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HIIT Defined - What is (or isn't) HIIT?

robertw486
robertw486 Posts: 2,398 Member
Since this seems to be an item often debated in other areas, I thought we should open it up for debate. Hopefully it will help others define what they believe is or isn't HIIT, and the possible benefits or lack thereof of using HIIT as part of a workout program.


Firstly, I'm going to quote what the ACSM literature defines as HIIT

"This type of training involves repeated bouts of high intensity effort followed by varied recovery times. The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without overexerting yourself. The recovery periods may last equally as long as the work periods and are usually performed at 40% to 50% of a person’s estimated maximal heart rate. The workout continues with the alternating work and relief periods totaling 20 to 60 minutes."

The above taken from This link https://acsm.org/docs/brochures/high-intensity-interval-training.pdf

I've used the ACSM definition for one primary reason. It's the only clearly defined view given by any professional organization that I have come across. Feel free to add any other definitions that are linked to health or fitness organizations, credible fitness professionals, or institutions. Let's just try to avoid what Billy Jim Bob thinks is HIIT, as we could all come up with something if we wanted. Limiting the definitions to professional levels rather than a fitness blog might help sort out fact based vs trendy buzzword sales pitches.

Per the ASCM literature, HIIT training can be up to an hour. The major basis they seem to use is a percentage of a max heart rate. Since this ties in to VO2max and oxygen uptake, it seems a valid gauge of effort to me. As for duration, I would consider an hour of anything to be taxing if an all out effort, and the interval and rest periods lessen the work time, so once again I would consider it a high intensity. As a note, I would suspect that many people could sustain an effort above VO2max for an hour if they used a 50/50 split of work vs recovery time. And I think many of us could agree that any effort above VO2max is a high intensity. And at the end of the day, it seems a fair enough gauge to me to accept HIIT as ACSM defines it. I do intervals from sub VO2max levels up to much higher levels, and it really won't bother me what others do or don't consider to be HIIT levels.


What do you consider HIIT, or what would disqualify a routine as HIIT? What studies, organizations, or professionals led you to this definition? Is is possibly to do HIIT at efforts below VO2max or does it require an effort into anaerobic range? Is the best gauge HR, HRR, VO2max, time vs perceived effort, or something else? What measures of power do you need to qualify something as HIIT, if any? How long could a person do do HIIT? When is it just intervals (or intermittent per Tabata) and when is it HIIT? Give an example of something you consider HIIT (or not), and qualify your statements.



I'm going to start with something easy to qualify as HIIT: Tabata IE1 protocol

Why? It seems to be one of the modern day routines accepted as HIIT, and is of an intensity high enough that few would dispute it is high intensity. Based on an output of 170% of VO2max, it's good that the work interval is only 20 seconds. However, the very brief rest period of 10 seconds ensures that if you reach that 7th or 8th interval, you will be at an oxygen deficit and breathing hard. Numerous studies have accepted it as HIIT, as well as documented both aerobic and anaerobic benefits. I'd say that anyone that doesn't get their heart rate well into the zones accepted by the ACSM is probably someone with a heart issue or just straight out superhuman. The highest heart rate I've ever recorded myself was doing Tabata IE1 on our elliptical machine.

Would I want to do it long term or often? I don't know really. Some time back I did a week of the protocol just for "fun" and lack of time on my hands. It wasn't as terrible as I thought it might be, but mixing it up is usually more fun for me personally. I'm usually somewhat a glutton for the punishment of high output efforts and pushes, but it left me feeling like I was so focused on the output between my timer beeps that I didn't really have any time to enjoy or dislike the workout much.

It would likely have been much more "enjoyable" on a bike. Due to the output level, probably a very high risk of injury on many machines and/or exercises. It was tricky on an elliptical. Maybe possible with uphill sprints, but unless you have Usain Bolt levels of speed, I'd suspect very hard to do on the flat when sprinting.


Maybe if we can form some agreement on where people draw the line of what is included in HIIT, we could move on to why (or why not) people might choose to use it as part of their exercise programs. It seems that HIIT is the trend now, and helping others figure out the actual studies and basis for use vs what a local trainer is selling might help some people out.
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Replies

  • LivingtheLeanDream
    LivingtheLeanDream Posts: 13,342 Member
    Does it really matter? :smiley: - and in my case I would say, no not personally as I'm at maintenance.
    I do my own form of HIIT on the bike, short bursts of high speeds etc. I don't think too much about it, some days I enjoy HIIT bursts, other days I'm not feeling like doing any so stick with steady paced cardio.

