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.

A comparison of muscle damage, soreness and performance following a simulated contact and non-contact team sport activity circuit

The aim was to compare the effect of a simulated team sport activity circuit (reflective of the activity demands of Australian football) either with or without body ‘contact’ on muscle soreness, damage, and performance when the circuit was repeated 48 h later. Eleven male, team-sport athletes completed a ‘non-contact’ (NCON) and a ‘contact’ (CON) version of the team sport activity circuit in a crossover design with at least 1 week between trials. The effect of CON and NCON on repeated 15 m sprint and vertical jump performance was assessed by completing the same version of the circuit 48 h after the initial trial. The effect on perceived soreness and blood markers of muscle damage and inflammation was also determined. Subsequent performance was affected to a greater extent by CON, with both best and mean sprint times significantly slower 48 h following CON (p < 0.05), while performance was maintained after NCON. Best and mean vertical jump performance was significantly impaired following CON (p < 0.05), while only best vertical jump was affected by NCON (p < 0.05). Perceived soreness and pressure sensitivity were elevated following both NCON and CON (p < 0.001); however, the increase in soreness was greater with CON (p = 0.012). Both CON and NCON resulted in elevated serum creatine kinase, myoglobin and lactate dehydrogenase, while c-reactive protein increased following CON but not NCON. In conclusion, Greater perceived soreness and decrements in performance of the simulated team sport activity circuit when repeated 48 h later were observed following CON.     

The neuromuscular,endocrine and mood responses to a single versus double training session day in soccer players

ObjectivesThis study profiled the 24 h neuromuscular, endocrine and mood responses to a single versus a double training day in soccer players.DesignRepeated measures.MethodsTwelve semi-professional soccer players performed small-sided-games (SSG’s; 4 vs 4 + goalkeepers; 6 × 7-min, 2-min inter-set recovery) with neuromuscular (peak-power output, PPO; jump height, JH), endocrine (salivary testosterone, cortisol), and mood measures collected before (pre) and after (0 h, +24 h). The following week, the same SSG protocol was performed with an additional lower body strength training session (back-squat, Romanian deadlift, barbell hip thrust; 4 × 4 repetitions, 4-min inter-set recovery; 85% 1 rep-max) added at 2 h after the SSG’s.ResultsBetween-trial comparisons revealed possible to likely small impairments in PPO (2.5 ± 2.2 W kg⁻¹; 90% Confidence Limits: ±2.2 W kg⁻¹), JH (−1.3; ±2.0 cm) and mood (4.6; ±6.1 AU) in response to the double versus single sessions at +24 h. Likely to very likely small favourable responses occurred following the single session for testosterone (−15.2; ±6.1 pg ml⁻¹), cortisol (0.072; ±0.034 ug dl⁻¹) and testosterone/cortisol ratio (−96.6; ±36.7 AU) at +24 h compared to the double session trial.ConclusionsThese data highlight that performance of two training sessions within a day resulted in possible to very likely small impairments of neuromuscular performance, mood score and endocrine markers at +24 h relative to a single training session day. A strategy of alternating high intensity explosive training days containing multiple sessions with days emphasising submaximal technical/tactical activities may be beneficial for those responsible for the design and delivery of soccer training programs.     

Variability of acute physiological responses and performance profiles of youth soccer players in small-sided games

The aim of this study was to examine the variability in physiological and perceptual responses and time-motion profiles of various small-sided soccer game (SSG) formats (2 versus 2, 4 versus 4 and 6 versus 6 players) and regimes (interval and continuous). Typical error (TE) was calculated for mean heart rate as a percentage of maximum heart rate (%HR(max)), global ratings of perceived exertion (RPE), blood lactate [La(-)] and various time-motion characteristics for 16 male soccer players (mean 16.2 years, range 15.6-17.9). The TE for HR responses were <5% for all SSGs. RPE also demonstrated small variability across all SSGs, with TE ranging between 1 and 2 units. In contrast, the TE% for [La(-)] was higher, ranging from 16% (2 versus 2-interval) to 34% (4 versus 4-interval). The TE% for total distance (TD) and distance covered at 0-6.9km/h was <5% for all SSGs, with 2 versus 2 interval and continuous games recording the lowest TE (2.2% and 2.9%, respectively). An increase in game format size does not appear to influence the variability of the acute physiological responses to SSGs, although continuous formats display less variability than interval formats. The TD, distance covered and percentage of total time moving at 0-6.9km/h demonstrated small variability across all formats and regimes. However, higher movement speeds zones (>8km/h) reflected increased variability, irrespective of game format or regime. Collectively, these results suggest that SSG training can provide a reliable aerobic training stimulus.     

