The purpose of this study was to examine the influence of chronological age (CA) and somatic maturation on body composition (BC) and bioimpedance parameters in male elite soccer players. BC and bioimpedance variables were measured in a sample of 249 players aged 9−18 years of age and registered in two professional Italian soccer teams. Results from segmental analysis showed transition time points where the influence of CA and somatic maturation on bioimpedance patterns and BC characteristics increased or subsided. The accelerated phases were assessed for fat free mass, total body water, and upper muscle area, with a starting time point at approximately −2.00 years from peak at velocity (YPHV), and for body cell mass, whose developmental tempo sped up around −1.00 YPHV. An increase in the rate of development was also observed close to −2.00 YPHV for phase angle (PA), although without accelerated phases. From a CA point of view, significant slope changes were found for all BC and bioimpendance variables, except for the calf muscle area. Although the starting points and the span of the accelerated phases were different, they subsided or disappeared at ~ 15 years, except for PA, whose growth waned at ~ 17 years.

The aim of this study was to analyze the efficiency of classic and specific bioelectrical impedance vector analysis (BIVA) in the assessment of maturity related differences in body composition among male elite youth soccer players, and to provide bioelectrical impedance reference data for this category. A group of 178 players (aged 12.1 ± 1.6 years) were registered in a professional Italian soccer team participating in the first division (Serie A). They were divided into three groups according to their maturity status while bioelectrical resistance and reactance were obtained. The classic and specific BIVA procedures were applied, which correct bioelectrical values for body height and body geometry, respectively. Percentage of fat mass (FM%) and total body water (TBW (L)) were estimated from bioelectrical values. Age-specific z-scores of the predicted age at peak height velocity identified 29 players as earlier-, 126 as on time-, and 23 as later-maturing. TBW was higher (p < 0.01) in adolescents classified as “early” maturity status compared to the other two groups and classic BIVA confirmed these results. Conversely, no differences in FM% were found among the groups. Specific vector length showed a higher correlation (r = 0.748) with FM% compared with the classic approach (r = 0.493). Classic vector length showed a stronger association (r = −0.955) with TBW compared with specific (r = −0.263). Specific BIVA turns out to be accurate for the analysis of FM% in athletes, while classic BIVA shows to be a valid approach to evaluate TBW. An original data set of bioelectric impedance reference values of male elite youth soccer players was provided.

Soccer is a multifactorial sport, in which players are expected to possess well developed physical, psychological, technical, and tactical skills. Thus, the anthropometric and fitness measures play a determinant role and could vary according to the competitive level. Therefore, the present study aimed to verify differences in body composition and physical performance between two soccer team. 162 young soccer players (from the Under 12 to Under 15 age categories; age: 13.01 ± 1.15 years) of different competitive levels (elite—n = 98 and non-elite—n = 64) were recruited. Anthropometric characteristics (height, weight, lengths, widths, circumferences, and skinfold thicknesses (SK)), bioelectrical impedance, physical performance test as countermovement jump (CMJ), 15 m straight-line sprints, Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo), and 20 + 20 m repeated-sprint ability (RSA)) were carried out. In addition, Body mass index (BMI), body composition parameters (percentage of fat mass (%F), Fat mass (FM, kg), and Fat-free mass (FFM, kg)) and the areas of the upper arm, calf and thigh were calculated, and the Bioelectric Impedance Vector Analysis (BIVA) procedures were applied. In addition, a linear discriminant analysis was assessed to determine which factors better discriminate between an elite and non-elite football team. Many differences were observed in body composition between and within each football team’s category, especially in triceps SK (p < 0.05), %F (p < 0.05), and all performance tests (p < 0.01). The canonical correlation was 0.717 (F(7,128) = 19.37, p < 0.0001), and the coefficients that better discriminated between two teams were 15 m sprint (−2.39), RSA (1−26), suprailiac SK (−0.5) and CMJ (−0.45). Elite soccer team players present a better body composition and greater physical efficiency. In addition, BIVA outcome could be a relevant selection criterion to scout among younger soccer players.

