Caffeine Supplementation and Physical Performance, Muscle Damage and Perception of Fatigue in Soccer Players: A Systematic Review

Abstract

Soccer is a complex team sport and success in this discipline depends on different factors such as physical fitness, player technique and team tactics, among others. In the last few years, several studies have described the impact of caffeine intake on soccer physical performance, but the results of these investigations have not been properly reviewed and summarized. The main objective of this review was to evaluate critically the effectiveness of a moderate dose of caffeine on soccer physical performance. A structured search was carried out following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in the Medline/PubMed and Web of Science databases from January 2007 to November 2018. The search included studies with a cross-over and randomized experimental design in which the intake of caffeine (either from caffeinated drinks or pills) was compared to an identical placebo situation. There were no filters applied to the soccer players’ level, gender or age. This review included 17 articles that investigated the effects of caffeine on soccer-specific abilities (n = 12) or on muscle damage (n = 5). The review concluded that 5 investigations (100% of the number of investigations on this topic) had found ergogenic effects of caffeine on jump performance, 4 (100%) on repeated sprint ability and 2 (100%) on running distance during a simulated soccer game. However, only 1 investigation (25%) found as an effect of caffeine to increase serum markers of muscle damage, while no investigation reported an effect of caffeine to reduce perceived fatigue after soccer practice. In conclusion, a single and moderate dose of caffeine, ingested 5–60 min before a soccer practice, might produce valuable improvements in certain abilities related to enhanced soccer physical performance. However, caffeine does not seem to cause increased markers of muscle damage or changes in perceived exertion during soccer practice.

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

“…As recently identified, caffeine supplementation may have a "responder" vs. "non-responder" nature, which limits the translation to "non-responder" populations [33]. The current investigation found a significant learning effect; however, it is possible that participants 2, 3,8,9,10,11,12,15,17,18,19, and 20 may have been "non-responders" to caffeine supplementation (see Table 1). The inter-individual differences in the ergogenicity of caffeine are thought to be related to genetic polymorphisms associated with the CYP1A2 and ADORA2A genes, which discern fast and slow caffeine metabolism/clearance [49,50].…”

“…Although 20 CrossFit ® -trained men completed the study, the sample size is reasonably small. However, the average sample size reported in a recently published systematic review on the effects of caffeine in trained soccer players was 15 participants; therefore, the current investigation reflects similar sample sizes compared to other studies regarding caffeine's ergogenic effect in trained populations [10].…”

“…The current investigation provides a unique addition to the literature, as participants were instructed to complete as much work as possible within the 20 min time limit while performing multiple multi-joint body weight exercises. Multi-joint exercises have been speculated to increase RPE [5]; however, similar to some investigations, significant changes in RPE between the caffeine and placebo conditions were not detected [10,20,46]. However, other investigations assessing the effects of caffeine on RPE during resistance training exercise have provided mixed results [5].…”

“…However, some athletes are not easily classified into physical demands that are strictly endurance-or strength/power-based in nature and require multiple facets of health-(e.g., aerobic capacity and muscular strength) and skill-related (e.g., agility, speed, and power) physical fitness [9]. Recently, Mielgo-Ayuso addressed this concern within soccer players; however, a majority of the reviewed investigations evaluated aspects of physical performance (i.e., speed, power, agility, and time-to-exhaustion) with limited data reported regarding simulated performance [10]. Reasonably, instructing athletes with diverse physical demands to consume caffeine for performance benefits has limited evidence to support its efficacy [10,11].…”

“…Recently, Mielgo-Ayuso addressed this concern within soccer players; however, a majority of the reviewed investigations evaluated aspects of physical performance (i.e., speed, power, agility, and time-to-exhaustion) with limited data reported regarding simulated performance [10]. Reasonably, instructing athletes with diverse physical demands to consume caffeine for performance benefits has limited evidence to support its efficacy [10,11]. Since preserving muscle function during competition is important for preventing premature fatigue, investigating the role of acute caffeine supplementation during combined exercise modalities is warranted.…”