Agility profile in sub-elite under-11 soccer players: is SAQ training adequate to improve sprint, change of direction speed and reactive agility performance?

"Who's Got Talent?" Change of Direction, Anthropometric Characteristics and Maturity Offset Differences Between Elite and Sub-Elite Young Soccer Player

Agility, anthropometrics and maturity-offset have been considered fundamental for talent identification in soccer. The aim of this study is to compare 83 young soccer players (U12) from elite (28) and sub-elite (55) teams, to investigate the influences of anthropometric characteristics and maturation on Change-of-Direction (CoD) with the ball (dribbling) and without the ball. ANCOVA was run to investigate potential differences in Agility T-Test and Shuttle Dribble Test between categories while simultaneously controlling for the effects of anthropometric variables such as Peak Height Velocity (PHV), Weight, and Height. Agility T-Test performance does not significantly differ between the two categories (F-value = 0.537, p > .05). However, the Weight significantly influences the results (F-value = 18.425, p < .001, Eta-Squared = 0.172) and also PHV has a significant impact on them (F-value = 10.099, p < .01, Eta-Squared = 0.094). The Shuttle Dribble Test performance significantly varies between two groups (F-value = 5.207, p < .05, Eta-Squared = 0.057). Only Weight significantly influences this test (F-value = 4.324, p < .05, Eta-Squared = 0.048). Our findings indicate that during the U-12 age period, technical skills emerge as a crucial discriminant factor between elite and sub-elite young soccer players, contrarily to the athletic performance without the ball. In addition, the maturity stage specifically influences the Agility T-Test and Weight is significantly related to lower time to complete both in Agility T-Test and SDT.

Effects of 6-Week Motor-Cognitive Agility Training on Football Test Performance in Adult Amateur Players - A Three-Armed Randomized Controlled Trial

Agility, defined as the ability to rapidly respond to unforeseen events, constitutes a central performance component in football. Existing agility training approaches often focus on change of direction that does not reflect the complex motor-cognitive demands on the pitch. The objective of this study is to examine the effects of a novel motor-cognitive dual-task agility training (Multiple-object tracking integrated into agility training) on agility and football-specific test performance parameters, compared to agility and a change of direction (COD) training. Adult male amateur football players (n = 42; age: 27±6; height: 181±7cm; weight: 80±12kg) were randomly allocated to one of the three intervention groups (COD, agility, agility + multiple object tracking). The Loughborough Soccer Passing Test (LSPT), a dribbling test with/without cognitive task as well as the Random Star Run (with/without ball) and the modified T-Test were assessed before and after a 6-week training period. Time effects within the T-Test (F = 83.9; p < 0.001; η2 = 0.68) and dribbling test without cognitive task (F = 23.9; p < 0.001; η2 = 0.38) with improvements of all intervention groups (p < 0.05) were found. Dribbling with cognitive task revealed a time effect (F = 7.8; p = 0.008; η2 = 0.17), with improvements exclusively in the agility and dual-task agility groups (p < 0.05). Random Star Run with and without ball exhibited a time (F = 38.8; p < 0.001; η2 = 0.5; F = 82.7; p < 0.001; η2 = 0.68) and interaction effect (F = 14.14; p < 0.001; η2 = 0.42; F = 27.8; p < 0.001; η2 = 0.59), with improvements for the agility and dual-task agility groups. LSPT showed no time, group or interaction effect. The effects of change of direction training are limited to change of direction and dribbling test performance within preplanned scenarios. In contrast, motor-cognitive agility interventions result in notable enhancements in football-specific and agility tests, incorporating decision-making and multitasking components. No differences were observed between agility and agility + multiple object tracking. To achieve a transfer to game-relevant performance, coaches should focus on integrating cognitive challenges into motor training.

SAQ training on sprint, change-of-direction speed, and agility in U-20 female football players

The purpose of the study was to investigate the effects of an 8-week speed, agility, and quickness (SAQ) training on performance changes in linear sprint speed, change-of-direction (COD) speed, and reactive agility of U-20 female football players. Nineteen female football players randomly served as either experimental (n = 9) or control groups (n = 10). The players were tested for physical fitness tests: linear sprint speed including both short and long distances (5- and 10-m sprints without a ball and 20- and 30-m sprints with and without dribbling), COD speed (arrowhead agility test with and without dribbling a ball, Southeast Missouri [SEMO] agility test, and 22-m repeated slalom dribbling test), and reactive agility. Significant group × time interactions were observed for sprint over long distances and COD speed but not for short sprint and reactive agility performances. Paired t-tests revealed considerable improvements in all performances from the pre-test to post-test for the SAQ group, except for the arrowhead agility (left; p = .07). The control group only exhibited significant improvements in 10-m sprint performance after general football training. Eight weeks of SAQ training were effective at enhancing acceleration, maximum sprint speed, and agility performances amongst highly trained U-20 female football players.

Acute Effect of Four Stretching Protocols on Change of Direction in U-17 Male Soccer Players

BACKGROUND

The ability to rapidly change direction while sprinting is a desirable athletic skill in soccer. Enhancing change of direction (COD) performance depends almost exclusively on specific training, with stretching traditionally considered one such intervention. However, the comparative impact of diverse stretching methods on COD in soccer players remains an area of interest. Therefore, this study aimed to compare the effects of different stretching methods on COD ability in soccer players.

METHODS

Twelve male soccer players playing in the national championship football division II (age: 16.3 ± 0.3 years, height: 1.81 ± 0.10 m, body mass: 67.7 ± 7.2 kg) were tested for COD performance (i.e., Illinois agility test) after (1) control condition (20 min general warm-up without stretching), (2) static stretching, (3) dynamic stretching, (4) combined static-dynamic stretching, and (5) combined dynamic-static stretching. The duration of stretching intervention was approximately 6 min for static and dynamic stretching and 12 min for both the combined stretching conditions. The experimental sessions were separated by 72 h.