Effect of caffeine supplementation on haematological and biochemical variables in elite soccer players under physical stress conditions

Objective

To evaluate the effect of caffeine on white cell distribution and muscle injury markers in professional soccer players during exercise.

Methods

22 male athletes completed a placebo controlled double blind test protocol to simulate a soccer match, followed by a Yo‐Yo intermittent recovery test.

Results

Exercise caused an increase in packed cell volume that was enhanced by caffeine. Caffeine and exercise had a synergistic effect on the blood lymphocyte count, which increased by about 38% after exercise, and by an additional 35% when combined with caffeine. Caffeine promoted an exercise independent rise in circulating monocytes, and a synergistic action of exercise and caffeine was observed on segmented neutrophils. Caffeine promoted thrombocytosis. Plasma adenosine deaminase, aspartate aminotransferase, and lactate dehydrogenase concentrations were enhanced by exercise, and alanine transaminase concentration was enhanced in both groups, with a synergistic effect of caffeine.

Conclusions

The pronounced increase in the white cell count in the group receiving caffeine appeared to be caused by greater muscle stress and consequently more intense endothelial and muscle cell injury. The use of caffeine may augment the risk of muscle damage in athletes.     

Influence of intense training cycle and psychometric status on technical and physiological aspects performed during the small-sided games in soccer players

The study investigated the effect of intense training cycle (IT) of early season preparation period (SPP) and psychological status on technical and physiological parameters during small-sided games (SSG) and the relationships between these variables. Sixteen professional soccer players participated in the study (mean±SD: age: 24.5±4.1). Training load (TL), Total quality recovery (TQR) and well-being indices were performed daily. TL increased progressively (%TL=31.56 [AU]). Physiological variables did not change after IT and were not influenced by well-being indices and TQR. Technical aspects were negatively altered after IT (p<0.05). TL was significantly correlated with successful passes (r=-0.57, p=0.02), interceptions (r=-0.83, p<0.001) and lost balls (r=0.73, p=0.002). Well-being and TQR were related to successful passes, interceptions and lost passes [(r=-0.55, p=0.03; r=-0.75, p=0.001; r=-0.69, p=0.004); (r=0.54, p=0.03; r=-0.76, p=0.001; r=-0.69, p=0.004), respectively]. TL, Well-being indices and TQR represent a useful strategy for coaches to control technical aspects in soccer players during SPP.     

Predictive modelling of the physical demands during training and competition in professional soccer players

ObjectivesThe present study aimed to predict the cut-off point-values that best differentiate the physical demands of training and competition tasks including friendly matches (FM), small sided games (SSG), large sided games (LSG), mini-goal games (MG) and ball circuit-training (CT) in professional soccer players.DesignExperimental randomized controlled trial.MethodsFourteen professional players participated in all tasks with the CT, SSG and MG consisting of 8 repetitions of 4-min game play, interspersed by 2-min of active recovery. The training data were compared to the first 32-min of the LSG and two competitive FM per player. All movement patterns from walking to sprint running were recorded using 10 Hz GPS devices while player perception of exertion was recorded via a visual analogue scale, post-task. Decision tree induction was applied to the dataset to assess the cut-off point-values from four training drills (SSG, LSG, MG, and CT) and FM for every parameter combination.ResultsDistance covered during jogging (2.3–3.3 m/s; >436 m), number of decelerations (≤730.5) and accelerations (≤663), and maximum velocity reached (>5.48 m/s) characterized the physical demands during competition (FM) with great variability amongst training drills.ConclusionThe use of these novel, cut-off points may aid coaches in the design and use of training drills to accurately prepare athletes for soccer competition.     

Fluid loss and body composition of elite Kuwaiti soccer players during a soccer match

AIM: The aim of this study was to assess the effect of the hot weather conditions of Kuwait on fluid loss (FL) and body composition of Kuwaiti soccer players. METHODS: During 5 preseason soccer games, 10 elite Kuwaiti soccer players participated in this study. The age and physical characteristics (mean+/-SD) of the subjects were: age 24+/-4.7 years; height 173.4+/-5.2 cm; mass 68.2+/-7 kg; and the percent body fat 12.3+/-3.7%, the mean temperature 45.4+/-2 degrees C, mean humidity was 23.6+/-4.2%. Measurements were taken at the beginning, half time, and the end of each game; FL was measured by body weight changes. Urine specific gravity was used to determine the state of hydration. Body composition was measured using Biodynamics Model 310e Body Composition Analyzer. RESULTS: There was a significant difference in body weight changes between 1st and 2nd half at P>0.05. The mean value of the FL at the end of the game was 3.1+/-1.4 L; indicating no significant difference in FL between 1st and 2nd half at P>0.05). The mean value urine specific gravity at the end game was 1.026+/-0.002; there was a significant difference between first, and second half for urine specific gravity (P>0.05). CONCLUSIONS: Results of this study indicated that the subjects did not consume enough fluid to offset FL. Players and coaches involved with activities in hot humid environments should pay closer attention to FL and body weight changes which occur during physical activity. Special care should always be taken to insure players consume extra water prior to each training session or game.     

