HIIT or SIT for exercise and what sort of intervals?

[electriceagle]

Traditionally, I have kept myself fit with incidental exercise -- running and biking because I enjoyed it or because I needed to get somewhere. Somewhere along the line, I added a bit of strength training as intentional exercise (weights, bodyweight, and exercise bands).

As I've continued to age, I've found that I need more exercise to stay in the same place with regard to fitness. I recently noticed a small tire doing its best to organize itself around my midsection, so I'm experimenting with replacing some of my usual sets of squats with high-intensity interval training (HIIT).

The premise of HIIT, which seems to be fairly well accepted, is that your body continues to use oxygen at a high rate and therefore burn calories at a high rate for 24-48 hours after the exercise is complete.

The problem with HIIT and SIT (its short-interval cousin) is figuring out what types of intervals to do. Most of the studies on HIIT are done with either running or bicycling as the mode of exercise. There seem to be two schools of thought on HIIT: the first says that the high-intensity interval should be no shorter than 2 minutes in order to bring the heart rate up and keep it there long enough to matter; the second says that shorter intervals allow you to exercise harder and that intensity, not duration, drives fat burn.

I've been poking through HIIT studies to try to figure out what sort of routine is optimal for fat burn. Here are a few examples:

1. https://doi.org/10.12965/jer.1734962.481
Twenty participants do either 15x(60s exercise + 30s rest) or 45x(20s exercise + 10s rest) 3 times per week for 6 weeks. The average fat mass decreases by about 8% in both groups (difference between the two is statistically insignificant).

2. https://doi.org/10.1080/00913847.2015.1037231
Twenty-five chubby guys on bikes do either 10x(60s exercise + 60s rest) or 5x(120s exercise + 120s rest). No statistically significant effect on fat mass or % body fat is noted.

3. https://doi.org/10.3389/fphys.2018.01048
Thirty-six chubby women on bikes do either 80x(6s exercise + 9s rest) or (240s exercise + 180s rest)(not a specific number of repetitions; they bicycled until they had outputted 400 kJ of energy). Three times a week for 12 weeks. The short exercisers see an 8% decrease in body fat; the long exercisers see a 12% decrease.

4. Zhang, H., et al.: EFFECT OF HIGH-INTENSITY INTERVAL TRAINING PROTOCOL...Kinesiology 47(2015)1:57-66
This study was performed by the same group as #4
This time the women have 240s of exercise and 600s of rest, and only bike until they have produced 300 kJ of energy. They see a 19% decrease in body fat even though they did less work and took more breaks than the long exercisers in #3.

5. https://doi.org/10.3389/fphys.2018.01738
Forty-nine active women do either 4x(30s exercise + 240s rest) or 4x(240s exercise + 180s rest) three times a week for eight weeks. Those doing the shorter exercise decrease waist circumference and abdominal skinfold by 2.5 cm and 9.7 cm, respectively. Those who do the longer exercise decrease waist circumference by 4.3 cm and abdominal skinfold by 5.3 cm.

You can see that the studies here are all over the place. I'm especially surprised by the weight loss by people who do as little as 6s of exercise per set... how do you even get moving for such a short time? Another big question is study #4 vs. study #3.

Does anyone have a well-supported idea of whether shorter (20-30s) or longer (120-240s) exercise periods are better and if so, what the parameters should be?

I'm trying to stay away from people who excitedly declare things on websites and focus my decisionmaking around actual research.

[nereo]

My 2¢:  You are over thinking it.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Regarding your specific question about whether shorter (more intense) or longer (less intense) exercise periods are “better” - well assuming you are devoted to either it depends on what your end goals are.  HIIT training absolutely works (it’s been done for decades, and used to just be called “interval training”) - but no amount of short-intensity/short durations will prepare an athlete for an endurance event like a marathon or a century cycling.  To do that you need to go on long runs/bikes/swims (though you need not run a full marathon to train for one). OTOH, I’m a distance athlete, and no amount of long endurance training will build the power needed.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

 

[electriceagle]

My 2¢:  You are over thinking it.

I love the smell of precision in the morning.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

Thanks. I'm still doing the exercise that I enjoy; its just that I need to add something to it for fat loss. Barring disruptions, I'm pretty good about self-motivation. If I decide that I'm going to do it, and it is reasonable, it will quite likely happen consistently.

[jeninco]

The New York Times has a couple of recommended HIIT/SIT protocols, although they may be behind a paywall.

The website 12minuteathlete.com has a whole variety of HIIT intervals that are 30 secs on/10 secs off X 6 exercises X repeat 3 times.

