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Predictive Contribution of the Superficial Neck Muscles to Short-Latency Rate of Force Development of the Head and Neck

Lucie Pelland, Ian A. Gilchrist, Wissal Mesfar, Jonathan Lommen, and Kodjo Moglo

Purpose: To evaluate the contribution of splenius capitis, sternocleidomastoid, and upper fibers of trapezius activation to the gains in rate of force development (RFD) of the head and neck during maximum voluntary ballistic contractions. Methods: RFD gain was facilitated by a single-session intervention for maximum voluntary ballistic contractions in the anterior direction, oriented at 45° to the midsagittal plane, which require active restraint of axial rotation. Muscle activation for the agonist (sternocleidomastoid) and 2 antagonists (splenius capitis and upper fibers of trapezius) was evaluated. The study sample included 12 physically active men (mean age, 22.6 y). RFD (N·m·s−1; 0–100 ms) and integrated muscle activity (50 ms before and 100 ms after force onset) were measured at 10 minutes, 20 minutes, and 2 days postintervention, relative to baseline. Muscle activation predictive of RFD gains was evaluated by linear regression analysis. RFD reproducibility was evaluated using the coefficient of variation of the typical error. Results: The intervention yielded a 1.95- to 2.39-fold RFD gain (P ≤ .05), with greater RFD gain for participants with a lower peak moment of force (<10.9 N·m) than those with a higher peak moment (≥10.9 N·m) at baseline (P ≤ .002). For the low group, 65% to 74% of the RFD gain was predicted by ipsilateral sternocleidomastoid activation, with ipsilateral splenius capitis activation predicting 77% to 92% of RFD gain for the high group. Absolute peak and impulse of static force were greater for the high than for the low group (P ≤ .04). RFD reproducibility was high (coefficient of variation of the typical error ≤ 14.4%). Conclusions: The agonist- and antagonist-focused synergies might reflect different functional priorities, higher RFD gain compared with higher head–neck force.

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Relationships of Contact Technique in Training and Matches With Performance and Injury Outcomes in Male Rugby Union

Steve den Hollander, Michael Lambert, Demi Davidow, Ben Jones, and Sharief Hendricks

The aims of this study were 3-fold: (1) to compare technical proficiency scores between training and matches for tackling, ball-carrying, and rucking outcomes; (2) to determine the relationship between technique in training and technique in matches for tackling, ball carrying, and rucking; and (3) to determine how contact technique (in training and matches) relates to match performance and injury outcomes. Twenty-four male players from an amateur rugby union club participated in the study. At the beginning of the season, players’ contact technique proficiency was assessed in a training drill. Contact technique in matches was assessed during 14 competitive matches. The technique proficiency was assessed using standardized criteria, and the outcomes of each tackle, ball carry, and ruck were recorded. In training and matches, positive performance outcomes were associated with higher contact technique proficiency scores. For instance, in both settings, tackle technique was significantly lower in missed tackles when compared to effective and ineffective tackles. Players’ contact technique scores in matches also had a positive effect on their tackle performance in matches. Ball-carry technique was associated with tackle breaks in matches (P < .05, r 2 = .31). In training and match environments, tackler, ball-carrier, and ruck technique scores were significantly associated with effective tackles, ball carries, and rucks. Despite the relationship between technical proficiency scores and performance, there were small to moderately higher scores in training compared with matches. The current study highlights the importance of contact skill training, in different environments and conditions, to ensure that skills developed in training are transferred to match performance.

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Simultaneous Upper- and Lower-Limb Postactivation Performance Enhancement After Clean and Jerk

Cleonir Caldeira Jr, Adriano E. Lima-Silva, Valmor Tricoli, Cintia L.N. Rodacki, and Anderson C. Paulo

