Effects of a caffeine-containing energy drink on simulated soccer performance

Abstract

Background: To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake.

Methodology/principal findings: Nineteen semiprofessional soccer players ingested 630 ± 52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7 × 30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7 ± 4.7 v 35.8 ± 5.5 cm; P<0.05), mean running speed during the sprint test (25.6 ± 2.1 v 26.3 ± 1.8 km · h(-1); P<0.05) and total distance covered at a speed higher than 13 km · h(-1) during the game (1205 ± 289 v 1436 ± 326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30 ± 10 v 24 ± 8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1 ± 1.0 v 0.1 ± 0.1 µg · mL(-1); P<0.05).

Conclusions/significance: A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball.

Figure 1. Vertical jump height during a 15-s maximal jump test.

Vertical jump height during a 15-s maximal jump test with the ingestion of a caffeinated energy drink (3 mg of caffeine/kg of body weight) or the ingestion of a decaffeinated control drink. Data are mean ± SD for 19 soccer players. * Different from control (P<0.05).

Figure 2. Maximal running speed during a 7×30 m sprint test.

Maximal running speed during a 7×30 m sprint test with the ingestion of a caffeinated energy drink (3 mg of caffeine/kg of body weight) or the ingestion of a decaffeinated control drink. Data are mean ± SD for 19 soccer players. * Different from control (P<0.05).

Figure 3. Running distance at 10 min intervals during a simulated soccer game.

Running distance at 10 min intervals during a simulated soccer game with the ingestion of a caffeinated energy drink (3 mg of caffeine/kg of body weight) or the ingestion of a decaffeinated control drink. Data are mean ± SD for 19 soccer players. * Different from control (P<0.05).

Figure 4. Running distance covered at different speeds during a simulated soccer game.

Running distance covered at different speeds during a simulated soccer game with the ingestion of a caffeinated energy drink (3 mg of caffeine/kg of body weight) or the ingestion of a decaffeinated control drink. Data are mean ± SD for 19 soccer players. * Different from control (P<0.05). Dashed lines indicate the half time. Zone 1 (Standing) = 0–0.4 Km · H⁻¹; Zone 2 (Walking) = 0.5–3.0 Km · H⁻¹; Zone 3 (Low-Intensity Running) = 3.1–8.0 Km · H⁻¹; Zone 4 (Medium-Intensity Running) = 8.1–13.0 Km · H⁻¹; Zone 5 (High-Intensity Running) = 13.1–18.0 Km · H⁻¹; Zone 6 (Sprinting) = Speed Higher Than 18.0 Km · H⁻¹.