HIIT: how often?

[PowerManDL]

Originally Posted by Bytsi

I'll give you my 2cents - if you can maintain whatever you are doing for more than 30-60 seconds, it's not a full-out max effort. It may be an intense interval, but when you say you could "sprint" for 20 minutes straight, you're right - that is steady-state, not a sprint. Your definition of sprint is not the same as mine - for me, sprint in the context of HIIT would be running as fast as I possibly could, until I literally could not go another step at that pace. When I do this in my workouts, I can run for 20-30 seconds before I MUST slow down. Same on the stairmaster for me - I set it at a high enough level that I literally would fall off if I didn't slow it down after 30 seconds.

This is another area where the definitions get fuzzy: what are we talking about when we say "maximal effort"?

If you're talking pure speed/power, then you're correct, you can't keep that up for very long at all. Even elite-level 100m sprinters are slowing down by the end of the race, which is <11 seconds.

However there's also maximal anaerobic capacity, which is a little different. This is the activation and usage of glycogen for energy, and that can carry activity for upwards of 90-120 seconds before the lactate burn and lack of energy causes you to stop.

Those definitions tend to get blurred, as "maximal effort" in one is not the same as in the other.

For fat burning reasons, the second type of effort is what you're after, so you'd really want to aim for "maximal effort" in a zone from as short as 30s to as long as maybe 90s. This wouldn't be your top speed, but rather your best speed and effort in that time bracket.

I also don't think you need - or want - a long recovery time in true HIIT. What I understood of the original studies was that you want to stay anaerobic, but you can't stay anaerobic for more than approximately 60 seconds, by definition.

The original Tremblay study from 1994 that got everyone all in a rage (the one showing the 9x greater skinfold losses for less energy expenditure) about HIIT used this protocol:

Short intervals: 10-15 bouts of 15 seconds, progressing to 30s

Long intervals: 4-5 bouts of 60 increasing to 90s

Each bout was separated by a recovery period allowing HR to return to 130bpm, so it was a pretty decent recovery time.

Anaerobic metabolism can also function as purely anaerobic or oxygen-dependent, depending on length of exercise. The longer work intervals tend to be more of the latter.

[Bytsi]

For fat burning reasons, the second type of effort is what you're after, so you'd really want to aim for "maximal effort" in a zone from as short as 30s to as long as maybe 90s. This wouldn't be your top speed, but rather your best speed and effort in that time bracket.

Thanks - that was what I was trying to get at

Anaerobic metabolism can also function as purely anaerobic or oxygen-dependent, depending on length of exercise. The longer work intervals tend to be more of the latter.

I'm not sure I understand what you said in this part - doesn't anaerobic mean, by definition, without oxygen? I know the systems can, sometimes, be complimentary - like when your anaerobic system kicks in during an intensity increase when you are already aerobic. When you said "anaerobic metabolism can function as ... oxygen dependent" - were you saying it could be working at the same time as the aerobic system? If so, then I do understand what you're saying... otherwise, you lost me on that one!

I'm thinking this entire thread just goes to show how many different, yet effective, ways there are to work out and interpret protocols!

[PowerManDL]

Originally Posted by Bytsi

I'm not sure I understand what you said in this part - doesn't anaerobic mean, by definition, without oxygen? I know the systems can, sometimes, be complimentary - like when your anaerobic system kicks in during an intensity increase when you are already aerobic. When you said "anaerobic metabolism can function as ... oxygen dependent" - were you saying it could be working at the same time as the aerobic system? If so, then I do understand what you're saying... otherwise, you lost me on that one!

I'm thinking this entire thread just goes to show how many different, yet effective, ways there are to work out and interpret protocols!

What's happening in oxygen-dependent glycolysis is that the intensity is low enough for oxidation to play a role in glycogen re-synthesis. It's still being fueled by glycogen stores and is thus anaerobic, but oxidation is helping to refuel things.

This pathway actually contributes to a lot more than people realize, and it's a grey area between pure aerobic/oxidative metabolism and pure anaerobic glycolysis.

[Karen411]

Originally Posted by Willie

13' HIIT (2'warm up / cool down + 4' @ 30/30 + 1 minute rest + 4' @30/30)

Okay, I just want to ask a question to be sure I understand this (since I've misunderstood a lot of things before). This is 2 minutes warm-up, 4 minutes of 30 seconds sprint, 30 seconds recover cycle, 1 minute rest, 4 minutes of 30 seconds sprint, 30 seconds recover, then 2 minutes cool-down?

[A H]

day 1- lift + 13' HIIT (2'warm up / cool down + 4' @ 30/30 + 1 minute rest + 4' @30/30)

day 2-- intervals at 90% intensity @ 5'warm up / cool down + 20' of 1' work / 2' rest

day 3-- same as day 1

day 4-- 30-45' cardio steady state (remember, I'm a reformed cardio queen, and I see this as active recovery)

day 5-- same as day 2

day 6-- same as day 1


This suggestion made earlier in the thread is sort of what I do. I am the same way where in the past I have done tons of cardio and it never really made me spent so I was doing it for a long long time before I lifted and I dreaded going to do my low intensity lifts. I have exercised for a long long time so I was looking to decrease my gym time and maintain my body and/or hopefully increase muscle. Now i try to do

Day 1- NROWL lifts, 15 mins of HIIT 2 mins recovery 1 min sprint ( on the treadmill)

Day 2- 15 mins of HITT 2 mins recovery 1 min sprint (stairmaster) followed by 30 SS lower intensity minutes (stairmaster)

Day 3- Same as day 1

Day 4- Same as Day 2 or lower intensity cardio

Day 5- same as day 1

Day 6 - off
Day 7- off

Thoughts?