Studies on postactivation performance enhancement (PAPE) have used different exercises as a conditioning activity to investigate potentiation, but exclusively in upper limbs (UL) or lower (LL) limbs, or contralateral potentiation. A single exercise capable of inducing PAPE in both UL and LL is currently unknown. The present study explored the effect of the clean and jerk (C&J) as a conditioning activity for simultaneously producing PAPE interlimbs at the fourth, seventh, and 12th minutes postintervention. Twelve male weightlifters with 1-repetition maximum (1RM) in the C&J equivalent to ≥1.15 × body mass were randomly submitted to 2 experimental conditions (C&J and control [CON]). The C&J condition consisted of general warm-up (running on a treadmill and self-selected preparatory exercises) and 4 sets of 3 repetitions of C&J with 2 minutes between them (30%1RM, 50%1RM, 65%1RM, and 80%1RM) followed by a countermovement jump and a bench-press throw on a Smith machine after 4, 7, and 12 minutes, to measure the magnitude of PAPE in UL and LL. No previous exercise preceded countermovement-jump and bench-press-throw tests in the CON besides general warm-up. The main finding was that, regardless of time, the C&J resulted in greater height on countermovement jump and Smith machine bench-press throw when compared with the CON, presenting a similar effect size between UL and LL (34.6 [3.9] vs 33.4 [4.1] cm [+3.66%]; P = .038; effect size = 0.30 and 30.3 [4.7] vs 29.0 [5.1] cm [+4.44%]; P = .039; effect size = 0.26), respectively. Thus, C&J can be useful to produce PAPE simultaneously among members.

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Effectiveness of a Variable-Speed Control Based on Auditory Feedback: Is It Possible?

Leonardo Lagos-Hausheer, Renata L. Bona, and Carlo M. Biancardi

Purpose: Variable-speed control in the field is challenging for motion science. Tests were performed to evaluate speed, Froude number, and oxygen consumption if these varied when using the same frequency of steps. The objective of this study was to evaluate the use of auditory feedback to control variable speed on the treadmill and track during acceleration cycles around the transition speed. Methods: Twenty-four trained men participated. The protocol was based on 5 ramps of 50 seconds each around 80%, 90%, 100%, 110%, and 120% of the walking–running transition speed, recording the frequency of steps with a mobile phone during the treadmill test. The tests were replicated on the track using auditory feedback. Results: When evaluating each speed of the protocols separately for the same frequency of steps, the average speed on the track was always higher on average at 54.7% compared to the laboratory (P < .050), and on the track, it was 16.2% higher than in the laboratory (P > .050). Conclusions: It cannot be considered that the same frequency of steps is equivalent to the same speed in the laboratory and on the track. These results point to the importance of reliable speed control during open field tests.

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Academic Freedom? Not in the United States (at Least at the Mayo Clinic)

Carl Foster

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Volume 18 (2023): Issue 8 (Aug 2023)

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Mental Rehearsal Improves Passing Skill and Stress Resilience in Rugby Players

C. Martyn Beaven, Liam P. Kilduff, and Christian J. Cook

Purpose: Mental rehearsal is commonly employed, with positive visualization proposed to enhance complex skill performance. Additionally, video stimulus has been associated with enhanced kinesthetic sensations and rapid hormone fluctuations that may contribute to enhancing mental rehearsal and the conscious and unconscious emotional state for skill execution. Here, we assessed the impact of a 15-minute mental rehearsal intervention on rugby-specific tasks and the associated hormone profile. Methods: Professional rugby players (N = 10) volunteered for a randomized crossover study. They completed three 15-minute preparatory phases (positive or negative video-guided mental rehearsal or self-directed mental rehearsal alone) prior to an exercise stressor and rugby-specific passing task. Salivary testosterone and cortisol were monitored to assess stress responses. Results: Performance during the rugby passing task was improved following the positive video condition (91% [7.4%]) compared to the negative video (79% [6.0%]; ES: 1.22 ± 0.75) and self-visualization (86% [5.8%]; ES: 0.58 ± 0.75), with a significant correlation observed between passing performance and salivary testosterone (r = .47 ± .34, P = .0087). Positive video imagery prior to an exercise stressor also significantly enhanced physiological stress resilience (r = .39 ± .36, P = .0352). Conclusions: This pilot study demonstrates that mental rehearsal was enhanced by appropriate, context-specific video presentation. We propose that the interaction between sex steroids, the adrenal axis, and subsequent conscious and unconscious behaviors may be relevant to competitive rugby. Specifically, we suggest that relatively elevated free testosterone imparts a degree of stress resilience, which may lead to enhanced expression of competitive behaviors and provide an enhanced state for rugby skill execution.

