T Nation

Intensity vs Duration

I’ve been getting questions about this lately and wanted to address the question of whether sprint sessions are better for calorie expenditure than moderate intensity cardio.

Many people (on both sides of the fence) have impassioned opinions that they like to defend but let me show you what the data says…here is the study…

Comparison of energy expenditure elevations after submaximal and supramaximal running. Laforgia J, Withers RT, Shipp NJ, Gore CJ. Exercise Physiology Laboratory, School of Education, Flinders University of South Australia, Adelaide, Australia. Although exercise intensity has been identified as a major determinant of the excess postexercise oxygen consumption (EPOC), no studies have compared the EPOC after submaximal continuous running and supramaximal interval running. Eight male middle-distance runners [age = 2.1 +/- 3.1 (SD) yr; mass = 67.8 +/- 5.1 kg; maximal oxygen consumption (VO2max) = 69.2 +/- 4.0 ml.kg-1.min-1] therefore completed two equated treatments of treadmill running (continuous running: 30 min at 70% VO2max; interval running: 20 x 1-min intervals at 105% VO2max with intervening 2-min rest periods) and a control session (no exercise) in a counter-balanced research design. The 9-h EPOC values were 6.9 +/- 3.8 and 15.0 +/- 3.3 liters (t-test:P = 0.001) for the submaximal and supramaximal treatments, respectively. These values represent 7.1 and 13.8% of the net total oxygen cost of both treatments. Notwithstanding the higher EPOC for supramaximal interval running compared with submaximal continuous running, the major contribution of both to weight loss is therefore via the energy expended during the actual exercise.

Now let me summarize the findings...the authors wanted to equate the work done between both bouts (i.e. energy/calorie expenditure) so that subjects in both groups burned the same amount of calories DURING the exercise.

To do this group 1 had to run at 70% of VO2 max (about 85% HR max) for 30 min.

Group 2 had to do what I would consider quite a difficult series of 20 x 1 minute sprints at 105% of VO2 max with 2 min rest between runs. That’s a 60 min exercise bout for this second group!

When all was said and done (taking into account the calories burned AFTER the exercise was over), after 9 hours, the “sprint-type” group burned more total calories after the exercise. How many more? A WHOPPING 33 calories.

So, you can either go out and sprint for 1 min intervals separated by 2 min rest for a total of 1 hour at this high intensity and burn 539 cals. Or you can run for 30 minutes and burn 483 calories.

That extra 30 minutes of sprinting gets ya 56 more calories burned!

Now, none of this even speaks to what is actually burned. The interval bouts will undoubtedly burn more carbs while the continuous more fat. And if you want to talk catabolism, which do you think is more catabolic when you look at time spent and calories burned?

So, doing the continuous running, you are more time efficient and burn more fat (and may be less catabolic).

For those guys on here who continue to tell me Im wrong about cardio and that sprinting is the best way to get lean…here is the data…

I have to agree with these results, John.
High intesity cardio is very catabolic for me.
People of the HIT school seem to argue that
HIT will burn more total calories, which may
be true. But they never stop to ask where
these cals are coming from. I’ve read several
studies that show that longer duration, lower
intensity cardio will use a higher
percentage of calories from fat -
which is exactly what you want. Or at least
what I want. I still do sprints, but not for
fat loss. When trying to lose fat, I get best
results from low(er) intensity and longer
duration. This gets me lean w/o obliterating
too much muscle in the process. (Unlike you,
however, I can’t do 2x day cardio w/o going to
catabolic.) Lata.

I found when I did sprinting interval training it just made me feel overtrained.

From personal experience I agree with the longer duration cardio for fat loss. But I’m still somewhat sketchy on the empty stomach this. Often I do my cardio, and occasinally lift, on a empty stomach - although when lifting I try to get some protein in me before hand. I can help but think that cardio after not eating for 8+ hours is catabolic…what kind of supplementation could I use to deter this? I was thinking glutamine and some BCAAs in addition to my ECA. Is this a good idea?

