Abstract
Caffeine and nitrates have both been reported to enhance performance in power efforts; however, it is not clear which supplement is most effective. The aim of this study was to compare the effects of caffeine and nitrates on the performance of semi-professional soccer players during different fitness tests. Ten male soccer players in a randomized crossover design were assigned to receive caffeine (5 mg/kg body mass) (CG), nitrate ((250 mL/150 mg of NO3−) (NG), or a placebo (PG) on three different occasions. In each treatment, the participants performed the following tests: 10 m and 30 m sprints, the Illinois agility test, a countermovement jump test, a squat jump test, and a repeated sprint test (6 × 40 m). Caffeine boosted performance in jumps (CMJ: CGvsPG, p = 0.018; SJ: CGvsPG, p = 0.045 and CGvsNG, p = 0.001) and limited the decrease in performance in the RSA test (CGvsPG, p = 0.012). Nitrates limited the decrease in performance in the RSA test (NGvsPG, p = 0.035). In conclusion, the two supplements limited the decrease in performance in the test of repeated sprints, with caffeine showing a greater effect. Among the other tests, only caffeine improved performance, and only in the jumps. Thus, we can conclude that supplementation with caffeine 1 h before these kinds of activities at a dosage of 5 mg/kg of body weight can enhance performance.
Highlights
Soccer is an intermittent sport that includes low- and high-intensity actions
The results of this study showed that the caffeine supplement at a dose of 5 mg/kg of body weight improves jump performance (CMJ, squat jump (SJ)) and helps maintain performance in repeated sprint tests
We found that caffeine intake improved performance in both countermovement jump test (CMJ) and SJ
Summary
Soccer is an intermittent sport that includes low- and high-intensity actions. In a high-level soccer match, players cover 9 to 12 km [1] by walking or running at different speeds. The distance covered by high-intensity running is crucial to the performance of players and constitutes 8% to 12% of the total distance [1]. Previous studies have indicated that soccer players perform between 17 and 81 sprints in each match [2]. Their average duration is 2 to 4 s, and most of them (>90%) are less than 20 m [2]. It is obvious that high-intensity actions are important for performance in soccer
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