Interestingly, HIIT induced negative feelings in the study participants (seriously, one more box jump?!?), but this was associated with higher endorphin release to perhaps cancel it out.
A less intense hour-long aerobic class did not boost endorphins significantly, but it did increase “pleasurable feelings and euphoria.”
Clearly, the endorphin release mechanism is a bit of a mixed bag. The researchers believe at moderate training levels, the happy feelings may help you go back for more exercise. But at high intensities, the endorphins are there to manage all your neggy feelings about a killer workout. If the negative feelings prevail, they could discourage us from going back for more. However regardless, it does cause the good hormones to flow.
This study is important as the researchers believe exercise-induced endorphin release might determine whether we maintain motivation and keep coming back for one more circuit.
Take home: HIIT has many body and brain benefits – but you should ultimately choose the exercise you’ll be able to commit to in the long term.