Background: Tennis is a repetitive short-term high-intensity sport. As such, it could result in significant neuromuscular fatigue and decreased skill performance. Sodium bicarbonate (NaHCO3) and other alkalinizing agents have been proposed as potential performance aids for their effects on providing increased extracellular buffer capacity, leading to elevated proton (H+) efflux from the contracting musculature. This increased intramuscular (H+) during exercise has been considered a possible cause of muscle fatigue.

Hypothesis/purpose of study:To investigate the effect of NaHCO3 supplementation on skilled tennis performance after a simulated match

Subjects:Nine male, Division I, college tennis players (age, 21.8 years; height, 1.73 m), who have competed at the national level

Experimental design:Double-blind, randomized, cross-over, placebo-controlled study

Treatments and protocol:All participants completed a familiarization training session 1 week before 2 experimental trials (NaHCO3 and placebo) in a randomized order, 1 week apart. All trials were performed in the same outdoor tennis court with a hard surface, with no significant differences in temperature and humidity between trials. Participants were given NaHCO3 (0.3 g/kg body mass) or placebo (NaCl, 0.209 g/kg, equal amount of sodium) in 250 mL water. A standard breakfast (1.5 g/kg carbohydrate, including white bread, jam, and glucose drink) was ingested 20 minutes after the drink consumption. A 100-mL drink containing 0.1 g/kg NaHCO 3 or 0.07 g/kg NaCl was ingested after the third game in the simulated match. The Loughborough Tennis Skill Test (assessing accuracy and consistency of service and ground strokes to both sides of the court) was completed before and after the simulated match (12 games, alternating receiving and service). Heart rate, water consumption, and blood lactate, bicarbonate (HCO3), pH, and base excess were measured before and after the simulated match.