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ABSTRACT: Zabaloy, S, Freitas, TT, Alcaraz, PE, Gálvez-González, J, Pereira, LA, Comyns, T, Loturco, I, and Healy, R. Relative acceleration and maximum velocity in rugby players according to age category and playing position. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to: (a) assess the intrasession reliability of the acceleration time constant (i.e., τ) and τ-derived measures; (b) analyze the influence of τ and maximum velocity (Vmax) on 40-m sprint performance and to compare various sprint-related outcomes among rugby players from different playing positions and age categories; and (c) explore the associations between τ and several sprint performance metrics. A total of 300 male rugby players volunteered to participate in this study and were divided into age categories (i.e., under-14 [U14]: n = 91, age: 12.6 ± 0.5 years; under-16 [U16]: n = 85, age: 14.8 ± 0.5 years; under-18 [U18]: n = 75, age: 16.6 ± 0.5 years; and Seniors: n = 49, age: 24.2 ± 4.1 years). The results demonstrated good to excellent reliability for all measured parameters (intraclass correlation coefficient >0.75 and coefficient of variation <9.0%). Younger players (i.e., U14 and U16) displayed lower τ values (effect size: moderate to large; p < 0.02) compared with their older peers (i.e., U18 and Seniors), regardless of their playing position. Moreover, τ was associated with sprint performance metrics at varying levels of correlations (Rho: small to almost perfect; p < 0.001). In conclusion, younger players exhibited lower τ values than their older counterparts, irrespective of their playing positions. The model employed in this study demonstrated its accuracy in assessing several key sprint performance metrics, offering insights that can enhance sprint training programs for rugby players, which can be based on the associations observed among these different variables.

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This study aimed to determine, through the use of a highly sensitive statistical tool, whether real changes in performance were present; and compare the rates of meaningful variations in strength, speed, and power parameters at different time-points during the competitive season in national team rugby players. Thirty-two players were assessed 5 times across the season using the following tests: squat jump and countermovement jump tests; 30-m sprint velocity; and one-repetition maximum (1RM) in the half-squat and bench-press exercises. A repeated-measures analysis of variance was conducted to test for differences between successive time-points. Individual coefficients of variation values were used to set target scores for post-measurements and examine whether changes in performance parameters were greater than the natural test variance, thus providing an indication of whether "true changes" occurred. No significant changes were detected in the vertical jump height, 1RM measures, and sprint velocity and momentum throughout the 11-month period (P > 0.05). True changes occurred much more frequently for strength-power measures than for sprint velocity and momentum. Elite rugby union players did not exhibit significant variations in neuromuscular performance across the competitive period, when a group-based analysis was conducted. However, at the individual level, "true changes" in strength-power-(but not in speed-) related qualities were consistently observed over the competitive season.

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We examined the effectiveness of two different jump-squat (JS) loading ranges on the physical performance of rugby players. Twenty-eight elite male rugby players were divided into two JS training groups: a light-load JS group ("LJS"; JS at 40% of the one-repetition maximum [1RM] in the half-squat (HS) exercise) and a heavy-load JS group ("HJS"; JS at 80% HS-1RM). Players completed the distinct training programs over four weeks, three times per week, during the initial phase of the competitive period. Pre- and post-training tests were conducted in the following sequence: vertical jumps, a 30-m speed test, peak power in the JS and the HS, and maximum isometric force in the HS. Additionally, the rating of perceived exertion (RPE) was assessed at the end of all training sessions throughout the intervention. A two-way ANOVA with repeated measures, followed by the Tukey's post-hoc test, was employed to analyze differences between groups. The level of significance was set at p < 0.05. Effect sizes were used to assess the magnitude of differences between pre- and post-training data. Except for the RPE values (which were lower in the LJS group), no significant changes were detected for any other variable. In summary, using either a light- (40% HS-1RM) or a heavy-load (80% HS-1RM) JS during the initial phase of the competitive period is equally effective in maintaining physical performance levels attained during the preceding training period (pre-season), with the significant advantage of the light-load protocol resulting in lower levels of the RPE. This finding may have important implications for resistance training programming, especially in disciplines where acute and chronic fatigue is always a problematic issue.

