The influence of maturity on recovery and perceived exertion, and its relationship with illnesses and non-contact injuries in young soccer players

A high training load could increase the risk of injury in soccer players. However, there is still a lack of knowledge regarding the effect on young athletes, in whom a different maturity status could lead to different physiological responses to training. Therefore, the aim of this study was to investigate the association of internal load markers and recovery status with risk of illnesses and non-contact injuries in young soccer players characterised by different maturity status. Twenty-three U14 soccer players were monitored during a full season and categorised according to years from peak height velocity (PHV). Based on the estimated values, athletes were divided into three different groups: Pre-PHV, Circa-PHV and Post-PHV players. The following internal load markers were monitored: rating of perceived exertion (RPE), session rating of perceived exertion (S-RPE), weekly load (WL), cumulative loads for 2, 3, and 4 weeks (WL2, WL3, WL4), acute to chronic workload ratio for 2, 3 and 4 weeks (A:C2, A:C3, A:C4) and week-to-week percentage variation (%WL). Recovery status was quantified using the total quality recovery (TQR) scale. Z-score transformation was adopted for TQR and RPE values and the difference between the parameters was calculated (Z-TQR-RPE). The Kruskal-Wallis test was adopted to evaluate differences in TQR and RPE with respect to maturity offset. A multinomial regression analysis was performed to evaluate the association between internal load markers and risk of illness and non-contact injuries. The variables that showed a significant association were included in the receiver operating characteristic (ROC) curve analysis. The results revealed that RPE was significantly higher (p < 0.01) and TQR significantly lower (p < 0.05) in Post-PHV compared to Pre- and Circa-PHV. Moreover, RPE, A:C4, TQR and Z-TQR-RPE showed a significant (p < 0.01) association with non-contact injuries. The internal load markers included in ROC curve analysis showed poor predictive ability (AUC ≤ 0.6). A rapid increase in training load together with a decrease in recovery status may produce higher susceptibility to illnesses and non-contact injuries. The contrasting physiological responses found in relation to maturity status could explain the different injury predisposition in young soccer players

Assessment of the Offensive Play in Elite Water Polo Using the Team Sport Assessment Procedure (TSAP) over an Entire Competitive Season

In water polo, the team’s technical and tactical performance is determined by the sum of the players’ activities. This study aimed to investigate the playing offensive performance of an Italian First League team performed during all matches (n = 19) of the 2021/22 championship using the Team Sport Assessment Procedure (TSAP). For all subjects (n = 15), gaining possession of the ball (received balls (RB) and conquered balls (CB)) and disposing of the ball (neutral balls (NB); lost balls (LB); offensive ball (OB) and successful Shots (SS)) parameters, as well as volume of play (VP), efficiency index (EI) and performance score (PS) indexes, were analyzed in relation to the playing positions, season phase, match location and final score difference. Multiple linear regression showed a significant association between the playing position and VP and PS. Perimetral players showed the highest VP (65%) and PS (66%) values, and center defenders showed the highest values of CB (30%), while center forwards gained the highest amount of exclusion when handling the ball (48%). Although they were not significant, the other contextual factors showed that season phase and match location could affect the TSAP indexes. For water polo coaches, the TSAP represents an effective tool to assess how players interpret the match

A Video-Based Tactical Task Does Not Elicit Mental Fatigue and Does Not Impair Soccer Performance in a Subsequent Small-Sided Game

Mental fatigue can impair physical, technical, and tactical performance in sports. Since most previous research used general cognitive tasks to elicit mental fatigue, the aim of this study was to investigate whether a more sport-specific task could induce the effects of mental fatigue and impair the subsequent physical and technical performance in a soccer small-sided game. Ten soccer players performed two small-sided games on two different days in a crossover design. Before each small-sided game, they performed a video-based tactical task (30 min) and a control task (documentary watching, 30 min) in a randomized and counterbalanced order. Mental effort was measured through a visual analog scale after the tactical and control tasks. Subjective ratings of perceived exertion were assessed through the RPE questionnaire after the end of the SSG. Physical performance was assessed during the SSG through GPS technology. Results showed no differences (p &gt; 0.05) in physical performance between the two conditions. None of the technical variables were negatively affected by the video-based tactical condition, with the number of total passes (p = 0.003; ES = 0.72 medium) and successful passes (p = 0.003; ES = 0.82 large) results even improved by the video-based tactical task. The mental effort required by the video-tactical task was significantly higher than the control task (p = 0.002; ES = 2.09 huge). However, overall RPE did not differ between conditions. The video-based tactical task did not elicit mental fatigue and did not impair subsequent physical and technical performance. The higher ecological validity of the task and the higher motivation of the participants might have contributed to the results

