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Purpose: The monitoring of training loads and quantification of physical performance are common practices in youth soccer academies to support coaches in prescribing and programming training for individuals. The interaction between training load and physical performance is unknown during a preseason period in youth soccer players. The current study assessed changes in training load and physical assessments across a 4-week preseason period. The relationship between physical performance and match playing time in youth male soccer players was also investigated. Methods: The training loads of 25 professional youth academy male soccer players were monitored throughout a 4-week preseason period. Assessments of power, agility, speed, and aerobic capacity were undertaken in the first training session. Session ratings of perceived exertion (sRPE) and well-being questionnaires were collected during all training sessions and preseason matches. Playing time during subsequent competitive matches was recorded. Results: T test and 30-m-sprint assessments, conducted on the first day of preseason, were predictors of sRPE throughout preseason (t test χ2/df = 2.895, poor adjustment; 30-m sprint χ2/df = 1.608, good adjustment). YoYo Test performance was related with changes in perceived fatigue (χ2/df = 0.534, very good adjustment). Faster players reported higher values of sRPE, and players with higher aerobic capacity reported higher levels of fatigue across preseason. Well-being, perceived fatigue and soreness, and sRPE decreased across preseason. Greater match durations were related to higher levels of fatigue during preseason (P <.05). Conclusion: The current study highlights the relationship between training load, physical assessments, and playing time. Coaches and practitioners can use physical test data at the start of preseason as an indication of players that report higher sRPE, perceived fatigue, and reduced well-being across preseason, supporting decisions around individualized training prescriptions. [ABSTRACT FROM AUTHOR]

Background: The backbone of the eukaryotic tree of life contains taxa only found in molecular surveys, of which we still have a limited understanding. Such is the case of Picozoa, an enigmatic lineage of heterotrophic picoeukaryotes within the supergroup Archaeplastida, which has emerged as a significant component of marine microbial planktonic communities. To enhance our understanding of the diversity, distribution, and ecology of Picozoa, we conduct a comprehensive assessment at different levels, from assemblages to taxa, employing phylogenetic analysis, species distribution modeling, and ecological niche characterization. Results: Picozoa was among the ten most abundant eukaryotic groups, found almost exclusively in marine environments. The phylum was represented by 179 Picozoa's OTU (pOTUs) placed in five phylogenetic clades. Picozoa community structure had a clear latitudinal pattern, with polar assemblages tending to cluster separately from non-polar ones. Based on the abundance and occupancy pattern, the pOTUs were classified into four categories: Low-abundant, Widespread, Polar, and Non-polar. We calculated the ecological niche of each of these categories. Notably, pOTUs sharing similar ecological niches were not closely related species, indicating a phylogenetic overdispersion in Picozoa communities. This could be attributed to competitive exclusion and the strong influence of the seasonal amplitude of variations in environmental factors, such as temperature, shaping physiological and ecological traits. Conclusions: Overall, this work advances our understanding of uncharted protists' evolutionary dynamics and ecological strategies. Our results highlight the importance of understanding the species-level ecology of marine heteroflagellates like Picozoa. The observed phylogenetic overdispersion challenges the concept of phylogenetic niche conservatism in protist communities, suggesting that closely related species do not necessarily share similar ecological niches. 9DjsWS8J_yUMTxizMfQ8ty Video Abstract [ABSTRACT FROM AUTHOR]

The objective was to assess and compare the tactical conduct of players aged U-8, U-10, and U-12 during full- and small-sided games, focusing on tactical modeling and interaction dynamics. Each age group comprised three teams (n = 180; 60 per category; 20 per team), engaging in a tournament where teams faced each other once in both formats − 18 matches; 3 per category in each format. Full-sided games (GK + 10 vs.10 + GK; 100 × 68 m) and small-sided games (U-8: GK + 4 vs. 4 + GK (36 × 20 m); U-10: GK + 7 vs. 7 + GK (52.5 × 34 m); U-12: GK + 10 vs. 10 + GK (68 × 45 m). Standard playing times (3 periods of 12 minutes (U-8s); 3 periods of 15 minutes (U-10s); and 3 periods of 20 minutes (U-12s), with a 5-minute break. Variables were examined using descriptive analysis (mean, standard deviation, and confidence interval), with paired t-tests and Wilcoxon tests employed for inter-format comparisons. Despite players benefiting from more time and space in full-sided games (increased ball receptions and overall ball involvement), results from small-sided games indicate three key advantages: 1) More goals (U-8s: z = –3.44, p = .050) and shots on target (U-8: z = –3.25, p = .001; U-10: z = –2.72, p = .007); 2) Game space management—ball circulation in larger amplitude (U-10: t = –4.20, p = .001; U-12: t = –4.35, p < .001); and with more transitions (U-10: t = –3.60, p = .002; U-12: t = –4.16, p = .001) and 3) Fast decision-making—larger ball velocity circulation (U-08: t = –3.54, p = .003; U-10: t = –5.13, p < .001; U-12: t = –5.80, p < .001). [ABSTRACT FROM AUTHOR]

