Supervised lab sessions are not a good reflection of real-life exercise, however. So, as a final step in the study, the researchers asked the volunteers to go home and work out on their own for a month, keeping exercise logs, then return to the lab to talk at length with the researchers again.
This month of do-it-yourself workouts proved to be revealing. Almost everyone remained active, with most completing frequent, moderate exercise sessions, like the 45-minute bike rides at the lab. But many also threaded some sort of interval training into their weekly workouts, although few of these sessions replicated the structured intervals from the lab. Instead, people tended to sprint up and down stairs or grunted through some quick burpees and other body weight exercises.
Most interesting, during their subsequent, prolonged interviews with the researchers, the volunteers who interval trained on their own said they felt more engaged and