CONTEXT: Repeat-high-intensity efforts (RHIEs) have recently been shown to occur at critical periods of rugby league matches. PURPOSE: To examine the effect that caffeine has on RHIE performance in rugby league players. METHODS: Using a double-blind, placebo-controlled, crossover design, 11 semiprofessional rugby league players (age 19.0 ± 0.5 y, body mass 87.4 ± 12.9 kg, height 178.9 ± 2.6 cm) completed 2 experimental trials that involved completing an RHIE test after either caffeine (300 mg caffeine) or placebo (vitamin H) ingestion. Each trial consisted of 3 sets of 20-m sprints interspersed with bouts of tackling. During the RHIE test, 20-m-sprint time, heart rate (HR), rating of perceived exertion (RPE), and blood lactate were measured. RESULTS:Total time to complete the nine 20-m sprints during the caffeine condition was 1.0% faster (28.46 ± 1.4 s) than during the placebo condition (28.77 ± 1.7 s) (ES = 0.18, 90%CI -0.7 to 0.1 s). This resulted in a very likely chance of caffeine being of benefit to RHIE performance (99% likely to be beneficial). These improvements were more pronounced in the early stages of the test, with a 1.3%, 1.0%, and 0.9% improvement in sprint performance during sets 1, 2, and 3 respectively. There was no significant difference in RPE across the 3 sets (P = .47, 0.48, 1.00) or mean HR (P = .36), maximal HR (P = .74), or blood lactate (P = .50) between treatment conditions. CONCLUSIONS:Preexercise ingestion of 300 mg caffeine produced practically meaningful improvements in RHIE performance in rugby league players.
RCT Entities:
CONTEXT: Repeat-high-intensity efforts (RHIEs) have recently been shown to occur at critical periods of rugby league matches. PURPOSE: To examine the effect that caffeine has on RHIE performance in rugby league players. METHODS: Using a double-blind, placebo-controlled, crossover design, 11 semiprofessional rugby league players (age 19.0 ± 0.5 y, body mass 87.4 ± 12.9 kg, height 178.9 ± 2.6 cm) completed 2 experimental trials that involved completing an RHIE test after either caffeine (300 mg caffeine) or placebo (vitamin H) ingestion. Each trial consisted of 3 sets of 20-m sprints interspersed with bouts of tackling. During the RHIE test, 20-m-sprint time, heart rate (HR), rating of perceived exertion (RPE), and blood lactate were measured. RESULTS: Total time to complete the nine 20-m sprints during the caffeine condition was 1.0% faster (28.46 ± 1.4 s) than during the placebo condition (28.77 ± 1.7 s) (ES = 0.18, 90%CI -0.7 to 0.1 s). This resulted in a very likely chance of caffeine being of benefit to RHIE performance (99% likely to be beneficial). These improvements were more pronounced in the early stages of the test, with a 1.3%, 1.0%, and 0.9% improvement in sprint performance during sets 1, 2, and 3 respectively. There was no significant difference in RPE across the 3 sets (P = .47, 0.48, 1.00) or mean HR (P = .36), maximal HR (P = .74), or blood lactate (P = .50) between treatment conditions. CONCLUSIONS: Preexercise ingestion of 300 mg caffeine produced practically meaningful improvements in RHIE performance in rugby league players.
Authors: Ronald J Maughan; Louise M Burke; Jiri Dvorak; D Enette Larson-Meyer; Peter Peeling; Stuart M Phillips; Eric S Rawson; Neil P Walsh; Ina Garthe; Hans Geyer; Romain Meeusen; Lucas J C van Loon; Susan M Shirreffs; Lawrence L Spriet; Mark Stuart; Alan Vernec; Kevin Currell; Vidya M Ali; Richard Gm Budgett; Arne Ljungqvist; Margo Mountjoy; Yannis P Pitsiladis; Torbjørn Soligard; Uğur Erdener; Lars Engebretsen Journal: Br J Sports Med Date: 2018-03-14 Impact factor: 13.800