Speed and agility have been described as crucial abilities for soccer players. The purpose of this study was to analyze, in detail, the variance in speed and agility tasks explained by lower-body power after controlling for age and body composition. The participants were 96 male soccer players aged 16.1 ± 1.6 years. Body composition (stature, body fat percentage—BF%, body mass, and fat-free mass—FFM), lower-body power (countermovement jump—CMJ, and squat jump—SJ), speed (5-, 10-, and 35 m sprints), and agility (t-test) were assessed. Among body composition parameters, BF% presented the highest number of significant relationships with speed and agility, with the strength of correlations ranging from small (5 m sprint, r = 0.25) to large (35 m sprint, r = 0.52). The strongest correlation coefficient emerged between FFM and the 35 m sprint (r = −0.65). Significant correlations were found between vertical jump performance and the 35 m sprint (CMJ: r = −0.68; SJ: r = −0.69), followed by the t-test (CMJ: r = −0.35; SJ: r = −0.47). The hierarchical multiple regression model could explain 22% to 67% of the variance observed in agility scores and speed. BF% remained the most statistically significant negative predictor of all regression models. The CMJ remained a statistically significant positive predictor of the 35 m sprint (β = −0.581, p ≤ 0.01) after controlling for age and body composition. Integrating programs targeting lower-body power might be important to enhance speed and agility performance in youth soccer. On the other hand, future research based on multidisciplinary approaches to investigate the effects of nutritional strategies in reducing or preventing gains in BF% is still needed, which remained a significant predictor of sprint and agility performance in the final models. [ABSTRACT FROM AUTHOR]

Tensiomyography (TMG) has been described as an effective method for identifying differences in muscle response to athletic training stimuli. However, there is a lack of studies that evaluated changes in muscle contractile properties in response to anaerobic effort and related these changes to Wingate test parameters in more than one lower limb superficial muscle. The main contribution of this work is to evaluate changes in the contractile properties of muscles in response to anaerobic exercise. In a group of 20 physically active men, the body composition analysis was performed using a Tanita DC-360 device. The anaerobic effort was assessed by a Wingate test (30 s), and the contractile properties of muscles were measured using a TMG S2 device. The TMG parameters were measured in selected superficial muscles of the dominant lower limb. The study also calculated indices of the differences (d) and the size of the effect (r). An anaerobic effort in the form of the Wingate test resulted in greater stiffness (Dm) in the vastus lateralis muscle (p = 0.0365; r = 0.47) and a delayed response to stimulus (Td) in the vastus lateralis (p = 0.0239; r = 0.51) and vastus medialis (p = 0.0031; r = 0.66) muscles. The half relaxation time (Tr) (p = 0.0478; r = 0.44) and sustained contraction time (Ts) (p = 0.0276; r = 0.49) in the rectus femoris muscle were also increased. In contrast, a prolonged stimulus-response time (Td) with a decrease in sustained contraction time (Ts) was observed in the gastrocnemius lateralis (Td: p = 0.0054; r = 0.64 and Ts: p = 0.0012; r = 0.74) and gastrocnemius medialis (Td: p = 0.0229; r = 0.52 and Ts: p = 0.0054; r = 0.64) muscles. A significant decrease in contraction time (Tc) (p = 0.0051; r = 0.63) occurred only in the soleus muscle. In addition, significant correlations were shown between selected changes in contractile properties of muscle and parameters of the Wingate anaerobic test. Anaerobic exercise has a significant effect on changes in skeletal muscle contractility parameters. TMG is an effective method for identifying differences in muscle response to sports training stimuli. [ABSTRACT FROM AUTHOR]