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Peak Running Demands in Elite Women’s Rugby Sevens and Rugby Union Match Play: A Comparative Study

Anthony Couderc, Mathieu Lacome, Jeremy Cheradame, Christopher Carling, and Julien Piscione

Purpose: In women’s rugby, players regularly interchange between the rugby sevens (R7) and rugby union (RU) formats. Yet, the game demands and particularly the physical aspects respective to both formats vary and players must be able to respond accordingly. The aim of this study was to compare peak running demands in R7 and RU players. Methods: A total of 51 international women players participated. HSBC World Sevens Series (n = 19) and Six Nations Rugby Union tournament matches (n = 10) were analyzed for a total of 437 individual match observations. Global positioning systems were utilized to measure total (in meters) and high-speed (above 16 km·h−1, in meters) distance and frequency of accelerations (above 2.5 m·s−2, n) during different rolling-average periods (1–7 min) to obtain peak running activity values. Power law modeling was used to obtain slope and intercept. For all variables, peak values and the value at the 90th percentile (P90) were analyzed. Results: No intercept difference (P = .25; −0.12 ± 0.17) was observed between formats for total distance (161 vs 155 m·min−1). In contrast, R7 players reported a higher intercept (P = .01; −0.29 ± 0.17) for high-speed distance (66 vs 51 m·min−1), while the intercept was higher (P = .01; 0.31 ± 0.20) in RU for accelerations performed (6.1 vs 5.4 n·min−1). Regarding P90, higher values (P < .001) were observed in R7 for total and high-speed distance and accelerations. Conclusions: While peak overall intensity was similar, P90 on the high-speed spectrum was higher in R7. Information on the most demanding match-play periods specific to both women’s rugby formats can inform training specificity by tailoring sessions to ensure sufficient exposure to these peak demands and, consequently, aid transitioning between formats.

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Enhancing the Initial Acceleration Performance of Elite Rugby Backs. Part I: Determining Individual Technical Needs

James J. Wild, Ian N. Bezodis, Jamie S. North, and Neil E. Bezodis

Purpose: This study sought to quantify the within-individual relationships between spatiotemporal variables and initial acceleration sprint performance in elite rugby backs and to establish a normative data set of relevant strength-based measures. Methods: First, the spatiotemporal variables, ratios of step length to step rate and of contact time to flight time, and initial acceleration performance were obtained from 35 elite male rugby backs (mean [SD] age 25 [3] y) over the first 4 steps of 3 sprints. Angular and linear kinematic aspects of technique and strength-based qualities were collected from 25 of these participants. Second, the same spatiotemporal variables were collected from 19 of the participants on 3 further occasions (12 trials in total) to determine the within-individual associations of these variables and initial acceleration performance. Results: Moderate to very large meaningful within-individual relationships (|r| = .43–.88) were found between spatiotemporal variables and initial acceleration performance in 17 of the 19 participants. From these relationships, a theoretically “desirable” change in whole-body kinematic strategy was individually determined for each participant, and normative strength-based measures to contextualize these were established. Conclusions: Meaningful within-individual relationships are evident between sprint spatiotemporal variables and initial acceleration performance in elite rugby backs. Individualized approaches are therefore necessary to understand how aspects of technique relate to initial acceleration performance. This study provides an objective, evidence-based approach for applied practitioners to identify the initial acceleration technical needs of individual rugby backs.

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Longitudinal Development of Physical Characteristics and Function in Japanese Junior Rugby Union Players

Akira Kumazaki, Tomomi Fujimoto, and Yuiko Matsuura

Purpose: To longitudinally investigate the development of physical characteristics and function during 3 years of high school among Japanese junior rugby players and examine the differences in these parameters between the positions. Methods: In 83 junior rugby players (forwards: n = 46, backs: n = 37) from one Japanese high school team who had participated in national high school competitions, anthropometric variables (height, body mass, fat and lean body mass, and body mass index), upper- and lower-body strength (eg, 1-repetition-maximum [1RM] bench press, isokinetic knee muscle strength at 60°/s and 180°/s), and sprint and jump performance were measured. Upper- and lower-body strength relative to body mass and lean body mass were also calculated. Results: All anthropometric indices improved with increasing age, and the values were higher in forwards than in backs (all P < .05). The 1-repetition maximum bench press (forwards: 40.8%, backs: 52.5%) and isokinetic knee strength (eg, extension at 60°/s, forwards: 15.4%, backs: 10.0%) improved with age (from 16 to 18 y), and they were higher in forwards than in backs (all P < .05). Meanwhile, the 1RM bench press relative to lean body mass did not differ between the positions. Isokinetic knee muscle strength at 60°/s and 180°/s relative to lean body mass and sprint and jump performance did not improve with age. Conclusion: These results indicate that Japanese junior rugby players need to develop larger physiques and continuously increase their lower-body strength to improve sprint and jump performance.