Purpose: To investigate the convergent validity, reliability, and sensitivity over a week of training of a standardized running test to measure neuromuscular fatigue. Methods: Twenty male rugby union players were recruited for the study, which took place during preseason. The standardized running test consisted of four 60-m runs paced at  ~5 m·s−1 with 33 seconds of recovery between trials. Data from micromechanical electrical systems were used to calculate a running-load index (RLI), which was a ratio between the mechanical load and the speed performed during runs. RLI was calculated by using either the entire duration of the run or a constant-velocity period. For each type of calculation, either an individual directional or the sum of the 3 components of the accelerometer was used. A measure of leg stiffness was used to assess the convergent validity of the RLI. Results: Unclear to large relationships between leg stiffness and RLI were found (r ranged from −.20 to .62). Regarding reliability, small to moderate (.47–.86) standardized typical errors were found. The sensitivity analysis showed that the leg stiffness presented a very likely trivial change over the course of 1 week of training, whereas RLI showed very likely small to a most likely large change. Conclusions: This study showed that RLI is a practical method to measure neuromuscular fatigue. In addition, such a methodology aligns with the constraint of elite team-sport setup due to its ease of implementation in practice.

Introduction: This study aimed to explore the relationship between elite rugby union match and post-match sleep architecture and to investigate the effects of a high-heat capacity mattress (MAT) and a whole-body cryotherapy session (WBC) on post-match sleep architecture. Methods:Nineteen elite male U23 rugby union players performed in three official matches, followed by three experimental conditions, in a randomized order: MAT, WBC, and no intervention (CONT). Match load was evaluated using global positioning system (GPS) trackers and video analyses. Sleep architecture was assessed by polysomnography (PSG). Core body temperature (CBT) and mattress surface temperature were monitored during sleep. Linear mixedeffects models were conducted to assess the effects of each experimental condition on sleep, with match load variables as covariates. Results: A lower wake after sleep onset (β = -10.5 min, p < 0.01) and higher rapid-eye-movement sleep proportion (β = +2.8%, p < 0.05) were reported for MAT compared with CONT. Moreover, a lower mean CBT (β = -0.135°C, p < 0.001) and mean mattress surface temperature (β = -2.736°C, p < 0.001) during sleep were observed for MAT compared CONT. Whole-body cryotherapy did not affect nocturnal CBT nor interfere with sleep architecture. For every 100-m increase in high-speed running distance, a higher slow-wave sleep (SWS; β = +1.1%, p = 0.05) and lower light sleep proportion (β = -1.2%, p < 0.05) proportion were observed. Conversely, for every 10 supplementary collisions, a lower SWS (β = -1.9, p = 0.09) and higher light sleep (β = +2.9%, p < 0.001) proportion were observed. Conclusion: MAT use had a positive effect on sleep architecture after an elite rugby union match, potentially through a more efficient nocturnal heat transfer.

Background: Concussions are a source of major concern in rugby, and a limited number of studies have attempted to identify risk factors for these injuries. Purpose: To investigate the incidence of match concussion and associated risk factors, including individual workload, anthropometric variables, playing position, and season phase, in elite rugby union players. Study Design: Case-control study; Level of evidence 3. Methods: All concussions and explanatory variables were collected for every match over 5 consecutive seasons (2014-2018) in 1334 professional players participating in the French Top 14 championship. Concussion risk was estimated using mixed effects Poisson regression. Results: Mean match concussion incidence equated to 10.4 (95% CI, 9.3-11.5) concussions for 1000 hours of game exposure. A peak was reached in the 2016-2017 season (13.7; 95% CI, 11.0-16.5). A greater risk was observed in the playoffs as compared with the first phase of the season (incidence rate ratio, 3.96; 95% CI, 2.10-7.35). In comparison with other positions, half-backs incurred the highest rate of concussion events (incidence, 16.1; 95% CI, 11.8-20.3). Irrespective of playing position, those with greater height and lower body mass reported a higher risk of concussions ( P = .02), especially during tackling actions for lighter players ( P = .01) and during other match events for taller players ( P = .03). When adjusted for season phase, players who had accumulated a higher amount of playing time since the beginning of the season demonstrated a lower risk of concussion ( P = .005). Conclusion: Inter- and intraseasonal variations in concussion rates were observed. Within positional groups, lighter and taller players were more at risk, with the highest incidence generally observed in half-backs. Workload was measured by the number of matches played before a concussion event, and it appeared to have a protective rather than deleterious effect on concussion risk.

Purpose: To explore the effects of travel related to international rugby sevens competition on sleep patterns. Methods: A total of 17 international male rugby sevens players participated in this study. Actigraphic and subjective sleep assessments were performed daily during 2 separate Sevens World Series competition legs (Oceania and America). The duration of each competition leg was subdivided into key periods (pretour, precompetition, tournament 1, relocation, tournament 2, and posttour) lasting 2 to 7 nights. Linear mixed models in combination with magnitude-based decisions were used to assess (1) the difference between preseason and key periods and (2) the effect of travel direction (eastward or westward). Results: Shorter total sleep time (hours:minutes) was observed during tournament 2 (mean [SD], 06:16 [01:08]), relocation (06:09 [01:09]), and the pretour week (06:34 [01:24]) compared with the preseason (06:52 [01:00]). Worse sleep quality (arbitrary units) was observed during tournament 1 (6.1 [2.0]) and 2 (5.7 [1.2]), as well as during the relocation week (6.3 [1.5]) than during the preseason (6.5 [1.8]). When traveling eastward compared with westward, earlier fall-asleep time was observed during tournament 1 (ES − 0.57; 90% CI, −1.12 to −0.01), the relocation week (−0.70 [−1.11 to −0.28]), and the posttour (−0.57 [−0.95 to −0.18]). However, possibly trivial and unclear differences were observed during the precompetition week (0.15 [−0.15 to 0.45]) and tournament 2 (0.81 [−0.29 to 1.91]). Conclusion: The sleep patterns of elite rugby sevens players are robust to the effects of long-haul travel and jet lag. However, the staff should consider promoting sleep during the tournament and relocation week.