Beradi your full of it! Listen I am a Mr Forever Natural and when I stopped listening to all the B.S about high fat diets and super high protein and did interval cardio for no more than 20 minutes I got my bodyfat down to 4.7%. Listen the reason why you experience so much catabolism sprinting is
a) 1 hour of sprints is too much the idea of cardio is to increase metabolism first burn calories later which can be done in 20 minutes b) you eat so little complex carbs you dont get the protein sparing advantage from them. Yet I understand people react differently to carbs but even so you need high quality complex carbs so you can do the 20 interval cardio which incidently combines the best of both worlds (i.e. sprints remind the body that you are not a marathoner check out olympic sprinters to prove my point) and the 20 aerobics solution by Bill Philips works even though I don’t respect the guy the only time I got ripped was when I followed his aerobics solution his weight training advice is average admittedly.
Beradi you neglect to tell people if you have low carbs steer clear of intense aerobics as you dont have sufficient protein sparing carbs.
So in conclusion guys if you want to eat complex carbs you need to do 20 - 30 minutes of inteval cardio if you follow low carbs do light cardio as Beradi suggests

antony…how can you tell this guy he’s full of it? he’s constantly posting remarkable evidence and coming up with sensational ideas, philosophies and theories–regarding training, dieting, supplementation, etc–with hardcore evidence to back it up in the form of both personal experience and scientific research. I’m not saying that you’re full of it, by any means. You found what works well for YOU, my man, and that’s really what JB wants for all of us–to find what is optimal for each and every one to achieve desired results. I don’t mean to put words in someone’s mouth and if I’m stepping on toes I hope someone will kick my ass back in place. I personally like to do my cardio in a similar fashion in which you do–interval training or similar to the Bill Phillips approach. I’ve achieved great leanness thru this method and am happy with the results. Does that mean I’ll never try another method? Maybe, maybe not. I just think that if you experienced remarkable results–which you have, 4.7% is friggin’ awesome, bro–let us know how you achieved them. Remember there are always exceptions to the rules.

That is one study. I can just as easily come up with a study that would completly dispute the results of the above. H

One other comparison I’d like to see is the effects on various hormones in the cardio group vs the sprint group. Things like growth hormone, testosterone and cortisol. All of us here would probably agree that if we could pick only one form of exercise to look good and stay young it would be lifting weights…do we burn as many calories as endurance athletes?..no…but we usually look better, feel better, stay younger longer and if we don’t pig out we probably maintain as low if not lower a bf% then the typical runner. This being the case with weight trainers vs endurance athletes I think it’s also obvious there is a signficant physical difference when comparing the <800 meter sprinter and the >800 meter runner. I’m sure a lot of the physical difference are due to genetics but I’d be interested to see some long term hormonal studies on this.

You guys are great!

I post results from well controlled scientific studies and you give personal anecdotes about your own progress refuting them. Now that’s wonderful. Do what it takes to make yourself lean. Im posting this so that people figure out how to train more efficiently.

I want to address some things, though.

Antony, I guess you didnt even read the study or the post. 1 hour of sprinting is exactly what it took to elevate the metabolism later on in the day! And it only elevated it by like 30 calories. Im glad that sprinting works for you but it doesnt work because of some magical ability to shread fat after the workout. 20 min of sprinting will give a small and inconsequential increase in metabolism after training relative to regular cardio.

And before anyone starts telling me that sprinters are ripped so sprints must work…listen up…sprinters are sprinters because they have those types of bodies! They were born with the ability to get big, hard muscles with high amount of fast twitch fibers. It’s called self selection…those born to do certain sports gravitate toward them. It’s not a cause and effect of training.

But I guess it’s time for some former high school runner to come on here to tell me Im wrong because he was skinny before running the 100m at weekend dual meets and then he got big legs. So I must, again, be wrong. And so is the research.

Craig, this study was an example of the research that speaks exactly to your original post. Since you can so easily find another study to refute this (because you're obviously and exercise physiologist and well versed in the scientific journal publications on this topic), please do. Post it here and prove me wrong big guy!

Finally, I train elite endurance athletes. And if you guys think that 30 minutes of moderate intensity exercise is freakin endurance training, you are sadly mistaken. If I put you on the bike at the maximum power output level (VO2 max) at your cardio limitation for 3 minutes; you will die at about the 3-4 minute point, your legs will burn so badly and you'll probably puke. Now, when I take an elite endurance cyclist and put him on the bike at the same workload, he can keep it up for 1 hour and he calls it a "light day". Trust me, I do this in the lab regularly.

Finally, sprinting is not the same as wt training so any comparisons in this light fall apart.

Guys, Im not just some dude posting on here. I run research experiments year-round in a performance and biochem lab. Do you honestly think that I am missing something when you decide to chime in and rip on my ideas?

