With interval training, you perform short bursts of intense exercise, then take a longer period to recover. For example, sprint all out for 20 seconds, then walk for 60 seconds. Interval training burns more calories because of the intense bursts of work. The faster you burn 3,500 calories, the faster you will burn fat. You can do interval training with any method of exercise, inclulding running, swimming, biking and step aerobics.
Significance
Interval training allows you to exercise at higher levels of intensity compared to continuous aerobic exercise. When you alternate between short bouts of very-high-intensity exercise with lower-intensity exercise, your body is able to process lactic acid build-up, therefore reducing fatigue. You are then able to burn calories and fat at a faster rate compared to less intense, longer aerobic exercise.
Improved Ability to Burn Calories and Fat
Training at such high intensities utilizes your body's short-term energy systems: the ATP-PCr systems and the glycolytic system. The ATP-PCr system makes use of creatine phosphate stores in your muscle for high-intensity exercise lasting no more than 10 seconds. When the exercise bout lasts for up to 3 minutes, you are using mostly muscle glycogen, the stored form of glucose. When you consistently train at high intensities using these systems, you increase your capacity to work harder, thereby more calories and fat at a faster rate.
Post-Exercise Calorie and Oxygen Consumption
At rest, your body needs oxygen and calories from carbohydrates, fat and protein to maintain life. You need more calories and oxygen to perform exercise, especially at high intensities. Once you stop exercising, your body still requires calories and oxygen as it works to bring you back to resting levels. Your body uses more calories and oxygen after high-intensity interval training than after steady-state aerobic exercise to return to a resting state.
Time Frame
The key to interval training is exercising at high intensities for at least 10 seconds, but no more than three minutes. The National Strength and Conditioning Association recommends specific work-to-rest ratios for interval training: if your work interval lasts up to 10 seconds, use a ratio between 1:12 and 1:20; if your work interval lasts 15 to 30 seconds, your ratio is 1:3 to 1:5; if your work interval lasts from one to three minutes, use a ratio of 1:3 or 1:4. For instance, if you sprint for 20 seconds, using a ratio of 1:3, your rest period should be 60 seconds.
Considerations
You can burn calories and fat faster when you do interval training at least two days a week. However, you need to use a different work-to-rest ratio to prevent over-training and to reduce your risks of injury. For example, your first session could be a sprint for 15 seconds with a walk of 45 seconds for 20 minutes total. Your second session of the week could be a sprint for 60 seconds and a walk for three minutes for 30 minutes total. Keep in mind that your 60-second sprint is faster than your run, but slower than your 15-second all-out effort. There needs to be at least two days between interval sessions.
References
- "Essentials of Strength Training and Conditioning"; Thomas R. Baechle and Roger W. Earl; 2000
- "Exercise Physiology, Energy, Nutrition & Human Performance"; William D. McArdle, Frank I. Katch and Victor L. Katch; 2007
Member Comments
jameskrigney December 3
Great article. I've been hearing so much about interval training but didn't even know where to begin.
A few questions:
About the ten second interval: The rest period would be 10 X 20 = 200 seconds, or a little over three minutes?
Can you recommend any pre-made schedules for someone who has recently gotten into running but has not tried interval before?
Finally, I am trying to find a way to make my iPod play nice with interval timing. I know I can make my own tracks, but I'm hoping there's a way to randomize a playlist (or two -- one slow, one fast)in spurts of specific time, and maybe with a 5-second warning. Any suggestions?
Thanks!
87shanna January 10
There is some fitness music on itunes that is interval based. Type in fitness music into the search. It takes some looking to find the interval music but I have seen it and bought some a while back.
mlestrux January 12
If you can get apps on your iPod, I would suggest downloading the Interval Timer app. This is so helpful because you can set your work time, rest time, and how many circuits you want to do so you don't have to continually mess with a stopwatch.
It also interfaces with your music so you can control your iPod through the app and you can set up your own preferences to change songs after reps.
KundaliniMike December 4
@ Jameskrigney: 1:20 is the high end. Go lower, like 1:3 or 1:5.
mountaingen January 10
Interesting. I generally will run at 6 miles/hour and then do 1 minute sprints at 8 miles/hour every 4-5 minutes. I wonder if I need to lower my rest mileage to get the best benefits?
cynthiamotherof January 10
This is great!
chairdr1 January 11
I listen to a podcast called Cut the Fat. Can be downloaded on Itunes. Dr. Ray Hinnish and Blythe Alberg are the hosts. This has been helpful to me and what was first started me calorie counting. Seems like most of the research "out there" confirms interval training as a way to burn fat.
thall24 January 11
BPM on xm radio really works as well. Can be downloaded on Iphone or Droid.
thall24 January 11
I used to walk on the treadmill for an hour at a time at 4mph @ 10% incline. I would typically burn about 1000 calories but was not getting great results. Since I have implemented HIIT (since jan 1, 2011) I have cut a ton of fat and have lost about 7 lbs already! I do 25-30 minutes on the treadmill. My program consists of 5 minute warm up (4mp @ 5% incline) then go to 30 second sprints (7.8 mph) and walk for 60 seconds (4 mph). I do this for 20 minutes. At minute 25 I then go to 4mph walk and cool down for 5 minutes. Killer routine. I am exhausted when I am dont but it feels good and I can really see it working. I do this 3-4 days a week. I also do this on the elliptical.
