Title: High Intensity Interval Training in a Real World Setting: A Randomized Controlled Feasibility Study in Overweight Inactive Adults, Measuring Change in Maximal Oxygen Uptake
Authors: Lunt H, Draper N, Marshall HC, Logan FJ, Hamlin MJ, et al
Journal: PLOS ONE
Date: 2015
Impact Factor: 4.2
Web-link
Why they did it?
High-intensity interval training (HIIT) is a mode of exercise which consists of alternating periods of short (30sec-1min) intense anaerobic exercise with lower-intensity recovery periods. In controlled experimental studies in exercise laboratory settings (usually universities), HIIT has shown to be remarkably effective for increasing cardiorespiratory fitness and reducing cardiometabolic risk factors. These findings have been shown with healthy adults among those with chronic conditions (type 2 diabetes/cardiovascular disease). Since most HIIT sessions last between 10-20 minutes, a proposed benefit of this training mode is that it requires a minimal time investment. Therefore, providing a bigger bang for your exercise buck! However, given the very intense nature of HIIT, which requires a high level of motivation, it is unclear whether the average community-dwelling adult would persist with this training mode. The aim of this study was to examine the effectiveness of HIIT training in a non-laboratory setting.
How they did it?
In this randomized controlled feasibility study, 49 (36 females) middle aged (age range =35-59 years) overweight/obese (BMI range =27.7–39.3 kg/m2), inactive adults were allocated into 1 of 3 groups: (1) Aerobic Training (continues jogging), (2) Walking, & (3) HIIT (short sprints with walking recovery). Click on the article link for a full description of each training program. Over a 12-week period, participants were offered the chance to attend 36 supervised group sessions which were held in a community park. The main outcome was changes in cardiorespiratory fitness measured using VO2max, before and after the 12 week intervention. Attendance at exercise sessions was also monitored.
What they found?
Attendance at both the walking and HIIT sessions was 75%, and 59% in the aerobic training. From the HIIT group, 3 participants who developed injuries considered to be related to the intensity of the intervention were excluded from the study. The walking subgroup had the fewest adverse events. For the main outcome, cardiorespiratory fitness, only the Aerobic Training had a +1.01 VO2max improvement. Surprisingly, the walking and HIIT showed slight declines in VO2max!
Ok, what does this mean to me?
This is among the first studies examine how effective HIIT in a real world setting. While studies have shown that HIIT is effective in highly motivating exercise laboratory settings with men in white coats yelling at you to exercise harder, the health-related outcomes of training mode in the community are not as impressive. Considering that the exercise session in this study were supervised, it could be assumed that if you prescribed HIIT to your client to undertake on their own between sessions, adherence to such this intense exercise mode is likely to be very low.