title: Carbohydrate and Caffeine Improves High-Intensity Running of Elite Rugby League Interchange Players During Simulated Match Play.
abstract: Clarke, JS, Highton, J, Close, GL, and Twist, C. Carbohydrate and caffeine improves high-intensity running of elite rugby league interchange players during simulated match play. J Strength Cond Res 33(5): 1320-1327, 2019-The study examined the effects of carbohydrate and caffeine ingestion on simulated rugby league interchange performance. Eight male elite rugby league forwards completed 2 trials of a rugby league simulation protocol for interchange players 7 days apart in a randomized crossover design, ingesting either carbohydrate (CHO; 40 g·h) or carbohydrate and caffeine (CHO-C) (40 g·h + 3 mg·kg) drink. Movement characteristics, heart rate, ratings of perceived exertion (RPE), and countermovement jump (CMJ) height were measured during the protocol. CHO-C resulted in likely to very likely higher mean running speeds (effect size [ES] 0.43-0.75), distance in high-intensity running (ES 0.41-0.64), and mean sprint speeds (ES 0.39-1.04) compared with CHO. Heart rate was possibly to very likely higher (ES 0.32-0.74), and RPE was likely to very likely lower (ES -0.53 to 0.86) with CHO-C. There was a likely trivial to possibly higher CMJ in CHO-C compared with CHO (ES 0.07-0.25). The coingestion of carbohydrate with caffeine has an ergogenic effect to reduce the sense of effort and increase high-intensity running capability that might be used to enhance interchange running performance in elite rugby league players.
authors.affiliation: University of Chester, Chester, United Kingdom.|Warrington Wolves RLFC, Halliwell Jones Stadium, Warrington, Cheshire.
authors.forename: Jon S
authors.initials: JS
authors.lastname: Clarke
authors.affiliation: University of Chester, Chester, United Kingdom.
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Highton
authors.affiliation: Research Institute of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Close
authors.affiliation: University of Chester, Chester, United Kingdom.
authors.forename: Craig
authors.initials: C
authors.lastname: Twist
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D002110:Caffeine / Q000494:pharmacology*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D005538:Football / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D009068:Movement; D005082:Physical Exertion / Q000502:physiology; D012420:Running / Q000502:physiology*; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D002110:Caffeine