Purpose. This study aims to explore disparities in locomotor metrics such as total distance (TD), high-speed running (HSR), accelerations (Acc), decelerations (Dec), and maximum speed (MS) across five soccer positions - centre defenders, fullbacks, midfielders, wingers, and forwards - during the 1-, 3-, and 5-minute match intensity periods (MIP). Additionally, it seeks to assess the difference in those locomotor metrics between the first and second halves of the match. Methods. An observational, retrospective cohort study was undertaken with a professional team covering 32 official matches. A total of 20 soccer players participated in this study. Data were collected using a 10-Hz GNSS unit (Apex pro series, StatSports, Northern Ireland). The MIP considered different time durations (1, 3, 5 min in the 1st and the 2nd halves). Results. Soccer players exhibited position-specific differences in locomotion, with Wingers covering the most distance and forwards showing the highest Acc and Dec. HSR was most notable in the fullbacks. The second half saw varied changes, with midfielders increasing in distance covered. ANCOVA revealed significant positional differences in TD during longer MIPs and between match halves. HSR varied across positions but only differed between halves in the 5-minute MIP. Acc and Dec displayed half-time differences, while maximal speed was consistently higher in the second half. Conclusions. This study highlights the impact of player position and matches progression on locomotor metrics in soccer, underscoring the need for customised training and strategic adaptability to maximise performance throughout the game. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to systematically investigate the physiological and physical fitness adaptations resulting from small-sided games (SSGs) training programs in basketball players competing at youth competitive levels, as compared to other training approaches and/or control groups. To achieve this, we conducted a literature search on PubMed, Scopus, SPORTDiscus, and Web of Science, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. From the initial 626 studies retrieved, five were considered eligible for the current study. Among the five included articles, four conducted comparisons between the effects of SSGs and running-based high-intensity interval training. Regarding this, the four studies revealed a significant improvement in the final velocity during the 30–15 Intermittent Fitness Test, ranging from 4.07% to 7.29% following SSG-based interventions. This improvement was not significantly different from the comparator group. Additionally, two studies indicated that the SSGs group showed a significant advantage in change-of-direction time, with improvements ranging from −2.11% to 6.69% after interventions, and these results were not significantly different from the comparator group. However, the effects on repeated sprint ability yielded contradictory findings; two studies reported significant improvements ranging from −5.00% to −2.16%, while two others did not show significant effects following SSGs-based interventions. Similarly, in the linear sprint, the results of SSGs-based interventions were inconsistent. In summary, based on the available research, it can be concluded that SSG-based training is effective in significantly enhancing aerobic performance and change of direction, comparable to alternative approaches. However, the effects on repeated sprint ability and sprint performance are not consistently demonstrated. [ABSTRACT FROM AUTHOR]

Football is known for its fast-paced and intensive activities from a professional standpoint, exposing professional football players to a high injury risk across their sportive careers. This study aimed to describe and characterise the sportive injuries of a First Portuguese Football League professional football team over three consecutive seasons. Seventy-one male professional football players (age = 25.7 ± 3.4 years; stature = 181.6 ± 6.5 cm; body mass = 77 ± 7.2 kg) participated in this study, comprising eight goalkeepers (11.3%), 20 defenders (28.2%), 17 midfielders (23.9%), and 26 forwards (36.6%). All players were followed throughout seasons 2019/2020, 2020/2021, and 2021/2022. Descriptive statistics were used to summarise the data collected. Absolute values present the number of football players and the total number of injuries. The demographic data of the participants are presented by mean and standard deviation. The frequency of the injuries by age, sectorial position, type, zone, specific location, laterality, mechanism, severity, recurrence, and occurrence are represented by absolute values and their percentages. In total, 84 injuries were recorded. Each player missed an average of 16.6 days per injury. Lower limbs were massively affected by injuries across all three seasons, mainly with muscular injuries in the quadriceps and hamstrings and sprains in the tibiotarsal structure. The injury incidence was considerably higher in official matches than in training sessions. The two moments of the season that proved most conducive to injuries were the months of July and January. Our results emphasise the importance of monitoring sports performance, including injury occurrence and assisting in identifying risk factors in professional football. Designing individualised training programs and optimising prevention and recovery protocols are crucial for maximising this global process. [ABSTRACT FROM AUTHOR]

In football, knee and hip muscle strength assessment have been recommended for injury prevention (Mosler et al., 2017; Namazi et al., 2019). Additionally, bilateral strength differences in the knee and hip joints have been related to an increased risk of injury. The aims of this study were threefold: (1) to compare knee and hip muscle strength performance between professional players competing at different levels; (2) to assess bilateral strength differences according to the preferred leg (PL) and the non-preferred leg (NPL); and (3) to compare knee and hip muscle strength performance in two-time moments of the season. This study considered 33 professional football players: 13 were in the elite group (EG) competing in the First Portuguese Football League, and 20 were in the sub-elite group (SEG) competing in the Fourth Portuguese Football League. Participants were assessed for body composition, isokinetic knee strength at 60º/s, and hip adduction strength at two-time moments (TM) separated by five months. Peak torque normalised by bodyweight (PT/BW) of knee extensors (KE) and knee flexors (KF) were used for analysis. The differences between groups in strength were analysed using the Mann-Whitney U test. The Wilcoxon Signed Rank Test was conducted to verify differences between the performance of the PL and NPL in each group and to compare the performance between TM1 and TM2. At TM1, the EG presented a significantly better performance in KF PT/BW and hip adduction strength for the PL and NPL (p ≤ 0.01). In TM2, the EG performed substantially better in KE PT/BW and KF PT/BW (p ≤ 0.01). In both groups, no substantial bilateral strength differences were observed in knee and hip adduction performance. From TM1 to TM2, significant increases were found in knee strength in both groups (p ≤ 0.01). Overall, the EG players outperformed their lowerdivision peers in strength assessments significantly. The results also indicate significant knee and hip muscle strength increases during the season (except for the EG in hip adduction strength), probably as a response to the exposure to training and competition. [ABSTRACT FROM AUTHOR]

