To describe the physiological responses to tournament tennis in relation to prevailing environmental conditions, match notation, and skills that underpin performance. 14 male professional tennis players (mean (SD) age, 21.4 (2.6) years; height, 183.0 (6.9) cm; body mass, 79.2 (6.4) kg) were studied while contesting international tennis tournaments. Environmental conditions, match notation, physiological (core temperature, hydration status, heart rate, blood variables), and performance indices (serve kinematics, serve velocity, error rates) were recorded. Hard and clay court tournaments elicited similar peak core temperature (38.9 (0.3) v 38.5 (0.6) degrees C) and average heart rate (152 (15) v 146 (19) beats/min) but different body mass deficit (1.05 (0.49) v 0.32 (0.56)%, p<0.05). Average pre-match urine specific gravity was 1.022 (0.004). Time between points was longer during hard court matches (25.1 (4.3) v 17.2 (3.3) s, p<0.05). Qualitative analysis of first and second serves revealed inverse relations between the position of the tossing arm at ball release and the position of the ball toss and progressive match time (respectively, r = -0.74 and r = -0.73, p<0.05) and incurred body mass deficit (r = 0.73 and r = 0.73, p<0.05). Participants began matches in a poor state of hydration, and experienced moderate thermoregulatory strain and dehydration during competition. These adverse physiological conditions may compromise performance and influence notational analyses.
