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The purpose of this study was to quantify the physical demands of representative adolescent rugby union match-play and investigate the difference between playing positions and age groups. Players (n = 112) were classified into 6 groups by playing position (forwards and backs) and age group (U16, U18, and U20). The physical demands were measured using microsensor-based technology and analyzed using magnitude-based inferences to assess practical importance. Backs had a greater relative distance (except U16s) and a greater high-speed running distance per minute than forwards, with the magnitude of difference between the positions becoming larger in older age groups. Forwards had higher values of PlayerLoad (PL) per minute (accumulated accelerations from the 3 axes of movement) and PL slow per minute (accumulated accelerations from the 3 axes of movement where velocity is <2 m⋅s-1) than backs at all age groups. Relative distance, low-, and high-speed running per minute all had a trend to be lower in older age groups for both positions. PlayerLoad per minute was greater in U18 than that in U16 and U20 for both positions. PlayerLoad slow per minute was greater for older age groups besides the U18 and U20 comparisons, which were unclear. The contrasts in physical demands experienced by different positions reinforce the need for greater exposure to sprinting and collision-based activity for backs and forwards, respectively. Given PL metrics peak at U18 and locomotor demands seem to be lower in older ages, the demands of representative adolescent rugby union do not seem to be greater at U20 as expected. [ABSTRACT FROM AUTHOR]

This study determined the magnitude of change in adductor strength after a competitive match in academy rugby union players and examined the relationship between locomotive demands of match-play and changes in postmatch adductor strength. A within-subject repeated measures design was used. Fourteen academy rugby union players (age, 1 7.4±0.8 years; height, 1 82.7±7.6 cm; body mass, 86.2±11.6 kg) participated in the study. Each player performed 3 maximal adductor squeezes at 45² of hip flexion before and immediately, 24, 48, and 72 hours postmatch. Global positioning system was used to assess locomotive demands of match-play. Trivial decreases in adductor squeeze scores occurred immediately (21.3±2.5%; effect size [ES] = 20.11±0.21; likely, 74%) and 24 hours after match (20.7±3%; ES = 20.06±0.25; likely, 78%), whereas a small but substantial increase occurred at 48 hours (3.8±1.9%; ES = 0.32±0.16; likely, 89%) before reducing to trivial at 72 hours after match (3.1±2.2%; ES = 0.26±0.18; possibly, 72%). Large individual variation in adductor strength was observed at all time points. The relationship between changes in adductor strength and distance covered at sprinting speed (...O2max ≥ 81%) was large immediately postmatch (p = 0.056, r = 20.521), moderate at 24 hours (p = 0.094, r = -- 0.465), and very large at 48 hours postmatch (p = 0.005, r = 20.707). Players who cover greater distances sprinting may suffer greater adductor fatigue in the first 48 hours after competition. The assessment of adductor strength using the adductor squeeze test should be considered postmatch to identify players who may require additional rest before returning to field-based training. [ABSTRACT FROM AUTHOR]

The article cites the findings of a study which demonstrate that anthropometric and physical characteristics develop across age categories and provide comparative data for English Academy Rugby Union players. According to the study, momentum, maximal speed, and the ability to maintain acceleration were all discriminating factors between age categories, suggesting that these variables may be more important to monitor rather than sprint times.