Abstract
PurposeCollision sports are characterised by frequent high-intensity collisions that induce substantial muscle damage, potentially increasing the energetic cost of recovery. Therefore, this study investigated the energetic cost of collision-based activity for the first time across any sport.MethodsUsing a randomised crossover design, six professional young male rugby league players completed two different 5-day pre-season training microcycles. Players completed either a collision (COLL; 20 competitive one-on-one collisions) or non-collision (nCOLL; matched for kinematic demands, excluding collisions) training session on the first day of each microcycle, exactly 7 days apart. All remaining training sessions were matched and did not involve any collision-based activity. Total energy expenditure was measured using doubly labelled water, the literature gold standard.ResultsCollisions resulted in a very likely higher (4.96 ± 0.97 MJ; ES = 0.30 ± 0.07; p = 0.0021) total energy expenditure across the 5-day COLL training microcycle (95.07 ± 16.66 MJ) compared with the nCOLL training microcycle (90.34 ± 16.97 MJ). The COLL training session also resulted in a very likely higher (200 ± 102 AU; ES = 1.43 ± 0.74; p = 0.007) session rating of perceived exertion and a very likely greater (− 14.6 ± 3.3%; ES = − 1.60 ± 0.51; p = 0.002) decrease in wellbeing 24 h later.ConclusionsA single collision training session considerably increased total energy expenditure. This may explain the large energy expenditures of collision-sport athletes, which appear to exceed kinematic training and match demands. These findings suggest fuelling professional collision-sport athletes appropriately for the “muscle damage caused” alongside the kinematic “work required”.
Highlights
Team-based collision sports such as rugby league, rugby union, rugby sevens, American Football and Australian Football are defined by frequent high-intensity collisions (Clarke et al 2017; Edwards et al 2017; Gray and Jenkins 2010; Hausler et al 2016; Quarrie et al 2013)
There was a very likely higher (200 ± 102 AU; effect size (ES) = 1.43 ± 0.74; p = 0.007) sessional ratings of perceived exertion (sRPE) during the COLL training session and a very likely greater (− 14.6 ± 3.3%; ES = − 1.60 ± 0.51; p = 0.002) decrease in wellbeing 24 h after the COLL training session compared with the nCOLL training session
Differences in accumulated sRPE across the COLL training microcycle (1785 ± 236 AU) were unclear (89 ± 327 AU; ES = 0.30 ± 0.84; p = 0.533; supplementary material, Table 3) compared with the nCOLL training microcycle (1696 ± 253 AU). This is the first study to investigate the energetic cost of collisions across any sport
Summary
Team-based collision sports such as rugby league, rugby union, rugby sevens, American Football and Australian Football are defined by frequent high-intensity collisions (Clarke et al 2017; Edwards et al 2017; Gray and Jenkins 2010; Hausler et al 2016; Quarrie et al 2013). Isometric holding, blocking, wrestling, hit-ups and impacts with the playing surface (Naughton et al 2017) Both collision frequency and magnitude are sport, match and position specific; typically reflect increases in physical fitness, anthropometric quality and playing ability within professional athlete cohorts (Clarke et al 2017; Hausler et al 2016). An acute phase inflammatory response and tissue remodelling period are initiated (Hyldahl and Hubal 2014), substantially upregulating whole body protein turnover (Peake et al 2017) Such dramatic perturbations of homeostasis are likely to be energetically expensive (Welle and Nair 1990), potentially increasing post-exercise metabolism (Burt et al 2014) and the energetic cost of recovery for up to 120 h after competitive match play (McLellan et al 2011), throughout the season (Fletcher et al 2016)
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