  • lemurcat12
    lemurcat12 Posts: 30,886 Member
    This is the sort of thing I'd consider HIIT (this and of course something like tabata): https://www.runnersworld.com/running-tips/run-faster-with-high-intensity-interval-training

    I've done it in bike training classes too (winter classes on a trainer with electronic monitoring).

    The only reason I do it (I hate it, mostly) is because I think it can help make you fitter for running or biking (and with running sometimes it's the only way to make a boring treadmill session -- dictated by snow or what not -- seem bearable).

    I'd be careful assuming you are working all out in a way that counts as HIIT if you aren't already in good shape (if you aren't it's not good for you to really go all out and your mind will think you are before you really are, mostly), and I also wouldn't use estimates of max heart rate to determine, since heart rate is quite variable. Also, over time as you run, especially if you aren't yet in great shape, you will have drift and end up running, say, a half marathon looking like you are at a max heart rate for the second half and obviously you weren't running at that intensity.
  • stanmann571
    stanmann571 Posts: 5,727 Member
    No problem with that definition, as it clearly excludes

    Squats
    Pushups
    etc

    It permits
    Burpees,
    Running,
    rowing,
    etc

    My quibble with that definition, is by setting 80% as the barrier to entry, for a relatively well conditioned athlete(for whom HIIT is appropriate) 80% is not sufficient stimulus.
  • heybales
    heybales Posts: 18,842 Member
    I think that definition seems rather broad too - and starts overlapping other interval types that have a different focus.
    With 80% as start, no wonder they say you could do 8 min.
    Shoot, I could do 20-30 min at 91% during a good aerobic base season, that was the LT level.

    And HIIT sure shouldn't be the overarching type, it's a subset of interval type training.
    They don't even mention any other type of interval training - it's steady state or intervals, so give HIIT a try.
    http://www.acsm.org/public-information/acsm-blog/2017/10/26/interval-based-exercise-many-names-possibilities

    I think they are just lumping everything under HIIT - perhaps jumping on the fad name being applied to everything.


    I guess the only thing I've seen are the studies and the specific effect they were going for.
    https://www.exrx.net/FatLoss/HIITvsET
    That's along the lines of what I saw years ago in books prior to internet - 15-45 sec max effort (so no time to be looking or worrying about getting above certain HR%, lag time would be too long), with recovery 3 x as long.
    8-15 bouts. The longer recovery allowed the max effort to remain pretty consistent.
    Whereas attempting that Tabata at max effort (which I know it's not supposed to be max), with recovery 1/2 as long, led to huge degrade in what that max effort could accomplish. Obviously still felt max, but speed no where near the same after a few bouts.

    https://www.exrx.net/Sports/HIIT
    Whereas that had different purpose (ignore the mis-termed link). Helped improve endurance factors. And I've used that in training leading up to a half/marathon to get endurance improved quickly.

    And the more traditional intervals many know from perhaps school training.
    https://www.exrx.net/Aerobic/IntervalTraining
  • robertw486
    robertw486 Posts: 2,398 Member
    Does it really matter? :smiley: - and in my case I would say, no not personally as I'm at maintenance.
    I do my own form of HIIT on the bike, short bursts of high speeds etc. I don't think too much about it, some days I enjoy HIIT bursts, other days I'm not feeling like doing any so stick with steady paced cardio.

    For me, it doesn't really matter. I do what I do regardless, and sometimes that includes intervals of varied exertion, time, and rest period. For some reason on the bike I tend to do as a minimum 1-2 minute pushes rather than super short high intensity. Maybe if I lived where it wasn't so flat that would change some. I just introduced the subject since any mention of HIIT in many forum areas sparks disagreements on what is or isn't HIIT.

    @GottaBurnEmAll - I think that would be the end of any high intensities for me. Anything that produces a migraine would keep me away!



