Terence Moriarty, MA

If your clients haven't already asked you about it, they will. High-intensity interval training is a mainstay in personal training programs and group fitness classes. There are several reasons why HIIT is a good workout, one of them being its brevity. Research indicates that the four most common barriers to exercise are not having time, feeling too tired, getting enough exercise at one's job, and having no motivation to exercise (Brownson et al. 2001).