The Influence of Caffeine on Tolerance to Sport-Specific High-Intensity Exercise in Young Elite Soccer Players.

Background: Modern elite football places extremely high demands on the athlete's body, so it is of practical interest to study the effect of various dietary supplements on load tolerance and postexercise recovery. Furthermore, there is a lack of research on the effects of caffeine on key measures of load tolerance in football such as delayed-onset muscle soreness (DOMS), rate of perceived exertion (RPE) and heart rate (HR) at different time points after the exercise.

Methods: 54 young players aged 15-17 years from a leading Russian football academy took part in a randomised trial using the balanced placebo design. They were divided into 4 groups: 1 - told caffeine/given caffeine, 2 - told caffeine/given placebo, 3 - told placebo/given placebo and 4 - told placebo/given caffeine. All participants consumed two capsules 60 min before testing, each containing 200 mg of caffeine or placebo. Sprinting, counter-movement jump, change of direction run, dribbling, T-test and the repeated sprint ability test were used to create conditions for high-intensity sports-specific load. A visual analogue scale was used to assess the severity of muscle soreness. RPE was assessed using the Borg Rating of Perceived Exertion scale. HR immediately postexercise (HRpe), HR after 2 min of passive rest (HRrest) and recovery HR (HRrec = HRpe - HRrest) were obtained.

Results: The data demonstrated that a single caffeine intake of 400 mg had no statistically significant effect on RPE (p = 0.948), HRpe (p = 0.698) or HRrec (p = 0.920) across the groups. Additionally, the severity of DOMS 24 h postexercise did not differ significantly between the groups (p = 0.077).

Conclusion: Acute caffeine ingestion does not affect the subjective and objective indicators of training load in young football players aged 15-17 years with low levels of anxiety and low levels of daily caffeine intake.