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In the final part of this three-article collection on the training strategies of Brazilian Olympic sprint and jump coaches, we provide a detailed description of the resistance training methods and exercises most commonly employed by these speed experts. Always with the objective of maximizing the sprint and jump capabilities of their athletes, these experienced coaches primarily utilize variable, eccentric, concentric, machine-based, isometric, complex, and isoinertial resistance training methods in their daily practices. Squats (in their different forms), Olympic weightlifting, ballistics, hip thrusts, lunges, calf raises, core exercises, leg curls, stiff-leg deadlifts, and leg extension are the most commonly prescribed exercises in their training programs, during both the preparatory and competitive periods. Therefore, the current manuscript comprehensively describes and examines these methods, with the additional aim of extrapolating their application to other sports, especially those where sprint speed is a key performance factor.

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This is the second article in a three-article collection regarding the plyometric, speed, and resistance training practices of Brazilian Olympic sprint and jump coaches. Here, we list and describe six out of the ten speed training methods most commonly employed by these experts to enhance the sprinting capabilities of their athletes. Maximum speed sprinting, form running, resisted sprinting, overspeed running, uphill and downhill running, and sport-specific movement methods are critically examined with reference to their potential application in different sport contexts. In an era when sprint speed is of critical importance across numerous sports, practitioners can employ the methods outlined here to design efficient training programs for their athletes.

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PURPOSE: To investigate the relationships between a series of direct and indirect measures of linear and multidirectional speed performance in elite female rugby sevens players. METHODS: Nineteen players from the Brazilian national team performed 40-m linear sprint and 505 change-of-direction (COD) tests on the same day. Based on the linear sprint and COD test performances, the COD deficit (CODD) and deceleration deficit (DD) were also obtained. A Pearson product-moment correlation analysis was used to determine the relationships between linear sprint and COD-derived variables. RESULTS: Linear sprint and 505 COD velocities were not significantly associated (P > .05). Large to very large significant associations (r values ranging from .54 to .78; P < .05) were detected between linear sprint velocity for the different distances tested (10, 15, 30, and 40 m) and CODD. The COD velocity presented a very large inverse significant correlation with CODD and DD (r = -.77 and -.79 respectively; P < .05). A large and significant correlation was identified between CODD and DD (r = .79; P < .05). CONCLUSIONS: Significant associations were observed between linear sprint and CODD, suggesting that faster players are less efficient at changing direction. No relationship was found between sprint velocity and DD, highlighting the independent nature of linear sprints and deceleration capabilities. A comprehensive and detailed analysis of multidirectional speed performance should consider not only linear sprint and COD performances but also complementary COD-derived variables such as the CODD and DD.

Asunto(s)

Rendimiento Atlético , Carrera , Humanos , Femenino , Rugby , Desaceleración , Brasil

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ABSTRACT: Loturco, I, McGuigan, MR, Freitas, TT, Bishop, C, Zabaloy, S, Mercer, VP, Moura, TBMA, Arruda, AFS, Ramos, MS, Pereira, LA, and Pareja-Blanco, F. Half-squat and jump squat exercises performed across a range of loads: differences in mechanical outputs and strength deficits. J Strength Cond Res 37(5): 1052-1056, 2023-The aim of this study was to compare the peak force (PF), peak power (PP), and peak velocity (PV) outputs produced during half-squat (HS) and jump squat (JS) exercises executed at 20, 40, 60, and 80% of 1 repetition maximum (1RM) in the HS (HS 1RM) and to compute and compare the strength deficit (SDef) achieved in these exercises across these loads. Twenty-four national rugby union players (age: 25.7 ± 3.6 years) performed HS 1RM and a progressive loading test in the HS and JS exercises. The PF, PP, and PV values were obtained in all loads for both exercises, and the SDef was calculated as the percentage difference between the PF at distinct relative intensities and the PF at HS 1RM. The differences in HS and JS variables were determined using an analysis of variance with repeated measures. Higher PF, PP, and PV outputs were generated in the JS in comparison with the HS exercise ( p < 0.05); moreover, the SDef magnitudes were significantly lower in the JS ( p < 0.01), for all loading conditions. Importantly, the differences in SDef, and as a consequence, PF, PP, and PV decreased progressively with increasing load. Overall, the loaded JS exhibited increased levels of PF, PP, and PV and reduced levels of SDef when compared to the traditional HS performed across a range of loads. The JS is indicated to reduce the SDef and improve the athletes' ability to apply force at higher velocities. Nevertheless, with heavier loads (i.e., ≥80% HS 1RM), its potential advantages and effectiveness may be seriously compromised.