If you look through a bunch of the workouts, you'll find a surprising assortment of different exercises repeated as hard/fast as you can for 30 seconds, ranging from burpees (of all varieties), to box jumps, to pull-ups, pushups, air squats, running in place, jumping rope, etc. etc.  The workouts used to be available via the website, but I just looked over there briefly, and you'd probably either have to do some digging around or buy the app for a month. (I copied a lot of them onto index cards, so when I want to do one I just flip through the index cards: you could also just write down a list of the exercises as they come up, and then after a while cancel the app and choose 6 to fit your needs when you want to do a HIIT workout.)

Huge-ass bonus: 12 minutes isn't very long, and 30 seconds is short enough to endure most discomfort.

My feedback: I did the 12-minute workouts (along with running/biking/swimming/hiking/skiing) for years, and found them quite helpful.  However, I finally (at 53) broke down and headed back to an actual gym, doing a program that I pay an actual (highly qualified) trainer to write for me. Even when I'm not working with her -- which is most of the time -- it's her gym, so she sees me doing things and either offers "gentle corrections" or programs me in strengthening for whatever seems to her to be the weak spots. It's a fairly significant time commitment, but chances are pretty good I'm going to live to my late 80s, and I'd like to take care of the body I have.

[PDXTabs]

I'm going to go a little off topic here I guess. I have been very successful losing/maintaining weight by cutting out alcohol and adding intermittent fasting.

However, there is a growing body of evidence that sitting is bad for you:

Both the total volume of sedentary time and its accrual in prolonged, uninterrupted bouts are associated with all-cause mortality, suggesting that physical activity guidelines should target reducing and interrupting sedentary time to reduce risk for death. - https://www.acpjournals.org/doi/10.7326/M17-0212

So if your goal is to not die then frequent breaks from being sedentary seems like a good idea.

[Metalcat]

My 2¢:  You are over thinking it.

I love the smell of precision in the morning.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

Thanks. I'm still doing the exercise that I enjoy; its just that I need to add something to it for fat loss. Barring disruptions, I'm pretty good about self-motivation. If I decide that I'm going to do it, and it is reasonable, it will quite likely happen consistently.

Fat loss is much easier to manage through diet than adding exercise intensity.

[electriceagle]

My 2¢:  You are over thinking it.

I love the smell of precision in the morning.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

Thanks. I'm still doing the exercise that I enjoy; its just that I need to add something to it for fat loss. Barring disruptions, I'm pretty good about self-motivation. If I decide that I'm going to do it, and it is reasonable, it will quite likely happen consistently.

Fat loss is much easier to manage through diet than adding exercise intensity.

True, but chocolate cake and good beer are two of my joys in life. I'd rather exercise harder than give them up.

[Metalcat]

My 2¢:  You are over thinking it.

I love the smell of precision in the morning.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

Thanks. I'm still doing the exercise that I enjoy; its just that I need to add something to it for fat loss. Barring disruptions, I'm pretty good about self-motivation. If I decide that I'm going to do it, and it is reasonable, it will quite likely happen consistently.

Fat loss is much easier to manage through diet than adding exercise intensity.

True, but chocolate cake and good beer are two of my joys in life. I'd rather exercise harder than give them up.

Yeah, I get that, DH is almost 50 and has found that each year after 35, it became harder and harder to offset his diet, even with his hours of exercise daily.

[Kierun]

I like Tabatas, https://jps.biomedcentral.com/articles/10.1007/s12576-019-00676-7

[nereo]

My 2¢:  You are over thinking it.

I love the smell of precision in the morning.

The best exercise regiment (when your goal is overall improvement of health) is the one you enjoy and will stick to.  Ultimately consistency wins out every time over the most “optimal” training plan.  You opened your question by saying you kept yourself fit with “incidental” exercise.

Ideally you’d want to decide what your end desired result will be (more power? Weight loss/management? Endurance?). YOu’ll get a variety of benefits if you can combine both, but again - unless you stick with the plan it won’t matter. So concentrate on what you actually enjoy, and then add some of what you aren’t getting. For me that’s consistent, long sessions of distance swimming (and cycling on my off-days), but I make a point to intersperse some HIIT 2-3x each week.

Thanks. I'm still doing the exercise that I enjoy; its just that I need to add something to it for fat loss. Barring disruptions, I'm pretty good about self-motivation. If I decide that I'm going to do it, and it is reasonable, it will quite likely happen consistently.

Fat loss is much easier to manage through diet than adding exercise intensity.

Indeed. There is also a persistent conflation of weight and fitness. They are correlated of course but not the same thing. There are lots of people of ‘normal’ weight who have poor overall fitness. There are also many people who are physically fit but carry more weight than they should.

If your goal is weight loss the solution will be different than if your goal is strength or stamina or flexibility.