This letter offers a constructive review of the article \'Influence of the time-task constraint on ocular metrics of semi-elite soccer\' by Luis-del Campo et al. (2023), focusing on methodological considerations and avenues for future research enhancement. The study investigates the impact of task constraints on eye-tracking metrics among semi-elite soccer players, aiming to gauge mental workload during training sessions. While the study presents valuable insights, there are opportunities for methodological refinement. Suggestions include emphasizing sample size determination, randomization of the experimental conditions, and employing robust statistical analyses to mitigate potential biases. Moreover, future studies could benefit from integrating external load measures alongside heart rate monitoring to comprehensively assess training task variations. Despite these considerations, the study underscores the promising application of eye-tracking techniques in evaluating mental workload during soccer training, paving the way for further exploration and refinement of methodologies to enhance player performance assessment and training optimization in the field.

Objectives: The relationship between task constraints and player behaviors is of interest to coaches tasked with designing practice to optimize learning. This study aims to compare the skill involvements and cooperative team behavior of teams of youth soccer players engaged in a goal exaggeration and/or a prescriptive coach instruction condition compared to a free-play control condition. Methods: Twenty male soccer players aged 12-15 participated in small-sided games under four conditions: free-play, goal exaggeration, prescriptive coach instruction, and combination over four weeks. Using video footage, teams\' collective skill involvements (shot, pass, dribble) and passing network characteristics (closeness, density, and betweenness) were measured for each game. Results: A Friedmans rank test identified that playing conditions resulted in significant differences in attempted dribbles (p < .001), goals scored (p < .001), network density (p = .001), closeness (p < .001) and betweenness (p = .002). Teams attempted to dribble the most in the free-play and goal-exaggeration conditions, and the most goals were scored in the goal-exaggeration and combination conditions. Additionally, teams exhibited more well-connected passing networks (i.e. higher density, higher closeness, and lower betweenness values) in the combination condition and higher network density in the explicit instruction condition. Conclusions: The results of this study indicate that coach instruction may be more associated with cooperative team behavior, whereas free-play or manipulating task constraints in the absence of instruction may be associated with players attempting more individual actions.

UNASSIGNED: The aim of this study was to analyze the effects of space and number of players manipulation on the external and internal load demands of youth futsal athletes.
UNASSIGNED: Forty-two male U17 players (age = 15.62 ± 0.58 years) from three futsal teams participated in the study. In this cross-sectional study that lasted 8-week, the player\'s sample practiced six futsal tasks (T1-T6) and a futsal game played under the official rules (T7). From T1-T6, two task constraints were manipulated: (i) the number of players and, (ii) the space of play. The WIMU PRO™ Ultra-Wideband (UWB) tracking system was used to measure the external and internal load during the futsal tasks. External load was quantified using kinematic and mechanical variables extracted from positional data and, the internal load was quantified using Heart rate (HR) and rating of perceived exertion (RPE). Repeated measures ANOVA was used for comparison purposes.
UNASSIGNED: In general, the results showed high external (total distance, distance 18.1-21, above 21 Km/h, and high intensity acceleration and deceleration, p < 0.001) and internal load (heart rate average and rating of perceived exertion, p < 0.001) in the tasks with low number of players and high area. In relation to the match, the tasks with small relative area per player (GK + 2 vs. 2 + GK and GK + 3 vs. 3 + GK in 20 × 20 m) promoted low external load.
UNASSIGNED: It was concluded that increasing the relative area by reducing the number of players involved in the tasks in the form of small-sided games (GK + 2 vs. 2 + GK and GK + 3 vs. 3 + GK), in relation to the futsal game (GK + 4 vs. 4 + GK), can be considered a pedagogical strategy to increase the external and internal load demands of young futsal players.

