.179, p < 0.001, d > 1.2) during the most intense period (8.4 ± 2.7 vs. 16.4 ± 4.6 seconds). Recovery time between high-intensity efforts was approximately 30 seconds during the most intense period (33.3 ± 19.7 seconds). The work:rest ratio between high-intensity bouts increased (F[1,99] = 2.018, p < 0.001, d > 0.6) from 1:12 for the match average to 1:2 during the most intense period. The distance of each discrete high-intensity running bout increased (F[1,99] = 1.958, p < 0.001, d > 0.6) approximately 13% during the most intense period compared with that of the match average (6.7 ± 1.8 vs. 5.8 ± 0.6 m). Central defenders were running at high-intensity for less (F[4,95] = 4.907, p < 0.05, d > 0.6) time than full-backs, wide midfielders, and attackers (12.9 ± 2.4 vs. 17.9 ± 3.4, 18.3 ± 5.5, and 16.9 ± 3.8 seconds). Central defenders had a greater recovery time (F[4,95] = 3.083, p < 0.05, d > 0.6) between high-intensity efforts than wide midfielders. No differences were evident between playing positions for maximum running speed and average distances of high-intensity running. These results show that high-intensity running, work:rest ratios, and average high-intensity distances change markedly during the most intense period of matches and are highly dependent on positional role. Therefore, conditioning drills and performance tests should closely mimic distances, work:rest ratios, and recovery times of those found during the most intense period of matches.

Gender differences in match performance characteristics of soccer players competing in the UEFA Champions League

The aim of this study was to examine gender differences in match performance characteristics of elite soccer players. Fifty-four male and fifty-nine female soccer players were tracked during UEFA Champions League matches using a multi-camera system (Amisco, Nice, France). Male players covered more (P<.01) distance than female players in total during a match (Effect Size [ES]: 0.5) and at higher speed thresholds (>15, >18, 18-21, 21-23, 23-25 and >27kmh(-1); ES: 0.7-1.4). Decrements in the second versus first half (P<.01) were only evident in female players for the distance covered in total and at selected speed thresholds (12-15, >12 and >15kmh(-1); ES: 0.6). Male central midfielders covered more (P<.01) total distance during a match than female central midfielders and at selected speed thresholds (15-23kmh(-1); ES: 1.3-2.2). Male full-backs and wide midfielders covered a greater distance (P<.01) than female players in the same positions at higher speed thresholds (>15, 21-23, 23-25, 25-27 and >27kmh(-1); ES: 1.5-3.1). The distance covered during the most intense 5min period of the match (>15kmh(-1)) was higher (P<.01) in male compared to female players (ES: 1.0) but no distance deficit in the next versus the average 5min period was observed for either gender (ES: 0.1-0.2). No gender differences were found for technical events such as the number of ball touches, time in possession of the ball or total duels won during both halves and the entire match (ES: 0.1-0.3). However, female players lost the ball more often (P<.05) and displayed lower pass completion rates than male players during both halves and the entire match (ES: 0.5-0.9). The data demonstrate that large gender differences exist for match performance characteristics of players competing at the highest competitive standard of European soccer. Such detailed analyses could be useful for gender-specific training information for optimal preparation. However, more research is warranted to establish gender-specific speed thresholds for elite soccer players.

Implications of Big Data Analytics on Population Health Management

As healthcare providers transition to outcome-based reimbursements, it is imperative that they make the transition to population health management to stay viable. Providers already have big data assets in the form of electronic health records and financial billing system. Integrating these disparate sources together in patient-centered datasets provides the foundation for probabilistic modeling of their patient populations. These models are the core technology to compute and track the health and financial risk status of the patient population being served. We show how the probabilistic formulation allows for straightforward, early identification of a change in health and risk status. Knowing when a patient is likely to shift to a less healthy, higher risk category allows the provider to intervene to avert or delay the shift. These automated, proactive alerts are critical in maintaining and improving the health of a population of patients. We discuss results of leveraging these models with an urban healthcare provider to track and monitor type 2 diabetes patients. When intervention outcome data are available, data mining and predictive modeling technology are primed to recommend the best type of intervention (prescriptions, physical therapy, discharge protocols, etc.) with the best likely outcome.

Comment on 'Performance analysis in football: a critical review and implications for future research'

MacKenzie and Cushion (2013) recently reviewed performance analysis research in association football (soccer). Their critical review focused on several themes related to methodological approaches such as sample size, match context and operational definitions and the implications of research findings to professional practice. In this response letter, we comment on additional pragmatic concerns regarding these key themes as well as some of the difficulties commonly faced when conducting performance analysis research.