RESULTS

COD improved after dynamic stretching when compared to any other condition (p: 0.03-0.002; ηp2: 0.56-0.73), except for the control condition (p = 0.146; ηp2 = 0.18). In contrast, static stretching induced a detrimental effect on COD when compared only to the dynamic stretching condition (p < 0.01; ES = 1.35).

CONCLUSION

Dynamic stretching exercises used by male soccer players in the warm-up improved COD. Other forms of stretching exercises, particularly static stretching, negatively impacted the COD performance. Therefore, coaches can consider integrating dynamic stretching protocols tailored to the athletes' specific needs. Moreover, extending the investigation to encompass a wider range of athletes, including different age groups and genders, would enhance the applicability and generalization of the findings.

Resultant equations for training load monitoring during a standard microcycle in sub-elite youth football: a principal components approach

Applying data-reduction techniques to extract meaningful information from electronic performance and tracking systems (EPTS) has become a hot topic in football training load (TL) monitoring. The aim of this study was to reduce the dimensionality of the internal and external load measures, by a principal component approach, to describe and explain the resultant equations for TL monitoring during a standard in-season microcycle in sub-elite youth football. Additionally, it is intended to identify the most representative measure for each principal component. A principal component analysis (PCA) was conducted with a Monte Carlo parallel analysis and VariMax rotation to extract baseline characteristics, external TL, heart rate (HR)-based measures and perceived exertion. Training data were collected from sixty sub-elite young football players during a 6-week training period using 18 Hz global positioning system (GPS) with inertial sensors, 1 Hz short-range telemetry system, total quality recovery (TQR) and rating of perceived exertion (RPE). Five principal components accounted for 68.7% of the total variance explained in the training data. Resultant equations from PCA was subdivided into: (1) explosiveness, accelerations and impacts (27.4%); (2) high-speed running (16.2%); (3) HR-based measures (10.0%); (4) baseline characteristics (8.3%); and (5) average running velocity (6.7%). Considering the highest factor in each principal component, decelerations (PCA 1), sprint distance (PCA 2), average HR (PCA 3), chronological age (PCA 4) and maximal speed (PCA 5) are the conditional dimension to be considered in TL monitoring during a standard microcycle in sub-elite youth football players. Current research provides the first composite equations to extract the most representative components during a standard in-season microcycle in sub-elite youth football players. Futures research should expand the resultant equations within training days, by considering other well-being measures, technical-tactical skills and match-related contextual factors.

Clustering U-14 Portuguese regional team football players by lower limb strength, power, dynamic balance, speed and change of direction: understanding the field position factor

Objectives

The aim of this study was to cluster U-14 Portuguese regional team football players based on variables related to lower limb strength and power, dynamic balance, linear sprint, and change of direction.

Method

The sample consisted of 22 young male soccer players (13.83 ± 0.44 years). A set of variables related to lower limb strength and power, dynamic balance, linear sprint, and change of direction was measured.

Results

Overall, a non-significant field position was observed. The countermovement jump (p < 0.001, η² = 0.73), squat jump (p < 0.001), and 30 m linear sprint (p = 0.001) were the main variables responsible for establishing the clusters. Cluster 1 was characterized by a high slalom, i.e., it took longer to complete the test (speed and change of direction) and a low composite score in the dynamic balance. Cluster 2 was characterized by high squat jump, countermovement jump, and reactive strength ratio (lower limb strength and power). Cluster 3 was characterized by low squat jump and countermovement jump (lower limb strength and power), and a high 30 m sprint, i.e., it took longer to complete the test (speed and change of direction). Based on the results of the territorial map, the clusters consisted of: (i) cluster 1: two forwards, one midfielder, and five defenders; (ii) cluster 2: three forwards, two midfielders, and two defenders, and; (iii) cluster 3: four midfielders and three defenders.

Conclusions

Players from different field positions composed the three clusters. There was no cluster composed exclusively of players of the same field position. The development of individualized and specific enrichment training programs should consider a cluster analysis, as the positional effect can be overlooked.

Effects of Plyometric Training with Resistance Bands on Neuromuscular Characteristics in Junior Tennis Players

The purpose of this study is to investigate the effect of 6 weeks (conducted twice per week for a total of 12 sessions) of plyometric training with resistance bands on different neuromuscular characteristics among the sample of junior tennis players. Thirty junior tennis players between the ages of 12 and 14 years (age 13.5 ± 1.8 years; weight 51.3 ± 12.5 kg; height 162.7 ± 12.6 cm) were allocated to either the control group (standard in-season regimen) (CG; n = 15) or the experimental group, which received additional plyometric training with resistance bands (TG; n = 15). Pre- and post-tests included: anthropometric measures; 20 m sprint time (with 5, 10, and 20 m splits), squat jump (SQ Jump); vertical countermovement jump (CMJ); vertical countermovement jump with arm swing (CMJ_free arms); single leg (left) countermovement jump (CMJ_L); single leg (right) countermovement jump (CMJ_R); standing long jump (L_Jump); single leg (left) triple jump (SLTH-L); single leg (right) triple jump (SLTH-R); generic change of direction speed (CODS) (20Y test and T-test); reactive agility test (WS-S). After the training intervention, the TG showed significant (“p < 0.05”) improvements in CMJ (F = 7.90, p = 0.01), CMJ_L (F = 5.30, p = 0.03), CMJ_R (F = 11.45, p = 0.00), and SLTH-L (F = 4.49, p = 0.04) tests. No significant changes were observed in the CG after the training intervention. Our findings provide useful information for coaches to create a wide range of tennis-specific situations to develop a proper performance, especially for their player’s neuromuscular fitness.