Aerobic capacity plays a crucial role in football performance, making it a focal point in training processes. Small-sided games (SSGs) are widely used in football training, but the relationship between aerobic capacity and running performance during SSGs remains unclear. The aim of this study was to investigate possible correlations between maximum oxygen uptake (VO2max) and running performance in youth football players in SSGs (4:4, 3:3, 2:2, 1:1) with three different pitch sizes per player (150, 100, 75 m2/player). Sixteen male U15 football players participated in the study. Players underwent the Yo-Yo intermittent recovery test level 1, and their VO2max was estimated based on their performance. Subsequently, players participated in SSGs wearing GPS devices to measure internal and external load. Pearson or Spearman correlation was applied for statistical analysis depending on the normal distribution of the data. The results reveal that, for 4:4 and 3:3 relationships, larger pitches led to a greater impact of aerobic capacity (total distance (TD): 4:4, 150 m2/pl, r = 0.715, p = 0.002; 100 m2/pl, r = 0.656, p = 0.006; 75 m2/pl, r = 0.586, p = 0.017). In the 2:2 relationship, the opposite was observed, with more correlations appearing on smaller pitches (TD: 2:2, 100 m2/pl, r = 0.581, p = 0.018; 75 m2/pl, r = 0.747, p < 0.001). In the 1:1 relationship, correlations with VO2max, total distance, and speed were observed only on the larger pitch. In conclusion, the aerobic capacity of young football players can influence running performance indicators in SSGs. Therefore, aerobic capacity could serve as a criterion for team composition, making SSGs more competitive. Additionally, the variation in correlations in the 2:2 relationship and their limited presence in the 1:1 relationship may be attributed to technical-tactical factors, such as increased ball contacts and one-on-one situations typically occurring in smaller setups.

OBJECTIVE: The aim of this study was 2-fold: (1) to examine the relationships between psychophysiological responses and locomotor demands with variations in technical performance during 2v2 and 4v4 conditioned games and (2) to compare psychophysiological and locomotor responses among players exhibiting higher and lower technical performance levels during the conditioned games.
METHODS: Twenty-four male youth soccer players (16.3 ± 0.8 y old) participating at the trained/developmental level underwent monitoring for psychophysiological responses (including heart rate, rating of perceived exertion, and visual analog scale), locomotor demands (such as distance covered), and technical performance variables (including successful and unsuccessful passes and shots, as well as lost balls) across 2v2 and 4v4 formats. These formats were applied 4 times within a single session and were replicated twice over 2 weeks.
RESULTS: Large correlations between the number of lost balls per minute and mean heart rate were found in both the 2v2 and 4v4 games (r = .586 and r = .665, respectively). Successful shots were inversely and largely correlated with mean heart rate (r = -.518) in 4v4 games. The number of interceptions per minute was inversely and significantly correlated with the visual analog scale in 2v2 and 4v4 games (r = -.455 and r = -.710, respectively). The frequency of lost balls was significantly higher among players who attained a higher mean heart rate (2v2: +42.9%, P = .031, d = -0.965; 4v4: +57.1%, P < .001, d = -2.072).
CONCLUSIONS: Coaches should be aware that highly psychophysiologically demanding scenarios may significantly impair technical performance. Therefore, prioritizing technical performance by deliberately adjusting the intensity should be considered.

暂无摘要。

This study aimed to explore the perceptual-cognitive characteristics of coaches as they assessed team performance in youth soccer. The primary focus was to investigate the alignment between coaches\' subjective analyses of team behaviour and objective analyses, while also examining the relationship between coaches\' gaze behaviour and their levels of coaching experience, particularly considering the potential differences that may exist among coaches with varying levels of experience. Sixty-five male and female adults with various soccer coaching experience (experienced, novice, other team sport experience, and non-team sport experience) watched five 4-minute videos and assessed team behaviour. These subjective evaluations were compared to objective data obtained from video analysis and GPS, which included measures of completed skills, spatiotemporal characteristics, and passing networks. The participants\' fixation duration and frequency were measured for each video clip, and the area around the ball specifically. The study found no significant differences between groups regarding the number of times participants\' subjective analysis aligned with the objective data (p = 0.059, ɳ2 = 0.07). However, coaches with soccer coaching experience demonstrated a higher fixation frequency and more revisits to the ball area when compared to participants without soccer experience (p = <.001, ɳ2 = 0.09). The current study offers a unique approach to uncovering soccer coaching expertise by combining objective and subjective evaluations of team performance. In summary, the study reveals that coaching experience did not impact how often coaches subjective analyses matched objective data. However, soccer coaches had distinctive gaze behaviour patterns where they revisited the area around the ball more often.
Coaches’ perceptions of collective behaviour in soccer teams do not align with objective data, regardless of their level of coaching experience.Gaze behaviour differs between coaches with varying expertise levels.Both experienced and novice coaches visually revisit the area around the ball more often than non-coaches when assessing team performance.Quantitative data may provide an additional level of team analysis than subjective coach assessment alone.