Match running performance fluctuations in elite soccer: indicative of fatigue, pacing or situational influences?

The aims of this study were to: (1) quantify match running performance in 5-min periods to determine if players fatigue or modulate high-intensity running according to a pacing strategy, and (2) examine factors impacting high-intensity running such as score line, match importance and the introduction of substitutes. All players were analysed using a computerised tracking system. Maintaining 'high' levels of activity in the first half resulted in a 12% reduction (P < 0.01) in the second half for high-intensity running (effect size [ES]: 0.8), while no changes were observed in 'moderate' and 'low' groups (ES: 0.0-0.2). The 'high' group covered less (P < 0.01) high-intensity running in the initial 10-min of the second versus first half (ES: 0.6-0.7), but this was not observed in 'moderate' and 'low' groups (ES: 0.2-0.4). After the most intense periods, players demonstrated an 8% drop in high-intensity running (P < 0.05) compared to the match average (ES: 0.2) and this persisted for 5-min before recovering. Players covered similar high-intensity running distances in matches with differing score lines but position-specific trends indicated central defenders covered 17% less (P < 0.01) and attackers 15% more high-intensity running during matches that were heavily won versus lost (ES: 0.9). High-intensity running distances were comparable in matches of differing importance, but between-half trends indicated that only declines (P < 0.01) occurred in the second half of critical matches (ES: 0.2). Substitutes covered 15% more (P < 0.01) high-intensity running versus the same time period when completing a full match (ES: 0.5). The data demonstrate that high-intensity running in the second half is impacted by the activity of the first half and is reduced for 5-min after intense periods. High-intensity running is also influenced by score line and substitutions but not match importance. More research is warranted to establish if fluctuations in match running performance are primarily a consequence of fatigue, pacing or tactical and situational influences.

The effect of high and low percentage ball possession on physical and technical profiles in English FA Premier League soccer matches

The aim of this study was to examine the effects of high (HPBPT) and low percentage ball possession teams (LPBPT) on physical and technical profiles in elite soccer matches. Match performance data were collected from players in the English FA Premier League (n = 810) using a multiple-camera computerised tracking system. Physical indicators such as the total (10690 ± 996 vs 10778 ± 979 m; effect size [ES] = 0.11) and high-intensity running distance covered in matches (931 ± 299 vs 938 ± 311 m; ES = 0.13) did not differ between HPBPT and LPBPT. However, high-intensity running with ball possession in HPBPT was 31% higher (P < 0.01) than LPBPT (449 ± 266 vs 343 ± 236 m; ES = 0.42) but 22% lower without ball possession (423 ± 153 vs 539 ± 177 m; ES = 0.73). Players in HPBPT performed 44% more (P < 0.01) passes than those in LPBPT (35.3 ± 14.2 vs 24.6 ± 11.2; ES = 0.83). This trend was also evident (P < 0.05) for successful passes, received passes, touches per possession, shots, dribbles and final-third entries (ES range of 0.20-0.94). Central defenders of LPBPT covered 33% less (P < 0.01) high-intensity running with ball possession than central defenders of HPBPT. While fullbacks, attackers, central and wide midfielders of LPBPT covered more (P < 0.01) high-intensity running without and less with ball possession than their HPBPT counterparts (ES range of 0.91-1.23). Technical indicators such as total passes and passes received were higher (P < 0.01) across all positions in HPBPT than LPBPT (ES range of 0.82-1.52). The data demonstrate that percentage ball possession does not influence the overall activity profile of a team but impacts on the composition of high-intensity running efforts (with and without ball) and some technical elements of performance. Position-specific changes in physical and technical profiles were evident for teams employing different ball possession percentages and this information could aid training preparation.

The effect of playing formation on high-intensity running and technical profiles in English FA Premier League soccer matches

