RESUMO
This study aimed to compare the changes in body composition and physical qualities of under 19's backs and forwards during the season (i.e. from pre-season [Pre-S] to end-season [End-S]). Twenty-seven male youth rugby union players (mean ± SD: age, Forwards [n = 11]: 17.5 ± 1.2 and Backs [n = 16]: 17.0 ± 0.9 years) participated in this study. Participants were tested twice (i.e. at Pre-S and End-S) and completed: anthropometric, body composition, countermovement and squat jumps, 30-m sprint, squat and bench press 1-repetition maximum (SQ-1RM and BP-1RM). Significant differences were observed between Pre-S and End-S for body mass (BM) and lean mass (LM), among both playing positions (p < 0.034; ES > 0.71), whereas all other variables remained unchanged. Regarding physical performance, backs and forwards showed greater SQ-1RM and BP-1RM, respectively (p < 0.043; ES>-0.69). Moreover, backs and forwards exhibited higher split times from 5 to 30 m (p: 0.013 to <0.001). Substantial increases were observed in BM and LM for backs and forwards, which may have negatively impacted acceleration (i.e. 5-m sprint time) and initial sprint momentum for both playing positions. Our findings highlight the importance of carefully balancing changes in BM and body composition, to avoiding the detrimental effects of these variations on sprint performance.
RESUMO
ABSTRACT: Zabaloy, S, Giráldez, J, Fink, B, Alcaraz, PE, Pereira, LA, Freitas, TT, and Loturco, I. Strength deficit in elite young rugby players: Differences between playing positions and associations with sprint and jump performance. J Strength Cond Res 36(4): 920-926, 2022-The aims of this study were twofold: to compare the strength-related performance between young forwards and backs rugby players and to examine the correlations between strength deficit (SDef), strength parameters, and sprint and jump performance. Fifty-seven male rugby players (mean ± SD: age, 17.4 ± 1.3 years) performed anthropometric and body composition assessments, vertical jumps, 30-m sprint, and squat (SQ) and bench press (BP) 1-repetition maximum tests (1RM SQ and BP). The differences in the tested variables between positions were analyzed through an independent t-test. A Pearson's correlation coefficient was used to assess the relationships among the variables. Significant differences were observed for anthropometric and body composition measures and jump and sprint performance between positions (p < 0.05; effect size [ES]: 0.60-1.34), except for 5-m velocity (p = 0.080; ES: 0.57). Backs demonstrated higher relative 1RM than forwards in both exercises (p = 0.009 and p = 0.008; ES = 0.88 and 0.91, for SQ and BP, respectively). In addition, backs demonstrated lower SDef from 70 to 90% 1RM (p < 0.048) but small-to-moderate nonsignificant lower SDef against lighter loads compared with forwards (50-60% 1RM). Overall, SDef across all loads (r: -0.378 to -0.529) and 1RM SQ (r: 0.504 to -0.590) were significantly related to sprint performance. Therefore, young rugby players who present lower magnitudes of SDef and superior 1RM SQ performance tend to be faster in linear sprints.