Injury incidence and risk factors in youth soccer players: a systematic literature review. Part II: Intrinsic and extrinsic risk factors

Injury is defined as a complex phenomenon determined by the non-linear interaction of several intrinsic and extrinsic factors. The objective of the present study was to perform a systematic literature review on the injury risk factors in young soccer players. After electronic database searching, articles in line with the inclusion criteria were selected for the systematic review. Injury risk factor data were extracted and grouped in intrinsic and extrinsic risk factors. The main findings of the current review are as follows: (1) alteration in neuromuscular control such as limb asymmetry and dynamic knee valgus are important intrinsic risk factors; (2) maturation status may impair neuromuscular control and increase the risk of injury; (3) fatigue and poor recovery contribute to the onset of overuse injuries; (4) the impact of anthropometric factors is still unclear; (5) previous injuries increase the risk of re-injuries; (6) highly skilled players are more exposed to risk of injuries; (7) high external workloads increase the risk of injuries; (8) playing position, as well as sport specialization, exposes young soccer players to greater injury risk. Many factors (e.g., neuromuscular control, training load, maturity status) can modify the susceptibility to injury in young soccer players. Being aware of the complex interaction between these factors is essential to identify players at higher risk of injury, develop adequate prevention strategies, and from a scientific point of view move from a reductionist to a complex system approach

Predictive Analytic Techniques to Identify Hidden Relationships between Training Load, Fatigue and Muscle Strains in Young Soccer Players

This study aimed to analyze different predictive analytic techniques to forecast the risk of muscle strain injuries (MSI) in youth soccer based on training load data. Twenty-two young soccer players (age: 13.5 ± 0.3 years) were recruited, and an injury surveillance system was applied to record all MSI during the season. Anthropometric data, predicted age at peak height velocity, and skeletal age were collected. The session-RPE method was daily employed to quantify internal training/match load, and monotony, strain, and cumulative load over the weeks were calculated. A countermovement jump (CMJ) test was submitted before and after each training/match to quantify players' neuromuscular fatigue. All these data were used to predict the risk of MSI through different data mining models: Logistic Regression (LR), Random Forest (RF), Support Vector Machine (SVM). Among them, SVM showed the best predictive ability (area under the curve = 0.84 ± 0.05). Then, Decision tree (DT) algorithm was employed to understand the interactions identified by the SVM model. The rules extracted by DT revealed how the risk of injury could change according to players' maturity status, neuromuscular fatigue, anthropometric factors, higher workloads, and low recovery status. This approach allowed to identify MSI and the underlying risk factors

Injury incidence and risk factors in youth soccer players: a systematic literature review. Part I: epidemiological analysis

The analysis of the epidemiological data and the risk factors underlying injuries is crucial to promote prevention strategies in young soccer players. The objective of the present study was to perform a systematic literature review on the epidemiological data, described in the first part, and injury risk factors, presented in the second part. After electronic database searching, articles in line with the inclusion criteria were selected for the systematic review. Epidemiological data were extracted and discussed in this first part of the review. Data were grouped as follows: injury incidence, injury severity, and re-injury, injury types, injury mechanisms, and anatomical location. The principal findings of this first part of the review are as follows: (1) injury incidence is higher in older players and during matches than during training; (2) sex and maturity status may increase risk of injury; (3) male soccer players are more prone to muscle strains and ligament sprains while female players suffer more ligament sprains; (4) most injuries are located in the ankle and thigh in young male soccer players, and in the ankle and knee in female players; (5) severe injuries are less frequent but the incidence increases in older players. Re-injuries represent only a small percentage. Although soccer is considered a safe sport, many injuries are recorded in young soccer players every year. Injury predisposition changes in relation to age, sex, and biological age. Coaches and physical trainers should be aware of individual differences in order to promote prevention strategies and personalised training

The influence of maturity on recovery and perceived exertion, and its relationship with illnesses and non-contact injuries in young soccer players

