Adam Owen

The acute:chonic workload ratio in relation to injury risk in professional soccer

OBJECTIVES To examine the association between combined sRPE measures and injury risk in elite professional soccer. DESIGN Observational cohort study. METHODS Forty-eight professional soccer players (mean±SD age of 25.3±3.1 yr) from two elite European teams were involved within a one season study. Players completed a test of intermittent-aerobic capacity (Yo-YoIR1) to assess players injury risk in relation to intermittent aerobic capacity. Weekly workload measures and time loss injuries were recorded during the entire period. Rolling weekly sums and week-to-week changes in workload were measured, allowing for the calculation of the acute:chronic workload ratio, which was calculated by dividing the acute (1-weekly) and chronic (4-weekly) workloads. All derived workload measures were modelled against injury data using logistic regression. Odds ratios (OR) were reported against a reference group. RESULTS Players who exerted pre-season 1-weekly loads of ≥1500 to ≤2120AU were at significantly higher risk of injury compared to the reference group of ≤1500AU (OR=1.95, p=0.006). Players with increased intermittent-aerobic capacity were better able to tolerate increased 1-weekly absolute changes in training load than players with lower fitness levels (OR=4.52, p=0.011). Players who exerted in-season acute:chronic workload ratios of >1.00 to <1.25 (OR=0.68, p=0.006) were at significantly lower risk of injury compared to the reference group (≤0.85). CONCLUSIONS These findings demonstrate that an acute:chronic workload of between 1.00 and 1.25 is protective for professional soccer players. A higher intermittent-aerobic capacity appears to offer greater injury protection when players are exposed to rapid changes in workload in elite soccer players. Moderate workloads, coupled with moderate-low to moderate-high acute:chronic workload ratios, appear to be protective for professional soccer players.

High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk?

OBJECTIVES This study investigated the association between high-speed running (HSR) and sprint running (SR) and injuries within elite soccer players. The impact of intermittent aerobic fitness as measured by the end speed of the 30-15 intermittent fitness test (30-15VIFT) and high chronic workloads (average 21-day) as potential mediators of injury risk were also investigated. DESIGN Observational Cohort Study. METHODS 37 elite soccer players from one elite squad were involved in a one-season study. Training and game workloads (session-RPE×duration) were recorded in conjunction with external training loads (using global positioning system technology) to measure the HSR (>14.4kmh-1) and SR (>19.8kmh-1) distance covered across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated with 90% confidence intervals based on 21-day chronic training load status (sRPE), aerobic fitness, HSR and SR distance with these reported against a reference group. RESULTS Players who completed moderate HSR (701-750-m: OR: 0.12, 90%CI: 0.08-0.94) and SR distances (201-350-m: OR: 0.54, 90%CI: 0.41-0.85) were at reduced injury risk compared to low HSR (≤674-m) and SR (≤165-m) reference groups. Injury risk was higher for players who experienced large weekly changes in HSR (351-455-m; OR: 3.02; 90%CI: 2.03-5.18) and SR distances (between 75-105-m; OR: 6.12, 90%CI: 4.66-8.29). Players who exerted higher chronic training loads (≥2584 AU) were at significantly reduced risk of injury when they covered 1-weekly HSR distances of 701-750m compared to the reference group of <674m (OR=0.65, 90% CI 0.27-0.89). When intermittent aerobic fitness was considered based on 30-15VIFT performance, players with poor aerobic fitness had a greater risk of injury than players with better-developed aerobic fitness. CONCLUSIONS Exposing players to large and rapid increases in HSR and SR distances increased the odds of injury. However, higher chronic training loads (≥2584 AU) and better intermittent aerobic fitness off-set lower limb injury risk associated with these running distances in elite soccer players.