The Relationship Among Acceleration, Deceleration and Changes of Direction in Repeated Small Sided Games

The change of direction (COD) ability is perhaps the most significant fitness component in team sport games. One of the best ways to develop COD as well as other components of the game in soccer is the regular inclusion of small sided games (SSGs) in the training process. Therefore, the aim of this research was to determine changes in physiological and kinematic variables in repeated SSGs in youth soccer players. Additionally, we investigated the relationship between selected IMA variables such as acceleration, deceleration and changes of direction. Participants included sixteen U17 soccer players from a 2^nd league professional team with a high aerobic capacity. The study design involved six 3-min 4 × 4 SSGs with goalkeepers and with a 3-min rest interval between games, during two training sessions played on a field of 25 x 35 m. The results showed that the intervention protocol consisting of repeated SSGs generated an intensity below the anaerobic threshold. This allowed for the maintenance of all variables (Heart Rate, Total Distance Covered, Velocity, Acceleration, Deceleration, Change of Direction) at a similar level throughout the subsequent six SSGs. The analysis revealed that in the six SSGs, players performed the most Acc and Dec, then COD Right and the least COD Left. From the third game on, a decrease in the number of COD Right was noticed. We hypothesized that progressive neuromuscular fatigue on the dominant side caused a more symmetrical trend in COD.

Development and trainability of agility in youth: A systematic scoping review

Background

Agility is acknowledged as a crucial factor of performance in various open skill sports in both adult and youth athletes. However, despite its significance for sports performance the development and the trainability of agility are under-researched within the pediatric literature. A systematic scoping review was considered most appropriate to provide researchers and practitioners with an overview of the current body of literature approaching agility in youth.

Objectives

The objectives of this scoping review were to map the extent, range, and nature of existing evidence regarding trainability and "natural" development of agility and to summarize corresponding study results.

Methods

The scoping review protocol was pre-registered at Open Science Framework. Systematic searches were conducted using the databases PubMed, Scopus, ProQuest, Web of Science, SURF, and SPONET to identify sources covering agility in youth. Among other inclusion criteria, only references applying unplanned agility concepts were included.

Results

Ultimately, 41 reports were included comprising 23 observational studies, 14 experimental studies, and 4 references of secondary research. A total of 3,087 subjects were assessed in the included studies. Subject groups were predominantly male, above 10 years of age, and soccer athletes. Outcomes of observational studies indicate an effect of age and maturation on agility performance resulting in a non-linear "natural" development of agility. Furthermore, relationships between contributing perceptual-cognitive factors and agility performance tend to increase with progressing age, whereas relationships between physical factors and agility performance diminish. Evidence of training studies suggests that agility is trainable in youth, albeit with various underlying mechanisms.

Conclusions

This systematic scoping review is the first mapping of the body of literature about agility in youth. It outlines the current evidence base, reveals research gaps, and points out future directions to support researchers and practitioners in this field. Although, increasing research activity in this field is discernible, agility research in youth is still in its infancy. Considering the significance of agility for sports performance, future research is postulated to design evidence-based strategies for long-term agility development in young athletes.

Anthropometric and Physiological Profiles of Hungarian Youth Male Soccer Players of Varying Ages and Playing Positions: A Multidimensional Assessment with a Critical Approach

BACKGROUND

This study aimed to create preliminary anthropometric and physiological profiles of Hungarian male soccer players belonging to different age categories (14, 15, 16, and 17-18-years) and assigned to different playing positions (forward, defender, midfielder, goalkeeper).

METHODS

Anthropometric and physiological profiles were created for four age groups: 14- (n = 20), 15- (n = 16), 16- (n = 22) and 17-18-year-olds (n = 23) representing the Hungarian soccer academy. Additionally, the variables were analyzed across the four player positions mentioned above.

RESULTS

The mean values of body mass, fat mass and BMI were within normal limits, although in some cases the anthropometric and body composition values were too high, particularly among the 17-18-year-olds. The mean values of HR_rest were lowest among the 15-year-olds. The highest mean and maximal values of rVO_2max and rVO₂/AT [57.6 ± 8.12 (43.8-68.3) and 51.2 ± 7.24 (38.9-60.8) mL/kg/min, respectively] were noted in 14-year-olds. Goalkeepers performed significantly better than the remaining soccer players in terms of the most anthropometric and physiological characteristics, except for the Yo-Yo test (p < 0.001).

CONCLUSIONS

The values of anthropometric parameters increased with age. As expected, the oldest group achieved the best results in the performance tests. Goalkeepers outperformed the players representing other playing positions in the tests when assessing lower limb strength, sprint performance (5- and 10-m distance), and agility tests. From a practical point of view, the presented anthropometric and physiological profiles of players representing different age groups and playing positions can be useful for soccer coaches, strength and conditioning specialists, and athletic trainers of other soccer clubs in terms of the individualization and optimalization of soccer training.

Relationship between sprint, jump, dynamic balance with the change of direction on young soccer players' performance

The aim of the present paper was to determine the relationship between linear sprinting and jump performance, dynamic balance and change of direction on young soccer players. Ninety-four healthy young highly trained male soccer players belonging to the same high-performance academy agreed to participate in the study [twenty-seven soccer players U16 (14.8 ± 0.4 years; height: 170.6 ± 5.6 cm; body mass 64.7 ± 8.4 kg)] and [sixty-seven soccer players U19 (16.6 ± 1.3 years; height: 173.7 ± 7.2 cm; body mass 66.7 ± 8.0 kg)]. Participants completed 3 testing sessions, 7 days apart. Data from a CMJ, Crossover Hop Test, 10-m sprint test, 505 COD tests and the 90° COD test were collected. Moderate correlations were found in some of the cases (r values were between 0.2 and 0.5 in all cases, being p < 0.05), indicating that linear sprinting, jumping performance and dynamic balance are influential factors in agility but are not the main limiting factor. The highest correlation was found between the cross-over hop test and the 505 COD test (r = 0.44; p < 0.001). The main evidence from the current study suggested that linear sprinting, jumping performance and dynamics balance are determinants of COD, namely explaining the variations in such a skill. The current study revealed that short-distance sprint and jumping performance significantly explain the variations of COD performance on young soccer players.

