Table 1

Demographic data by court surface

TotalClayHard CourtSand-fill artificial grassRed-sand-fill artificial grassMultiple court surfaces
Number of respondents (%)3320600 (18.1)718 (21.6)627 (18.9)927 (27.9)448 (13.5)
Total number of questionnaires over all six measurements (%)11 1372894 (26.0)2378 (21.4)2085 (18.7)2620 (23.5)1160 (10.4)
Age, years (SD)49.0 (15)49.0 (14.9)48.8 (15.5)48.4 (14.2)48.9 (14.8)47.6 (14.2)
Injury <12 months (%)1740 (52)346 (58)367 (51)320 (51)484 (52)223 (50)
Tennis hours per
player per month
(SD)
8.8 (5.3)8.0 (4.0)7.6 (3.8)7.0 (3.4)8.0 (3.9)12.0 (4.9)*
  • Values are given as mean (SD) of frequency (%).

  • *Indicates a significant difference compared with clay (p<0.05).