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Craig A. Williams

In my 2015 editorial, I selected two research publications with a focus on an applied sports sciences perspective. This year I have chosen to focus on two publications from a methodological viewpoint, highlighting the importance of laboratory procedures and extraction of data through a systematic review respectively. The first publication by Leites and colleagues (J Appl Physiol) addresses questions in relation to thermoregulation and carbohydrate metabolism in young people. This topic is difficult to conduct due to additional ethical and safety concerns due to exercising in the heat. Nonetheless, there are important basic science questions to be answered. Using a range of measurement techniques including rectal thermometry, 13C-enriched carbohydrate isotopes and procedures to standardize the heat stress equally between a group of men and boys, this project demonstrates an exemplary range of experimental skills. In my second selected paper by Lesinski et al., (Brit J Sports Med), both a systematic review and a meta-analyses were conducted to investigate the dose-response relationships of resistance training on physical performance in youth athletes. As the requirement for more evidence based practice is demanded, the move away from a narrative review to a more methodological and rigorous approach is to be encouraged. It is, in my opinion, a skill that we should be encouraging all our early career pediatric researchers to learn from the outset, the outcome of which can only make our discipline stronger.

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Craig A. Williams

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Craig A. Williams

In 2017, considerable attention has been paid by researchers on early sports specialization for youth athletes. Issues related to injury, burnout, and talent development to name a few have been debated, particularly when contrasted against other opposing youth development approaches, such as a multisport approach. The increasing professionalization of young athletes, a particular concern of this author, is coupled with the ensuing physical and mental pressures on these youngsters, as highlighted by the 2 highlighted publications in this commentary. Moreover, the financial costs to parents to support talented youngsters lead me to conclude that we must not treat them as “mini-adult athletes.” Trying to predict too far into the sporting future of a 9- or 10-year athlete can lead us to forgetting that they are just a 9 year, who typically wants to play, have fun, and be with their friends. Embarking on concentrated training programs, endless travel for tournaments, and an overemphasis on winning can be detrimental to participation rates as shown by recent data in the United States. Therefore, the challenge for researchers in elite youth sports is to ensure that practices we pursue with our young charges promote their health and well-being and that sports is for the benefit of the athlete and not the other way around.

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Craig A. Williams

Youth sport participation offers many benefits including the development of self-esteem, peer socialization, and general fitness. However, an emphasis on competitive success—often driven by goals of elite-level travel team selection, collegiate scholarships, Olympic and National team membership, and even professional contracts—has seemingly become widespread. This has resulted in increased pressure to begin high intensity training at young ages. Such an excessive focus on early intensive training and competition at young ages rather than skill development can lead to overuse injury and burnout.

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Craig A. Williams and Peter Keen

This study investigated the maximal isokinetic muscle power characteristics in adolescent boys and adult men by comparing voluntary maximal efforts on a novel isokinetic cycling ergometer. Thirteen boys and 12 men performed between seven and ten 6-s (unpaced, maximal) sprints at crank velocities ranging from 80–170 rev · min−1 (8.3–17.8 rad · s−1). Maximum power over a single revolution (Pmax) and mean power for the total of complete revolutions in 5 s (MP5s) were recorded, and the optimal crank velocity for both parameters was calculated for each subject. Men’s Pmax were significantly higher (P < .05) than boys. There were no significant differences in the optimal velocity at Pmax and MP5s or the theoretical maximum velocity at Pmax and MP5s for men or boys. All subjects showed a linear torque velocity relationship (r > 0.90) for both Pmax and MP5s. Absolute differences in isokinetic power between adolescent boys and adult men cannot be attributable to the differences in crank pedal velocities as optimal velocities were similar in both groups.