Whole-body sensorimotor skill learning in football players: No evidence for motor transfer effects

Besides simple movement sequences, precise whole-body motor sequences are fundamental for top athletic performance. It has long been questioned whether athletes have an advantage when learning new whole-body motor sequences. In a previous study, we did not find any superior learning or transfer effects of strength and endurance athletes in a complex whole-body serial reaction time task (CWB-SRTT). In the present study, we aimed to extend this research by increasing the overlap of task requirements between CWB-SRTT and a specific sports discipline. For this purpose, we assessed differences between football players and non-athletes during motor sequence learning using CWB-SRTT. 15 non-athletes (CG) and 16 football players (FG) performed the CWB-SRTT over 2 days separated by one week. Median reaction times and movement times were analyzed as well as differences in sequence-specific CWB-SRTT learning rates and retention. Our findings did not reveal any differences in sequence-specific or non-sequence-specific improvement, nor retention rates between CG and FG. We speculate that this might relate to a predominately cognitive-induced learning effect during CWB-SRTT which negates the assumed motor advantage of the football players.

The Mediating Effect of Change of Direction Speed in the Relationship between the Type of Sport and Reactive Agility in Elite Female Team-Sport Athletes

The main aim of this study was to examine the mediating effect of the change of direction speed (CODs) on reactive agility (RA) in female players participating in different team sports (TS). In total, there were 31 elite female players from the Polish national basketball (n = 12, aged 24.98 ± 3.38) and handball (n = 19, aged 27.34 ± 4.68) teams participated in this study. Two experiments using the 'five-time shuttle run to gates' test with similar movement patterns were used to determine the players' RA and CODs. A simple mediation model was utilised to investigate the potential mediation role of CODs and its effect on RA. The results revealed a primary, statistically significant effect of TS on RA (B = 0.796, p = 0.005), which decreased and became statistically insignificant after including the CODs variable into the model of mediation analysis (B = 0.337, p = 0.192). The RA test results were mediated by changes in CODs (B = 0.764, p < 0.001). Likewise, TS affected CODs (B = 0.602, p = 0.016). The general conclusion is that the relationship between TS and RA is not inherent. The direct effect of TS on RA disappears in the presence of the mediator CODs. Study results confirm the relevance of using the mediation analysis to apply in sport training. Identification of the critical ingredients of the athletes' agility performance can improve training programs by focusing on effective components.

Differences in Squat Jump, Linear Sprint, and Change-of-Direction Performance among Youth Soccer Players According to Competitive Level

The aim of this investigation was to analyze significant differences in performance depending on the level of play (elite vs. amateur) in youth soccer players (under 17 years. old (U17) and U19). A cross-sectional study was conducted, and 45 elite and amateur male youth soccer players (16.56 ± 0.9 years old) were evaluated in their performances in squat jump (SJ), 10 m linear sprint (LS), 20 m LS, 505 agility test (505) and Illinois agility test (IAT). Differences in performances were analyzed with a 2 × 2 MANOVA, post-hoc ANOVAs, and Hedges’ g (g) for pairwise comparisons of subgroups (level of play and age group). This investigation showed that the elite player performance was significantly (p < 0.05) better in all performance tests than amateur players in both age groups. Interestingly, this investigation showed that the more complex the target exercise, the larger the effect sizes for group differences (SJ: g = 0.64–1.18, LS: g = 0.05–2.23, change-of-direction (COD): g = 3.01–6.84). The SJ, LS, 505, and IAT may prove useful in talent selection test batteries to separate between competitive levels in youth soccer players.

Effects of Three Preseason Training Programs on Speed, Change-of-Direction, and Endurance in Recreationally Trained Soccer Players

Background: Modern coaches experience a drastic reduction of the available training time with an increasingly large number of competitions during the competitive season. Thus, they must choose wisely the most efficient methods to improve the physical fitness of their players during the preseason. Among all the methods, this study compared the effects of plyometric training (PT), sprint interval training (SIT), and small-sided games (SSGs) on the performance of recreationally trained soccer players.

Methods: Seventy-three participants were randomly assigned in one of the three experimental groups (i.e., PT [n = 23], SIT [n = 26] or SSGs [n = 24]) and completed two sessions per week for a total of 3 weeks. Meanwhile, the whole group maintained their habitual soccer-specific training program who do not interfere in the preparation of the season. Repeated sprint ability (RSA), maximal aerobic speed (MAS), and a 30-m sprint were assessed at baseline (PRE) and post-training (POST).

Results: Performance in SSGs decreased for the average speed from 0 to 10 m (V_0−10m; −0.84 km h⁻¹, −4 ± 5%, p < 0.001), the maximal distance (D_max) covered in the 30-s RSA test (−3.65 m, −3 ± 6%, p < 0.01) and MAS (−0.52 km h⁻¹, −3 ± 6%, p < 0.01). PT increased the mean distance (D_mean) covered in the 30-s RSA test (+5.98 m, 5 ± 4%, p < 0.001) and MAS (+0.58 km h⁻¹, 7 ± 5%, p < 0.01) while an improvement of all parameters but the maximal sprint speed reached during the 30-m trip (V_max) was found in the SIT group (V_0−10m: +1.462 km h⁻¹, 8 ± 5%, p < 0.001; D_max: +7.89 m, 6 ± 5%, p < 0.001; D_mean: +8.69 m, 7 ± 5%, p < 0.001 and MAS: +1.74 km h⁻¹, 12 ± 8%, p < 0.001). All SSG POST values were significantly lower than PT and SIT (p < 0.01). D_mean and MAS in POST were also significantly higher in SIT than in the PT group (p < 0.001).

