MUJIKA, I., S. PADILLA, J. IBAÑEZ, M. IZQUIERDO, and E. GOROSTIAGA. Creatine supplementation and sprint performance in soccer players. Med. Sci. Sports Exerc., Vol. 32, No. 2, pp. 518–525, 2000.
Purpose: This investigation examined the effects of creatine (Cr) supplementation on intermittent high-intensity exercise activities specific to competitive soccer.
Methods: On two occasions 7 d apart, 17 highly trained male soccer players performed a counter-movement jump test (CMJT), a repeated sprint test (RST) consisting of six maximal 15-m runs with a 30-s recovery, an intermittent endurance test (IET) consisting of forty 15-s bouts of high-intensity running interspersed by 10-s bouts of low-intensity running, and a recovery CMJT consisting of three jumps. After the initial testing session, players were evenly and randomly included in a CREATINE (5 g of Cr, four times per day for 6 d) or a PLACEBO group (same dosage of maltodextrins) using a double-blind research design.
Results: The CREATINE group’s average 5-m and 15-m times during the RST were consistently faster after the intervention (0.95 ± 0.03 vs 0.97 ± 0.02 s, P < 0.05 and 2.29 ± 0.08 vs 2.32 ± 0.07 s, P = 0.07, respectively). Neither group showed significant changes in the CMJT or the IET. The CREATINE group’s recovery CMJT performance relative to the resting CMJT remained unchanged postsupplementation, whereas it tended to decrease in the PLACEBO group.
Conclusion: In conclusion, acute Cr supplementation favorably affected repeated sprint performance and limited the decay in jumping ability after the IET in highly trained soccer players. Intermittent endurance performance was not affected by Cr.
Recent investigations have focused on the possible ergogenic value of supplementing the athletes’ diet with approximately 20 g·d−1 of creatine (Cr) monohydrate for 5 to 7 d. It has often been shown that this type of acute Cr supplementation can result in increased total muscle Cr (5,15,21,24,25,27,29,30,39,49) and phosphocreatine (PCr) (15,21,29,30,52) concentrations. Studies have also shown that this elevated intramuscular PCr can enhance the rate of ATP and PCr resynthesis after high-intensity efforts, causing a delayed onset of muscular fatigue and an increased performance during repeated bouts of high-intensity exercise (1,5,15,18,26,27,35).
In a recent review of the literature, it was suggested that highly trained athletes who participate in sports in which performance relies on repeated efforts could benefit from Cr ingestion by means of an increased ability to perform intermittent high-intensity exercise bouts either during training or competition (38). This would be the case in competitive soccer. Indeed, it has been reported that, among professional players, high-intensity running accounts for about 8–18% of the total playing time during a soccer match, whereas 70–80% of the playing time is spent walking or running at a low intensity (8,45,53,54). In addition to the intermittent high-intensity running pattern, players also perform 10–19 tackles and 9–13 headings, most of which involve jumping for aerial possession of the ball (8,19,54). Moreover, a relationship has been reported between the quality of the soccer play and the amount of high-intensity exercise performed during a match (19).
This investigation was thus designed to determine whether acute oral Cr supplementation could enhance performance and recovery in highly trained soccer players performing sport-specific exercise tasks, and to analyze the influence of this intervention on the main metabolic pathways supplying the necessary energy for the completion of those tasks.
Departamento de Investigación y Desarrollo, Servicios Médicos, Athletic Club de Bilbao, Basque Country, SPAIN; and Centro de Investigación y Medicina del Deporte, Instituto Navarro de Deporte y Juventud, Pamplona-Iruña, Navarra, SPAIN
Submitted for publication November 1998.
Accepted for publication May 1999.
Address for correspondence: Iñigo Mujika, Ph.D., MEDIPLAN SPORT S.L., Obdulio López de Uralde 4, bajo, 01008 Vitoria-Gasteiz, Basque Country, Spain. E-mail: email@example.com.