Here’s the thread on Yuri Elkaim’s site on Intervals:

    Interval Training Revisited

    Yesterday, I was interviewed by the great folks at the Runners Roundtable. We discussed many running-related topics including stretching best practices and dietary recommendations for optimal performance.

    However, we also touched upon the power of interval training, yet many listeners still had questions that were unanswered about this type of training.

    It’s funny because I find hardcore runners the most resistant to adopting interval training into their running plan. I don’t know why?

    I think a lot of it stems from misunderstanding or even no understanding at all as to what interval training is really all about.

    For instance, one listener thought that interval training ONLY trains your aerobic energy system.

    How does that make sense?

    It totally depends on the type of interval training protocol one is following.

    Let me give 2 distinct examples.

    Interval Protocol #1

    1. Sprint for 10 seconds

    2. Jog for 30 seconds

    – repeat for 20 minutes

    Interval Protocol #2

    1. Run at 90% for 2 minutes

    2. Jog for 1 minute

    – repeat for 20 minutes

    These 2 examples both have you running for 20 minutes, however, there’s a major difference in the outcome goal of each one.

    In example #1, short bursts of all out effort with adequate recovery time will allow you to greatly improve your aerobic capacity (or VO2 max) without the onset of lactic acid. Thus, this would be more of an aerobic energy system training method.

    Conversely, example #2 would lead to a great deal of lactic acid build up because of the intensity and duration of the work interval and a shorter recovery interval. This workout would be great for improving your lactate threshold and getting used to running faster for a longer period of time.

    Do you see the difference?

    When it comes to interval training there are so many possible combinations of work and recovery intervals that it’s impossible to say that this type of training has no place for runners or athletes in general.

    After all, interval workouts produce greater cardiovascular benefits and help to burn more fat in less time than conventional cardio workouts.


    I don’t think your Interval Protocols #1 or #2 qualify as interval workouts as runners understand them. Or at least as I understand them.

    Protocol #2 is a tempo run, which is designed to improve one’s lactate threshold.

    I don’t know what Protocol #1 is designed for. It is too fast to be an interval and too short to be a repeat.

    I use terminology adapted from “Daniels’ Running Formula.” In that world, an interval workout is designed to improve one’s VO2max. To reach the max, and thereby stress it for adaptation, one must run for a certain period and limit the recovery. The recover is the “interval.” In its simplest manifestation, one runs for 5 minutes. From scratch, it takes 3 minutes to reach one’s VO2max. Five minutes allows for 2 minutes in that zone. One takes a somewhat shorter, i.e., under 5 minute, break before the next.

    Alternatively, one can run 400s. But that doesn’t get into the VO2max zone except that if one shortens the interval one doesn’t fully recover and one doesn’t start the next one from scratch. So, e.g., one workout I do (corresponding to a Daniels workout, is 16 X 400 at 80 w/ 40 sec. break. (The data for this are set forth at page 125 of Daniels’ Running Formula, 2nd ed.)

    The third variable, after distance and interval, is speed. I get to the 80 seconds not randomly but because it corresponds to the appropriate pace for someone who is in 35:30 10K shape. When I was younger and faster, the pace would be quicker as well. And every bit of running, from first to last, is at the same pace. Were I to do the first ones too fast, the last ones would be too slow. (This calculation is based up the “Running Formula” whence the book gets its name.)

    Now it may well be that “90%” matches one’s interval pace, but I can’t say since I don’t know what it is 90% of. And your description of the purpose matches tempo runs.

    The formula tells me that my pace in a tempo run, which would be ideally 20 minutes, about 88/400. The pace is slower because the system being stressed differs from the one being stressed in an interval workout.

    As to protocol #1, given the full recovery, I don’t know how one will get to the VO2max. Indeed, a third type of workout is the repeat, in which you run faster than in an interval workout and have full recovery, which works the anaerobic system as well (and more importantly) one’s form.

    In a sense your #1 is more akin to short, steep hill workouts. Brad Hudson describes these — 8 seconds (later extended to 10 and then 12 seconds) “at maximal intensity on the steepest hill we can find.” The purpose of this workout, however, is to build strength and to “increase the power and efficiency of the stride.” (Run Faster, at 35.) They are more like weightlifting and I periodically supplement my other workouts (or sometimes do part of a workout on a track and then head up a nearby hill) with them. By definition they are full recovery since it takes a while to jog back down the hill.