Conclusion: This study suggests that both PT and SIT could be a better alternative to SSGs to boost performances during preseason. Moreover, SIT seems to produce higher improvements in physical performances than PT.

Comparison of whole-body sensorimotor skill learning between strength athletes, endurance athletes and healthy sedentary adults

Motor sequences represent an integral part of human motor ability. Apart from simple movement sequences, complex coordinated movement sequences are the building blocks for peak athletic performance. Accordingly, optimized temporal and spatial coordination of muscle action across multiple limbs may be a distinguishing feature between athletes and non-athletes in many sports. In the present study, we aimed to assess differences between strength and endurance athletes and non-athletes during learning of a complex whole-body serial reaction time task (CWB-SRTT). For this purpose, 26 nonathletes (NAG) and 25 athletes (AG) learned the CWB-SRTT over 2 days separated by 7 days. Mean response times of participants were recorded and statistically analyzed for sequence-specific and non-sequence-specific improvements, as well as differences in learning rates and retention. Furthermore, AG was subdivided into strength (SG) and endurance (EG) athletes, and all analysis steps were repeated. Our results show a better mean response time of AG compared to NAG. However, we could not detect differences in sequence-specific or non-sequence-specific learning, as well as different retention rates between NAG and AG or SG and EG. We assume here that a potential lack of motor transfer between general athletic abilities and the specific complex motor sequence mainly accounts for our findings.

Effects of Non-Sport-Specific Versus Sport-Specific Training on Physical Performance and Perceptual Response in Young Football Players

This study aimed to compare the effects of non-sport-specific and sport-specific training methods on physical performance and perceptual response in young football players. Seventy-nine under 11 participants were selected and assigned to non-sport-specific (NSSG), sport-specific (SSG), and control (CNTG) groups. The NSSG training protocol consisted of combined stimuli based on balance, agility, and jump rope drills. The SSG training protocol included technical exercises, defensive and offensive game-based drills, and a small-sided game. The CNTG included the participants not taking part in any sport training. All participants were tested for general motor coordination (Harre test), dynamic balance (Lower Quarter Y-balance test), and dribbling before and after 10 weeks of training (NSSG and SSG) or habitual activity (CNTG). At post-intervention, perceived enjoyment was requested by the Physical Activity Enjoyment Scale (PACES). A two-way repeated measure analysis of covariance was used to detect interactions and main effects of time and groups controlling for baseline values. Whereas, a one-way analysis of variance was used to evaluate PACES-related differences between groups. NSSG gained greater improvements (p < 0.05) compared with SSG in the Harre and Lower Quarter Y-balance tests, while dribbling skills improved similarly in both groups. Regarding PACES, NSSG and SSG presented a comparable perceived enjoyment. These findings suggest that a 10-week non-sport-specific training is an enjoyable practice capable to promote greater improvements in general motor coordination and dynamic balance compared with sport-specific training in youth football players. This can occur without impairment of football-specific skills.

Relationship between Cognitive Functions and Sport-Specific Physical Performance in Youth Volleyball Players

The aim of this study was to investigate the relationship between basic cognitive functions and sport-specific physical performance in young volleyball players. Forty-three female volleyball players (age 11.2 ± 0.8 years) were tested for cognitive performance by measuring simple reaction time (clinical reaction time), executive control (Flanker task), and perceptual speed (visual search task). Moreover, a set of tests was used to assess physical abilities as volleyball-specific skills (accuracy of setting, passing, and serving) and motor skills (change of direction, vertical jump, and balance). A cumulated value for both cognitive and sport-specific physical performance tests was computed by adding up each test’s domain outcomes. Pearson’s r correlation analysis showed a large positive correlation (r = 0.45, d-value = 1.01) of the cumulated score summarizing cognitive functions with the cumulated score summarizing sport-specific physical performance. Moreover, small-to-medium correlations (d-value from 0.63 to 0.73) were found between cognitive and motor skills. Given the cumulative scores, these results suggest that volleyball athletes with superior basic cognitive functions present better sport-specific physical performance. Our findings encourage to extend the knowledge of the associations between cognitive and motor skills within a sports performance context.

Slow-Speed Resistance Training Increases Skeletal Muscle Contractile Properties and Power Production Capacity in Elite Futsal Players

The purpose of this study was to explore the effects of slow-speed resistance training with low intensity (SRT) on muscle power output in elite futsal players with respect to traditional resistance training. The authors hypothesized that the muscle deoxygenation during SRT causes early recruitment of fast twitch fibers that would positively affect strength and power performance. Thirty male elite futsal players were recruited and randomly assigned either to SRT group or to traditional resistance training (TRT) group. All players underwent an 8-weeks experimental protocol consisting of 2 training sessions per week at both leg curl and leg extension machines. In the SRT, players lifted 50% of one maximum repetition (1RM) involving 3 s for eccentric and concentric actions. In the TRT, players lifted 80% of 1RM involving 1 s for eccentric and concentric actions. All players were tested twice (pre and post) for sprint and jump performances, maximal isometric voluntary contraction (MVC) and maximal isokinetic peak torque (Peak TQ) and total work (TW) at 60 and 120°/s (on knee extensors and flexors). The two groups presented remarkable differences in the within-group changes for all the variables. SRT exhibited greater improvements in both Peak TQ and TW for knee extensors and flexors at 120°/s. Conversely, TRT showed greater improvements in MVC, and in both Peak TQ and TW for knee extensors and flexors at 60°/s, except for Peak TQ of the knee extensors, where no significant difference was found between TRT and SRT. Countermovement jump showed a decrease in eccentric time and an increase in concentric force in SRT group. SRT and TRT resulted effective to enhance the strength performance indices during the 8-weeks experimental protocol. Peak torque at 120°/s explained more of the contractile characteristic effects of SRT training than MVC, suggesting that slow-speed training can cause fast twitch fibers hypertrophy in elite athletes. Since slow-speed training is supposed to produce a decreased exercise-induced muscle damage, SRT method is a suitable option in strength training for futsal and team sports.

