Vítor Severino

Anthropometric and Physiological Profiling of Youth Soccer Goalkeepers

Studies focused on position-related characteristics of young soccer players often ignore the goalkeepers. The aim of this study was to examine the effect of playing position on anthropometry, physiological attributes, soccer skills, and goal orientation across adolescence. One hundred forty-five soccer players age 11-19 y were assessed in training experience, body size, maturation, physiological parameters, soccer skills, and goal orientation. Factorial ANOVA was used to test the effect of age group, playing position, and respective interaction terms, while analysis of variance was used to compare goalkeepers vs outfielders in middle (under 13 [U-13] and U-15) and late (U-17 and U-19) adolescence. Discriminant analysis was used to identify the variables that contributed to explaining playing positions. Age group was a consistent source of variation for all variables except task and ego orientations. Fat mass, agility, endurance, dribbling speed, shooting accuracy, and passing were affected by the gradient derived from the classification between goalkeepers and outfielders. It was possible to correctly classify the playing position based on fat-free mass and 3 manipulative skills in younger players and on 4 skills in U-17 and U-19 soccer players. Future research should include longitudinal information to improve our understanding of the factors that contribute to distinguish goalkeepers from outfielders.

Reproducibility of peak power output during a 10-s cycling maximal effort using different sampling rates

The study was aimed to investigate the reproducibility of performance parameters obtained from 10-s maximal cycling effort against different braking forces in young adult athletes. The sample (n = 48) included male athletes aged 18.9-29.9 years (175.5 ± 6.9 cm, 76.2 ± 10.1 kg). The exercise protocol was performed in a cycle-ergometer against a random braking force (4% to 11% of body mass). Intra-individual variation was examined from repeated tests within one week. Descriptive statistics were computed and differences between sessions were tested using paired t-test. The coefficient of correlation between repeated measures, technical error of measurement (TEM), coefficient of variation and ICC were calculated. Agreement between trials was examined using the Bland-Altman procedure. Mean values of peak power were relatively stable when obtained from sampling rates of 50 Hz and ranged between 1068 watt and 1082 watt (t(47) = 1.149, p = 0.256, ES-r = 0.165) or while corresponding to a sampling rate of 1 Hz (t(47) = 0.742, p = 0.462, ES-r = 0.107). Correlations between repeated measures were high (+0.907, 95% CI: +0.839 to +0.947) and TEM about 59.3 watt (%CV = 5.52%; ICC = 0.951, 95% CI: 0.912 to 0.972). The present study suggests that reproducibility of peak power in male adult athletes tended to be acceptable and within individual error appeared unrelated to braking force.

Reproducibility of estimated optimal peak output using a force-velocity test on a cycle ergometer

The current study aimed to examine the reproducibility of estimated peak power and estimated pedal velocity in a multi-trial 10-s all-out cycling test among adult athletes (n = 22; aged 23.50±4.73 years). Stature, sitting height and body mass were measured. Leg length was estimated as stature minus sitting height. Body volume was obtained from air displacement plethysmography and was subsequently used to calculate body density. Fat mass and fat-free mass were derived. The short-term power outputs were assessed from the force-velocity test (FVT), using a friction-braked ergometer on two separated occasions. Differences between repeated measurements were examined with paired t-test and effect sizes calculated. No significant differences were found between session 1 (898 W, 142 rpm) and session 2 (906 W, 142 rpm). Test-retest procedure showed acceptable reliability for estimated peak power output [technical error of measurement (TEM) = 31.9 W; % coefficient of variation (CV) = 3.5; intra-class correlation coefficient (ICC) = 0.986] and pedal velocity (TEM = 5.4 rpm, %CV = 3.8, ICC = 0.924). The current study demonstrated a reasonable reproducibility of estimated peak power and pedal velocity outputs in non-elite male athletes and supports that a familiarization session including a complete FVT protocol is not required.

