Table 2. Selected physiological responses and maximal running speed reached at the end of the different 30-15 protocols. Data are means (±SD). Group A Group B 30-15IFT 30-15IFT-LINE 30-15IFT-CONT 30-15IFT 30-15IFT-28m VIFT (km·h-1) 19.7 (1.2) 21.7 (1.9) * 16.1 (1.0) *†  18.8 (2.1) 18.7 (1.8) HRpeak(b·min-1) 197 (10) 197 (7) 194 (8) 198 (9) 199 (9) HR/speed 3.9 (.8) 3.4 (.6) 5.8 (1.1) *†  4.2 (1.0) 3.9 (.8) § [La]b (mmol·L-1) 12.3 (2.5) 11.3 (2.6) 9.6 (3.2) *‡ 11.3 (2.1) 11.5 (2.8) RPE 9 (1) 9 (1) 8 (1) 8 (1) 8 (1) V : maximal running speed, HR : peak heart rate, [La]: blood lactate concentration, RPE : rating of perceived exertion, 30-15 : original 30-15, 30-15 : modified version of the 30-15 without a rest period, 30-15 : modified version of the 30-15 without change of direction, 30-15 : modified version of the 30-15 with 28-m shuttles. *: difference . 30-15 (p < 0.05) † : difference . 30-15 (p < 0.05) ‡: difference . 30-15 with effect size considered as moderate (>0.5) §: difference . 30-15 with effect size considered as small (0.2