The purpose of this study was to compare the effects of 2 generic aerobic training models, based on peak running velocity in Carminatti's test (PVT-CAR) in U-20 elite soccer players. Seventeen soccer players (age: 17.9 ± 1.0 years; 178.6 ± 5.0 cm; 73.6 ± 6.6 kg; 11.1 ± 1.3%) from a team competing in a national junior league took part in the study. The athletes performed a series of pre- and posttraining tests (incremental test on a treadmill to determine the maximal oxygen uptake [(Equation is included in full-text article.)], velocity at maximal oxygen uptake [(Equation is included in full-text article.)], the lactate threshold [LT], and T-CAR). The interval training models applied were with 180° direction change (T12:12; n = 9) and without direction change (T6:6; n = 8). No significant interaction (time vs. group) was observed for the majority of variables analyzed (p > 0.05), although significant main effects in time were evident regarding peak treadmill velocity (PVTREAD) (F = 56.3, p < 0.0001), (Equation is included in full-text article.)(F = 35.8, p < 0.0001), LT (F = 57.7, p < 0.0001), and PVT-CAR (F = 52.9, p < 0.0001). Moreover, there was no significant change in (Equation is included in full-text article.)between pre and posttraining period (F = 4.26, p = 0.056) in both training groups. Thus, it can be concluded that the prescribed training with and without direction change in the intensity of the PVT-CAR increases the PVTREAD, the (Equation is included in full-text article.), the LT, and the PVT-CAR similarly.

The aim of this study was to identify the morphological configuration of youth athletes from professional soccer clubs and to verify their differences according to the tactical position on the field. Overall, 67 male players aged 15 to 17 years were evaluated. The examined anthropometric measurements included body mass, body height, skinfolds (triceps, subscapular, supraspinal and medial calf), girths (flexed and tensed arm and calf) and breadths (humerus and femur). For statistical purposes, analysis of variance and post hoc Bonferroni and Kruskal-Wallis tests were used. We concluded that goalkeepers were heavier and taller than center backs (p = 0.015 and p = 0.001), midfielders (p = 0.005 and p <0.001) and center forward players (p = 0.024 and p <0.001). The average somatotype for defense, forward and goalkeeper positions was a balanced mesomorph. Midfield players showed ectomorphic-mesomorph characteristics. It was concluded that goalkeepers were characterized as being taller and heavier and that somatotype features of athletes were similar between positions, except for midfield players.

Muscle injuries are among the main reasons for medical leavings of soccer athletes, being a major concern within professional teams and their prevention associated with sport success. Several factors are associated with a greater predisposition to injury, and genetic background is increasingly being investigated. The aim of this study was to analyze whether ACTN3 R577X and ACE I/D polymorphisms are predictors of the incidence and severity of muscle injury in professional soccer athletes from Brazil, individually and in association. Eighty-three professional athletes from the first and second divisions of the Brazilian Championship were evaluated regarding the polymorphisms through blood samples. Nighty-nine muscle injuries were identified during the seasons of 2018, 2019 and 2020 and categorized according to severity. ACTN3 XX individuals had a higher frequency of severe injuries compared to the RX and RR genotypes (p = 0.001), and in the dominant model (compared to RX+RR), with p < 0.001. The trend p-value test showed an increased number of injuries/season following the order XX > RX > RR (p = 0.045). Those with the ACE II genotype had almost 2 fold the number of injuries per season compared to those with the ID+DD genotypes (p = 0.03). Logistic regression showed that the polymorphisms are predictors of the development of severe injury (ACTN3 R577X model with p = 0.004, R2: 0.259; ACE I/D model with p = 0.045, R2: 0.163), where ACTN3 XX individuals were more likely to suffer from severe injury (OR: 5.141, 95% CI: 1.472–17.961, p = 0.010). The combination of the ACTN3 577X allele and the ACE II genotype showed an increased number of injuries per season, enhanced by 100% (1.682 injuries/season versus 0.868 injuries/season, p = 0.016). Our findings suggest that both polymorphisms ACTN3 R577X and ACE I/D (and their interaction) are associated with the susceptibility and severity of non-contact muscle injury in soccer players.

Purpose. the aim of the study was to examine the differences of the anaerobic speed reserve (ASr) in soccer players according to the playing positions (defenders, midfielders, and forwards). Methods. Overall, 120 elite-level national Brazilian soccer players (46 defenders, 45 midfielders, and 29 forwards) performed a field incremental test to estimate maximal aerobic speed (MAS) and a 30-m sprint to determine maximal sprinting speed (MSS). the difference between MAS and MSS was used to estimate ASr. Players were classified by position and by MAS and MSS performance. For each playing position, they were ranked and divided into higher and lower MSS (MSS-H and MSS-L, respectively) and MAS (MAS-H and MAS-L, respectively) groups. the players' ASr was compared among these groups. Results. the comparison of ASr within playing position showed no difference among defenders, midfielders, or forwards. In addition, a higher ASr was found for the fastest players (MSS-H) in all playing positions as compared with their MSS-L counterparts. When ASr was compared between MASH and MAS-L, a significant difference (p < 0.05) was observed. A high correlation was noted between ASr and MSS (r = 0.72; p < 0.001) and between ASr and MAS (r =-0.63; p < 0.001). Conclusions. MSS is the main index that determines the magnitude of ASr, which should be considered when characterizing the soccer players' running speed profile. However, no difference was found when the playing positions were compared, indicating similar characteristics of the running profile in a large sample of soccer players.

The aims of this study were to compare the internal training load (ITL) in soccer players of two competitive age groups (under-15 [U-15] and under-19 [U-19]) during an 8-week preseason training period and compare the associated changes in physical performance measures. Eighteen U-15 and twelve U-19 players were monitored over an 8-week period during the preseason phase. The ITL was monitored using the session rating of perceived exertion (RPE) method. Before and after the preseason period, physical performance was assessed by best (RSAbest) and mean (RSAmean) times in a repeated sprint ability (RSA) test and peak velocity derived from the Carminatti test (PVT-CAR). Total weekly ITL increased with age (U-15: 13770 ± 874 AU vs. U-19: 33584 ± 2506 AU; p < 0.001). In addition, U-19 players perceived training sessions as heavier than U-15 players (6.1 ± 0.3 vs. 5.3 ± 0.3 AU, respectively; p < 0.001). After the preseason period, very likely to almost certainly positive changes were observed for all performance measures in both age groups. However, the U-15 group had possibly superior gains in RSAbest (+1.40%, 90%CL -0.29 to 3.05, with ES = 0.35) and likely higher effects in RSAmean (+1.89%, 90%CL 0.04 to 3.70, with ES = 0.53) and PVT-CAR (+2.71%, 90%CL 0.35 to 5.01, with ES = 0.37) compared to the U-19 group. In conclusion, our findings demonstrate that the U-19 group accumulate higher total weekly ITLs than the U-15 group during the preseason phase due to longer and heavier training sessions. However, the U-15 group obtained superior gains in soccer-specific physical abilities while accumulating half the total ITLs during lighter training sessions.