The aim of this study was to examine the effect of playing formation on high-intensity running and technical performance during elite soccer matches. Twenty English FA Premier League games were analysed using a multiple-camera computerized tracking system (n = 153 players). Overall ball possession did not differ (P < 0.05) between 4-4-2, 4-3-3 and 4-5-1 formations (50%, s = 7 vs. 49%, s = 8 vs. 44%, s = 6). No differences were observed in high-intensity running between 4-4-2, 4-3-3 and 4-5-1 formations. Compared with 4-4-2 and 4-3-3 formations, players in a 4-5-1 formation performed less very high-intensity running when their team was in possession (312 m, s = 196 vs. 433 m, s = 261 vs. 410 m, s = 270; P 5 0.05) but more when their team was not in possession (547 m, s = 217 vs. 461 m, s = 156 vs. 459 m, s = 169; P < 0.05). Attackers in a 4-3-3 performed ~30% more (P < 0.05) high-intensity running than attackers in 4-4-2 and 4-5-1 formations. However, the fraction of successful passes was highest in a 4-4-2 (P < 0.05) compared with 4-3-3 and 4-5-1 formations. The results suggest that playing formation does not influence the overall activity profiles of players, except for attackers, but impacts on very high-intensity running activity with and without ball possession and some technical elements of performance.

High-intensity activity profiles of elite soccer players at different performance levels

The aims of the study were to (a) determine the high-intensity activity patterns of soccer players at different performance levels and playing positions, (b) investigate temporary and end game fatigue in elite domestic and international soccer matches, and (c) quantify acceleration and maximal running speed profiles of elite soccer players. Elite domestic (n = 100) and international (n = 10) soccer players were analyzed using a multicamera computerized tracking system. No differences were found for high-intensity running distance (2,520 +/- 678 vs. 2,745 +/- 332 m), mean recovery time (67 +/- 15 vs. 71 +/- 26 seconds), or maximal running speed (7.76 +/- 0.31 vs. 7.66 +/- 0.34 mxs-1). The distance covered in high-intensity running irrespective of playing level was 18% lower (p < 0.05) in the last than in the first 15-minute period of the game (391 +/- 117 vs. 478 +/- 141 m). The decline in high-intensity running immediately after the most intense 5-minute period was similar between international (222 +/- 33 vs. 109 +/- 37 m or 51% decline) and elite domestic (243 +/- 81 vs. 114 +/- 51 m or 53% decline) players. Wide midfielders, central midfielders, fullbacks, and attackers covered a greater (p < 0.01) distance in high-intensity running than central defenders (3,243 +/- 625, 2,949 +/- 435, 2,806 +/- 408, 2,618 +/- 745 vs. 2,034 +/- 284 m). Results demonstrate that high-intensity running is reduced during various periods of elite soccer matches, and high-intensity activity profiles and fatigue patterns are similar between international and elite domestic players but vary markedly between playing positions. These data provide valuable information to the fitness coach regarding the high-intensity active profile of elite soccer players that could be used to develop soccer-specific training drills.

Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer

The aims of this study were to (1) determine the reproducibility of sub-maximal and maximal versions of the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2 test), (2) assess the relationship between the Yo-Yo IE2 test and match performance and (3) quantify the sensitivity of the Yo-Yo IE2 test to detect test-retest changes and discriminate between performance for different playing standards and positions in elite soccer. Elite (n = 148) and sub-elite male (n = 14) soccer players carried out the Yo-Yo IE2 test on several occasions over consecutive seasons. Test-retest coefficient of variation (CV) in Yo-Yo IE2 test performance and heart rate after 6 min were 3.9% (n = 37) and 1.4% (n = 32), respectively. Elite male senior and youth U19 players Yo-Yo IE2 performances were better (P < 0.01) than elite youth U16s and sub-elite players (2,603 ± 451 and 2,534 ± 549 vs. 1,855 ± 535 vs. 1,749 ± 382 m). The intra- and inter-season CV for Yo-Yo IE2 test performance were 4.2 and 5.6%, respectively. A correlation was observed (P < 0.05) between Yo-Yo IE2 test performance and the total (r = 0.74) and high-intensity (r = 0.58) running distance covered in a match. A correlation was also evident (P < 0.01) between Yo-Yo IE2 test heart rate after 6 min expressed in percentage of maximal heart rate and the peak values for high-intensity running performed by midfielders in 5-min (r = -0.71), 15-min (r = -0.75) and 45-min periods (r = -0.77). The present data demonstrate that the Yo-Yo IE2 test is reproducible and can be used to determine the capacity of elite soccer players to perform intense intermittent exercise. Furthermore, the Yo-Yo IE2 test was shown to be a sensitive tool that not only relates to match performance but can also differentiate between intermittent exercise performance of players in various standards, stages of the season and playing positions.