Recreational small-sided games (SSGs) have demonstrated positive effects on body composition and physical fitness, while minimizing adverse outcomes. In this randomized controlled study, we aimed to investigate the impact of incorporating an additional 16-week intervention program involving recreational soccer SSGs on parameters related to body composition and physical fitness in sedentary young adult males and females. Sixty sedentary participants, with a mean age of 20.2 years, were randomly assigned to either the small-sided games group (SSG; n = 30) or the active control group, which participated in regular physical education classes (CG; n = 30). The SSG group engaged in the same activities as the control group but additionally participated in a recreational SSG football program. This program involved continuous and intermittent moderate-to high-intensity exercises conducted on 20 m × 30 m and 30 m × 50 m football fields. In contrast, the CG group received 1 h of physical education once a week. The interventions were administered for a duration of sixteen weeks. Baseline, 8-week, and post-intervention assessments were conducted to measure body mass (BM), body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR), skinfold thickness (SFT), standing broad jump (SBJ), vertical jump (VJ), handgrip strength (HG) for both left and right hands, shuttle run distance (SRD), and shuttle run estimated VO2max. Results indicated that both male and female participants in the SSG group exhibited significant improvements in BM, BMI, SFT, WC, HC, and WHR following the intervention (p < 0.05), whereas the control group demonstrated no significant changes over the study period (p > 0.05). Additionally, SSG participants (regardless of sex) displayed significant enhancements in SBJ, VJ, HG, SRD, and VO2max (p < 0.05), while the control group did not exhibit any significant alterations (p > 0.05). The findings from this experimental study suggested that a 16-week recreational soccer SSG intervention effectively enhanced body composition and physical fitness among overweight sedentary young adults, offering a pleasurable alternative to conventional training approaches.

The objectives of this study were twofold: (a) to analyze the variability of 3v3 and 5v5 small-sided games (SSG) formats in sedentary young adults, and (b) to compare the physiological and locomotor demands of 3v3 and 5v5 SSG formats while considering variations based on sex. The study followed a longitudinal design over 4 months. Thirty sedentary young adults with a mean age of 20.2 ± 1.0 years, height of 1.67 ± 0.06 m, and body mass of 86.3 ± 11.8 kg were included in the study. The participants engaged in 3v3 and 5v5 SSG formats, with each format being played 10 times per month. During each session, heart rate (HR), rate of perceived exertion (RPE), and total distance were measured and analyzed. The within-player variability for HR ranged from a minimum of 1.6% to a maximum of 2.8% (considering the levels at each month), while the between-players variability for HR ranged from a minimum of 1.4% to a maximum of 2.6% (considering the levels at each month). Similar variability patterns were observed for the other outcomes. In terms of comparisons between the formats, the 3v3 format resulted in higher RPE than the 5v5 format for both male (p = 0.006) and female (p = 0.628) participants, as well as for the other outcome measures. In summary, these findings highlight the reproducibility of physiological responses in 3v3 and 5v5 SSG among sedentary individuals. Notably, the 3v3 format consistently induced higher RPE levels. These findings underscore the importance of programming SSG based on sex and format preferences for optimizing exercise outcomes in sedentary.

Purpose: Despite the accuracy of heart rate (HR) as an indicator of the aerobic engagement has been evaluated in several intermittent on-court activities, its validity as an oxygen uptake (V˙O2) indicator during shuttle running over short paths remains uncertain. Moreover, it is unclear whether speed may affect such validity. This study evaluated the HR ability in estimating the V˙O2 during 5-m shuttle running at different speeds. Methods: V˙O2 and HR of 12 physically active young men were recorded during an incremental forward running (FW) protocol and a 5-m shuttle test at 50%, 60%, and 75% of maximal aerobic speed (MAS). Slope and intercept of the relationship between HR and V˙O2 (HR/V˙O2) were individually determined, in both protocols. The HR measured during the shuttle test was used in the FW HR/V˙O2 to estimate V˙O2 at each shuttle speed. A paired Student\'s t-test compared slopes and intercepts of the two HR/V˙O2. A two-way RM-ANOVA and an equality test examined, respectively, the differences and the equality between measured and estimated V˙O2. Lastly, a Bland-Altman plot described the accuracy and precision of the estimated V˙O2 at each shuttle intensity. Results: Slopes and intercepts of the HR/V˙O2 appeared not different between FW and shuttle running. At 50%MAS, HR underestimated the V˙O2 (~7%), whereas returned accurate values at the two higher velocities, although with high variability (±18%). Conclusions: When using HR as V˙O2 indicator during shuttle running over short paths, a separated analysis of the HR validity as V˙O2 indicator is recommended especially when administering different exercise intensities.