Not that John needs anyone to defend him, but it is my sworn duty to appear and bite someone’s head off when necessary, so here I am. Having read this discussion a few hundred times over many years going back to the '70s, keep in mind “there is no right or wrong way” to burn fat calories through cardio. Everyone is different; don’t we all know that by now? The anecdotal “evidence” posted by thousands of weight trainers is just that: a personal experience. Saying that what worked for you is best is akin to going up to the biggest guy in the gym and asking him how “to get big like you.” Just because John Berardi talks like a real guy, and posts often, and takes the time to interpret studies, doing much more than merely giving us the abstract, doesn’t mean he’s just another yahoo with an email account. This guy is one of the top researchers in this field; he’s for real! And he’s on here all the time answering your questions, and in this case, anticipating your questions. I think this is invaluable, and studies conducted in this manner mean more than a hell of a lot of guys telling us what worked for them or some guy they know from the gym. There, I feel better now.

Some of you guys truly are amazing. I’m with JB here, as both the scientific evidence and especially the “real world” evidence support John. I think it’s a wonderful thing that HIIT came about though. Obviously, prior to its introduction, people just couldn’t reduce adipose tissue while concurrently preserving LBM. That’s my sarcastic quote for the day.

However, as I’ve said before, if it works for you, keep doing it. There’s no point in trying to help you out if all you do is attempt to decry everything we do and say. It’s fine to have your own opinion. Hey, that’s why JB and I hold our mini UFC in the backyard every year, since we don’t always agree. However, when you do disagree, come with something other than negative remarks and false statements. Just my 2 pieces of coin.

I thought that the studies people cite in favor of high-intensity intervals show relatively the same amount of calories burned with 1 hour of moderate cardio, and 20 minutes (including maybe 5 warm-up) of interval training and waiting 40 minutes to eat. Then, there was a study that showed that post-exercise calorie burn was low for weighttraining and moderate aerobics (maybe around 30 cals) but not for 20 minutes of interval training. Can anyone think of a reason that matching sprints and moderate cardio for the same calorie expenditure during exercise would be a flawed approach? Brian

That is the first study I’ve seen that shows an endurance run to have the same effect as interval training. The studies I’ve seen had shorter intervals, shorter total duration, less total calorie expenditure and showed much better resuls for fat loss in the interval training group than the continuous group.

The same pricks who criticise are the ones who want you to personally analyze their insulin sensitivity, piss on them.

The forum is set up to exchange ideas and argue under a controlled setting, but show some respect. Next time you think Mr. Berardi is blowing smoke up your ass, think, would you argue with your personal physician? What’s the difference in the near future Mr. Berardi will have a Ph.D. (and to us he will be a Dr.) and this honor is rewarded through the investment of time alone, it involves taking your science to a new level that you can prove amongst your peers.

99% of the individuals that log on to the site don't question Mr. Berardi's writing. Mr. Berardi respectfully ask that you keep posting despite certain negative individuals. You have impacted my training and I am sure that goes for many others as well.

I also see that the same article John is using to refute the claim that high intensity is better for fat loss is used in the references of people saying that fat loss is best achieved with high intensity bouts. I guess I’ll go and look this one up myself.



I believe Tremblay found that those using HIIT reduced bodyfat 3 times more than enduance training, and was 9 times more effective on a calorie expenditure basis (i.e., the HIIT people burned less actual calories DURING exercise, but still lost more fat).

Just an occasional lurker.

brian, the only way to know whether the extra calorie costs after exercise are due to the high intensity intervals is to match based on total cals of the bout. post exercise calorie burning is more with intervals, no doubt. but much less so than most think. one thing to keep in mind is the measurement period. the study above measured until both groups got back to baseline. so after that, the differences between bouts no longer were present.

jimmy, if you could point me in the direction of some of those studies, that would be cool. again, the cals burned are less with short interval training vs longer duration during the bout. and cals burned after are higher with interval training. but my contention is that the extra cals after intervals dont amount to much.

Thanks for the reference ted. I have to go get this at the library. A review of an abstract is limited in what it can tell us. I wanna go read the protocol and see just how much more fat was lost and examine whether there was some study design flaw or if it was a tight one. Claude Bouchard and Tremblay are good researchers though so it's probably a good design. Remember, though, that the 9x number refers to a relative increase per calorie. Im interested in the total cals burned!

Here is another study...