Effects of traditional balance and slackline training on physical performance and perceived enjoyment in young soccer players

The aim of this study was to evaluate the effects of 12-week balance and slackline training programs on physical performance and perceived enjoyment scale in young soccer players. Forty-one preadolescent soccer players were assigned to two experimental groups performing traditional balance (BLT) or slackline training (SLT), and a control group. Pre-post assessment encompassed Balance Error Scoring System (BESS), Star Excursion Balance test (SEBT), sprint with 90° turns (S90), and countermovement jump (CMJ). The rate of perceived enjoyment scale (PACES) was applied at the end of the experimental period. SLT and BLT improved similarly in BESS, SEBT and S90. No changes were detected in the CMJ. Regarding PACES score, SLT presented significantly higher values than BLT. Young athletes may benefit from a motivating training approach, thus, a designed program based on slackline drills should be preferable to improve physical performance in terms of balance and change of direction ability in preadolescent soccer players.     

A comparison of the physiological profiles of elite Gaelic footballers, hurlers, and soccer players

Background: Gaelic football, soccer, and hurling are prominent field games in Ireland and involve participants undertaking a variety of playing tasks and skills which place various physiological demands on the participants. The aim of this study was to evaluate and compare the mid-season physiological profiles of elite players.

Methods: Physiological assessment was carried out on 29 inter-county Gaelic footballers, 30 inter-county hurlers, and 21 League of Ireland soccer players.

Results: Significant differences were reported for % body fat (p<0.05), aerobic capacity (p<0.05), flexibility (p<0.05), upper body strength (p<0.05), upper body strength endurance (p<0.05), abdominal endurance (p<0.05), and speed endurance (p<0.05), while there were no differences recorded for height, weight, or speed levels. A relatively heterogeneous body size is evident for all three sports. Soccer players had lower body fat levels, greater aerobic capacity, greater strength endurance, and greater flexibility compared to both Gaelic footballers and hurlers, possibly due to specific training and conditioning programmes or physical adaptation to match play The greater strength of both Gaelic footballers and hurlers and the superior speed endurance levels of Gaelic footballers also reflect the physical nature of the sports. Similar speed levels amongst all three sports reflect the importance of speed for performance.

Conclusions: The various physiological attributes for Gaelic football, soccer, and hurling reflect the physical requirements for success and participation in each of these field games.

     

Predictive modeling of the ratings of perceived exertion during training and competition in professional soccer players

ObjectivesEvaluate the ability of predicting the ratings of perceived exertion from the external load variables in professional soccer players through a chronological perspective (i.e., past features values are considered additional features) through machine learning models by considering the playing position.DesignProspective cohort study.MethodsThirty-eight elite soccer players aged 19-27 years were observed during 151 training sessions, 44 matches across a full season. External load variables (58 derived from Global Positioning System and 30 from accelerometers) and the internal load derived from ratings of perceived exertion were collected for each player and each session and match. Machine learning models (linear regression, K-NN, decision trees, random forest, elastic net regression, XGBoost) were compared and interpreted in order to deepen the relationship between external load variables and ratings of perceived exertion according to the player position in a predictive perspective.ResultsApplication of the machine learning models on the dataset provided enough predictive power to reduce the Root Mean Squared Error of 60 % from dummy predictions. The most accurate models (Root Mean Squared Error ≈ 1.1 for random forest and = 1 for XGBoost) highlighted a memory effect in subsequent ratings of perceived exertion values. Past ratings of perceived exertion values over one month were the strongest predicting factors of ratings of perceived exertion as compared to various external load indicators.ConclusionsThe tree-based machine learning models showed statistically significant predictive ability, indicating valuable information for understanding the training load responses based on ratings of perceived exertion changes.     

