American Council on Exercise Releases Study Results on HIIT Exercise for Newcomers

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The American Council on Exercise (ACE), along with the University of Wisconsin-La Crosse, conducted a study on the effectiveness of high intensity interval training, commonly known as HIIT, among those starting exercise from a previously sedentary lifestyle. The study produced surprising results, given HIIT-style’s status as the ideal way to exercise over the past few years, revealing that participants who engaged in HIIT workouts saw improvements in their health at similar rates to those who engaged in steady-state cardio exercise.

The study took 65 sedentary young adults between the ages of 18 and 28 and had them exercise on a stationary bike three times per week for eight weeks. Researchers randomly assigned participants to one of three groups: a Tabata group, which cycled at high intensity for 20 seconds followed by 10 seconds of recovery; an interval group, which cycled at high intensity for 30 seconds followed by 60 seconds of recovery; and a steady-state group, which cycled for 20 minutes at a moderate-to-vigorous pace. Researchers tracked improvement by measuring participants’ pre-program VO2 max, aerobic power, peak power output, mean power output and combined exercise capacity.

The most similar rates of change appeared in participants’ VO2 max scores, which improved by 19 percent for those engaging in steady-state cardio and 18 percent for those who engaged in Tabata or interval workouts. However, the only measure that saw a substantial improvement using HIIT exercise compared to other forms came in the aerobic power measurement, where Tabata exercises saw a 24 percent improvement, compared to a 17 percent improvement in steady state exercisers and a 14 percent improvement in interval exercisers.

Researchers also asked participants to rate their enjoyment of their exercise, and found that all three groups reported lower levels of enjoyment as the program wore on, with Tabata participants recording the lowest level of enjoyment. While this doesn’t mean health and fitness professionals should avoid using these styles in their training programs, ACE did use this to highlight the importance of adapting a program to an individual client and his or her tastes in its conclusion. ACE also emphasizes that the findings of this study relate to fitness newcomers, rather than those who have an established pattern of exercise in their lives.