Change of direction asymmetry across different age categories in youth soccer

Background

In youth, the development of change of direction (COD) and sprint performance is a key component for successfully competing in soccer across age. During a COD, the presence of directional asymmetries may be detrimental due to the unpredictable nature of the sport. Therefore, the aims of the study were to investigate asymmetries in COD ability and to examine the differences in COD and sprint performance across age in young soccer players.

Methods

Sixty-eight sub-elite soccer players of different age categories (U18, U17, U16, U15) were tested on a 10-m linear sprint test and 90°COD (5-m entry and exit) test in both directions. Asymmetric index (AI) of COD deficit was obtained for dominant (fastest) and non-dominant directions (slowest).

Results

The results showed that U16 were more asymmetrical than U18, U17, and U15 from large to moderate effects. The sprint time improved linearly across age with U18 and U15 displaying the fastest and slowest 10-m sprint performance (p < 0.01), respectively. Moreover, COD ability measured by COD deficit did not change across age (p > 0.05).

Conclusion

Given the results of this study, practitioners are encouraged to assess asymmetries between dominant and non-dominant directions rather than solely players’ COD ability in young soccer players.

Mental fatigue impairs physical activity, technical and decision-making performance during small-sided games

The aim of this study was to investigate the effects of mental fatigue on physical activity, technical and decision-making performance during small-sided games. Nine sub-elite soccer players were enrolled in the study. The players performed two small-sided games on two occasions within a crossover experimental design. Before each game, they underwent a mental fatiguing task (Stroop task) and a control task (documentary watching) in a randomized, counterbalanced order. Players' physical activity, technical, and decision-making performance were obtained during small-sided games by GPS and video scouting. Results showed that distance in acceleration covered per min, negative passes, passing accuracy, and shot accuracy were likely impaired than control task after a mental fatiguing protocol. Decision-making performance of negative passes, passes accuracy, and dribbling accuracy resulted also likely decreased compared with control task. These findings demonstrated that mental fatigue impacted on technical, GPS-derived, and soccer-specific decision-making performance during SSG. In conclusion, avoiding cognitively demanding tasks before playing soccer-specific activities may be advisable to preserve players' physical activity, technical, and decision-making skills.

Assessing the Reliability and Validity of Agility Testing in Team Sports: A Systematic Review

Yepes, MM, Feliu, GM, Bishop, C, and Gonzalo-Skok, O. Assessing the reliability and validity of agility testing in team sports: A systematic review. J Strength Cond Res XX(X): 000-000, 2020-The aims of this systematic review were to (a) examine the reliability of the reactive agility tests and (b) analyze the discriminatory validity of the agility tests. A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We explored PubMed, SPORTDiscus, and Cochrane Plus databases looking for articles about agility in team sports. After filtering for article relevance, only 42 studies met the inclusion criteria; 37 of which assessed the reliability of agility tests and 22 assessing their validity. Reliability showed a high intraclass correlation coefficient (ICC) in almost all studies (range 0.79-0.99) with the exception of 2 studies. In addition, other studies also assessed the reliability of decision time (ICC = 0.95), movement time (ICC = 0.92), and decision accuracy (ICC = 0.74-0.93), all of which exhibited acceptable reliability. Furthermore, these data show high discriminatory validity, with higher performance level players being faster than lower performance level players (mean = 6.4%, range = 2.1-25.3%), with a faster decision time (mean = 23.2%, range = 10.2-48.0%) with the exception of 1 study, and better decision accuracy (mean = 9.3%, range = 2.5-21.0%). Thus, it can be concluded that reactive agility tests show good reliability and discriminatory validity. However, most agility tests occur in simple contexts whereby only 2 possible responses are possible. Therefore, future research should consider creating more specific and complex environments that challenge the cognitive process of high-level athletes.

Short-Term Compound Training on Physical Performance in Young Soccer Players

This study aimed to investigate the effects of a five-week compound training (with strength and plyometric exercises performed on separate days) on sprint, change of direction, and vertical jump in young soccer players. Eighteen novices in strength and plyometric training were assigned to either a compound training (CMPT) or a control condition (CNT). Both groups trained three times per week. One session was dedicated to soccer-specific drills. The other two weekly sessions were dedicated to circuit-based training routines employing on one-day strength exercises and on the other day plyometric exercises in the CMPT group. At the same time, the CNT group performed two weekly soccer-specific training sessions. All players were tested by 15-m sprint, change-of-direction and acceleration test (CODAT), squat jump, and countermovement jump with arms swing tests. CMPT group improved CODAT, squat jump and countermovement jump to a higher extent compared to CNT group (large vs small or trivial effects, p < 0.05), while both groups had similar 15-m sprint performance (p > 0.05). These results support the use of compound training to improve change of direction and vertical jump performances in young novice soccer players, which are unfamiliar with structured and advanced strength and plyometric training.