Effects of different running programs on VO2 max, percent fat, and plasma lipids. Thomas TR, Adeniran SB, Etheridge GL. This study attempted to determine the effects of interval and continuous running on factors associated with cardiovascular health. Fifty-nine untrained men and women, ages 18-32 years, were randomly assigned to one of four groups: (1) 4 mile: running continuously at 75% of maximal heart rate (approximately 500 Cal/session) (2) 2 mile: running continuously at 75% of maximal heart rate (approximately 250 Cal/session) (3) interval: running one min at 90% maximal heart rate followed by three min of walking for eight sets (approximately 500 Cal/session) (4) control: no exercise program. The training was performed three times per week for 12 weeks. Treadmill VO2 max and percent body fat by hydrostatic weighing were assessed pre- and post training. Pre and post analyses were performed on plasma for triglycerides (TG), cholesterol (Chol), and high density lipoprotein cholesterol (HDL-C). Analysis of covariance indicated that only the interval group improved more than the control in VO2 max. Percent fat decreased in all exercise groups, but no program was superior. Changes in TG, Chol, or HDL-C were not different among groups. Although men and women differed on the pretests in VO2 max, percent fat, and HDL-C, their response to the training was similar. These results indicate that interval training may benefit aerobic capacity more than continuous running in young adults who have moderately high initial fitness levels. The data also indicate that cardiovascular fitness parameters are not easily altered by short term exercise in young active men and women.

In this one, running 4 miles, 2 miles, or doing 32 min of intervals all promoted the same amount of weight loss.


I keep forgetting to mention this…For you guys dying for that post-exercise calorie burning…

What you guys are losing sight of in this debate is that I recommend cardio AFTER weights. Well since wt training increases post exercise calorie expenditure, then you're already taken care of in that regard. At that time you need to burn calories! And the best way to do that is to work out doing cardio at this time. You've already got the increase for after the workout waiting for you. Now you need the raw calorie expenditure. See what I mean?

We often debate things in isolation but Im talking about adding this to your weight regimen. This creates a different integrative metabolic situation.

Mr. Berardi,
Given the huge amount of variance in how individuals respond to exercise, I’d have to say that the second study is much more convincing simply due to the much larger sample. A sample size of 8 is still better than individual anecdotes, but it’s very difficult to make any sort of extrapolation from it. Just out of curiosity I do have two quick questions about the second study:

  1. What was the concomitant variable?
  2. What was the significant level used in the analysis?

Also, those of us who don't have the time to do the research and read the journals greatly appreciate what amounts to you doing it for us. Thanks.


OK, I’m not claiming to have any hard, numerical scientific evidence here, but I will give some personal, anecdotal evidence of what has and hasn’t worked for me (which seems to go against the study that you’ve cited - however, I think the main reason for that is that DIFFERENT THINGS WORK FOR DIFFERENT PEOPLE, not that you’re “wrong,” John).

I’m 26, male, 5’11", currently 202 at around 8 percent bodyfat. My weight training sessions are brief but intense; 4 times per week, about an hour each, and only 3 to 5 sets per bodypart, with varying rep schemes. Whenever I have tried the moderate intensity, longer duration cardio for fat burning (i.e. getting from maybe 12% bf down to 8%), which in my case was 20 or 25 minutes on the Stairmaster at what I consider a brisk jogging pace, I had pretty miserable results. Yes, I lost “weight,” some of which was fat. But I also lost quite a bit of muscle mass, was weaker during my weight training sessions (which were always done BEFORE the cardio), looked more “deflated,” and for many hours after a cardio session I would feel COMPLETELY wiped out, like my entire CNS had just been fried – if the woman wanted to get it on that night she could just forget it! I had the inate sense that, without a doubt, it was destroying my recovery ability and just plain tearing my down. However, the next time I went on a cutting cycle I tried the interval training approach to cardio. Again on the Stairmaster, I would sprint for 30 seconds, jog for 30 seconds, sprint for 30, etc. I started at a total of only 4 minutes and, over the course of about six weeks, never got over a total of 7 minutes. I lost the desired amount of fat in that period (from 12% down to 8%), maintained all of my lifting strength, still had the appearance of muscle fullness, and most importantly of all, didn’t feel utterly WIPED OUT from these interval sessions. I know, I know, I haven’t gone into my diet, supplementation, etc., but suffice it to say that they were quite similar both times. Just my personal story.