ShannaLeigh36 January 13
I did your workout today. KICKED MY BUTT! thanks!
WellesleyH January 11
I'm not clear how interval training burns so much fat when it targets "mostly muscle glycogen." I understand the increase caloric need, but so confused how this energy is being derived from fat stores. Fat is a slow efficient source of fuel and not a quick provider of energy.
freemachine January 11
You are correct. The article is misleading. High intensity burns carbs, not fat. The idea behind interval training is to make your body as inefficient as possible so that you burn through carbs quickly. When you deplete all of your O2 your body will convert carbs into lactic acid in order to squeeze out a few more calories worth of ATP (from the carbs in the absence of O2). For any of you who took biochemistry in college you'll recall: glucose --(glycolysis)--> pyruvate. The fate of pyruvate depends on the availability of O2. With O2, the pyruvate enters the Krebs (TCA) Cycle and moves on towards oxidation. In the absence of O2, pyruvate is anaerobically converted to lactic acid. Anyway, you can convert the lactic acid back to pyruvate when O2 is available again, and this (Cori) cycle occurs in the liver. This is where the resting part of the interval comes in.
In summary, make your body totally inefficient and burn as much glucose as possible. Remaining glucose that is converted to lactic acid can be recovered in the Cori cycle and the reformed pyruvate can be oxidized with O2 as normal. This is just a brute force approach that maximizes the calories you burn. Interval training DOES NOT BURN FAT!
As a side note, if you want to burn mostly fat, then you should stay away from your target heart rate. A lower aerobic pace will give you a steady consumption of fat as a fuel. I forget the percentage of THR, but I think it's something like no more than 60-80% of your THR. Sprinting will definitely take you up to and probably beyond your THR.
I'm not calling BS on this article because people do lose weight doing intervals, just not for the reasons provided. All chemistry explanations aside, if it works for you then that's all that matters.
I hope this helps.
Nidus January 13
Yeah I kinda agree it maybe slightly mis-worded but it's splitting hairs really.. it's hard to compare interval training to longer duration cardio. But long-term adding intervals will also increase your lean muscle mass, and improve the speed at which you can do steady-state long distance cardio too. These should ultimately lead to burning more 'total calories' - which is perhaps what the I think the article meant, rather than "fat".
kennybeal January 11
Does it make sense to combine interval training with long runs? How about doing long runs on non-interval training days?
lauranelson55 January 11
I would definitely separate the two. The lower the intensity, the longer the duration. Once you do the HIIT, you will be absolutley tired...the duration of these HIIT workouts will be much shorter than your distance days. Does this help!?
heybales January 11
I would suggest in addition, don't even do it the day after. You'll soon get sick or injured, because if you are doing the SIT or HIIT correctly, you'll be dead tired the next day too. It is just like doing weights, so same advice of not working out the same muscles the next day would apply.
momma_little January 11
Wow, this was a very informative article! I'm going to save this one!
SevenWellness January 11
Well put together article. I started using interval training during my HIIT (high intensity interval training) class as well as during Personal Training sessions in 2010. My clients are burning a much higher amount of calories and getting amazing results.
Chris Knight - Fitness and Nutrition Expert for Seven Wellness
pycotic1 January 11
I am lost. I run 45 minuter a day..five days a week at a 5.5 mph rate. How can I implement interval training into this. I really want to...I am hearing so much great stuff about it. Should I sprint 108 yrds every qaurter mile or is that wrong? Any help would be appriciated.
heybales January 11
Need heart rate monitor and knowledge of your max HR.
Make 2 days a week for intervals, with 2 days in-between.
First day after intervals, much slower pace, probably for 30 min. You gotta recover. Second day after, make normal pace/time.
Interval day, 5-10 min warmup at 50% MHR.
30 sec sprint at whatever pace feels like giving it all.
Back to slightly below normal pace (6mph?) until HR is down to 120-130.
Repeat for those 30 min.
Cool down slow jog for 5-10 min.