    It seems that the 80% threshold allowed under the ACSM guidelines and definition is dismissed by several. To some extent I had the same thought, but then changed by view. To reach 80% doing my elliptical IE1 required 3-4 intervals at 170% VO2max. With something as simple as a rest period long enough to allow some HR recovery, I think short intervals could be made really intense if offset by a rest period long enough to recover to a reasonable heart rate. 80% via steady state and 80% through a work period of a minute or so are two different animals in my opinion.


    Also I fully agree with the general health and safety aspects mentioned by @lemurcat12 and @sijomial . In all fairness the ACSM literature covers those points as well, and I'd say at least checking with a doctor is a good idea.
  • MikePfirrman
    MikePfirrman Posts: 3,307 Member
    edited July 2019
    80% is harder than most think it is. It's mainly because most don't have a clue what their true HR max is. First of all, you have to be in pretty decent shape just to try to do a HR Max test, then on one, you usually don't even reach it. Personally, I have to really push to reach 90% of HR Max and it's not pleasant at all. I think many push to 70% or 75% and think they are doing HIIT just because they've never pushed hard enough to know.

    I tried running for years. I was terrible at it. My body/joints limited my HR more than my heart did. I'm able to push my HR up more on the Stationary Bike, Assault Bike and C2 rower than I ever was running or doing calesthenics (though things like jump squats do a pretty nice job).

    I recently purchases a HRM again and a popular HR monitoring App that's pretty solid. Funny thing is they have a "community" and many of these folks continually post up that they are working at 97% or 100% of Max HR. No they aren't!! That just demonstrates how clueless most are when it comes to HR max. If you can't row, run or do an Assault Bike all out for 20 to 25 minutes, you can't know what your HR max is. Even then, you are not reaching it but you're getting closer. Most that have an idea of what their HR max is do cardio 6 plus hours a week. They tend to be serious endurance athletes. The "HIIT" trend doesn't usually market to these serious folks, they market to those that never do cardio. Therein lies the problem.

    There have been several threads on determining a true Max HR on here before.
  • mmapags
    mmapags Posts: 8,934 Member
    Does it really matter? :smiley: - and in my case I would say, no not personally as I'm at maintenance.
    I do my own form of HIIT on the bike, short bursts of high speeds etc. I don't think too much about it, some days I enjoy HIIT bursts, other days I'm not feeling like doing any so stick with steady paced cardio.

    I think it only matters for 2 reasons. The first is if you are training to improve your V02 max because you compete in endurance events.

    The second is that there is so, so much hype about HIIT today that all kinds of things get called HIIT. So, some clarity of definition can be beneficial.

    For you, or me, as individuals who like our workouts it doesn't matter what they are technically. But, as we've seen repeatedly in some threads, some people adamantly insist on calling things HIIT whether they are or not.
  • Powerclean2deadlift
    Powerclean2deadlift Posts: 35 Member
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)
  • mmapags
    mmapags Posts: 8,934 Member
    sijomial wrote: »
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)

    Weights = heavy things you lift when doing strength/resistance training.
    The fatigue from hitting your muscular endurance is not what HIIT is about, it's cardio and pushing your CV systems to extreme levels. Think all out sprints or pushing to your maximum for short bursts on a bike. You seem to be conflating circuit training with HIIT?

    You can't do real HIIT every day, it's far too taxing on your CNS and the fatigue level would be enormous if you foolishly tried to do real HIIT daily.

    HIIT and fat loss aren't linked, real HIIT is a low calorie burner due to the necessity for short overall duration and a good proportion of the overall time spent is recovery. Besides which if you truly want to use daily exercise to create a calorie deficit you are looking at long duration, low to moderate intensity cardio that won't cause recovery issues (not that IMHO exercise is for fat loss in the first place).

    You beat me to it and took the words right out if my mouth. All of that^^
  • mmapags
    mmapags Posts: 8,934 Member
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)

    Your post is an example of some of the confusion about what is or isn't HIIT.
  • AnnPT77
    AnnPT77 Posts: 33,967 Member
    mmapags wrote: »
    Does it really matter? :smiley: - and in my case I would say, no not personally as I'm at maintenance.
    I do my own form of HIIT on the bike, short bursts of high speeds etc. I don't think too much about it, some days I enjoy HIIT bursts, other days I'm not feeling like doing any so stick with steady paced cardio.

    I think it only matters for 2 reasons. The first is if you are training to improve your V02 max because you compete in endurance events.