Internal training load and its longitudinal relationship with seasonal player wellness in elite professional soccer

Monitoring internal training load has been extensively used and described within team sport environments, however when compared to internal physiological measures such as heart rate (HR) and rating of perceived exertion (RPE), the literature is sparse. The primary aim of this investigation study was to assess differences of playing position on ITL, session-RPE and wellness across two different training microcycles (1 vs. 2 competitive games), in addition with examining the relationship between ITL and Hoopers Index across an entire season. Thirty-five professional soccer players from the Portuguese premier league participated in the study (25.7±5.0years; 182.3±6.4cm; 79.1±7.0kg). Analysis of variance revealed higher values of DOMS (Means(M): 3.33 vs. 3.10; p=0.001; effect Size (ES)=0.087), fatigue (M: 3.18 vs. 2.99; p=0.001; ES=0.060) and HI (M: 11.85 vs. 11.56; p=0.045; ES=0.034) in 2-game weeks compared with 1-game weeks. Correlation between ITL and HI levels found significant negative correlations between ITL and DOMS (ρ=-0.156), ITL and sleep (ρ=-0.109), ITL and fatigue (ρ=-0.225), ITL and stress (ρ=-0.188), and ITL and HI (ρ=-0.238) in 2-game weeks. Results from 1-game microcycle only highlighted negative correlations between ITL and stress (ρ=-0.080). It was concluded from the study that greater fatigue potential, muscle soreness, stress and ITL was significantly more apparent within a 2-game microcycle. As a result, care should be taken when planning the lead into and out of a 2-game fixture microcycle highlighting key specific recovery strategies to damped the increased stress effect. Additionally, the potential utilization of squad rotation strategies may be a positive approach with aim of managing the fatigue effect.

Analysis of a training mesocycle and positional quantification in elite European soccer players

Ensuring adequate levels of training and recovery at the elite level of professional soccer to maximise player performance has continued to drive the necessity to monitor the training load and physical training output of soccer players. The aim of this investigation was to analyse a training mesocycle whilst quantifying positional demands imposed on elite European soccer players. Sixteen players were assessed using global positioning systems and ratings of perceived exertion over a competitive training six-week mesocycle period. The positional demands and training loads were analysed in addition to match conditions (match location, match score) and player’s age. Results from the investigation revealed that typical daily training loads (i.e. total distance, high-intensity distance, sprint distance, average speed, ratings of perceived exertion) did not differ throughout each week of the mesocycle in-season period. Further analysis revealed training loads were significantly lower on match day-1 when compared to training loads on match day-2, match day-3 and match day-4 preceding a match (p < 0.05). Significant differences in physical outputs were also found between match day-2, match day-3 and match day-4 highlighting a structured periodised tapered approach (p < 0.05). Lower average speeds were reported in training post-successful matches compared to defeats (p < 0.05), and more specifically when a match was played away compared to home fixtures (p < 0.05). To conclude, practitioners can maintain a uniformed and structured training load mesocycle whilst inducing variation of the physical outputs during the microcycle phase. Additionally, the investigation also provides a tapering approach that may induce significant variation of the positional demands.

Maximal Sprinting Speed of Elite Soccer Players During Training and Matches

The aim of the present study was to compare (a) the maximal sprinting speed (MSS) attained by soccer players during matches (MSSmatch) according to their level of play (professional first French division vs. elite amateur fourth French division) and the playing positions and (b) the MSS attained by professional soccer players during 14 different types of small-sided games (SSG, MSSSSG) and match-play. All players monitored through the study performed a 40-m sprint test to assess individual MSS (MSStest) and compare it to the training and match activity, with the calculation of the percentage of MSStest (%MSStest) reached. No differences were found according to the level of play; however, positional wide players achieved a higher MSSmatch, %MSStest, and MSSSSG than central players (both defenders and midfielders) during matches and SSG. MSSmatch were higher than all MSSSSG, and MSSSSG were positively correlated with the area of the pitch (0.45, p < 0.001), its length (0.53, p < 0.001), and the number of players involved (0.38, p < 0.001). The closer SSG was to match situation in terms of rules, the higher the MSSSSG. Wide players reached higher MSS in match and SSG than central players, confirming the relevance of using SSG close to match situation to specifically prepare elite players to the maximal running speed demand of the match.The aim of the present study was to compare 1) the maximal sprinting speed (MSS) attained by soccer players during matches (MSSmatch) according to their level of play (professional 1st French division vs. elite amateur 4th French division) and the playing positions; and 2) the MSS attained by professional soccer players during 14 different types of small-sided games (SSG, MSSSSG) and match-play. All players monitored through the study performed a 40-m sprint test to assess individual MSS (MSStest) and compare it to the training and match activity, with the calculation of the percentage of MSStest (%MSStest) reached. No differences were found according to the level of play, however positionally, wide players achieved a higher MSSmatch, %MSStest, and MSSSSG compared to central players (both defenders and midfielders) during matches and SSG. MSSmatch were higher than all MSSSSG, and MSSSSG were positively correlated with the area of the pitch (0.45, p<0.001), its length (0.53, p<0.001) and the number of players involved (0.38, p<0.001). The closer SSG was to match situation in term of rules, the higher the MSSSSG. Wide players reached higher MSS in match and SSG than central players, confirming the relevance of using SSG close to match situation to specifically prepare elite players to the maximal running speed demand of the match.