Soccer is a sport practiced all over the world, in which players are expected to show specific physical and technical skills. Soccer academies look for young talented individuals to develop promising players. Although several parameters could affect the players’ performance, the relative age effect (RAE) and the maturity status appeared debated. Therefore, this study compared the differences in RAE and biological maturity among the players of two Italian soccer teams of different levels and to understand their interaction effects with the competition level on youth players’ physical characteristics and abilities. One hundred and sixty-two young soccer players from the U12 to U15 age categories of the elite (n = 98) and non-elite (n = 64) teams were recruited. The prevalence of maturity status and RAE was observed. Many anthropometric parameters, BIA vectors, and motor tests (CMJ, Sprint, RSA) were carried out. The maturity status had a greater effect on several anthropometric characteristics and on 15 m sprint, while it affected the CMJ only in U12 (F = 6.187, p ≤ 0.01). Differently, the RAE seemed to priorly affect the U13 and U15 categories in body composition, whereas its effect appeared on the 15-m sprint (F(3, 45) = 4.147, p ≤ 0.01) and the RSA (F(3, 45) = 3.179, p ≤ 0.05) in the U14 category. In addition, early matured players or those who were born in the first six months presented cellular characteristics similar to adult elite players. Soccer professionals should be encouraged to monitor the maturity status to better interpret changes in the physical performance of young soccer players to guide adequate training plans.

Background. Football is one of the world's most popular sport with most players being younger than 18 years. Playing football can induce beneficial health effects in youth, but there is also a high risk of injury. In young football players, the relationship between injury risk in the different periods from peak height velocity (PHV) remains unclear. The objective of the study was to investigate the associations between the injury risk and injury burden in young Italian football players in different periods from PHV (pre-PHV, PHV and Post-PHV). Methods. One hundred and forty-one young players (age = 13.9 ± 0.8 years) were subdivided in three groups on the basis of maturity status: PHV was set by taking 6 months before and 6 months after the age at PHV; the 12 months before this year were allocated as the year before PHV (Pre-PHV); the 12 months after this year were allocated as the year after PHV (Post-PHV). The number of injuries was calculated for each player per year; injuries were classified by location, type, body-site and mechanism of injury (traumatic or overuse). Training and match injury incidence was also calculated and resulted 4.2 ± 6.9 per 1000 h and 10.0 ± 34.2 per 1000 h, respectively. Results. In total 25214 hours of exposure were recorded. A total of 83 injuries were reported. Most injuries (77%) were located in the lower limbs; the most common injuries were joint/ligament injuries (36%). Traumatic injury showed a tendency to increase from the year before PHV to the year of PHV, and after this period a decrease can be observed; while, overuse injuries incidence remains constant until PHV, and then decreased in the year after PHV, albeit the differences were not statistically significant. A non-significant higher training injury incidence was found at PHV, while match injury incidence was higher at Pre-PHV. Days missed due to injury show an increase up to PHV, and then a considerable decrease in the year after PHV; the difference among groups were statistically significant (p = 0.039); moreover, the effect size between PHV and Post-PHV was moderate. The mean of exposure shows a significant increase from the year before PHV to the year after PHV (p = 0.0089), furthermore, the effect size between Pre-PHV and Post-PHV was large. Conclusions. The results of this study on young Italian football players confirm the overall increased vulnerability of the athletes in the PHV period. Great attention should be given to the maturity status of the subjects. To try to limit injuries, training programs should be calibrated on the state of maturity of the players and not on their chronological age.

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This paper deals with the conception, the experimental and numerical characterization of an innovative post-tensioned CLT wall system equipped with external and replaceable hysteretic devices. The cyclic behavior of the post-tensioned walls was firstly investigated at the mechanical laboratory of CIRI-EC of University of Bologna by means of experimental tests on single component of the structural system and on the full-scale post-tensioned CLT walls prototypes. Results from experimental tests demonstrate the capability of the conceived post-tensioned wall systems to withstand significant drift without damage on the main timber and steel components.A good dissipative capacity of the wall configurations equipped with dissipaters was also observed. A nonlinear Finite Element model capable of reproducing the wall system hysteretic behavior was developed in the OpenSees framework. Implemented FE numerical model demonstrated a good capability of reproducing the experimental response.