Introduction: Biological maturity level has shown to affect sport performance in youths. However, most previous studies have used noninvasive methods to estimate maturity level. Thus, the main aim of the present study was to investigate the association between skeletal age (SA) as a measure of biological maturation level, match locomotion, and physical capacity in male youth soccer players.Method: Thirty‐eight Norwegian players were followed during two consecutive seasons (U14 and U15). Match locomotion was assessed with GPS‐tracking in matches. SA, assessed by x‐ray, physical capacities (speed, strength and endurance) and anthropometrics were measured in the middle of each season. Analysis of associations between SA, match locomotion, and physical capacities were adjusted for the potential confounding effect of body height and weight.Results: In matches, positive associations were found between SA and maximal speed and running distance in the highest speed zones. Further, SA was associated with 40 m sprint time and countermovement jump (CMJ) height, and with intermittent‐endurance capacity after adjusting for body height (U14). Associations between SA and leg strength and power, and between SA and absolute VO_2max were not significant after adjusting for body weight. There was no association between SA and total distance covered in matches.Conclusion: Biological maturity level influence match locomotion and performance on physical capacity tests. It is important that players, parents and coaches are aware of the advantages more mature players have during puberty, and that less mature players also are given attention, appropriate training and match competition to ensure proper development.

The main aim of the present study was to compare skeletal maturity level and physical capacities between male Norwegian soccer players playing at elite, sub‐elite and non‐elite level. Secondary, we aimed to investigate the association between skeletal maturity level and physical capacities. One hundred and two U14 soccer players (12.8‐14.5 years old) recruited from four local clubs, and a regional team were tested for bone age and physical capacities. Bone age was estimated with x‐ray of their left hand and used to indicate maturation of the skeleton. Players went through a comprehensive test battery to assess their physical capacities. Between‐groups analysis revealed no difference in chronological age, skeletal maturity level, leg strength, body weight, or stature. However, elite players were superior to sub‐elite and non‐elite players on important functional characteristics as intermittent‐endurance capacity (running distance: 1664 m ± 367 vs 1197 m ± 338 vs 693 m ± 235) and running speed (fastest 10 m split time: 1.27 seconds ± 0.06 vs 1.33 seconds ± 0.10 vs 1.39 seconds ± 0.11), in addition to maximal oxygen uptake (), standing long jump, and upper body strength (P < .05 for all comparisons). Medium‐to‐large correlations were found between skeletal maturity level and peak force (r = 695, P < .01), power (r = 684, P < .01), sprint (r = −.471, P<.001), and jump performance (r = .359, P < .01), but no correlation with upper body strength, , or intermittent‐endurance capacity. These findings imply that skeletal maturity level does not bias the selection of players, although well‐developed physical capacity clearly distinguishes competitive levels. The superior physical performance of the highest‐ranked players seems related to an appropriate training environment.

Background: Previous studies have shown associations of physical fitness and cognition in children and in younger and older adults. However, knowledge about associations in high-school adolescents and young adults is sparse. Thus, the aim of this study was to evaluate the association of physical fitness, measured as maximal oxygen uptake (V̇O2max), muscle mass, and weekly training, and cognitive function in the executive domains of selective attention and inhibitory control, in healthy male high-school students. Methods: 54 males (17.9 ±0.9 years, 72 ±11kg and 182 ±7cm) completed a V̇O2max test, a body composition test, and a visual cognitive task based on the Posner cue paradigm with three types of stimuli with different attentional demands (i.e. stimuli presentation following no cue, valid cue or invalid cue presentations). The task consisted of 336 target stimuli, where 56 (17%) of the target stimuli appeared without a cue (no cue), 224 (67%) appeared in the same rectangle as the cue (valid cue), and 56 (17%) appeared in the rectangle opposite to the cue (invalid cue). Mean reaction time (RT) and corresponding errors was calculated for each stimuli type. Total task duration was nine minutes and 20 sec. In addition, relevant background information was obtained in a questionnaire. Results: Linear mixed model analyses showed that higher V̇O2max was associated with faster RT for stimuli following invalid cue (Estimate=-2.69, SE=1.03, p=.011), and for stimuli following valid cue (Estimate=-2.08, SE=1.03, p=.048). There was no association of muscle mass and stimuli (F=1.01, p=.397) or of weekly training and stimuli (F=.99, p=.405). Conclusion: The results suggest that cardiorespiratory fitness is associated with cognitive performance in healthy male high-school students in the executive domains of selective attention.