The influence of the extra-time period on physical performance in elite soccer

The aim of this study was to examine the influence of extra-time periods on physical performance profiles in elite soccer. Match performance data were collected from players (n=99) during the 2014 FIFA World Cup Finals (FWC). Performance was analysed per minute for total distance covered and distance run in 3 categories: ≤11.0 km. h-1 (low), 11.1-14.0 km. h-1 (medium) and ≥14.1 km. h-1 (high-speed). Additional variables such as the time spent in low, medium and high activities, maximal running speed and the number of sprints per minute were also assessed. Analysis of players who completed the demands of the full 120 min of playing time revealed that total distance, high-intensity running, top speed and high intensity activities declines by 12%, 18%, 3% and 15% respectively, from the first to the second half of the match (P<0.01). In contrast, low intensity activities increase in the second half and especially in the extra-time period in comparison with the first half (P<0.05). The reduction in overall performance is much more acute in extra-time. All of the physical markers studied showed a decline of 15-20% during the extra-time period in comparison to the first half of playing time (P<0.01). As a result, it is vital that technical and physical coaching staff are aware of the decline in this game phase and consequently, influence the team from a tactical and physical focus within a training perspective.

How and When to Use an Injury Prevention Intervention in Soccer

Soccer is a high intensity intermittent contact sport exposing elite level players to contin‐ ual physical, technical, tactical, psychological, and physiological demands (Owen et al, 2011; Dellal et al, 2011). Due to the huge financial rewards of being successful at the elite level of the sport, the demands placed upon the players are ever growing because of increased fixture schedules that generally include less recovery periods between train‐ ing and competitive match play, disposing players to a greater risk of injury (Dellal at al, 2013; Dupont et al, 2010; Rey et al, 2010; Morgan and Oberlander 2001; Junge and Dvorak 2004). The number of competitive matches played by elite European soccer play‐ ers (Table 1) during one season can be >80, with 1.6 to 2 matches per week throughout its entirety (excluding friendly games) (Figure 1). It should be noted that, a player com‐ peting at the higher echelons of world soccer such as Lionel Messi has accumulated be‐ tween 64 to 69 official competitive games throughout seasons 2011-2012, 2010-2011, and 2009-2010 as shown in Table 2. As reported in this context, modern day soccer involves a continued, intensive cycle and predisposes players to greater injury risks due to accu‐ mulative fatigue or overload. Previous research has already found a correlation between low training and match availability due to injury, with decreased team success (Arnason et al, 2004). This is of particular importance for teams unable to replace players due to limited funds or resources, and subsequently highlights the need for all clubs irrespec‐ tive of budgets, resources and funding potential to minimize injury risk of players in or‐ der to be more successful. After all, there seems to be no point in pushing players constantly to be physically, technically and tactically better if they are consistently un‐ available to play.