High-intensity running in English FA Premier League soccer matches

The aims of this study were to (1) determine the activity profiles of a large sample of English FA Premier League soccer players and (2) examine high-intensity running during elite-standard soccer matches for players in various playing positions. Twenty-eight English FA Premier League games were analysed during the 2005-2006 competitive season (n=370), using a multi-camera computerised tracking system. During a typical match, wide midfielders (3138 m, s=565) covered a greater distance in high-intensity running than central midfielders (2825 m, s= 73, P=0.04), full-backs (2605 m, s=387, P < 0.01), attackers (2341 m, s=575, P < 0.01), and central defenders (1834 m, s=256, P < 0.01). In the last 15 min of a game, high-intensity running distance was approximately 20% less than in the first 15-min period for wide midfielders (467 m, s=104 vs. 589 m, s=134, P < 0.01), central midfielders (429 m, s=106 vs. 534 m, s=99, P < 0.01), full-backs (389 m, s=95 vs. 481 m, s=114, P < 0.01), attackers (348 m, s=105 vs. 438 m, s=129, P < 0.01), and central defenders (276 m, s=93 vs. 344 m, s=80, P < 0.01). There was a similar distance deficit for high-intensity running with (148 m, s=78 vs. 193 m, s=96, P < 0.01) and without ball possession (229 m, s=85 vs. 278 m, s=97, P < 0.01) between the last 15-min and first 15-min period of the game. Mean recovery time between very high-intensity running bouts was 72 s (s=28), with a 28% longer recovery time during the last 15 min than the first 15 min of the game (83 s, s=26 vs. 65 s, s=20, P < 0.01). The decline in high-intensity running immediately after the most intense 5-min period was more evident in attackers (216 m, s=50 vs. 113 m, s=47, P < 0.01) and central defenders (182 m, s=26 vs. 96 m, s=39, P < 0.01). The results suggest that high-intensity running with and without ball possession is reduced during various phases of elite-standard soccer matches and the activity profiles and fatigue patterns vary among playing positions. The current findings provide valuable information about the high-intensity running patterns of a large sample of elite-standard soccer players, which could be useful in the development and prescription of specific training regimes.

The relationship between preseason range of motion and muscle strain injury in elite soccer players

The purpose of the study was to determine the influence of preseason lower-extremity range of motion (ROM) on the risk of muscle strain injury during a competitive season for elite soccer players. Thirty-six elite male soccer players (age, 25.6 +/- 4.7 years) had maximum static ROM for 6 movements of the lower extremity measured prior to the 2003-2004 English Premier League season. Player age, body size, dominant limb, and playing position were documented also. All lower-extremity muscle strain injuries were recorded prospectively during the competitive season, as was the total amount of time spent in training and games for each player. Soccer players sustaining a muscle strain injury in the hip flexors or knee flexors had lower preseason ROM (p < 0.05) in these muscle groups compared with uninjured players. Similar trends were observed for the remaining muscle groups, but all failed to reach statistical significance (p > 0.05). Most significantly, soccer players with lower preseason ROM in the hip flexors and knee flexors had a statistically higher risk for a muscle strain injury to these muscle groups during a competitive season. Age, body size, limb dominance, and playing position were not significant intrinsic risk factors for the development of muscle strain injuries. Screening of flexibility for soccer players should be conducted during preseason, and flexibility training should be prescribed to players with reduced ROM to lower the risk of developing a muscle strain injury.

The effect of static, ballistic, and proprioceptive neuromuscular facilitation stretching on vertical jump performance

The purpose of this study was to compare the acute effects of different modes of stretching on vertical jump performance. Eighteen male university students (age, 24.3 +/- 3.2 years; height, 181.5 +/- 11.4 cm; body mass, 78.1 +/- 6.4 kg; mean +/- SD) completed 4 different conditions in a randomized order, on different days, interspersed by a minimum of 72 hours of rest. Each session consisted of a standard 5-minute cycle warm-up, accompanied by one of the subsequent conditions: (a) control, (b) 10-minute static stretching, (c) 10-minute ballistic stretching, or (d) 10-minute proprioceptive neuromuscular facilitation (PNF) stretching. The subjects performed 3 trials of static and countermovement jumps prior to stretching and poststretching at 5, 15, 30, 45, and 60 minutes. Vertical jump height decreased after static and PNF stretching (4.0% and 5.1%, p < 0.05) and there was a smaller decrease after ballistic stretching (2.7%, p > 0.05). However, jumping performance had fully recovered 15 minutes after all stretching conditions. In conclusion, vertical jump performance is diminished for 15 minutes if performed after static or PNF stretching, whereas ballistic stretching has little effect on jumping performance. Consequently, PNF or static stretching should not be performed immediately prior to an explosive athletic movement.