30-15IFT
The 30-15IFT was conducted according to the procedures outlined by Buchheit (11). Briefly, athletes performed 30 s shuttle runs interspersed with 15 s of passive recovery, having initial velocity of 10 km.h-1, with increments of 0.5 km.h-1 every 45 s. The 30-15IFT was performed over a 40 m shuttle distance, within which the subject had to run back and forth at a pace governed by a prerecorded beep, so that at each short beep sound the subjects should be within 3 m zones at each extremity or in the middle of the course. During the 15 s recovery period, athletes walked in the forward direction to join the closest line from where they started the next stage from a standing position. Exhaustion was defined as the inability to match the covered distance with the audio signal on three consecutive occasions. The last completed stage (VIFT) was used to predict VO2max using the equation below, proposed by Buchheit et al. (15):