If done correctly, you'll see why you need 2 recovery days until the next one. And why 1 real good recovery day is needed.
www.exrx.net/FatLoss/HIITvsET.html
lauranelson55 January 11
Pycotic1. You should actually take a break from running the 45 minutes a day. If you are working out and only sticking to this cardio 6 days a week, begin by alternating your schedule. Change is good for any workout routine, anyway. Maybe on Monday, Wednesday and Friday you can stick to the 45 min running. On Tuesday, Thursday, Saturday, you can try HIIT. Warm up by walking for 5 minutes. Sprint for 30 seconds (I usually sprint around 10 mph-but start lower and slowly progress to higher speeds), walk for a minute and 20 seconds (it takes a good 10 seconds for the treadmill to get to running speed), sprint for 30 seconds, walk for a minute and 20 seconds.....keep the intervals up for about 20 minutes. You should do around 10 sets total. Then end the intervals with another 5 minutes of walking on the treadmill. In 30 minutes, you will bee done with your cadrio. You will recieve twice the reward as you would with your normal 45 min a day running. Try throwing some weights in there, too!
1790house January 11
I've been doing interval training as part of my swimming routine. I was swimming 1 mile, twice a week. When I plateaued, I switched one of my swim days to a 1/2 mile intervals. Swim 5 laps, then sprint 1. After 36 laps, you're done! It kick started my weight loss again. In the end, I lost 50 lbs (down from 213 to 163) I keep this routine going as part of my maintenance program. It's been over a year, and I'm still going strong.
micheleabella January 11
I LOVE HIIT!! I do this Mon, Wed, and Fri a.m. with a weight workout and I am energized all day! If you are a begginer or trying to lose weight try this website that I found researching HIIT awhile back: www.losebellyfatworkout.com it's great to get you started!! :)
GO HIIT!!!!!
heybales January 11
There have been some excellent studies regarding various forms of interval training. Some are great for raising your lactate threshold, that level that you are now anaerobic and won't last long. Some are great for just increasing endurance.
Here's one you can do at any level of fitness. The "sprint" is just a faster pace than what you can normally do. Very interesting study that shows how you can double your endurance level. Friend already running 7:00 min/miles did this and increased speed just a little, but really noticed his length of time increase.
Oh, the reason why intervals burns more fat than steady state aerobic is the same reason weight lifting does. It's the recovery. Hence the reason the next day should not have any aerobic, or at a very low recovery heart rate. The reason I like the study program is because it's just 2 weeks to notice the difference, then you can get back to enjoyable bike rides, in my case, instead of training.
What regular HIIT can do for you - www.exrx.net/FatLoss/HIITvsET.html
What a 2 week SIT program can do for you - www.exrx.net/ExInfo/HIIT.html
This program is basically 6 sessions over 2 weeks (3xweek).
Warmup for 5 min.
Sprint for 30 sec as all out as you can. If walking, jog. If jogging, run, if biking pick it up, if swimming do a lap all out.
Back to normal pace for 4 min. May need to go below normal for 30 seconds, but get it back up to normal.
Do that routine 4 to 7 times during each of those 6 sessions.
Notice at the end how much easier to do all 7. The recovery is easier, the sprint is faster.
And if you had pushed yourself for some long period of time before, you'll probably find you can go a whole lot longer now.
I'll throw those 2 weeks in my routine every once in awhile, when I feel getting stagnate.
scampisi January 12
All the research I've done shows that anaerobic exercise will not be able to burn fat since the conversion of fat to usable glucose requires oxygen. That is why all the charts and all the workouts that have "target zones" identify the 65-70% of maximum heart rate range as the "fat burning" zone. Of course, the intervals will burn more calories, but like this article states, it is burning those calories from stored muscle glycogen . . . not from fat.
However, the article points out that HIIT will strengthen you so that your workouts produce more wattage which produces a higher amount of calories burned . . . but during those intense workouts, those calories are NOT converted fat.
heybales January 13
Very true that during exercise, very little fat is burned. It's only during the recovery periods between the sprints that fat would be burned, and not even a great percentage then.
For aerobic exercise, especially in the fat burning zone, you only get benefit during the workout. I can recover from that zone in about 5 minutes.
But for any anaerobic exercise, it's what happens later for recovery that is going to burn the most fat. Your metabolism will be elevated for hours, same as with weight lifting.
And studies have shown intervals win big time there.
www.exrx.net/FatLoss/Misconceptions.html
en.wikipedia.org/wiki/High-intensity_interval_training#Benefits
katdono January 13
I've lost about 20 pounds in the last year and I attribute it to interval training. I've always been athletic and worked out. But my body didn't change much - I always maintained a 150 weight on my 5'7" frame. But, through interval training (and being more conscious of my eating habits) I shed the 20 pounds and I feel GREAT!
MtnBykr January 19
Interval training really works. I'm the type of Person who tries to stay in tune with my body and can see slight changes is strength, weight or even endurance (when using a gps and timer). I can tell you, that you will see the results of interval training in-between these high intensity workouts. Weight lifting becomes more intense and you will last longer. On top of that you will notice, a calming effect. You will reduce fatigue and breathe easier. It's amazing how the body adapts and strengthens so easily, but the benefits of interval training are incredible. Vascular endurance training is the most important workout you can do, it will improve overall performance.
kedenn01 January 25
I always feel as if I get too bulky with interval training... =/