    The second is that there is so, so much hype about HIIT today that all kinds of things get called HIIT. So, some clarity of definition can be beneficial.


    For you, or me, as individuals who like our workouts it doesn't matter what they are technically. But, as we've seen repeatedly in some threads, some people adamantly insist on calling things HIIT whether they are or not.

    To expand on the bolded: I don't really care as much about the naming (it just makes communication difficult, and causes hurt feelings when someone doesn't appreciate their perfectly good exercise being called "not real HIIT" because they think that "being HIIT" is somehow a better thing than being circuits or regular intervals or some other format (wth?)).

    I think it's more significant that people seem to label quite a large range of things "HIIT", then claim that all of those things have the the same benefits that concrete research linked to the early CV HIIT modalities (VO2max improvements, materially higher EPOC%, whatever) without additional research to support the benefits under that extended definition. When trainers, fitness companies (and others who monetize fitness info) do that, that's arguably fraud.

    Don't get me wrong: I believe most of those modalities have benefits, and important, useful ones. But they ought to demonstrate, via sound research, what the specific benefits are, before they claim them.

    From my reading, differences in exercise modalities, emphasis (contribution of strength to performance, vs. "pure" cardio, say), and intensity can potentially make material differences in the fitness adaptation(s) that occur, and in how rapidly or efficiently they occur. Putting the same label on a materially different activity doesn't give it the same benefits. How different is "materially"? That's a research question.
  • heybales
    heybales Posts: 18,842 Member
    I wonder how often Tabata style intervals (I don't even want to call them HIIT) are being done for the purpose the study found regarding aerobic improvements compared to longer time doing LISS, or purely because someone thinks it burns more calories compared to who knows what in that case?

    I know the vast majority of topics where I see HIIT mentioned it's because of burning fat or calorie burn or such, not that they can get a shorter workout in and be just as effective as something longer.
  • heybales
    heybales Posts: 18,842 Member
    edited July 2019
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)

    Think of it this way.

    Could what you are doing be done with different intervals than High Intensity (there are different types, plain IT, SIT)?
    Could what you are doing be done with no intervals - steady state?

    Can't really do an interval version of something if that's the only way of doing it.
    Well, except pink dumbbells in the hands of a strongman for 20 min of curls.
  • Powerclean2deadlift
    Powerclean2deadlift Posts: 35 Member
    sijomial wrote: »
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)

    Weights = heavy things you lift when doing strength/resistance training.
    The fatigue from hitting your muscular endurance is not what HIIT is about, it's cardio and pushing your CV systems to extreme levels. Think all out sprints or pushing to your maximum for short bursts on a bike. You seem to be conflating circuit training with HIIT?

    You can't do real HIIT every day, it's far too taxing on your CNS and the fatigue level would be enormous if you foolishly tried to do real HIIT daily.

    HIIT and fat loss aren't linked, real HIIT is a low calorie burner due to the necessity for short overall duration and a good proportion of the overall time spent is recovery. Besides which if you truly want to use daily exercise to create a calorie deficit you are looking at long duration, low to moderate intensity cardio that won't cause recovery issues (not that IMHO exercise is for fat loss in the first place).

    Your bit about confusing circuit training with HIIT - Yes i think you are correct. Thank you
  • Powerclean2deadlift
    Powerclean2deadlift Posts: 35 Member
    heybales wrote: »
    sijomial wrote: »
    I would take issue with the ACSM "definition" on quite a few points but this is actually quite silly IMHO.
    "The intense work periods may range from 5 seconds to 8 minutes long, and are performed at 80% to 95% of a person’s estimated maximal heart rate, the maximum number of times your heart will beat in a minute without over exerting yourself."
    • 8 minutes is ridiculous.
    • Estimating max HR opens up a large margin of error as actual max HR can diverge massively from estimates.
    • Maximal HR isn't "without over exerting yourself" - it's the maximum HR you can achieve by pushing yourself to maximal effort.
    • 80% is a really low percentage, on my most recent one hour FTP test I averaged over 86% of my tested max HR for the whole hour. I'm a fit but elderly recreational cyclist not a super fit elite athlete!

    It's also a bit odd that when I did a VO2 max test under ACSM guidelines it included max HR testing with two measures of maximal effort (plateau in O2 uptake, respiratory exchange ratio indicating switching to anaerobic energy sources). You don't get to that point without over exerting yourself.

