HIIT Workouts

sijomial wrote: »

A true HIIT workout is cardio of such extreme intensity that the duration must be short and a good proportion of that duration will be recovery time - you will not be burning 500cals or anywhere close.

I think you mean circuit training as you mention reps and sets?
In which case using cable machines would be my current favourite, minimal rest and alternating push/pull, variable reps but mostly 10 - 15 depending on exercise, variable sets (more based on total duration) - but it's still unlikely to burn 500 cals!

EPOC is that's what you mean by burning some while resting is vastly over-estimated in terms of significance, it's trivial.

PiscesIntuition wrote: »

Oh my!

We all agree that increasing heart rate over a short period of time is what gets faster results. Whether it’s circuit training or HIIT.

If you think about what our ancestors did, you will better understand how short bursts over a short period of time would have been better than long cardio. Long cardio would be like running from an animal or enemy for an hour.

I believe they both have their place when it comes to fat loss and muscle building.

AnnPT77 wrote: »

PiscesIntuition wrote: »

Oh my!

We all agree that increasing heart rate over a short period of time is what gets faster results. Whether it’s circuit training or HIIT.

If you think about what our ancestors did, you will better understand how short bursts over a short period of time would have been better than long cardio. Long cardio would be like running from an animal or enemy for an hour.

I believe they both have their place when it comes to fat loss and muscle building.

I'm not certain we do all agree on any such thing, at least not if we're using the terminology in the same way ("short period of time", "faster results", and - for sure "HIIT"). Increasing heart rate is useful, but how much to increase it, and over what period of time, for which results . . . that's different.

First, let's back up to the "HIIT" term (which I realize the post I'm replying to is trying to set aside as a distraction, but I think it's possibly more useful to try to understand it so we can talk about it sensibly.)

The Wikipedia article on it (https://en.wikipedia.org/wiki/High-intensity_interval_training) isn't terrible, IMO, with respect to the classical definition of "HIIT": A cardiovascular exercise alternating intervals at anerobic-intensity levels with intervals at lower intensity. The exercises used in the relevant research were things like stationary bike (most common), rowing machine, running, stairs/hills. By and large, what was tested were workouts most of us would consider quite short, and part of that shortness comes from the fact that those intensities can only be repeated a limited number of times before the definitionally-necessary level of performance becomes unachievable. (As an aside, those performance limits may change with growing fitness, but the implication is that the fitter person needs to work objectively harder to achieve the anaerobic state that defines the the classic HIIT intensity, so duration is still limited as the subject's capabilities improve.)

While many of the research protocols use some kind of HR% descriptively, I think it's more useful for practitioners to think of those as after-the-fact assessments (not benchmarks the practitioner uses her/himself in real time to decide whether the interval is intense enough (for the reasons @sijomial mentions); and to remember that in the research setting, they're almost certainly relying on tested/verified max heart rates, not age-estimated max heart rates (which latter are inaccurate enough to be seriously misleading for a suprisingly large segment of the population).

"New HIIT" (my term) takes some of the general ideas about pacing from those earlier studies, and applies them to different exercise activities (often forms of circuit training (high-rep resistance work), calisthenics or activities like battle ropes, tire flips, etc.) Are these "good" exercises? Sure. Can it be useful to do them in an intense interval pacing format? Sure. Does doing so have all and exactly the same benefits as the HIIT on which the earlier research was done? Hmmm. For sure, the reasons for elevated heart rate in these "new" exercises (i.e., the stresses to which we're asking the body to adapt) can differ from those of the exercises in which the earlier research was done, among other issues.

So, old HIIT or new HIIT has benefits, no question about that. It's short, and intense. It is "time efficient" for weight loss in the sense that it burns more calories per minute of intense exercise than the same minutes of moderate or low intensity of that same activity.

Does it burn more calories for the whole exercise time period, as compared with moderate intensity? That depends on how intense the intense intervals are, how moderate the recovery intervals are, and the length of each of those.

One is burning higher calories during the intense interval, and lower in the recovery interval, so loosely the calorie burn is the duration-weighted average of the two activities. (Example, unrealistic invented numbers just to make the concept clearer: If my intervals add up to 20 minutes at high intensity that burn 5 calories per minute, and 10 minutes at recovery intensity that burn 2 calories, my total burn is ((20 x 5) + (10 x 2) = 120 calories). If the contrasting moderate-intensity steady state activity burns 3 calories a minute, the HIIT burns more calories; if the moderate-intensity steady state activity burns 4 calories a minute, they're equal. And so forth.))

