Effects of the playing surface on plantar pressures and potential injuries in tennis.

OBJECTIVES To examine the influence of different playing surfaces on in-shoe loading patterns during tennis-specific movements. METHODS Ten experienced male players performed two types of tennis-specific displacements (serve and volley (SV) and baseline play (BA)) on two different playing surfaces; eg, clay vs Greenset. Maximum and mean force and pressure, contact time, contact area and relative load were recorded by an insole with 99 sensors (X-Pedar system) divided into 9 areas. RESULTS Regarding the whole foot, mean (SD) force (SV: 615 (91) vs 724 (151) N; -12.4%, p<0.05 and BA: 614 (73) vs 717 (133) N; -11.6%, p<0.05) was lower on clay than on Greenset, whereas contact time was longer (SV: 299 (113) vs 270 (148) ms; +16.5%, NS and BA: 354 (72) vs 272 (60) ms; +30.3%, p<0.001). Greenset induced higher loading in the hallux (SV: +15.3%, p<0.05 and BA: +11.4%, not significant) and lesser toes areas (SV: +12.6%, p<0.05 and BA: +18.0%, p<0.01). In contrast, the relative load on the medial (SV: +27.4%, p<0.05 and BA: +16.1%, p = 0.06) and lateral midfoot (SV: +23.3%, p<0.05 and BA: +28.3%, p<0.01) was higher on clay. CONCLUSIONS This study demonstrates that playing surface affects plantar loading in tennis: Greenset induced higher loading in the hallux (SV: +15.3%, p<0.05 and BA: +11.4%, NS) and lesser toes areas (SV: +12.6%, p<0.05 and BA: +18.0%, p<0.01) but lower relative load on the medial (SV: -27.4%, p<0.05 and BA: -16.1%, p = 0.06) and lateral midfoot (SV: -23.3%, p<0.05 and BA: -28.3%, p<0.01) than clay.