    Perhaps it is more akin to a short hill workout that some coaches add as an element of a t

    Now I don’t know any serious runner, of which I count myself one, who does not do interval workouts as well as tempo runs. Repeats are rarer.

    In the end, my point is that pointing to a single workout as the key is silly since each workout has to be part of a whole. I’m sure you recognize that, but I took from RunnersRoundTable (and I apologize that I was disconnected for a brief portion of the discussion) that interval training was being suggested as something more than it was, and it also seems that your use is inconsistent with the terms as commonly (albeit not universally) understood. The degree to which one does these various types of workouts also varies by the events for which one is aiming. I would do only a few interval workouts in marathon training and many more if I was shooting for a 5K since the need to push one’s VO2max in a race won’t arise in the former as it will in the latter.

    And, of course (and I’m sure this is done elsewhere on your site) it is crucial that one define the pace of any workout and also not to have everyone simply do it at X pace. The Goldilocks principle applies, not-too-fast/not-too-slow.


    Thanks for your elaborate comment Joe.

    I agree that when it comes to running one method isn’t better than all the rest. Rather a combination is what produces the best results. In fact all the training programs I put together be it 5k, 10k, half-marathon training and even the conditioning programs from my soccer players all involve different types of training including high-intensity interval training, race pace runs, and tempo runs.

    Whether one person calls intervals something else is really just semantics.

    At the end of the day, I feel that if someone wants great results and doesn’t want to spend hours training, then interval training is their best option.

From RunnerDude (a co-host on RRT):

    Hi Yuri!
    I agree, interval training is one of the best ways to get great results when you’re crunched for time. It’s also just a great strategy to add once a week to your normal routine along with tempo runs, easy runs, and long runs. Unless you’re a hardcore runner, pace isn’t that essential when doing intervals. But, a good rule of thumb is to your your 10K race pace for longer intervals (maybe up to something like a 1600m) and use your 5K race pace for your shorter intervals such as 200m, 400m, etc. If you’re training for a short-distance like a 5K then you may want to run your shorter intervals at a slightly faster pace than your 5K pace. McMillan Running has a great running calculator that can actually calculate out the various interval paces for the various race distance and race pace you’re training for, if you’re curious (the link for the calculator is in the upper righth-hand corner of the screen.



    The correct pace for a workout is crucial to its purpose and one needn’t be hardcore to care about it. And it’s not that difficult to figure out.

    I’m familiar with McMIllan’s calculator but I am partial to the one on RunWorks because it is based upon Daniels. Also note that McMillan has one plug in her “Best Time,” but that’s misleading. Instead one uses a recent race as a proxy for one’s current condition. The purpose of pace is to stress one’s current fitness, not where one once was. And it is particularly important not to plug a goal race-time because that defeats the whole purpose of the training.


    I cringe at the use of the word “great.” One will never be great by only running two or three times a week. “Great” is not some abstract. I could run a 40 minute 10K running a few times a week and perhaps some would say that’s impressive for a 53 year old. But for me it’s not.

    I realize, Yuri, that you say “Interval Training iPod Workouts to Help You RUN FASTER, Farther, and Longer Than Ever With Just 2 Runs Per Week…Or Your Money Back!” But, really, what’s the point? Running is relative. The objective is to be the best runner one can be. 32, 36, 45 minute 10K. Yes, there comes a point where the marginal benefit of that extra 10 miler is not worth the effort. But what one need do within the normal parameters of running at least five times a week, mixing various types of workouts at various times in the training cycle — and RunnerDude I do not agree that one should simply add an interval workout once a week; I probably do 10 interval workouts a year and only two or three in a six-month build-up for a marathon. These are points I discuss in a couple of posts, “What Kind Of Runner Would I Be?” (here, here)

    One of my teammates is the best masters runner in the NYC-area and on a run he said people forever come up to him and ask him what the “secret” is. He says, “there is no secret. It’s hard, intelligent work.”