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Entrenamiento de Fuerza , Humanos , Adulto Joven , Adulto , Postura , Ejercicio Físico , Atletas , Terapia por Ejercicio , Fuerza Muscular

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ABSTRACT: Pereira, LA, Freitas, TT, Zabaloy, S, Ferreira, RCA, Silva, ML, Azevedo, PHSM, and Loturco, I. Sprint and jump training on sand versus grass surfaces: effects on the physical performance of young soccer players. J Strength Cond Res 37(9): 1828-1833, 2023-The aims of this study were to (a) examine the effects of a 6-week sand training program including both sprint and jump exercises on the speed-related and vertical jump performance of elite young soccer players and (b) compare the changes induced by a sand training scheme with those induced by a similar training program (in volume, intensity, and exercise types) performed on grass. Twenty-four under-20 soccer players were randomly allocated to 2 training groups, as follows: "sand" ( n = 12) or "grass" ( n = 12) groups. Athletes performed squat and countermovement jumps, linear sprints, and Zigzag change-of-direction speed tests at pre-, mid- (after 6 training sessions), and postintervention (after 12 training sessions). Both groups exhibited similar increases in the vertical jump and Zigzag performance after the 6-week training period ( p values ranging from 0.0001 to 0.025; effect size ranging from 1.05 to 3.78, for main effect of time). No significant changes were detected for the linear sprint velocity for both the groups ( p values ranging from 0.079 to 1.00; effect size ranging from 0.07 to 0.65, for main effect of time). In summary, training on sand or grass surfaces resulted in similar improvements in the physical performance of elite young soccer players. This study confirms the current evidence on the effectiveness of both soft and harder training surfaces in improving the sprint and jump performance of team-sport athletes.

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Rendimiento Atlético , Entrenamiento de Fuerza , Carrera , Fútbol , Humanos , Fuerza Muscular , Rendimiento Físico Funcional , Entrenamiento de Fuerza/métodos , Arena

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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.

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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.

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Rendimiento Atlético , Fútbol Americano , Adolescente , Ejercicio Físico , Humanos , Masculino , Fuerza Muscular , Rugby

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ABSTRACT: Zabaloy, S, Carlos-Vivas, J, Freitas, TT, Pareja-Blanco, F, Loturco, I, Comyns, T, Gálvez-González, J, and Alcaraz, PE. Muscle activity, leg stiffness and kinematics during unresisted and resisted sprinting conditions. J Strength Cond Res 36(7): 1839-1846, 2022-This study aimed to compare muscle activity, leg stiffness, and kinematics (contact and flight time [FT], stride length and frequency, and trunk angle [TA]) of unloaded sprinting to resisted sprint (RST) using different loads. Twelve male rugby players (age: 23.5 ± 5.1 years; height: 1.79 ± 0.04 m; body mass 82.5 ± 13.1 kg) performed 30-m sprints using different loading conditions (0, 10, 30 and 50% of velocity loss-Vloss-from the maximum velocity reached under unloaded condition). Muscle activity from 4 muscles (biceps femoris long head, rectus femoris [RF], gluteus medius and gastrocnemius), leg stiffness (Kleg), and kinematics were measured during the acceleration and maximum velocity (Vmax) phases of each sprint. Heavier loads led to significantly lower biceps femoris long head activation and higher rectus femoris activity (p < 0.01-0.05). Significant reductions in Kleg were observed as loading increased (p < 0.001-0.05). Kinematic variables showed substantial changes with higher loads during the acceleration and Vmax phase. In conclusion, the heavier the sled load, the higher the disruptions in muscle activity, Kleg, and kinematics. When coaches and practitioners intend to conduct resisted sprint training sessions without provoking great disruptions in sprint technique, very-heavy sled loads (greater than 30% Vloss) should be avoided. However, heavy sled loads may allow athletes to keep specific positions of the early acceleration phase for longer time intervals (i.e., first 2-3 strides during unresisted sprints).

