High-intensity interval training (HIIT) is no more effective than steady-state exercise for sedentary people new to exercise and may actually turn these people off of exercise, a study commissioned by the American Council on Exercise (ACE), San Diego, found.
HIIT advocates say that this type of intense interval exercise with short rest periods can produce significant results in a shorter time, which can help time-strapped people improve their health. The ACE study set out to see if this was the case.
Conducted by researchers at the University of Wisconsin–La Crosse, the study compared the physiologic responses of two HIIT workouts (Tabata and a less intense interval training workout) with steady-state cardio exercise in previously inactive young adults.
"In the study, the HIIT workouts didn't produce significantly greater improvements in markers of aerobic and anaerobic exercise performance compared to steady-state cardio for sedentary young adults," said ACE Chief Science Officer Cedric X. Bryant, Ph.D. "Arguably, one of the more interesting findings of this study was the significantly lower level of enjoyments reported by individuals in the Tabata training group compared to the other two training groups."
This lower level of enjoyment associated with Tabata workouts could potentially result in poor long-term adherence, according to American Council on Exercise.
In the study, which was led by Carl Foster, Ph.D., researchers recruited 65 relatively sedentary young adults between 18 and 28 years old who hadn't exercised more than twice per week at a low-to-moderate intensity in the prior three months. Prior to randomly assigning each participant to one of three eight-week, three-sessions-per-week stationary cycling programs, researchers measured the study participants' exercise capacity. The first group performed 20 minutes of steady-state, moderate-to-vigorous intensity exercise. The second performed four minutes of Tabata training in sets of 20 seconds of highly intense exercise followed by 10 seconds of unloaded, recovery pedaling. The third group performed 20 minutes of interval training consisting of sets of 30 seconds of intense exercise followed by 60 seconds of recovery pedaling. Each week, participants rated their enjoyment level of the exercise program.
Indicators of fitness and cardiorespiratory health, such as VO2max and body-weight normalized power output, improved for all of the groups over the course of the study at similar rates despite the differences in the exercise programs. Members of the Tabata group indicated the lowest amount of enjoyment, and their enjoyment declined the most over time. All groups' enjoyment levels decreased steadily over the eight-week period.
"While very important, the effectiveness of a fitness program matters relatively little if participants find it unpleasant and something they would unlikely adhere to for the long haul," Bryant added. "The results of this study appear to suggest that the high-intensity nature of the Tabata workouts served as a turnoff for previously inactive participants. These findings help to reinforce the principle that it is critically important that health and fitness professionals design exercise programs that are individualized and appropriate for the needs, interests and abilities of their clients or activity participants."