The presence of the relative age effect (RAE) has been widely reported; however, its underlying causes have not yet been determined. With this in mind, the present study examined if anthropometry and performance were different amongst older and younger soccer players born in the same year. Eighty-eight young soccer players participated in the study (age 9.75 ± 0.30). Anthropometric measurements, physical tests (sprint, agility, endurance test, jump and hand dynamometry) and the estimation of the maturity status were carried out. Most players (65.9%) were born in the first half of the year. Older players were taller (P < 0.05), had longer legs (P < 0.01) and a larger fat-free mass (P < 0.05). Maturity offset was smaller in the older boys (P < 0.05); however, age at peak height velocity was similar. Older boys performed better in velocity and agility (P < 0.05) and particularly in the overall score of performance (P < 0.01). Stepwise regression analysis revealed that chronological age was the most important variable in the agility test and the overall score, after the skinfolds (negative effect). We report differences in anthropometry and physical performance amongst older and younger pre-pubertal soccer players. These differences may underlie the RAE.

The aim of this study was to analyse the talent identification process of a professional soccer club. A preselection of players (n = 64) aged 9–10 years and a final selection (n = 21) were performed by the technical staff through the observation during training sessions and matches. Also, 34 age-matched players of an open soccer camp (CampP) acted as controls. All participants underwent anthropometric, maturity and performance measurements. Preselected outfield players (OFs) were older and leaner than CampP (P < 0.05). Besides, they performed better in velocity, agility, endurance and jump tests (P < 0.05). A discriminant analysis showed that velocity and agility were the most important parameters. Finally, selected OFs were older and displayed better agility and endurance compared to the nonselected OFs (P < 0.05). Goalkeepers (GKs) were taller and heavier and had more body fat than OFs; also, they performed worse in the physical tests (P < 0.05). Finally, selected GKs were older and taller, had a higher predicted height and advanced maturity and performed better in the handgrip (dynamometry) and jump tests (P < 0.05). Thus, the technical staff selected OFs with a particular anthropometry and best performance, particularly agility and endurance, while GKs had a different profile. Moreover, chronological age had an important role in the whole selection process.

The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players' results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB.

Wheelchair basketball players are classified in four classes based on the International Wheelchair Basketball Federation (IWBF) system of competition. Thus, the aim of the study was to ascertain if the IWBF classification, the type of injury and the wheelchair experience were related to different performance field-based tests. Thirteen basketball players undertook anthropometric measurements and performance tests (hand dynamometry, 5 m and 20 m sprints, 5 m and 20 m sprints with a ball, a T-test, a Pick-up test, a modified 10 m Yo-Yo intermittent recovery test, a maximal pass and a medicine ball throw). The IWBF class was correlated (p<0.05) to the hand dynamometry (r= 0.84), the maximal pass (r=0.67) and the medicine ball throw (r= 0.67). Whereas the years of dependence on the wheelchair were correlated to the velocity (p<0.01): 5 m (r= −0.80) and 20 m (r= −0.77) and agility tests (r= −0.77, p<0.01). Also, the 20 m sprint with a ball (r= 0.68) and the T-test (r= −0.57) correlated (p<0.05) with the experience in playing wheelchair basketball. Therefore, in this team the correlations of the performance variables differed when they were related to the disability class, the years of dependence on the wheelchair and the experience in playing wheelchair basketball. These results should be taken into account by the technical staff and coaches of the teams when assessing performance of wheelchair basketball players.

This study investigated whether anthropometric characteristics, generic and specific sprinting, agility, strength, and endurance capacity could differentiate between First-Division and Third-Division wheelchair basketball (WB) players. A First-Division WB team (n = 8; age = 36.05 ± 8.25 years, sitting body height = 91.38 ± 4.24 cm, body mass = 79.80 ± 12.63 kg) and a Third-Division WB team (n = 11; age = 31.10 ± 6.37 years, sitting body height = 85.56 ± 6.48 cm, body mass = 71.18 ± 17.63 kg) participated in the study. Wheelchair sprint, agility, strength, and endurance tests were performed. The First-Division team was faster (8.7%) in 20 m without the ball, more agile (13-22%), stronger (18-33%), covered more distance (20%) in the endurance test, and presented higher values of rate of perceived exertion for the exercise load (48%) than the Third-Division team. Moreover, the individual 20-m sprint time values correlated inversely with the individual strength/power values (from r = -0.54 to -0.77, p ≤ 0.05, n = 19). Wheelchair basketball coaches should structure strength and conditioning training to improve sprint and agility and evaluate players accordingly, so that they can receive appropriate training stimuli to match the physiological demands of their competitive level.

The purpose of this study was to investigate the relationship between biomechanical variables and running economy in North African and European runners. Eight North African and 13 European male runners of the same athletic level ran 4-minute stages on a treadmill at varying set velocities. During the test, biomechanical variables such as ground contact time, swing time, stride length, stride frequency, stride angle and the different sub-phases of ground contact were recorded using an optical measurement system. Additionally, oxygen uptake was measured to calculate running economy. The European runners were more economical than the North African runners at 19.5 km · h(-1), presented lower ground contact time at 18 km · h(-1) and 19.5 km · h(-1) and experienced later propulsion sub-phase at 10.5 km · h(-1),12 km · h(-1), 15 km · h(-1), 16.5 km · h(-1) and 19.5 km · h(-1) than the European runners (P < 0.05). Running economy at 19.5 km · h(-1) was negatively correlated with swing time (r = -0.53) and stride angle (r = -0.52), whereas it was positively correlated with ground contact time (r = 0.53). Within the constraints of extrapolating these findings, the less efficient running economy in North African runners may imply that their outstanding performance at international athletic events appears not to be linked to running efficiency. Further, the differences in metabolic demand seem to be associated with differing biomechanical characteristics during ground contact, including longer contact times.