Purpose: The purpose of this study was to investigate the validity of timing gates and 10-Hz global positioning systems (GPS) units (Catapult Optimeye S5) against a criterion measure (50-Hz radar gun) for assessing maximum sprint velocity (V_max).Methods: Nine male professional rugby union players performed 3 maximal 40-m sprints with 3 min rest between efforts with V_max assessed simultaneously via timing gates, 10-Hz GPS_Open (Openfield software), GPS_Sprint (Sprint software), and radar gun. Eight players wore 3 GPS units, while 1 wore a single unit during each sprint.Results: When compared with the radar gun, mean biases for GPS_Open, GPS_Sprint, and timing gates were trivial, small, and small, respectively. The typical error of the estimate (TEE) was small for timing gate and GPS_Open while moderate for GPS_Sprint. Correlations with radar gun were nearly perfect for all measures. Mean bias, TEE, and correlations between GPS units were trivial, small, and nearly perfect, respectively, while a small TEE existed when GPS_Openfield was compared with GPS_Sprint.Conclusion: Based on these findings, both 10-Hz GPS and timing gates provide valid measures of 40-m V_max assessment compared with a radar gun. However, as error did exist between measures, the same testing protocol should be used when assessing 40-m V_max over time. Furthermore, in light of the above results, it is recommended that when assessing changes in GPS-derived V_max over time, practitioners should use the same unit for each player and perform the analysis with the same software, preferably Catapult Openfield.

Repeated physical contact in rugby union is thought to contribute to post‐match fatigue; however, no evidence exists on the effect of contact activity during field‐based training on fatigue responses. Therefore, the purpose of this study was to examine the effect of contact during training on fatigue markers in rugby union players. Twenty academy rugby union players participated in the cross‐over study. The magnitude of change in upper‐ and lower‐body neuromuscular function (NMF), whole blood creatine kinase concentration [CK] and perception of well‐being was assessed pre‐training (baseline), immediately and 24 h post‐training following contact and non‐contact, field‐based training. Training load was measured using mean heart rate, session rating of perceived exertion (sRPE) and microtechnology (Catapult Optimeye S5). The inclusion of contact during field‐based training almost certainly increased mean heart rate (9.7; ±3.9%) and sRPE (42; ±29.2%) and resulted in likely and very likely greater decreases in upper‐body NMF (−7.3; ±4.7% versus 2.7; ±5.9%) and perception of well‐being (−8.0; ±4.8% versus −3.4; ±2.2%) 24 h post‐training, respectively, and almost certainly greater elevations in [CK] (88.2; ±40.7% versus 3.7; ±8%). The exclusion of contact from field‐based training almost certainly increased running intensity (19.8; ±5%) and distance (27.5; ±5.3%), resulting in possibly greater decreases in lower‐body NMF (−5.6; ±5.2% versus 2.3; ±2.4%). Practitioners should be aware of the different demands and fatigue responses of contact and non‐contact, field‐based training and can use this information to appropriately schedule such training in the weekly microcycle.

This study examined the relationship between accelerometer metrics and both collisions and running demands during rugby union match-play. Twelve under-18 forwards and 14 under-18 backs were recruited from a professional rugby union club. Six competitive matches were filmed during which players wore micro-technological units (Optimeye S5, Catapult Innovations, Melbourne, Australia). Video footage was analysed for total collisions, while GPS data was analysed for total distance. Accelerometer metrics analysed were Player load^™ (PL), Player Load^™ 2D (PL2D), and Player Load^™ slow (PLslow). A total of 81 player observations were included in the final analysis. Data were analysed using ordinary least squares regression. A 10-fold cross validation analysis was used to validate the findings. All PL variables demonstrated very large relationships with collisions in the forwards, while PLslow demonstrated the largest relationship (large) with collisions in the backs. Therefore, based on the strong relationship in both forwards and backs, PLslow may provide the most useful metric for measuring collision-based activity in both positional groups during match-play. Additionally, nearly perfect and very large relationships were observed between PL and total distance for forwards and backs respectively, suggesting that PL can be successfully used to quantify running demands when other methods are unavailable, for example during indoor training.

