The aim of this study was to examine the influence of a pressurized tennis ball 6% greater in diameter (Type 3) than a standard sized (Type 2) ball on performance and the physiological responses to the Loughborough Intermittent Tennis Test (LITT) (Davey et al., 2002). Eight competitive tennis players (males, n = 4, age 24.8 [+ or -] 3.5 years, body mass 81.3 [+ or -] 3.1 kg, height 1.74 [+ or -] 0.02 m, estimated V[O.sub.2max] 54.4 [+ or -] 2.6 ml x [kg.sup.-1] x [min.sup.-1] females, n = 4, age 26.3 [+ or -] 3.1 years, body mass 67.0 [+ or -] 6.7 kg, height 1.68 [+ or -] 0.02 m, estimated V[O.sub.2max] 49.9 [+ or -] 3.3 ml x [kg.sup.-1] x [min.sup.-1]; mean [+ or -] [S.sub.x]) ...