    Using HR as a gauge for short sprints/bursts of maximal effort/power is badly affected by lag in HR rising to meet demand - especially if you are fit.
    Using VO2 max as a measure has the drawbacks that few people have it tested and even then it's not a constant.

    Here's a post I did earlier today in another HIIT thread with illustrates my viewpoint.....



    This is my take on HIIT....
    I would simply describe HIIT as cardio (not weights) than involves short bursts of maximal effort (or very, very close to maximal), for a very limited duration interspersed with periods of recovery. To illustrate what I mean.....

    w16pthguj8a4.png


    This is on a power meter equipped indoor bike, The power part shows it best.
    Ten minute high low intervals to start then five minute high low intervals - the high part is pretty intense, the recovery is easy. It's interval training but it's certainly not HIIT. It's "just" interval training.

    Now the bit right at the end with the six spikes could possibly qualify as HIIT. Short bursts of maximal effort with short recovery periods - I'm sprinting flat out every 30 secs for as long as I can hold on. You can see that both height of the spikes reduces (lower power each sprint 650 down to 370watts) and also the width of the spike (the duration I can keep sprinting).
    The HR graph shows that although my muscles are partly recovering my HR isn't. Normally with HIIT you would be having somewhat longer recovery time. I'm not a fan of using HR as a measurement as there's too much lag - that's why I go by maximal effort.

    By the way - I rarely do HIIT, this was unusual for me.
    I do a lot of interval training though, it doesn't have to have the label HIIT hung on it to make it a valid and useful training style.





    Question - what do you mean by "weights" - as that is quite broad?

    In terms of practicality I wouldn't use a barbell (I don't think?) but I might use strongman equipment? - I like using axel stones for HIIT.

    So overall my question is why would you not consider using weights to be HIIT? (I am asking as I want to lose fat and intend to add some HIIT in each day)

    Think of it this way.

    Could what you are doing be done with different intervals than High Intensity (there are different types, plain IT, SIT)?
    Could what you are doing be done with no intervals - steady state?

    Can't really do an interval version of something if that's the only way of doing it.
    Well, except pink dumbbells in the hands of a strongman for 20 min of curls.

    Got it. Thanks!
  • Musikelektronik
    Musikelektronik Posts: 739 Member
    This morning (because I couldn't get to the gym to do my normal cardio workout), I tried this "HIIT" workout at home. https://www.nbcnews.com/better/lifestyle/15-minute-full-body-hiit-workout-no-equipment-required-ncna977711

    Is it really "HIIT"?

    To be honest, the workout really got my heart rate up, which surprised me a little, and was harder than it looked. Whatever it is, it was a good "I can't get to the gym so I'll do this instead" workout.
  • Musikelektronik
    Musikelektronik Posts: 739 Member
    For what it's worth, I'm 55 and my best guess is my max HR is around 194 right now.

    I'm 51, and my "predicted" max heart rate (220 minus my age) is 169, which seems about right to me. The highest HR I've ever observed in a workout is about 165.

    If you're 55 and your max HR is about 194, you're obviously in much better shape than me, or you've been an endurance athlete for much of your life!

    Whatever the case, that's awesome. :)

  • MikePfirrman
    MikePfirrman Posts: 3,307 Member
    For what it's worth, I'm 55 and my best guess is my max HR is around 194 right now.

    I'm 51, and my "predicted" max heart rate (220 minus my age) is 169, which seems about right to me. The highest HR I've ever observed in a workout is about 165.

    If you're 55 and your max HR is about 194, you're obviously in much better shape than me, or you've been an endurance athlete for much of your life!

    Whatever the case, that's awesome. :)

    Actually, Max HR is mostly just hereditary. I'm also just a decent indoor rower. Among my rower friends I'm like the guy that shouldn't be good at all but I'm OK because I work harder at it! Also took two decades off and got really fat and smoked another decade. 10 years of harder training can make anyone a semi decent weekend warrior! You too! I started hard at rowing at 48 or 49.
  • phred_52
    phred_52 Posts: 189 Member
    80% is harder than most think it is. It's mainly because most don't have a clue what their true HR max is. First of all, you have to be in pretty decent shape just to try to do a HR Max test, then on one, you usually don't even reach it. Personally, I have to really push to reach 90% of HR Max and it's not pleasant at all. I think many push to 70% or 75% and think they are doing HIIT just because they've never pushed hard enough to know.