Biological maturation and growth influence youth athletes’ physical performance during adolescence. However, how this association develops over time remains unclear. Thus, this study examined associations between biological maturity and sprint speed, vertical jumping ability, leg strength, and aerobic capacity between ages 14.1 and 17.4 in youth male soccer players. A total of 103 players were followed. Performance in 40-m sprint, countermovement jump (CMJ), leg press, and maximal oxygen consumption (V̇O2max) was tested biannually at seven time points. Maturity was estimated using bone age from hand-wrist X-rays. Latent growth modelling examined changes in maturity-performance associations over time. Maturity was significantly (p < 0.05) associated with sprint, CMJ, leg strength (force and power), and V̇O2 max at ages 14.1, 14.7, and 15.3 years. The associations were, however, less significant over time. Specifically, maturity was no longer statistically associated with sprint and CMJ performance at 15.7 years, force and V̇O2 max at 16.4 years, and power at 16.8 years. There were no significant associations at 17.4 years. Biological maturity influences physical capacities during early adolescence, but its impact diminishes as players age. The timing of this decline appears to vary between physical performance domains, with sprint and jump performance stabilizing earlier than muscular strength and aerobic capacity.

Introduction: Earlier studies have demonstrated that the oldest in a competition class are more likely to succeed than the youngest, a phenomenon called relative age effect (RAE). Track and field give us an opportunity to investigate the advantage of being born early in the year based upon actual performance, since objective criteria are the performance indicators. Hence, the aim of the present study was to investigate the occurrence of RAE in Norwegian track and field athletes in events where physical capacity is important for success. Methods: All individual season best results from the register of The Norwegian Athletics Federation (n = 28 999) obtained in all competition classes from the age of 10 years to senior in both sexes on 60m and 600m from 2011 to 2020 were downloaded. One-way ANOVA and LSD post hoc analyses were used to analyze performance differences according to birth quartiles between athletes. Further, odds ratios (OR) were used to calculate the odds of being among the top-100 for athletes for those born in the first quartile of the year compared to the last. Results: The RAE was present in several of the competition classes in sprint compared to middle-distance running, and in more male than female competition classes. Overall, the OR of being among the top-100 in one of the competition classes on 60m sprint when born in first quartile compared to last quartile was 2.88 [2.30–3.62] for males and 1.54 [1.26–1.89] for females. Conclusion: Being born early in the year in events with high demand for specific physical capacities is an advantage in both sexes in most of the youngest competition classes. In males, the advantage of being born early in the year lasted longer in sprint than in middle-distance running, indicating that puberty affects performance in sprint and middle-distance running differently.

Biological maturity significantly impacts youth athletes’ physical performance throughout adolescence. However, how this differs between male and female youth athletes remains unclear. Thus, the present study aimed to assess associations between maturity, physical performance and motor coordination in females and males. Sixty-eight youth athletes (mean age 13.9 ± 0.8 years, 26 females) were included in the present study. Participants performed a 40 m sprint, standing long jump (SLJ), push-ups and a 2,000 m run. Motor coordination was evaluated using the short form of the Körperkoordinationstest für Kinder test. Bone age (BA), assessed by x-ray of the left hand and analyzed with an automated software, was used as a biomarker of biological maturity. Results showed that BA was significantly associated with performance for males on 40 m sprint (r = −.556, p < .001), SLJ (r = .500, p < .001) and 2,000 m run (r = −.435, p = .011). No associations were found between BA and physical performance among females, nor between BA and motor coordination for either females or males. In conclusion, maturity is associated with exercises that require maximal speed, explosive leg strength and endurance in males, but not in females, with maturity showing no impact on the motor coordination in either sex.