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Craig A. Williams and Jamie Blackwell

The purpose of the study was to determine the hydration status, fluid intake, and electrolyte losses of 21 male professional youth soccer players (age 17.1 ± 0.7 y) training in a cool environment. Pretraining and posttraining measurements of body mass, urine (freezing-point osmolality method), and sweat concentration (flame-emission spectroscopy) were collected. Fourteen players were found to be hypohydrated before training. The amount of fluid lost due to exercise equated to a 1.7% loss in body mass, which equated to a gross dehydration loss of 0.5%. Overall, the soccer players replaced 46% ± 88% of sweat loss during training, and only 4 remained hypohydrated after training. No significant correlations between sweat loss and sweat concentrations of Na+ (r = –.11, P = .67) or K+ (r = .14, P = .58) were found, but there was a significant correlation with Mg2+ (r = –.58, P < .009). This study found large variability in pretraining hydration status that the players were able to rehydrate during the training sessions. However, given the numbers starting training in a hypohydrated state, adequate hydration status before training should be considered by youth players, coaches, and sports-science support staff.

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Craig A. Williams, Eric Doré, James Alban and Emmanuel Van Praagh

This study investigated the differences in short-term power output (STPO) using three different cycle ergometers in 9-year-old children. A total of 31 children participated in three cycle ergometer sprint tests of 20 s duration: a modified friction braked Monark, a modified friction braked Ergomeca cycle ergometer, and a SRM isokinetic ergometer. Common indices of peak and mean power, peak pedal rate, time to peak power, and pedal rate were recorded. Indices of peak power 1 s for the Monark, Ergomeca and SRM ergometer were found to be 299 ± 55, 294 ± 55, 297 ± 53 W and mean power 20 s to be 223 ± 40, 227 ± 43 and 216 ± 34 W, respectively. The time to peak power was found to be 3 ± 2, 6 ± 2, 5 ± 3 s, respectively. The standard error of measurement was lower in mean 20-s power compared to 1-s peak power. Despite instrumentation and protocol differences these results demonstrate reproducibility in 9-year-old children that will allow researchers confidence in comparing STPO data obtained from different ergometers.

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Jonathan L. Oliver, Craig A. Williams and Neil Armstrong

The purpose of this study was to assess the reliability of a field and a laboratory test of repeated sprint ability (RSA). Twelve adolescent boys (15.3 ± 0.3 years) completed five trials of both a field RSA test (7 × 30 m sprints) and a laboratory RSA test (7 × 5 s sprints) performed on a nonmotorized treadmill. Mean coefficients of variation (CV) calculated across all trials were < 2.7% for field sprint times, and, in the laboratory, < 2.9% for velocity and < 8.4% for power output. Fatigue indices (FI) calculated from data in both environments exhibited mean CVs > 23%. The inconsistency in the FIs resulted from the mathematical procedures used in the FI calculation methods. Based on the reliability scores, it was concluded that results obtained from measured performance variables in the field and laboratory, and not calculated FIs, should be used to report RSA.

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Craig A. Williams, Jon L. Oliver and James Faulkner

Purpose:

The aim of the study was to longitudinally assess speed and jump performance characteristics of youth football players over a 3 y period.

Methods:

Two hundred players across five age squads (U12–U16) from an English Football League academy participated. Sprint performance (10 and 30 m) and countermove-ment jump height were assessed at 6 mo intervals. Pairwise analyses determined the level of change in performance between consecutive intervals.

Results:

Sprint performance changes tended to be greatest during the early teenage years, with observed changes exceeding the smallest worthwhile effect (1.0% for 10 and 30 m sprints). Changes in jump performance were above the smallest worthwhile effect of 1.8% for all but one interval. Large individual variability in the magnitude of change in sprint and jump performance, perhaps due to the confounding effect of growth and maturation, revealed few significant differences across the 6 mo intervals. Cumulative changes in performance demonstrated strong linear relationships, with a yearly rate of change of 6.9% for jump height, and 3.1 and 2.7% for 10 m and 30 m sprint time respectively. The magnitude of change in performance tended not to differ from one interval to another.

Conclusions:

The results of this study may primarily be used to monitor and predict the rate of progression of youth football players. In addition, these results may be used as a benchmark to evaluate the effectiveness of a current training program.