    I use the 220 less 57= 163 max HR. I just wanted to comment on the harder, decent shape, and it's not pleasant

    I'm not fit really. Recently started back at gym 5/23, but skipped many days, so total days so far is 25. I strive for 2 hrs on bike with a steady HR between 125-130 (77-79%). I don't find that really all that difficult. I also do many short, 30-60 second bursts getting HR 145-147, with max of 153 attained. Only effect I felt, was thinking my heart would burst, lol.

    After reading all this about max HR's etc., I figured I'd try on bike :smile:, so cranked tension, went all out for 45 sec., and was only able to hit 153, so now I'm soooo jealous of ya'll joking

    But kudos to you.

  • lemurcat2
    lemurcat2 Posts: 7,885 Member
    For what it's worth, I'm 55 and my best guess is my max HR is around 194 right now.

    I'm 51, and my "predicted" max heart rate (220 minus my age) is 169, which seems about right to me. The highest HR I've ever observed in a workout is about 165.

    If you're 55 and your max HR is about 194, you're obviously in much better shape than me, or you've been an endurance athlete for much of your life!

    Whatever the case, that's awesome. :)

    Actually, Max HR is mostly just hereditary. I'm also just a decent indoor rower. Among my rower friends I'm like the guy that shouldn't be good at all but I'm OK because I work harder at it! Also took two decades off and got really fat and smoked another decade. 10 years of harder training can make anyone a semi decent weekend warrior! You too! I started hard at rowing at 48 or 49.

    Yeah, my max heart rate has always been quite a bit higher than predicted too, whether I'm in good shape or not.
  • promisesstandin
    promisesstandin Posts: 150 Member
    I haven't read all the responses so I apologize in advance if this has been answered. Would someone please give feedback on what might be happening to me when I try to do HIIT? I'm not in the greatest of shape but have managed to lose 100 lbs. mostly by correcting diet with dense nutrition and with some caloric deficit. Just as background, I went back to maintenance for 2 months to reset my metabolism because I was at a plateau and figured my system had adjusted to the deficit (went into homeostasis) so I've been referring at maintenance. Anyway, getting ready to go back into deficit and am wondering what might have been happening with my HIIT experience before.

    Heres' what it looked like: Elyptical type machine. Walk for 2-3 mins. casual, then pump it as fast and as long as possible HR around 155bpm (usually less than one minute but sometimes a little more), then walk it out til I'm at a resting HR or at least under 90bpm, sustain resting level for 2-3 mins. then push it up to high intensity again. This lasted for about 20-30 mins. Current stats: 59yo female, resting BP around 98/62 (down from 139/89 year ago), 166lb. 5'7", no meds.

    Here's the problem: After a few "cycles" of HIIT, I would feel as if the machine reset to a higher tension in the pedals - though it was set manually to the same intensity for the whole work out. That being said, what I felt periodically was like a ton of bricks to push the pedals during the intensity part, I would push through it like I went from 3rd gear to 20th gear on a bike, it would take about 10 seconds of hard pushing and then the release in the pedals would come and I could continue at a regular pace. I asked others at the gym about and they confirmed that the settings on the elyptical hadn't changed. I can only guess that my muscles were completely deleted in energy but why, after 10 seconds, the energy would return was puzzling. Also, I could only take about three rounds of the pedals feeling like I was in 20th gear before I'd have to just quit my HIIT workout even if that meant I only stayed on for 20 mins. BTW: I make it a choice to not work out/HIIT if I have not slept well.

    Any ideas what could be causing this 20th gear sensation? Thanks, everyone!
  • robertw486
    robertw486 Posts: 2,398 Member
    I haven't read all the responses so I apologize in advance if this has been answered. Would someone please give feedback on what might be happening to me when I try to do HIIT? I'm not in the greatest of shape but have managed to lose 100 lbs. mostly by correcting diet with dense nutrition and with some caloric deficit. Just as background, I went back to maintenance for 2 months to reset my metabolism because I was at a plateau and figured my system had adjusted to the deficit (went into homeostasis) so I've been referring at maintenance. Anyway, getting ready to go back into deficit and am wondering what might have been happening with my HIIT experience before.