Acute kinematics and kinetics changes to wearable resistance during change of direction among soccer players

This study determined the acute changes in kinematics and kinetics when an additional load equivalent to 5% body mass was attached to the torso during change of direction (COD). In this within-subject repeated measures study, 14 male soccer players (age: 18.29 ± 0.32 years) volunteered to participate. Subjects performed COD under two conditions in randomized order: (1) no WR, and (2) with WR. No significant differences between the loaded and unloaded conditions in actual COD angle, approach speed, braking time, propulsive time, contact time, COD completion time (all p > 0.05, ES = 0.05-0.11), and all measured kinematic parameters (all p > 0.05, ES = 0-0.18). Nonetheless, ankle plantar/dorsi flexion ROM had possibly small increase in the loaded condition (ES = 0.24). Kinetics analysis has shown that the loaded condition was likely to have small increase in relative peak vertical propulsive ground reaction force (GRF, p = 0.11, ES = 0.41), and possible small increases in relative peak braking GRF (vertical: p = 0.21, ES = 0.42; total: p = 0.22, ES = 0.38), relative peak total propulsive GRF (p = 0.24, ES = 0.26), and relative braking impulse (horizontal, vertical, and total; p = 0.27-0.41, ES = 0.26-0.28). WR did not significantly change the acute movement techniques, meanwhile induced small increases in important kinetic stimuli for potential adaptation in COD.

The Importance of Reactive Agility Tests in Differentiating Adolescent Soccer Players

The ability to differentiate the elite from nonelite athletes is not clearly defined. We investigated level differences in speed, change of direction speed (CODS), and reactive agility in a group of trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14-19 years) were recruited. The players were grouped based on the level of play to elite, sub-elite, and amateur players. Players were tested for 5-, 10- and 20-m sprints, CODS, and reactive agility tests (RAT). Elite players had faster reaction movement time during RAT with live opponent stimuli (p ≤ 0.01) compared to sub-elite and amateur players. Moreover, elite players showed a faster time during light stimuli (p ≤ 0.01) but only compared to amateur players. The times for 5-m and 10-m sprint groups did not differ (p > 0.05). The results demonstrated that the skilled players (elite and sub-elite) performed better in reactive agility tests, speed, and COD speed compared to amateur players. Additionally, we can conclude that total and reaction time in the agility test with live opponent stimuli can be a significant factor that differentiates between adolescent soccer players considering their level.

Activity profile in elite Polish soccer players

The aim of the present study was to determine and characterize the activity of male Polish Premier League soccer players during elite-level matches, depending on playing position, activity intensity range, and match period. The study sample comprised 1178 players. Amisco Pro® was used to track the match activity players. Statistical analysis of the total distance covered by players revealed that the greatest distance was covered by central midfielders (11894 ± 765 m) and external midfielders (11751 ± 686 m). In terms of velocity, the greatest distance was covered by players in the V1 range (0 ≤ V1 < 11 km · h^-1, standing, walking), (7028 ± 294 m). The difference between the match periods was statistically non-significant, amounting to only 0.5%. As such they could prove useful for present and future comparisons between positions and represent the scientific basis for developing position-specific conditioning/training regimes for both clubs and individuals.

Field-based physical performance of elite and sub-elite middle-adolescent soccer players

The aim of the current study was to evaluate field-based physical performance of under 16 years (U16) elite and sub-elite soccer players. Forty elite (n = 20) and sub-elite (n = 20) soccer players were enrolled and tested for countermovement jump (CMJ), 10-m sprint and agility, in terms of sprint with 90° turns (S90), S90 with ball, Slalom, Slalom with ball, and reactive agility (RAT). Statistical and practical significant differences were observed in CMJ, S90 and RAT between elite and sub-elite. Elite players exhibited a likely better performance in Slalom, Slalom with ball and S90 with ball despite a non-significant difference by level of play. Concerning sprint ability, both groups showed similar performance in the 10-m sprint. Countermovement jump and agility tests are field-based physical assessments recommended to better distinguish between U16 elite and sub-elite soccer players.

Exercise training in overweight and obese children: Recreational football and high-intensity interval training provide similar benefits to physical fitness

