Table 3

 Quantitative performance indices of men’s professional tennis matches played on hard and clay courts

Hard courtClay court
Mean (SD)Mean (SD)
Of the two players contesting each match, values (mean (SD)) represent those of only the player participating in the investigation (n = 6). Values in parentheses (n) represent the number of data from which mean and SD are derived.
First serve velocity (kph)178 (9)172 (14)
(n = 445)(n = 375)
Second serve velocity (kph)135 (10)134 (12)
(n = 199)(n = 147)
First serve accuracy (%)56 (24)55 (24)
Points won on first serve (%)72 (33)76 (25)
Points won on second serve (%)63 (34)61 (35)
Unforced errors (%)24 (13)24 (17)