This study investigated the changes in measures of neuromuscular fatigue and physical performance in young professional rugby union players during a preseason training period. Fourteen young (age: 19.1 ± 1.2 years) professional rugby union players participated in the study. Changes in measures of lower body neuromuscular fatigue (countermovement jump (CMJ) mean power, mean force, flight‐time) and physical performance (lower body strength, 40 m sprint velocity) were assessed during an 11‐week preseason period using magnitude‐based inferences. CMJ mean power was likely to very likely decreased during week 2 (−8.1 ± 5.5% to −12.5 ± 6.8%), and likely to almost certainly decreased from weeks 5 to 11 (−10 ± 4.3% to −14.7 ± 6.9%), while CMJ flight‐time demonstrated likely to very likely decreases during weeks 2, and weeks 4–6 (−2.41 ± 1% to −3.3 ± 1.3%), and weeks 9–10 (−1.9 ± 0.9% to −2.2 ± 1.5%). Despite this, possible improvements in lower body strength (5.8 ± 2.7%) and very likely improvements in 40 m velocity (5.5 ± 3.6%) were made. Relationships between changes in CMJ metrics and lower body strength or 40 m sprint velocity were trivial or small (<0.22). Increases in lower body strength and 40 m velocity occurred over the course of an 11‐week preseason despite the presence of neuromuscular fatigue (as measured by CMJ). The findings of this study question the usefulness of CMJ for monitoring fatigue in the context of strength and sprint velocity development. Future research is needed to ascertain the consequences of negative changes in CMJ in the context of rugby‐specific activities to determine the usefulness of this test as a measure of fatigue in this population.

Purpose: To evaluate changes in performance of a 6-s cycle-ergometer test (CET) and countermovement jump (CMJ) during a 6-wk training block in professional rugby union players.Methods: Twelve young professional rugby union players performed 2 CETs and CMJs on the 1st and 4th mornings of every week before the commencement of daily training during a 6-wk training block. Standardized changes in the highest score of 2 CET and CMJ efforts were assessed using linear mixed modeling and magnitude-based inferences.Results: After increases in training load during wk 3 to 5, moderate decreases in CMJ peak and mean power and small decreases in flight time were observed during wk 5 and 6 that were very likely to almost certainly greater than the smallest worthwhile change (SWC), suggesting neuromuscular fatigue. However, only small decreases, possibly greater than the SWC, were observed in CET peak power. Changes in CMJ peak and mean power were moderately greater than in CET peak power during this period, while the difference between flight time and CET peak power was small.Conclusion: The greater weekly changes in CMJ metrics in comparison with CET may indicate differences in the capacities of these tests to measure training-induced lower-body neuromuscular fatigue in rugby union players. However, future research is needed to ascertain the specific modes of training that elicit changes in CMJ and CET to determine the efficacy of each test for monitoring neuromuscular function in rugby union players.

BACKGROUND: Post-match fatigue has yet to be investigated in academy rugby union players. OBJECTIVES: To determine the magnitude of change in upper-(plyometric push-up (PP) flight-time) and lower-body (countermovement jump (CMJ) mean power) neuromuscular function (NMF), whole blood creatine kinase (CK) and perception of well-being following a competitive match in academy rugby union players. METHODS: Fourteen academy rugby union players participated in the study. Measures were taken 2 h pre-match (baseline) and immediately post-match. Further testing was also undertaken at 24-, 48- and 72 h respectively post-match. Changes in measures from baseline were determined using magnitude-based inferences RESULTS: Decreases in CMJ mean power were likely substantial immediately (-5.5±3.3%) post-match, very likely at 24 h (-7±3.9), likely at 48 h (-5.8±5.4), while likely trivial at 72 h (-0.8±3.8) post-match. PP flight-time was very likely reduced immediately (-15.3±7.3%) and 24 h (-11.5±5.7%) post-match, while possibly increased at 48 h (3.5±6.0%) and likely trivial at 72 h (-0.9±5.4%) post-match. Decreases in perception of well-being were almost certainly substantial at 24 h (-24.0±4.3%), very likely at 48 h (-8.3±5.9%), and likely substantial at 72 h (-3.6±3.7%) post-match. Increases in CK were almost certainly substantial immediately (138.5±33%), 24 h (326±78%) and 48 h (176±62%) post-match, while very likely substantial at 72 h (57±35%) post-match. CONCLUSION: These findings demonstrate the transient and multidimensional nature of post-match fatigue in academy rugby union players. Furthermore, the results demonstrate the individual nature of recovery, with many players demonstrating different recovery profiles from the group average.