Asunto(s)

Rendimiento Atlético , Entrenamiento de Fuerza , Carrera , Adolescente , Adulto , Rendimiento Atlético/fisiología , Fenómenos Biomecánicos , Humanos , Pierna , Masculino , Músculo Esquelético , Entrenamiento de Fuerza/métodos , Carrera/fisiología , Adulto Joven

RESUMEN

The purpose of this study was to investigate the interval in which male rugby union players reach maximum speed in a 50 m sprint according to age categories and playing positions. This study also aimed to establish the optimal distance for the assessment of sprint speed and to compare the differences in anthropometrics, sprint and sprint momentum according to the age and playing position. Three hundred amateur rugby players performed anthropometric and physical fitness tests (10, 20, 30, 40 and 50 m sprint times, acceleration, velocity, and sprint momentum) during the in-season period. Participants from different age categories (under 14's (U14), under 16's (U16), under 18's (U18) and Seniors) and positions (forwards and backs) volunteered to participate in this study. Results revealed that most of the U14 and U16 players (58.2% and 55.3%, respectively) reached maximum speed in the interval between 20 and 30 m with lower sprint speed than U18 players and Seniors (44% and 49%, respectively). Comparisons between each interval showed significant differences for all U14 and U16 forwards, suggesting the fastest interval was between 20-30 m. No significant differences were found for U16 backs, U18 and Seniors, between sprint times in the 20-30 m and 3040 m intervals. In addition, between-group comparisons, demonstrated significant (p < 0.001) differences in U14 when compared to U16, U18 and Seniors in anthropometric variables, sprint times and sprint momentum. In conclusion, this study suggests that the optimal distance for the assessment of sprint speed of rugby players is 30 m and that body mass, sprint momentum and sprint speed clearly discriminate between players of different age categories and playing positions.

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This study assessed the validity of 5-m (TG5) and 10-m (TG10) split times measured with timing gates to estimate maximum sprint speed (MSS) against a criterion measure radar gun (RG) during the maximum velocity phase of a 30-m sprint. Nineteen amateur rugby players performed two 30-m sprints. The timing gates were placed at the starting line and at 5-, 10-, 20-, 25- and 30-m. In addition, a RG was used to measure instantaneous velocity. Both trials per participant were used selected as references. MSS obtained from TG10, TG5 and RG showed high intraclass correlation coefficients (0.971-0.978), low coefficients of variation (1.14-1.70%) and smallest detectable changes (<0.02 m/s). Pairwise comparison revealed differences (p = 0.002) in MSS when comparing TG10 to RG, but not TG5 and RG (p = 0.957). Almost perfect correlations were found between RG, TG5 and TG10 (r > 0.926, p < 0.001). In conclusion, MSS obtained from TG5, TG10 and RG presented good intra-session reliability. However, practitioners should be aware that substantial differences exist between TG10 and RG. For the assessment of MSS in team-sport athletes, it is recommended the use of TG5 for more accurate estimations when a gold standard criterion is not available.

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This study aimed to investigate the relationship between a specific isometric-strength sprint test (SIST) and unresisted maximum velocity (Vmax), sprint times across different loading conditions, and the velocity loss (Vloss) loads required to achieve each intended Vloss condition during resisted sprint training (RST) in rugby players. Additionally, the investigation examined the relationship between strength in the back-squat one-repetition maximum (1RM-SQ) as well as isometric squat (ISQT), jumps, and sprint performance variables. Twenty (n = 20) male amateur rugby players performed, on two separate occasions, a structural multiple-joint assessment of jumps, strength, and sprint performance. Interestingly, SIST revealed moderate correlations (r = 0.453 to 0.681; p < 0.05) between 1RM-SQ and ISQT. The SISTrel (relative to body mass), but not SIST, used in the present study showed moderate correlations (r = 0.508 to 0.675; p < 0.05) with the loads needed to reach 10%, 30%, and 50% of Vloss during RST. The SISTrel that measures resultant force application in a more sprint-related position explains much of the individual response of each athlete during sprinting towing a sled and can also be used to prescribe and quantify loads in the RST in a more objective and individual manner.