Acute influences of tennis services on cardiac output and brachial hemodynamics in young male tennis players

Objectives: This study aimed to examine the influences of tennis service exercise on cardiac output (CO) and bilateral brachial hemodynamics in young tennis players. Design: Experimental study. Methods: Ten young male tennis players (21 ± 2 years of age) participated. Each performed 100 tennis services without a return shot for experimental tennis exercise. Cardiovascular hemodynamic variables, including bilateral brachial blood flow (BF), shear rate (SR), blood pressure, and CO, were collected under three conditions: 1) baseline, 2) immediately after the tennis services (post), and 3) 1 h after the tennis services (1-hour). The positive incremental area under the curve (iAUC) for brachial hemodynamic variables was calculated. Results: Immediately after the 100 tennis services, CO, brachial BF, SR, and brachial vascular conductance (VC) in the dominant and non-dominant arms increased (p < 0.05). At the 1-hour condition, CO returned to baseline; the brachial BF, SR, and VC in the non-dominant arm returned to baseline levels, whereas the same variables in the dominant arm remained increased. The iAUC for brachial BF and VC in the dominant arm was higher than that in the non-dominant arm. Furthermore, the brachial BF/CO ratio index in the dominant arm increased at the post and 1-hour conditions, whereas that in the non-dominant arm was unchanged. Conclusions: Tennis service exercise specifically increases brachial BF, SR, and VC in the dominant arm, independent of increased CO. Our findings contribute to unveiling the underlying mechanisms of brachial artery adaptations in tennis players.