Purpose: Monitoring players’ training load allows practitioners to enhance physical performance while reducing injury risk. The aim of this study was to identify the key external load indicators in professional U19 soccer. Methods: Twenty-four-professional Italian young (U19) soccer players were monitored by using the rating of perceived exertion (CR-10 RPE scale) and a wearable inertial sensor during the competitive season. Three main components were detected by a Principal Component Analysis (PCA): i) volume metabolic related component, ii) intensity mechanical stimuli component, and iii) intensity metabolic/mechanical component. We hence computed two scores (i.e. Performance [PERF] and total workload [WORK]) permitting to investigate the weekly microcycle. Results: Correlation analysis showed that scores (i.e. PERF and WORK) are low correlated (r = -0.20) suggesting that they were independent. Autocorrelation analysis showed that a weekly microcycle is detectable in all the scores. Two-way ANOVA RM showed a statistical difference between match day (MD) and playing position for the three PCA components and PERF score. Conclusion: We proposed an innovative approach to assess both the players’ physical performance and training load by using a machine learning approach allowing reducing a large dataset in an objective way. This approach may help practitioners to prescribe the training in the microcycle based on the two scores. [ABSTRACT FROM AUTHOR]

In soccer, knee and hip muscle strength assessments have been recommended for injury prevention. The aims of this study were threefold: (1) to compare knee and hip muscle strength between professional players competing at different levels; (2) to compare strength performance according to the preferred leg (PL) and the non-preferred leg (NPL); and (3) to compare knee and hip muscle strength performance at two moments of the season. This study included 33 professional soccer players: 13 were in the elite group (EG), and 20 were in the sub-elite group (SEG). Body composition, isokinetic knee strength at 60º/s, and hip adduction strength were assessed at two different moments (M1 and M2). Values of peak torque (PT), peak torque/bodyweight (PT/BW), and the hamstring-to-quadriceps strength ratio (H:Q) for knee extensors (KEs) and knee flexors (KFs) for both legs were used for analysis. The statistical analysis included the Mann-Whitney U and the Wilcoxon Signed Rank tests. At M1, the EG presented a significantly better performance in KF PT/BW and in the squeeze strength test for the PL and the NPL (p ≤ 0.01). At M2, the EG performed substantially better in KE PT/BW and KF PT/BW (p ≤ 0.01). No substantial strength differences were observed in knee and hip muscle performance between the PL and the NPL. From M1 to M2, significant increases were found in knee strength in both groups (p ≤ 0.01). Overall, the EG players outperformed significantly their lower-division peers in strength assessments. The results indicate significant knee and hip muscle strength increases during the season, probably as a response to the exposure to training and competition., Competing Interests: The authors declare no conflict of interest., (Copyright: © Academy of Physical Education in Katowice.)

A number of species of Chydorus Leach, 1816 (Crustacea: Cladocera) need improvements in their taxonomy much more than any other genus within the family Chydoridae Dybowsky & Grochowski, 1894 emend. Frey, 1967, which makes the systematics of the genus still a puzzle that lacks several pieces. Here, we redescribe the African species Chydorus tilhoi Rey & Saint-Jeans, 1969 and compare its morphology with that of Chydorus sphaericus (O.F. Mller, 1776). The two taxa might be easily differentiated because C. tilhoi has a single and relatively large major head pore with a wide rim, labral keel elongated with a large spine, and postabdomen with postanal part elongated, narrowing distally and with denticles near its anal margin, organized in groups. These morphological traits are absent in C. sphaericus. Chydorus tilhoi and C. sphaericus also differ in the morphology of the first (Inner Distal Lobe setae), third (exopodite proportion), and fifth (exopodite shape) limbs. Based on the literature and our observations, the limb morphology of C. tilhoi has important similarities with that of C. breviceps, C. nitidulus and C. dentifer, and their translocation to a new genus seems to be a fundamental piece in the puzzle of Chydorus.