Sodium bicarbonate supplementation prevents skilled tennis performance decline after a simulated match

Tennis is an intermittent sport with the actual playing time being 17-28% of total match duration [1]. The remainder of the time is recovery between points and games. On average, the rallies last 4.3-7.7 sec in men's Grand Slam tournament matches [2]. At the stroke frequency of approximately 0.75 shots. sec-1 [2], the cumulative effect of the repetitive short-term high-intensity efforts throughout prolonged tennis matches could result in significant neuromuscular fatigue [1,3], which in turn may impair certain aspects of skilled performance [4,5]. Indeed, the stroke accuracy was significantly decreased in competitive tennis players near the point of volitional fatigue [6]. Stroke accuracy and velocity were also significantly decreased after a strenuous training session (average rating of perceived exertion (RPE) 15.9/20) in well-trained tennis players [7].One of the potential factors that may influence the skilled tennis performance is neural function. The central activation failure, changes in neurotransmitter levels and disturbance in excitation-contraction coupling have been suggested to play an important role in the development of fatigue in prolonged tennis matches [3,8]. The decline in maximal voluntary contraction and electromyographic activity of knee extensor muscles occurred progressively during a 3-hour tennis match, indicating a decreasing number of motor units that are voluntarily recruited [3]. The impairments in neural functions in lower limbs may lead to the slower acceleration in movement and the inability to reach the optimal stroke position. In addition, the neural impairments in forearm muscles may result in the poor control of the racquet.Alkalinizing agents including sodium bicarbonate (NaHCO3) have been proposed as ergogenic aids for their potential effects on providing enhanced extracellular buffer capacity, leading to the elevated proton (H+) efflux from the contracting musculature [9,10]. The increased intramuscular [H+] during exercise has