Design
Results are based on analyzes of data from a study which previously has been described in detail. In short, this was a randomized controlled trial (RCT) with two parallel groups, comparing an intervention group performing HIIT three times per week for 11 weeks with a control group with no change in pre-study physical exercise habits. Randomization of the total study sample was done in three consecutive blocks. Sample size was calculated according to the primary outcome in the original study [Trial registration: NCT02995460 (16/12/2016).