Daily and weekly training load and wellness status in preparatory, regular and congested weeks: a season-long study in elite volleyball players

ABSTRACT The study aimed to assess the changes in the perceived internal load and wellness status of volleyball players in preparatory, regular (i.e. uncongested), and congested weeks during a full season. Thirteen elite volleyball players were studied (237 training sessions and 37 official matches). Session-RPE, muscle soreness, stress, fatigue, sleep quality, and the Hooper Index were measured daily using questionnaires. Training sessions were classified based on the number of matches per week and the days before or after a match: preparatory (no match), regular (one match), and congested weeks (two or more matches). Pairwise comparisons found significantly greater session-RPE scores (p < 0.05) one day before the match (304.74 A.U.), in regular weeks than in congested weeks (204.40 A.U.). Matches during the congested weeks (364.71 A.U.) had significantly higher session-RPE scores (p < 0.05) than regular weeks (252.97 A.U.). Three days before the match involved significantly higher values of muscle soreness, fatigue, stress, and sleep quality than regular weeks. Match accumulation increased the session-RPE training load of the matches. This study provides insights into the training load and well-being status before competition, for training the day of competition, and after the competition.

The effects of large-sided soccer training games and pitch size manipulation on time–motion profile, spatial exploration and surface area: Tactical opportunities:

Analysis of the physical, technical and physiological variations induced through the use of different soccer game formats have been widely discussed. However, the coaching justification for the specific use of certain game formats based on individual and collective spatial awareness is unclear. As a result, the purpose of this study was to analyze 11 versus 11 game formats conducted across two pitch sizes (half-size: 54 m × 68 m vs full-size: 108 m × 68 m) to identify effects of time–motion profiles, individual exploration behavior and collective organization. A total of 10 amateur soccer players from the same team (23.39 ± 3.91 years old) participated in this study. Data position of the players was used to calculate the spatial exploration index and the surface area. Distances covered in different speeds were used to observe the time–motion profile. The full-size pitch dimensions significantly contributed to greater distances covered via running (3.86–5.52 m s−1) and sprinting (>5.52 m s−1). Total distance and number of sprints were also significantly greater in the full-size pitch as compared to the half-size pitch. The surface area covered by the team (half-size pitch: 431.83 m2 vs full-size pitch: 589.14 m2) was significantly larger in the full-size pitch condition. However, the reduced half-size pitch significantly contributed to a greater individual spatial exploration. Results of this study suggest that running and sprinting activities increase when large, full-size pitch dimensions are utilized. Smaller surface area half-size pitch contributes to a better exploration of the pitch measured by spatial exploration index while maintaining adequate surface area coverage by the team. In conclusion, the authors suggest that the small half-size pitch is more appropriate for low-intensity training sessions and field exploration for players in different positions. Alternatively, the large full-size pitch is more appropriate for greater physically demanding training sessions with players focused on positional tactical behavior.

Wellbeing perception and the impact on external training output among elite soccer players.

OBJECTIVES The objective of the investigation was to observe the impact of player wellbeing on the training output of elite soccer players. DESIGN Prospective cohort design. METHODS Forty-eight soccer players (age: 25.3±3.1years; height: 183±7cm; mass: 72±7kg) were involved in this single season observational study across two teams. Each morning, pre-training, players completed customised perceived wellbeing questionnaires. Global positioning technology devices were used to measure external load (total distance, total high-speed running distance, high speed running, player load, player load slow, maximal velocity, maximal velocity exposures). Players reported ratings of perceived exertion using the modified Borg CR-10 scale. Integrated training load ratios were also analysed for total distance:RPE, total high speed distance:RPE player load:RPE and player load slow:RPE respectively. RESULTS Mixed-effect linear models revealed significant effects of wellbeing Z-score on external and integrated training load measures. A wellbeing Z-score of -1 corresponded to a -18±2m (-3.5±1.1%), 4±1m (-4.9±2.1%,) 0.9±0.1kmh-1 (-3.1±2.1%), 1±1 (-4.6±2.9%), 25±3AU (-4.9±3.1%) and 11±0.5AU (-8.9±2.9%) reduction in total high speed distance, high speed distance, maximal velocity, maximal velocity exposures, player load and player load slow respectively. A reduction in wellbeing impacted external:internal training load ratios and resulted in -0.49±0.12mmin-1, -1.20±0.08mmin-1,-0.02±0.01AUmin-1 in total distance:RPE, total high speed distance:RPE and player load slow:RPE respectively. CONCLUSIONS The results suggest that systematic monitoring of player wellbeing within soccer cohorts can provide coaches with information about the training output that can be expected from individual players during a training session.