Does the HIIT burn more calories overall? That depends on duration. HIIT duration is somewhat self-limited by fatigue/exhaustion, as described above. I won't argue that moderate-intensity steady state is unlimited, but by definition "steady state" is something one can continue for quite a long time. So, time one wants to devote is a variable in considering what burns the most calories overall. If I have an hour available that I want to devote to exercise, there's no great reason to do something that's so intense I can only do it for 40 minutes. (Not to mention that, for example, I don't want my on-water rowing to be over lots faster, because why would I shorten fun if I have the time available? So I sometimes do somewhat-intense intervals on the water, but rarely max-intensity intervals (I save those for the more-boring rowing machine ).

Also relevant to those other terms, "short period of time" and "faster results": True high-intensity intervals (old or new HIIT, either one) require a longer recovery period in order to wire in some of the benefits. Obviously, how long varies, but recovery is a factor. If I can do moderate intensity steady state for half an hour every day (and want to), but can only do HIIT for half an hour every other day to get adequate recovery, there's a decent chance I'll burn more calories per week doing entirely moderate intensity exercise, if calories are the objective.

If fitness is the objective, it matters exactly what the fitness objective is. Intensity develops some capabilities most efficiently (such as VO2max), longer steady state develops others (such as endurance). (If well-rounded fitness is the objective, I'd personally argue that a mix of HIIT and steady state are the best bet.) Virtually any safe exercise that elevates heart rate, even elevating it rather modestly, has some benefits: We don't necessarily need a big increase over a short period in order to see a benefit.

What about the EPOC (excess post-exercise oxygen consumption, a.k.a. afterburn)? Research suggests a higher EPOC in percentage terms for HIIT (research on the classic form) vs. steady-state exercise of the same type. That's cool, but it's important to think through the arithmetic: A common number is 14% EPOC for HIIT, 7% for steady state. Wow, twice as much!

Or maybe not so wow. Let's say we're comparing HIIT and steady state sessions that each burned 500 calories, which most of us would consider a pretty decent session for calorie burn. The EPOC from HIIT is 70 whopping calories (0.14 x 500). The EPOC from steady state is 35 calories (0.07 x 500). Still twice as much from HIIT . . . but jeez, 35 calories. That kind of number is pretty much lost in the daily noise of unavoidable errors in food and exercise estimating while calorie counting. (More on this at https://bodyrecomposition.com/fat-loss/steady-state-versus-intervals-and-epoc-practical-application.html/)

So, HIIT (old or new) has advantages. Intensity, in general, has advantages. It also has potential limitations:

Intense exercise is typically more fatiguing per minute, because intensity has that physical effect. If that fatigue is enough to carry over into daily life, such that the person drags through the day doing less physically at work and home, then it's pretty easy to wipe out calorie advantages from the shorter HIIT (or sustained but short high intensity, maybe call it High Intensity Steady State (HISS)) workout. (The fact that it's shorter is still a good thing, for busy people who don't really enjoy exercise, of course.)

HIIT or other rapid pacing, especially in the "new HIIT" modalities (calisthenics, light-weight high-rep circuits, etc.) has greater potential for injury, especially in beginners, because of less opportunity to focus on maintaining proper form, and that risk becomes more acute as the workout continues and fatigue kicks in.

HIIT or extra-intense exercise in general can be discouraging for some beginners, possibly leading to quicker burnout and even giving up on exercise. Some people enjoy intensity, but the research suggests that many do not. For the latter, HIIT reinforces the idea that exercise has to be miserable and fatiguing to be effective - sort of a punishment for getting unfit or fat in the first place. (Ugh.) I'd argue that most exercise beginners are better served by a slow ramp-up of exercise that is (for them) relatively pleasurable, is energizing rather than fatiguing for the rest of their day, and that makes the risk of injury pretty moderate until good form is solidly established in muscle memory.

Lots of different exercise pacing strategies (HIIT, lower-intensity intervals, LISS, MISS, continuous high intensity, etc.) have value, whether for fitness or weight loss, and which is "best" varies. The time we have available matters, how much we enjoy the activity matters, personal enjoyment of things like sweating and panting matter, what our fitness or health goals are matters, and more.

I feel like HIIT gets a bunch of quasi-religious boosterism lately. I also feel like the term just gets broader all the time, as if being called HIIT makes any given activity/pacing way cooler than if we called it something else. But it's all good, in various ways, even under less thrilling names.

Edited: typos