A high training load could increase the risk of injury in soccer players. However, there is still a lack of knowledge regarding the effect on young athletes, in whom a different maturity status could lead to different physiological responses to training. Therefore, the aim of this study was to investigate the association of internal load markers and recovery status with risk of illnesses and non-contact injuries in young soccer players characterised by different maturity status. Twenty-three U14 soccer players were monitored during a full season and categorised according to years from peak height velocity (PHV). Based on the estimated values, athletes were divided into three different groups: Pre-PHV, Circa-PHV and Post-PHV players. The following internal load markers were monitored: rating of perceived exertion (RPE), session rating of perceived exertion (S-RPE), weekly load (WL), cumulative loads for 2, 3, and 4 weeks (WL2, WL3, WL4), acute to chronic workload ratio for 2, 3 and 4 weeks (A:C2, A:C3, A:C4) and week-to-week percentage variation (%WL). Recovery status was quantified using the total quality recovery (TQR) scale. Z-score transformation was adopted for TQR and RPE values and the difference between the parameters was calculated (Z-TQR-RPE). The Kruskal-Wallis test was adopted to evaluate differences in TQR and RPE with respect to maturity offset. A multinomial regression analysis was performed to evaluate the association between internal load markers and risk of illness and non-contact injuries. The variables that showed a significant association were included in the receiver operating characteristic (ROC) curve analysis. The results revealed that RPE was significantly higher (p < 0.01) and TQR significantly lower (p < 0.05) in Post-PHV compared to Pre- and Circa-PHV. Moreover, RPE, A:C4, TQR and Z-TQR-RPE showed a significant (p < 0.01) association with non-contact injuries. The internal load markers included in ROC curve analysis showed poor predictive ability (AUC ≤ 0.6). A rapid increase in training load together with a decrease in recovery status may produce higher susceptibility to illnesses and non-contact injuries. The contrasting physiological responses found in relation to maturity status could explain the different injury predisposition in young soccer players

A new approach to comparing the demands of small-sided games and soccer matches

To improve soccer performance, coaches should be able to replicate the match’s physical efforts during the training sessions. For this goal, small-sided games (SSGs) are widely used. The main purpose of the current study was to develop similarity and overload scores to quantify the degree of similarity and the extent to which the SSG was able to replicate match intensity. GPSs were employed to collect external load and were grouped in three vectors (kinematic, metabolic, and mechanical). Euclidean distance was used to calculate the distance between training and match vectors, which was subsequently converted into a similarity score. The average of the pairwise difference between vectors was used to develop the overload scores. Three similarity (Sim kin , Sim met , Sim mec ) and three overload scores (OVER kin , OVER met , OVER mec ) were defined for kinematic, metabolic, and mechanical vectors. Sim met and OVER met were excluded from further analysis, showing a very large correlation ( r > 0.7, p < 0.01) with Sim kin and OVER kin . The scores were subsequently analysed considering teams’ level (First team vs. U19 team) and SSGs’ characteristics in the various playing roles. The independentsample t -test showed ( p < 0.01) that the First team presented greater Sim kin ( d = 0.91), OVER kin ( d = 0.47), and OVER mec ( d = 0.35) scores. Moreover, a generalized linear mixed model (GLMM) was employed to evaluate differences according to SSG characteristics. The results suggest that a specific SSG format could lead to different similarity and overload scores according to the playing position. This process could simplify data interpretation and categorize SSGs based on their scores

Effects of Playing Position and Contextual Factors on Internal Match Loads, Post-Match Recovery and Well-Being Responses of Elite Male Water Polo Players

This study aimed to investigate the effects of playing position and contextual factors (match outcome, final score difference, match location, travel duration, number of scored and conceded goals) on the internal match load, players&rsquo; perceived recovery and players&rsquo; well-being. The session-RPE (s-RPE), Perceived Recovery Scale (PRS) and Hooper Index (HI) of 17 male elite water polo players were monitored during all matches (regular season and play-out) of the 2021/22 Italian Serie A1 championship. Three separate, mixed linear models for repeated measures showed significant main effects: drawn compared to won matches led to higher s-RPE values (mean &plusmn; SE = 277 &plusmn; 17.6 vs. 237.3 &plusmn; 20.6), while longer travel duration (estimate = &minus;0.148) and goals scored (estimate = &minus;3.598) led to lower s-RPE values; balanced compared to unbalanced matches led to higher PRS values (mean &plusmn; SE = 6.8 &plusmn; 0.3 vs. 5.1 &plusmn; 0.4), while playing time (estimate = &minus;0.041) and goals scored (estimate = &minus;0.180) led to lower PRS values; higher scores of the HI were registered for regular season compared to the play-out (mean &plusmn; SE = 15.6 &plusmn; 0.9 vs. 13.5 &plusmn; 0.8). This study marks the importance of ecological and non-invasive monitoring tools to assess internal match load, recovery and the well-being of elite water polo players