[PeterisP]

Such experiments essentially make a point that the main results of training sessions occur not because of the direct action on muscles and calorie burn during the exercise but rather because of some changes in body self-regulation that are triggered by the training session but act throughout the rest of the day/week.

If that 1 minute of 180bpm causes an upregulation of +1bpm (or an increase of base metabolism for calorie burn) for the whole next week in a way that moderate exercise doesn't, then it can quite plausibly have significant effects..