    Heres' what it looked like: Elyptical type machine. Walk for 2-3 mins. casual, then pump it as fast and as long as possible HR around 155bpm (usually less than one minute but sometimes a little more), then walk it out til I'm at a resting HR or at least under 90bpm, sustain resting level for 2-3 mins. then push it up to high intensity again. This lasted for about 20-30 mins. Current stats: 59yo female, resting BP around 98/62 (down from 139/89 year ago), 166lb. 5'7", no meds.

    Here's the problem: After a few "cycles" of HIIT, I would feel as if the machine reset to a higher tension in the pedals - though it was set manually to the same intensity for the whole work out. That being said, what I felt periodically was like a ton of bricks to push the pedals during the intensity part, I would push through it like I went from 3rd gear to 20th gear on a bike, it would take about 10 seconds of hard pushing and then the release in the pedals would come and I could continue at a regular pace. I asked others at the gym about and they confirmed that the settings on the elyptical hadn't changed. I can only guess that my muscles were completely deleted in energy but why, after 10 seconds, the energy would return was puzzling. Also, I could only take about three rounds of the pedals feeling like I was in 20th gear before I'd have to just quit my HIIT workout even if that meant I only stayed on for 20 mins. BTW: I make it a choice to not work out/HIIT if I have not slept well.

    Any ideas what could be causing this 20th gear sensation? Thanks, everyone!

    My guess is that as you get more depleted, you are just working through the acceleration curve of the machine. I did HIIT with a set power achievement level on my elliptical, and the motion makes it really hard to accelerate quickly. It takes a combination of resistance and leg speed. But until your leg speed gets up, the resistance seems harder.

    Power is a combination of torque (how hard you are pushing down) and RPM (leg speed). Due to the ellipse of the machine, the acceleration part can be a bit tricky as you wear down in energy levels. An easy way to confirm or deny this idea is to bump resistance down slightly as you accelerate, and as your leg speed increases bump the resistance setting up as well. Depending on the model of the machine you might be able to set the display to show you the data that is relevant. On mine I often toggle between resistance and strides per minute as the gauge of fatigue, and use calories per minute as the gauge of power.

  • Phirrgus
    Phirrgus Posts: 1,894 Member
    For what it's worth, I'm 55 and my best guess is my max HR is around 194 right now.

    I'm 51, and my "predicted" max heart rate (220 minus my age) is 169, which seems about right to me. The highest HR I've ever observed in a workout is about 165.

    If you're 55 and your max HR is about 194, you're obviously in much better shape than me, or you've been an endurance athlete for much of your life!

    Whatever the case, that's awesome. :)

    That formula seems to work for me as well. 59 (for a few more weeks lol) and hitting the bike as hard as I can gets me about 160 for a HR. That's a watch though, not a chest strap.

    And yeah, he's being modest about but @MikePfirrman got some serious CV health going on. Making me want to invest in a C2.
  • heybales
    heybales Posts: 18,842 Member
    edited July 2019
    Ditto to HRmax genetics, but being fit as you age sure seems to prevent the normal rate of lowering that occurs.
    191 (from 194) last I tested at age 49.
    But some people just have a low diesel heart with lower HRmax.

    I think the HR graphs being shown are good too for showing that when you do max for briefer amounts of time, you can sometimes keep it up, but the total "set" time is still not that long. If either starts lengthening, the ability to keep it high drops.

    This is from HIIT and SIT workout I enjoy doing from time to time, though it's been awhile at this point.

    The HIIT is 15 sec sprint, 45 walk. The SIT is 1 min sprint (which is attempted at level pace but all I got), 1 min walk.
    20 min gentle jog in the middle for recovery.

    5pbmbsyypdof.png

    25824xh5ikja.png

    As was mentioned about trying to think during this - I have the Garmin kicking off the buzzers so I only have to hear that. Math would be interesting.
    I think the reason why I can't get the HR up towards max better is running wasn't my main thing, though the 194 was based on running test.
    But that's the other nice thing about HIIT - all out is level of effort, pretty easy to hit. Get it, hiit, never mind.
  • promisesstandin
    promisesstandin Posts: 150 Member
    Thanks, RobertW: A thoughtful and helpful response. You're appreciated. :)