Thanks for the summary; found it when I was looking up more info after looking at the other article (https://news.ycombinator.com/item?id=8094119)

Most of the commentary from there probably pertains.

One thing I noticed in this study is that (unlike a few other articles where I couldn't find the primary sources), they didn't do a warmup period:

"The HIT training protocol was similar to that used previously by Jakeman et al. [20]. 16 sessions of HIT were spread over an eight week period, with one or two days of rest between each sprint. There was no warm-up or cool down in the training sessions. Each training session consisted of 10 repeated 6-s all-out cycling efforts against 7.5% of body weight for males and 6.5% for females (Monark peak bike Model 894E, Monark Exercise AB, Vansbro, Sweden), added to the bike once the participant was cycling at 100 rpm with 1 min of passive recovery between sprints." [emphasis mine]

Yeah, I was surprised by the fact that such a short duration of exercise (11 minutes of exercise twice / week) could have such a large impact on health. I wish there were more details on how much exercise each group had before the study -- my question is whether HIT on its own is good enough, or does it require normal exercise as well?

participants where untrained

Conventional wisdom says that you're not really working out unless you spend 10-25 minutes on warm up, an hour or more on working out, and some stretching to finish off and/or a cool down. That isn't even counting the time to go to the gym or the park, or the shower afterwards. No wonder people are inactive.

What conventional wisdom is that? The standard for warm up is 5 minutes isn't it? And a standard work out is 20-25 minutes as far as I'm aware. You can do a whole work out in 30 minutes.

My runs are 5 minutes warm up, I spend those 5 minutes walking to get from my house to a park, then 20-25 minutes running around the park (c25k plan) and then 5 minutes of walking back. You can fit that into almost any part of your day.

What about dressing up for the jog and afterwards showering and dressing up again? Also most people don't have a park in a 5 minute walking distance. I would say for most people they take 10-30 minutes to get to the training place, train at least 20 minutes and then 10-30 minutes back again and then 5-10 minutes of shower. Now that is quite a large part of the day.