Repeated dribbling ability in young soccer players: reproducability and variation by the competitive level

Abstract The intermittent nature of match performance in youth soccer supports relevance of ability to repeatedly produce high-intensity actions with short recovery periods. This study was aimed to examine the reproducibility of a repeated dribbling ability protocol and, additionally, to estimate the contribution of concurrent tests to explain inter-individual variability in repeated dribbling output. The total sample comprised 98 players who were assessed as two independent samples: 31 players were assessed twice to examine reliability of the protocol; and 67 juveniles aged 16.1 ± 0.6 years were compared by the competitive level (local, n = 34; national, n = 33) to examine construct validity. All single measurements appeared to be reasonably reliable: total (ICC = 0.924; 95%CI: 0.841 to 0.963); ideal (ICC = 0.913; 95%CI: 0.820 to 0.958); worst (ICC = 0.813; 95%CI: 0.611 to 0.910). In addition, the percentage of the coefficient of variation was below the critical value of 5% for total (%CV = 3.84; TEM = 2.51 s); ideal (%CV = 3.90, TEM = 2.48 s). Comparisons between local and national players suggested magnitude effects as follows: moderate (d-value ranged from 0.63 to 0.89) for all repeated sprint ability scores; large for total (d = 1.87), ideal (d = 1.72), worst (d = 1.28) and moderate for composite scores: the fatigue index (d = 0.69) and the decrement score (d = 0.67). In summary, the dribbling protocol presented reasonable reproducibility properties and output extracted from the protocol seemed to be independent from biological maturation.

Allometric scaling of peak and mean outputs derived from 30 s wingate test in adolescent basketball players

Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. Allometric scaling of peak and mean outputs derived from 30 s wingate test in adolescent basketball players

Growth, maturity profile and peak vo2 of 11 year-old male soccer players

This study examined the relationship between body size, biological maturity, total amount of practice, and aerobic fitness of youth soccer players. The sample included 30 male soccer players aged 11 years old. Morphological variables (weight, height, sitting height and subcutaneous skinfolds), maturity (maturity offset, percentage of predicted mature height and skeletal maturity using the Fels method), quantity of annual practice and years of federate practice were considered. Assessment of aerobic power was obtained using a direct, maximal and progressive treadmill protocol. Data analysis considered general and comparative descriptive statistic. Pearson’s correlation coefficient was calculated in order to consider the association between aerobic power outputs and morphology, maturity and sport participation parameters. ANOVA was used to compare variables by tactical playing position and among maturity status groups. Significance was maintained in 5%. The maturity status-associated analysis classifies more subjects on time (53%) followed by early mature (27%) and late mature (20%). Subjects classified as early matures showed higher average results for the morphological parameters (excluding sitting height/standing height ratio), amount of playing minutes and absolute aerobic power, while maturity delayed subjects showed higher relative aerobic power marks. Results illustrate defenders as taller, heavier, higher in adiposity, with superior amount of playing minutes and better in absolute aerobic power. We found strong correlations between absolute aerobic power and weight (r=+0.90, p<0.01), height (r=+0.76, p<0.01), maturity offset (r=+0.80, p<0.01) and percentage of predicted adult height (r=+0.77, p<0.01).Moderate correlation between absolute aerobic power and amount of playing minutes (r=+0.34, p<0.05) was also found. Aerobic power seems to be associated with body size and maturity status. It seems that the process of sportive selection favours body size and maturity advanced athletes. Nevertheless, it seems at youth soccer coaches tend to select those players to defensive playing positions.

Age-related variation in anthropometric and maturity characteristics of soccer goalkeepers aged 11-14 years

The purpose of this study was to compare variation in body size and physique considering somatic maturity status of young sub-elite soccer goalkeepers within two competitive age-groups. The sample included 17 sub-elite male soccer goalkeepers in two competitive age-groups, 11-12 years (n=8) and 13-14 years (n=9) proceeding from three clubs in the midlands of Portugal. Height, weight, arm span, body mass index, bicristal/biacromial ratio, sitting height/height ratio and four skinfolds were measured. Somatotype of Carter & Heath was calculated. Somatic maturity was assessed using the maturity offset and percentage of predicted mature height (%PMH). To analyse differences between young soccer goalkeepers of contrasting age-groups, the Mann- Whitney U test was performed. In sequence, the 11-12 and 13-14 years old groups differed significantly in chronological age, maturity offset and %PMH (p <0.01). Estimates for age at peak height velocity, expected to occur, respectively at about 13.97 years of age (95% CI: 13.63-14.31) and 14.07 years (95% CI: 13.62-14.53) show that the older group already experienced this event in 0.15 years (95% CI: -0.33-0.63). For anthropometric characteristics differences were found for weight (p <0.05), height, arm span and sitting height (p <0.01), but not for the other variables. In conclusion, variation in body size associated with the age-group in young soccer goalkeepers is mostly related to growth and maturation and the use of somatic indicators can be a very practical and useful instrument for coaches.