High intensity interval training (HIIT) is currently the most widely used training modality globally. The different methodological proposals and the possibilities of adaptation to almost anyone make HIIT a very popular option.
The results of a study have recently been published (Beltrami et al, 2021; Int J Sports Physiol Perform 19-Feb; doi: 10.1123 / ijspp.2020-0104) with the objective of comparing the cardiopulmonary response versus a traditional HIIT session versus to a session of similar duration and training load, but with a progressive decrease in the load in each interval, in cyclists and runners.
Fifteen cyclists (VO2max: 62 ml / kg / min) and 15 runners (VO2max: 58 ml / kg / min) participated who performed 2 HIIT sessions on different days. The sessions consisted of four 4-minute intervals with 3-minute active recovery. The power of each interval remained constant in the traditional HIIT session, while in the modified HIIT the first interval had an increase of 40 W (2 km / h) compared to the base load of the traditional HIIT, and ended with a load 40 watts less (-2 km / h) than base load, i.e. a downstream HIIT load.
The results showed that the mean VO2 during HIIT was higher in the “descending” HIIT session in cycling (89 % vs 86 % VO2max, P = .002) but not in running (91  % vs 90 % VO2max, P = .38). Time> 90% VO2max and time> 90% HRmax also showed the same data as VO2max. Mean heart rate, pulmonary ventilation, and blood lactate were higher in “downstream” HIIT, running, and cycling.
The authors concluded that during HIIT with a descending load, notable physiological disturbances were obtained (longer> VO2max), these responses being more marked in cycling.
JL. Chicharro (PhD) Opinion:
The “traditional” structure of HIIT maintains a load for a certain number of intervals, all adjusted to try to achieve the longest bearable time in VO2 values at> 90% VO2max, as the main objective. Any variant in the HIIT structure that allows generating more time at> 90% VO2max will be considered a very attractive alternative. Generating a HIIT structure in which the first loads are higher than the VAM / PAM (maximum aerobic speed / power) may be an alternative worth exploring.