This study compared the effects of recreational football and high-intensity interval training (HIIT) on body composition, muscular fitness, and cardiorespiratory fitness in overweight and obese children. Forty-two overweight/obese males aged 11-13 years [body mass index (BMI) >20.5 kg/m² ] were randomly assigned to a recreational football training group (n = 14; 157.9 ± 5.8 cm; 63.7 ± 12.6 kg), HIIT group (n = 14; 163.8 ± 9.4 cm; 71.5 ± 10.5 kg), or nontraining control group (n = 14; 162.7 ± 9.3 cm; 67.4 ± 16.1 kg). Physical fitness components were measured at baseline and after 12 weeks of training at the same time of the day and under similar conditions, including body composition, muscular fitness (lower-body power, change-of-direction speed, and flexibility), and cardiovascular fitness (Yo-Yo Intermittent Endurance test distance, resting heart rate, and blood pressure). Lean body mass (4.3%, ES = 0.40; 95% CI: -0.48, 1.29; P = .382) and muscle mass 4.4% (ES = 0.40; 95% CI: -0.48, 1.29; P = .378) very likely increased in the recreational football group, while possible improvements were observed in the HIIT group (lean body mass: 2.5%, ES = 0.22; 95% CI: -0.62, 1.06; P = .607, muscle mass: 2.8%, ES = 0.23; 95% CI: -0.61, 1.07; P = .594). Only trivial increases were observed in the control group for lean body mass (0.5%, ES = 0.05; 95% CI: -0.70, 0.79; P = .906) and muscle mass (1.1%, ES = 0.09; 95% CI: -0.65, 0.83; P = .814). Significant differences were found between the recreational football and control groups in post-training body mass (P = .034) and body mass index (P = .017). Body fat very likely decreased in the recreational football group (-7.7%, ES = -0.41; 95% CI: -1.29, 0.48; P = .376) and possibly decreased in the HIIT group (-5.2%, ES = -0.22; 95% CI: -1.05, 0.62; P = .607), with a trivial reduction in the control group (-1.1%, ES = -0.04; 95% CI: -0.78, 0.70; P = .914). Very likely increases in lower-body power were evident in the recreational football (17.0%, ES = 0.76; 95% CI: -0.15, 1.66; P = .107) and control groups (16.1%, ES = 0.55; 95% CI: -0.20, 1.31; P = .156), while small improvements were observed in the HIIT group (6.0%, ES = 0.24; 95% CI: -0.60, 1.08; P = .580, possible). Likely to most likely improvements in Yo-Yo Intermittent Endurance test performance and change-of-direction speed were noted in the recreational football group (Yo-Yo: 79.8%, ES = 1.09; 95% CI: 0.16, 2.03; P = .025, change-of-direction speed: -10.6%, ES = -1.05; 95% CI: -1.98, -0.12; P = .031) and the HIIT group (Yo-Yo: 81.2%, ES = 1.03; 95% CI: 0.15, 1.92; P = .025, change-of-direction speed: -5.4%, ES = -0.91; 95% CI: -1.79, -0.04; P = .045). Diastolic blood pressure likely decreased in the recreational football (-8.6%, ES = -0.74; 95% CI: -1.64, 0.17; P = .116) and HIIT groups (-9.8%, ES = -0.57; 95% CI: -1.40, 0.30; P = .195), with a possible increase in the control group (1.2%, ES = 0.21; 95% CI: -0.53, 0.96; P = .068). Recreational football and HIIT elicited improvements in all muscular and cardiorespiratory fitness measures. In contrast, the control group, which performed only physical education classes, increased body mass, BMI, and fat mass. Therefore, additional activities such as recreational football or HIIT might counter the prevalence of overweight and obesity in children.

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.

The dribbling agility test as a potential tool for evaluating the dribbling skill in young soccer players

The present study examined the construct validity and reliability of a new dribbling agility test (DAT) that incorporates reactive agility and multiple change of direction. To check its' validity, (a) DAT was performed by four groups (under 10, under 12, under 14 and under 16 yrs) of young soccer players (n = 125 in each group) and (b) a regression analysis was conducted to define the best DAT predictors. The reliability of DAT was assessed with repeated measurements. This test can differentiate the dribbling skill between groups (p < 0.01). Furthermore, 68% of the observed variance in DAT was explained by zigzag dribbling test, Illinois agility test, reaction time and running speed. The test-retest reliability was high in all groups (ICC = 0.77 - 0.90, p < 0.01). It was concluded that DAT can be a potential tool to evaluate the dribbling performance in young soccer players.

Physical Performance Comparison between Under 15 Elite and Sub-Elite Soccer Players

The aim of this study was to compare the physical performance profile among young soccer players of different competitive levels. Two teams of elite (n = 22) and sub-elite (n = 22) soccer players at national (highly skilled) and regional (moderately skilled) level were recruited in the study. All participants were tested using a modified Illinois change of direction speed test, a T-drill with and without a ball, a countermovement jump, and a 10-m sprint. The analysis revealed significant differences in favor of elite players in sprint (d = 1.54, large) and vertical jump (d = 2.03, very large) outcomes, while no differences were observed in both modified Illinois change of direction speed (d = 0.16, trivial) and T-drill (d = 0.20, small) tests between the groups. The ability to change direction and speed with and without a ball was found not to be suitable enough to highlight the difference among youth players with moderate-to-high level of play. In conclusion, multi-testing approach based on task-related power should include vertical jump and sprint performance to delineate players of a higher level.

Influence of well-being variables and recovery state in physical enjoyment of professional soccer players during small-sided games

This study aimed to assess the effects of the total quality of recovery and well-being indices (self-ratings of sleep during the preceding night, stress, fatigue and delayed onset muscle soreness) on rating of perceived exertion (RPE) and physical enjoyment (PE) during small-sided games. A total of 20 professional soccer players (25 ± 0.8 years) completed four 5-a-side game sessions of 25-min duration each (4 × 4 min work with 3-min passive recovery in-between). All variables were collected before each game session with the exception of RPE and Physical Activity Enjoyment Scale that were collected after. The results demonstrate that recovery state and pre-fatigue states were not contributing signals of affected internal intensity and enjoyment of players. The study established the objectivity and utility of RPE as a useful tool for determining internal intensity during soccer-specific training as well as PE for assessing emotional response during exercise or training session.

Pubertal development of body size and soccer-specific functional capacities in adolescent players

Pubertal growth in body size and functional capacities were examined in adolescent soccer players (n = 33). The average age at baseline was 10.9 (9.8-11.8 years). Peak height velocity (PHV) and growth curves for body mass and functional performance (countermovement jump, 15-m sprint, agility and Yo-Yo intermittent recovery test - level 1) were determined with Bayesian multilevel models. Estimates for PHV and age at PHV were 8.1 cm/year (95% credible interval: 4.2-18.5 cm/year) and 12.9 years (95% credible interval: 11.8-15.5 years), respectively. Peak body mass velocity occurred 0.48 year after PHV. Jump performance maximum velocity occurred about 2 years after PHV and peak sprint performance maximum velocity was coincident with PHV. Agility and intermittent endurance run performance showed a quadratic trend of improvement of performance, starting to level off at about 3-4 years after PHV. The modelling procedures were efficient to determine pubertal growth curves aligned for chronological age and age at PHV, considering individual differences in maturation when interpreting the development of performance in youth soccer.