Effects of an anterior cruciate ligament injury prevention program on performance in adolescent female soccer players

Female soccer players are three times more likely to suffer a non‐contact anterior cruciate ligament (ACL) tear compared with male soccer players. Several ACL injury prevention programs have been developed and are used to reduce injury risk. However, to date there is limited information on how such programs affect physical performance. The aim of this randomized controlled study was to investigate the effects of the Prevent Injury Enhance Performance (PEP) program in adolescent female soccer players. Four soccer teams were randomly assigned to an intervention (PEP) or control (CON) group and assessed at baseline, 6 weeks, and 12 weeks on linear sprinting, countermovement jump (CMJ), and two agility tests. A mixed model factorial ANOVA with repeated measures was used to assess for treatment effects on the dependent variables. Improvements in 27.3 and 36.6 m sprint times (<0.10 s) were evident during the first 6 weeks for PEP, but reverted back to baseline values by 12 weeks; there were no changes for 9.1 or 18.2 m sprint times in either group. There was no change in the CMJ height for PEP; however, there was a decrement at 6 and 12 weeks compared with baseline in CON. Performance on the Illinois and pro‐agility tests declined in both groups. Our findings demonstrate that improvements in linear sprint performance were small and transient in adolescent female soccer players, and that there was no benefit of the PEP program on CMJ or agility performance. ACL injury prevention programs designed as a structured warm‐up routine seem to lack the necessary stimulus to enhance athletic performance.     

Positional synchronization affects physical and physiological responses to preseason in professional football (soccer)

This study aimed to identify changes in tactical, physical and physiological performances in large-sided games during the preseason of elite footballers. Thirty professional football players participated in several GK+8vs.8+GK large-sided games across the first four weeks of the season. Players were monitored by GPS units and heart rate monitors to quantify physical, physiological and tactical performances. The variables were compared according to the preseason period, players’ positioning and professional experience. The training situation promoted similar physiological responses during the first and the last training period. However, players were revealed to have higher levels of positional synchronization during the last preseason period, indicating an improved tactical performance. Tactical variables seem to reflect the improvement of players’ performance during the preseason, measured in large-sided games situation, while affecting both physical and physiological demands. These results highlight the potential of positioning derived variables, concurrently to physical and physiological variables, for football training optimization.     

The effect of two different speed endurance training protocols on a multiple shuttle run performance in young elite male soccer players

There is not enough evidence on the impact of different speed endurance training regimes on footballers’ ability to perform multiple shuttle run performance. This study examined the effect of 4 weeks of speed endurance maintenance (SEM) and speed endurance production (SEP) training on the 5-meter multiple shuttle run test (5-m MST) performance in young elite soccer players. A parallel two-groups, longitudinal design was used. Fifteen players were divided to either SEM (8 repetitions of 20-s all-out sprint interspersed with 40 s of recovery) or SEP (8 repetitions of 20-s all-out bout interspersed with 120 s of recovery) training group. SEM improved the ability to tolerate fatigue and maintained the performance development during the 5-m MST while SEP increased only the 1^st sprint showing, simultaneously, an increased fatigue index and performance decrement. The selection of which training regimes to prioritize should be based on the players’ characteristics and individual game requirements

Abbreviations: SEP: Speed Endurance Production; SEM: Speed Endurance Maintenance; PRE: Baseline; POST: End of experimental protocol; 5-m MST: 5-meters Multiple Shuttle Run Test; TD: Total Distance; FI: Fatigue Index; MSTdec: Percentage Decrement Score; BMI: Body Mass Index     

An injury audit in high-level male youth soccer players from English,Spanish, Uruguayan and Brazilian academies

ObjectivesTo identify the most common injury types/locations in high-level male youth soccer players (YSP).DesignProspective cohort surveillance study.SettingProfessional soccer club academies.ParticipantsSix hundred and twenty-four high-level male YSP [Under 9 (U9) to U23 year-old age groups] from academies in England, Spain, Uruguay and Brazil.Main outcome measuresInjury type, location and severity were recorded during one season. Injury severity was compared between age groups, while injury type and location were compared between nations.ResultsFour hundred and forty-three training or match injuries were recorded, giving an injury rate of 0.71 per player. Non-contact injuries were most common (58.5%), with most (44.2%) resolved between 8 and 28 days. Most injuries (75.4%) occurred in the lower limbs, with muscle (29.6%) the most commonly injured tissue. U14 and U16 suffered a greater number of severe injuries relative to U12 and U19/U20/U23/Reserves. Tendon injury rate was higher in Brazil vs. Spain (p < 0.05), with low back/sacrum/pelvis injury rate highest in Spain (p < 0.05).ConclusionsThe proportion of severe injuries in U14 and U16 suggests YSP injury risk is maturation-dependent. Minimal differences in type and location between high-level YSP from four different countries suggest injury rates in this population are geographically similar.