40MINS WALKING OR 20MINS hiit?

Well, you can’t do 20 minutes of hiit. You’d do very short very close to throwing up intervals in these 20 minutes plus lots of regeneration time. The calories would likely be lower than walking.

But running burns a bit more than twice as many calories than walking over the same distance. Thus if you can run for 20 minutes, and then increase the duration.

The best thing for weightloss though is eating less

djaxon1 wrote: »

20 mins of hiit - if you can do it every day.
Walking is good but it is not intense. Not easy to increase calory burn. But may be easy to stick at.
I would guess a few minutes of very vigorous exercise would burn more calories than 40 mins walking - the "easy" parts make the "hard" parts do-able !
Calory intake is more important tho' .

Nope.

Forty minutes of walking probably burns more calories than 20 minutes of HIIT in the first place, and it's calorie that count. (Fitness trackers tend to over-estimate HIIT calories, BTW.) On top of that, a longer period of moderate activity is less fatiguing than a shorter high-intensity workout, so the walk is less likely to bleed daily-life activity calories out of the rest of a person's day. Further, most so-called HIIT modalities are higher risk for injuries, for beginners.

Most things called HIIT these days don't achieve the metrics that were part of the original HIIT protocols, on which most of the studies of benefit were based. It's way over-hyped.

All of this feeds into the myth that exercise needs to be miserable and exhausting in order to burn calories or improve fitness. It's just not true.

MMapags is right, all down the line.

I've done HIIT (the original type, max effort cardio alternated with easier intervals), mainly for sharpening up VO2max (and pain tolerance, frankly) before races. It's exhilarating, in an exhausting kind of way. At best, it's a spice in the meal of athletic training, not the main meal. Even elite athletes don't do it daily. Why would us regular people do so?

OP, start with the walking. Aim for a frequency, speed, and duration that is a tiny bit of challenge, but that is reasonably enjoyable and leaves you feeling energized, not exhausted, for the rest of your day (maybe just a few minutes of "whew" right afterwards). That's the sweet spot for calorie burn, generally. You get the exercise calories, and aren't so fatigued you rest more later in the day. Then, as your fitness improves, you can increase your pace, frequency or duration to keep just a bit of a challenge, if you like . . . or even try out some more intense exercise modes at that point. Start where you are, increase gradually.

Best wishes!

djaxon1 wrote: »

Well , what do yo base this on - "Forty minutes of walking probably burns more calories than 20 minutes of HIIT in the first place, . . ."

edit 2.5mph walk is my best guess to the OP's incorrectly framed question . What else do you do ?

and

djaxon1 wrote: »

(snip)

"Forty minutes of walking probably burns more calories than 20 minutes of HIIT"
- I find that hard to believe when walking is most likely 2.5mph. I find 4+mph v.fast.
I have got to around 15 cals/min over 30 mins - incline walking with slower "rests" - which may go more ~ 20 mins.

You're quoting me in these two posts, not Mmapags. Not his job to defend something I typed.

Am sure I'm right? No, smart people don't go around being sure of stuff that has a lot of estimates and experiential factors (hence the word "probably" in my statement you quoted).

But here's the basis for why I say that, since you asked :

As background, I'm a rower. I've competed, and not always unsuccessfully. I'll admit to being old, so I'm slower than the young'uns, but when training I tend to be at around the 75 percentile level for my age at various distances, so far from elite, but not truly terrible - I think reasonably fit.

Let's say I do 20 minutes of max effort intervals, 1 minute hard, 1 minute easy. We'll further say that all the intense intervals are at my best-ever actual rowing machine race pace (time per 500m, for a 2k race), which is 2:10. In reality, I will not achieve that pace at the start of each intense minute (it's a build), and I probably won't be able to hold all of it in the later intervals, so it's a generous (optimistic) estimate.

We'll compare gross calories, using a bodyweight of 135 pounds (for which I have substantial personal data, though I'm a little lighter now). I'll use the weight-adjusted Concept 2 calorie estimate for that; it's based on watts, and considered to be a pretty accurate estimating method.

Let's say I drop back to paces in the 2:50s on the easy intervals, which may also be optimistic for the later easy intervals, as I experience more cumulative fatigue.

So, generously, I do 10 minutes at 2:10, which is 130 calories (total); and 10 minutes at 2:54.5 (so I can use an actual number from one of my 10-minute cool-down rows), which is 76 calories.

