Does carbohydrate supplementation enhance tennis match play performance?

Journal of the International Society of Sports Nutrition Does carbohydrate supplementation enhance tennis match play performance? Rodrigo Vitasovic Gomes Caroline Dario Capitani Carlos Ugrinowitsch Michael Christopher Zourdos Jaime Fernandez-Fernandez Alberto Mendez-Villanueva Marcelo Saldanha Aoki 0 0 School of Arts, Sciences and Humanities, University of Sao Paulo , Av Arlindo Bettio, 1000, Sao Paulo 03828-000 , Brazil Background: Carbohydrate (CHO) ingestion may be an interesting approach to avoid significant decrement to the tennis match performance. The aim of the present investigation was to assess the effects of CHO supplementation on tennis match play performance. Methods: Twelve young tennis players (18.0 1.0 years; 176 3.4 cm; 68.0 2.3 kg; body fat: 13.7 2.4%) with national rankings among the top 50 in Brazil agreed to participate in this study, which utilized a randomized, crossover, double blind research design. The experiment was conducted over a 5-day period in which each player completed two simulated tennis matches of a 3-hour duration. The players received either a CHO or a placebo (PLA) drinking solution during simulated tennis matches. Athlete's performance parameters were determined by filming each match with two video cameras. Each player was individually tracked for the entire duration of the match to measure the following variables: (1) games won; (2) rally duration; (3) strokes per rally; (4) effective playing time (%); (5) aces; (6) double faults; (7) first service in; (8) second service in; (9) first return in and (10) second return in. Results: There were no differences between trials in any of the variables analyzed. Conclusions: CHO supplementation did not improve tennis match play performance under the present experimental conditions. Match analysis; Glycemia; Performance - Background There is strong evidence that appropriate selection of nutrients, timing of intake, and proper supplement choice are associated with optimal health and exercise performance [1]. During exercise, carbohydrate (CHO) supplementation is one of the most popular dietary recommendations to provide energy to skeletal muscles and the central nervous system [1-6]. Further, to ensure proper CHO delivery to the contracting skeletal muscles, the American College of Sports Medicine along with the Academy of Nutrition and Dietetics (AND) (formerly recognized as the American Dietetic Association) each recommend ingestion of a CHO solution during prolonged exercise [1,5]. This recommendation is supported by early empirical evidence regarding the positive effects of CHO supplementation to enhance endurance exercise performance [7,8]. However, even though a tennis match encompasses a long total period of time, the overall exercise requirements of a match differ from traditional endurance exercise. To illustrate, a tennis match involves intermittent bouts of high-intensity effort interspersed with periods of lowintensity activity, during which active recovery (between points) and passive periods (between changeover breaks in play) take place (20 s), over an extended period of time [9-11]. In the major international tournaments (e.g. Grand Slam events and Davis Cup), male players may play several matches within a relatively short period of time (i.e. <2 hours), however, some matches may extend to greater than 5 hours. Consequently, it is conceivable that such a long tennis match may deplete glycogen stores and produce a state of hypoglycemia [12]. Therefore, CHO ingestion may be an interesting approach to avoid significant decrements to a players performance. Presently, only a few studies have investigated the effects of CHO supplementation on tennis performance [13-18]. Moreover, the available data regarding the benefits of CHO supplementation on tennis performance are equivocal. For example, hitting accuracy decreased in the PLA trial when compared to the CHO trial [16]. Similarly, CHO supplementation maintained ground stroke accuracy and increased muscle power after simulated tennis tournament [17]. Conversely, a previous study did not observe any significant positive effect of CHO ingestion on serve and ground stroke velocity as well as stroke accuracy during tennis match play [13]. Additional investigations observed similar results showing no significant effect in the CHO condition when compared to a PLA regarding serve velocity or unforced error [14], fan drill speed and percentage points won and lost [15] during tennis match play. In contrast, Ferrauti & Weber [18] reported that CHO supplementation improved tennis specific running speed test, but interestingly this improvement in speed had no effect on stroke accuracy and games won during a match simulation. Ultimately, there have been controversial results regarding the effects of CHO supplementation on tennis performance [13-18], however, the authors of the present investigation hypothesized that CHO supplementation would serve to avoid performance decrement during prolonged tennis match play. Therefore, the aim of the present investigation was to assess the effect of CHO supplementation on tennis match play performance among nationally ranked young players. male tennis, involved in regular tennis competitions at the national level, with a national ranking between 10 and 55, volunteered to participate in this study. The mean training background of the players was 15 hoursper week, for a minimum of 5 years. Prior to participation, the experimental procedures and potential risks were fully explained to the athletes and their parents. Additionally, written informed consent was obtained from both the players and their parents. Players with any pre-existing medical conditions (i.e. musculoskeletal injuries, metabolic disorders, severe illness) that could have influence in their hormonal responses or performance were excluded from the study. The study protocol was approved by the Human Subject Committee of the University of So Paulo, CAAE: 09860412.6.0000.5391. Experimental design This study was conducted over a 5-day period, in which each player completed 3 hours of simulated tennis match play, on 2 separate occasions (Figure 1). Subjects ingested either a CHO or PLA beverage in a double blind, randomized, placebo-controlled crossover design. A 48-hour recovery period was granted between each match. During the 2 weeks prior to commencing the study, all players decreased training volume (from 2 sessions to 1 session per day) to ensure each athlete was properly recovered at the studys onset. Additionally, this study was conducted during a training camp and researchers carefully controlled food and fluid ingestion, and exercise volume. With the exception of the modified match structure, all games were played according the rules of the International Tennis Federation (ITF) [19] and conducted on an outdoor red clay court. Following the ITF rules, ten nis balls (Fort Clay Court Dunlop, Philippines) were Figure 1 Ex (...truncated)