Changes in markers of fatigue following a competitive match in elite academy rugby union players

ORIGINAL RESEARCH Changes in markers of fatigue following a competitive match in elite academy rugby union players G Roe,1,2 MSc; K Till,1,2 PhD; J Darrall-Jones,1,2 MSc; P Phibbs,1,2 MSc; J Weakley,1,2 MSc; D Read,1,2 MSc; B Jones,1,2 PhD 1 Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, West Yorkshire, United Kingdom 2 Yorkshire Carnegie Rugby Club, Headingley Carnegie Stadium, St. Michael’s Lane, Leeds, West Yorkshire, United Kingdom. Corresponding author: G Roe () 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. Keywords: collision sport, monitoring, sports injuries S Afr J Sports Med 2016;28(1):2‑5. DOI:10.17159/2078-516X/2016/v28i1a418 Rugby union is a collision sport that involves intermittent high-intensity activities, including sprinting, rucking, mauling, scrummaging and tackling, that are interspersed with periods of jogging, walking and standing.[1] Observations following [2,3] [4] one, two and four[5] competitive matches suggest that the highintensity activities and impacts sustained during rugby union match play result in acute post-match fatigue that may last for several days following competition. Fatigue may manifest as alterations in mood,[3] immune function[2] and hormone levels,[3] reductions in neuromuscular function (NMF)[3] and elevations in markers of muscle damage (e.g. an increase in creatine kinase concentration CK).[2,5] 2 SAJSM VOL. 28 NO. 1   2016 The authors’ understanding of post-match fatigue in rugby union players has been derived primarily from studies involving senior athletes. To date, no study has investigated post-match fatigue in academy rugby union players. The literature examining postmatch fatigue in other junior collision sport athletes is also far less voluminous than in senior players. A likely substantial reduction in lower-body NMF, as measured by countermovement jump (CMJ) peak power, has been observed in elite under‑18 Australian rules football players for up to 24 h following an intra-club preseason match[6] while in sub-elite youth rugby league players, reductions were reported as likely substantial immediately, and possibly substantial at 24 h and 48 h following two competitive matches.[7] Upper-body NMF, as measured by plyometric push-up peak power, has also shown very likely and likely substantial decreases at 24 h and 48 h respectively following two competitive sub-elite youth rugby league matches.[7] Furthermore, CK has been observed to peak at 24 h post-match and remain elevated at 48 h in sub-elite junior rugby league players.[7] However, no study has examined CK responses to match-play in this population beyond 48 h post-match. Understanding the time-course of recovery following a competi tive match is extremely important. Such knowledge can be applied to ensure that players have adequately recovered prior to undertaking subsequent training or competing in a later game. Failure to recover may lead to fatigue accumulation and result in injury, illness and poor performance.[2,8] Research in academy rugby union players provides scientific evidence with which to inform recovery and training practices in the post-match microcycle in this group of athletes. Therefore the purpose of the current study was to investigate the magnitude of change, and the time-course of recovery in markers of NMF, muscle damage and perception of well-being following a competitive match in academy rugby union players. Methods Subjects Fourteen players (age 17.4±0.8 years; height 182.7±7.6 cm; body mass 86.2±11.6 kg) were recruited from a professional rugby union academy. Players were excluded if they had an injury that prevented them from participating in the testing or were involved in less than 75% of the total game time. The University’s Ethics Board granted approval and written informed consent was acquired from all subjects along with parental consent. Procedures and design A within-group repeated measures design was used to examine the magnitude of change in markers of NMF, muscle damage (whole blood CK) and perception of well-being following a competitive match between academy rugby union players. Lower-body NMF was measured using a countermovement jump (CMJ), while upperbody NMF was measured using a plyometric push-up. The extent of muscle damage was examined by measuring changes in plasma CK and perception of well-being was quantified by means of a questionnaire. Measures of CMJ, plyometric push-up, plasma CK and perception of well-being were taken two hours pre-match (baseline) ORIGINAL RESEARCH and immediately post-match. Further testing was also undertaken at 24 h, 48 h and 72 h post-match at the same time of day as baseline measures to avoid diurnal effects on performance. During the testing period, players did not engage in any training or strenuous activity in the days following the match. Players were advised on nutritional intake but no recovery protocol was undertaken. Neuromuscular function Lower-body NMF was measured using mean power calculated from a CMJ, while upper-body NMF was measured using flight-time calculated from a plyometric push-up. Both of these measures have previously been proven reliable in this population (typical error = 3.1% and 4.2% respectively).[9] The CMJ and pl (...truncated)