It makes no sense to use HR to control intense intervals (HR lag makes it pointless), but based on look-backs to experiential data, I'd be hitting 85-90% max (160s) in the early intense intervals, and higher than that (close to max, around 180) in the later intense intervals. For anyone who can do HR math, it'll be obvious that I'm using a tested HRmax, not an age-estimated one, when I say that. (My age-estimated max now would be 156.)

You may say that one minute is a long rest. If I take a shorter rest, my average peak pace will fall quite short of that estimated peak power output in the later intervals, so that's a cost in calories. (I wish I could find the data from one of my classic Tabata workouts to illustrate this: 8 x 20 seconds hard, 10 seconds easy.) No matter how you look at it, I'm more likely to over-estimating the calories from that workout, not underestimating them.

So, we're at a total of a total of 206 calories for the 20 minutes. For the rest of the day, I'll be pretty thoroughly wrung out, and doing some resting, because intensity is exhausting. That's a daily life activity calorie penalty.

Now, the walk. It so happens that just yesterday, I went for a walk. Nice walk, steady pace, on the brisk side, but not at all physically stressful. By coincidence, relying on Garmin GPS-enabled fitness tracker (which also knows my true HRmax, BTW) with chest belt for this estimate, it took 41:48 minutes to walk 2.54 miles, which is a 3.6mph pace. (I can push to around 4.1 while still walking, i.e. one foot on the ground at all times, but I wasn't particularly pushing, just walking). Garmin says that burned 222 gross calories.

Let's call that 42 minutes, to get an average of 5.285 calories per minute. So, 40 minute walk would be about 212 calories, if we believe the Garmin data (I'm a little skeptical). If I use the 0.3 x miles x bodyweight in pounds to estimate net calories, and add back my estimated BMR, we get 158 calories, so somewhat less.

After the walk, I felt great, and did lots of stuff, including some other exercise. No fatigue penalty on my daily life calorie expenditure, probably the reverse, i.e., more energized.

So, estimated 203 gross calories (estimated quite generously) for a very intense 20 minute interval workout, 158-212 gross calories for a non-eventful 40 minute walk, without even considering the impact on the rest of the day.

When I said "Forty minutes of walking probably burns more calories than 20 minutes of HIIT", that kind of experience above is what I based that on.

Now, that rowing machine piece would be primarily-cardio HIIT, the kind the early studies of physiological benefits were based on. You seem to be talking about calisthenics or circuit-type HIIT, which is a different critter. HR monitor/fitness tracker estimates of calories for that are likely to be overstated. **** I don't do these, haven't researched how best to estimate, so I don't have comparables.

Now, all other things equal, a less fit person will reach a higher heart rate if working at the same objective intensity compared with a same-sized/age/etc. fit person. If they achieve the same objective output (watts, say), for the same time period, they burn approximately the same number of calories. Also, it's (I think) intuitively obvious that a relative exercise beginner won't actually be able to achieve and sustain the same maximum objective intensity as an experienced and reasonably fit person of the same size/age/etc. Those things are essentially part of the definition of exercise adaptation or fitness.

With this post, we're giving advice to a relative exercise beginner. Compared with an experienced person, a beginner will get fewer calories from intense intervals (can't go as hard, for as many intervals); and will be more exhausted (because not very conditioned to intense workouts). That's going to skew the numbers even further toward the likelihood that twice as long at low intensity is better (especially considering a 24-hour basis**) for calorie burn for a relative exercise beginner.

** Yes, I know about EPOC (excess post exercise oxygen consumption, a.k.a. afterburn). Reasonable research based estimates of EPOC for intense exercise run around 14% for intense activity, vs. 7% for moderate exercise. So, using the numbers from above, the EPOC from the intense intervals (using the whole 20 minutes, so possibly overstating) is 14% of 206 calories, which is 29 calories. The EPOC from the walk is 7% of 158-212, which is 11-15 calories. The difference of 14-18 calories is not worth worrying about, especially in light of the potential fatigue penalty.


**** Consider these, from an experienced fitness professional here on MFP:

https://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472
https://www.myfitnesspal.com/blog/Azdak/view/hrms-cannot-count-calories-during-strength-training-17698

They're oldies, but still true and informative.

My opinion is that walking is very good exercise -the most under-rated - and everyone should walk more . However it isn't going to burn that many calories and it takes time. Lots.
Compared to the sofa - it's even more fantastic !

On the bolded, we agree, at least for people for whom it's feasible to walk more.

Best wishes!