[A H]

sorry if my post was a little random. I didn't realize this thread went on to a second page when I put up my post. :p

[Jenn Equestrian]

Just from a scientific background: there is no such thing as a purely aerobic or anaerobic activity. Both systems contribute from their metabolic pathways relative to the activity being performed whether it is of high intensity/low intensity or short duration/long duration. You'd also be surprised how much aerobic metabolism contributes to anaerobic activites (like all out sprinting).

As for HIIT, The best means of performing these exercises is with the use of a HR monitor. That way, as you become fitter and adapt cardiovascularly you will still be exercising in at an appropriate speed. Normally, 65% of maxHR is considered the minimum working level to elicit the responses we're looking for in HIIT and would be considered moderate intensity. High intensity is 85% of maxHR. I'd say aim for around 85% of maxHR while performing HIIT intervals. Ideally you want your HR to return to at least 60% before tackling the next work interval; normally when it takes longer than two minutes for the HR to return to below 60% it's a sign that enough sets have been done.

Those are just general outlines used in exercise physiology. It's particularly important that people make sure they are in good cardiovascular health before using exercises like these.

Just adding in:
Aerobic metabolism is fueled by both fat and glycogen whereas anaerobic metabolism relies only on glycogen/glucose for energy substrate. Just because glycogen is the energy substrate does not mean that it is anaerobic.

[kfisherx]

Jenn three million thanks for these guidelines wrt HR. That makes it all so much more clear.

Also I have learned that I am held back on the treadmill due to fear not physical ability. I plan to continue to work through this.

[Jenn Equestrian]

K:

I totally relate to "fear factor" on the tready. I also think it's not knowing how much we're really capable of, so we don't realize we can go much quicker. Whenever I switch from the treadmill to the track I am surprised by how much that damn machine holds me back. There's a beauty to running with your body connected to the ground and using a flow to move and keep speed.

Some people have a GPS as well as HR monitor built into a watch, and I believe there's an Ipod shoe thingy that tracks distance as well. It would be interesting to do a run on the treadmill and then a few days later take the GPS out (as it gives your speed and distance) and once comfortable in the pace see just how fast you're going. If only those watches were reasonably priced lol!

[PowerManDL]

Be careful relying on the HR recommendations for HIIT. You aren't always able to accurately measure peak HR, and it's not always relevant.

[Jenn Equestrian]

PowerMan:

From a scientific perspective HR is one of the more objective measures for cardiovascular conditioning and is often more relevant than speed or distance. With HIIT, subjective reasoning isn't always the most effective.

I was curious what you mean by measuring peak HR is difficult? By peak HR are you refering to HRmax or a HR around 85%? HRmax is a calculation and never changes, even with improved cardiovascular condition. It is very possible to obtain accurate HR monitoring up to HR max, but that is dependant on what you use to monitor. If one is holding onto the elliptical or the sensors on the treadmill it will not be accurate. We've used multiple HR monitors in our labs, and the watch with band (which wraps around the hypochondrium) which tends to range from $75-$400 is actually as acurate as you'll get without being hooked up to a machine. I won't mention them, but some brands are also more reputable and well known for reliablility and accuracy.

[PowerManDL]

Originally Posted by Jenn Equestrian

PowerMan:

From a scientific perspective HR is one of the more objective measures for cardiovascular conditioning and is often more relevant than speed or distance. With HIIT, subjective reasoning isn't always the most effective.

Yes, from a purely scientific standpoint you're right. HR is a good measure for the CV training effect.

I was curious what you mean by measuring peak HR is difficult? By peak HR are you refering to HRmax or a HR around 85%? HRmax is a calculation and never changes, even with improved cardiovascular condition. It is very possible to obtain accurate HR monitoring up to HR max, but that is dependant on what you use to monitor. If one is holding onto the elliptical or the sensors on the treadmill it will not be accurate. We've used multiple HR monitors in our labs, and the watch with band (which wraps around the hypochondrium) which tends to range from $75-$400 is actually as acurate as you'll get without being hooked up to a machine. I won't mention them, but some brands are also more reputable and well known for reliablility and accuracy.

If spending 75-400 bucks is worth it to you, by all means do so.

Point being most average monitors aren't accurate enough to keep pace with the changes in HR over the times that it will vary, and are pretty useless for tracking things.

This is just striking me as a case of needless attention to a detail that isn't all that important. You can tell when the anaerobic stuff is kicking in.

But, hell, if you've got the disposable income, why not?

I'm just speaking from my usual pragmatic viewpoint.