Jim2-ExPhysRunner-Denton Discussion

The following is the final discussion in the thread. It was initiated by Jim2’s reply to the original poster and took place between Jim2, ExPhysRunner, and Denton over a one-week period of time.

Jim2 - There are intervals, and then there are “intervals”.

The use of the word “interval” can be confusing because it is often used generically to describe different types of workouts. However, the term is most commonly applied to a specific type of workout that is intended to improve aerobic capacity, or VO2max.

ExPhysRunner said, “I am not a big fan of prescribing interval workouts in distance as you run into the issue of how fast can one cover that distance.” He also said intervals lasting longer than 5 minutes “….is getting away from the idea of the workout (VO2max intervals) as 5 minute is at the upper end of the time frame for maintaining vVO2max.”

I could not agree with him more on both points!!

A simple way to define this workout and to remember how it should be run is to think of it as “three times 3-5” or “3-5 cubed”.

1) Each interval should last 3-5 minutes.

2) Each interval should be run at the pace that you can sustain for about 15 minutes….which is 3-5k race pace for most runners.

3) Each recovery between intervals should be 3-5 minutes….or about the same as the interval duration.

For most runners, those guidelines will require interval lengths of 400-1200 meters. That’s a wide range. And that’s the problem with recommending specific intervals distances, as opposed to durations. Intervals shorter than 3 minutes reduce the total time spent running at VO2max. Intervals longer than 5 minutes enable too much accumulation of blood lactate, which will negatively affect the workout by either shortening it or causing pace to degrade. Both detract from the purpose and effectiveness of the workout.

The number of intervals in a workout should be as many as you can handle at target interval pace. For most runners, that will be 4-8. Yasso 800’s (10x800) that are used by marathoners are essentially a modified version of VO2max intervals. They are run slightly slower than true VO2max pace, but the quantity of 10 make the workout a reasonable VO2max “test”.

Actually, there are three other types of intervals, but the simple term “intervals” isn’t usually used for them. They are more often called “cruise intervals”, repetitions and hill repeats.

Cruise intervals are a type of workout that can be used to emulate a tempo run to improve lactate threshold. They are longer and slower than VO2max intervals. They typically are 1-2 miles long and are run at threshold pace….the pace that one can race in about an hour, which falls in the range of 10k-half marathon race pace for most runners. Recovery between cruise intervals should be very short….no longer than a minute or so.

Repetitions are the fastest and shortest form of intervals….usually 100-400 meters at a pace that is as much as 20-25 seconds/mile faster than VO2max intervals with full recovery between them. Recovery periods can be 4-6 times as long as the repetition time. Repetitions help to increase leg turnover rate, improve running economy and develop the body’s ability to generate energy anaerobically.

Hill repeats are a form of intervals used to improve running strength, form and economy. They are usually 50-800 meters long. The shorter ones (50-200 meters) should be steep (10-15% grade) and run between repetition and 5k intensity (not pace). The longer ones (400-800 meters) should be not as steep (5-8%) and run at 5-10k race intensity.

Training for 10k racing (or marathoning, for that matter) should include all four types of “intervals”. You can run as many as two “intervals” workouts/week. Thus, one approach for a novice at training is to simply rotate the four types of workouts, which would ensure one of each type every two weeks. Another approach is to “periodize”, which means to focus of different development goals in different phases of a training cycle. That’s one good reason to choose a “cookbook” training program to use as a guide. Higdon, Glover, Daniels and others all have programs that will systematically lead you through a development process.

ExphysRunner has made some other excellent points in this thread. For instance, as he said, you should be running one “long” run each week. Depending on where you are in your development right now, it could be anywhere from 6 to 12 miles long at this point. If you aren’t running longer than 5 miles now, then increase the weekly long run gradually over a couple of months until it reaches 10-12 miles. That will do more for “stamina” development than any of the interval workouts. Any established cookbook 10k training program will guide you through it.

Denton - Having said all this 'interval stuff’, one can always go back to the tried and true fartlek. For many beginners this can be bad as they don't quite know how to do it, but IMHO the greatest all around workout is the famed 'monfartlek' of a 20min session run as 2 x 90 seconds hard - 90 seconds float - 4 x 60 seconds hard - 60 seconds float - 4 x 30seconds hard - 30seconds float - 4 x 15 seconds hard….'float' being what you would run on an easy day pace or a little quicker. I have figured that out that it's pretty close to getting VO2max style energy systems without the structure of hitting certain paces, but run by feel.

ExPhysRunner - Those work sides need to be pretty close to all out. Billat and Astrand (among others) have shown that 30 seconds all out with 30 seconds rest can be done for 15 minutes and be a very good VO2max workout. It seems counterintuitive until you learn more about exercise physiology.

Denton – No, not counterintuitive; just real life vs. a test tube. Sorta like deek’s (Derek Slayton’s) also famous 8 x 400 meters with 200 meter floats. That’s about15 mins of very hard work that never quite allows for the HR to drop. It's only counterintuitive if it doesn't do the job on the track, not if it can't be measured in a lab.

ExPhysRunner - A few things.

1) I think you are being too fine in your definition of an interval. It deals with a work/rest workout and the structure of it. You can have LT intervals for instance.

2) For VO2max, I follow Veronique Billat's ideas which is to run the 3 minutes at close to mile pace; if there is a longer interval then the pace has to slow.

3) Lactate is not a bad thing. It is a critical energy substrate for high intensity exercise. It does NOT cause acidity although it appears in conjunction with an increase in acidity. In fact, lactate actually helps to buffer the acidity.

4) The problem with longer workouts is that you cannot get the intensity high enough to drive VO2max.

5) Oddly enough you can do very short high intensity efforts with rest recoveries and achieve the same thing. For instance 30 or 60 second all out sprints with equal time of rest done over and over can achieve the same thing. The first one or two are anaerobic, but then after 3 or 4 they become increasingly aerobic and at a high enough intensity to sustain VO2max.

Jim2 – May I comment on your five points?

1) Are you sure you read all of my post? I thought I was quite broad in my description of the various types of intervals. I described four types, including LT cruise intervals.

Unless you were referring to my "narrowly" defining VO2max intervals as 3-5 minutes. I agree that they can be as short as 30 seconds. However, intervals that short are not very common among long distance runners, although they probably are among sprinters and middle distance runners. I was just offering a simple and descriptive way ("three times 3-5" or "3-5 cubed")
to remember how effective VO2max intervals should be done.

2) That’s not a bad approach, although mile pace puts you well into the anaerobic zone and accelerates the buildup of blood lactate and muscle acidosis. That would probably force a shorter VO2max workout session than would running them at true VO2max pace. Daniels calls for all VO2max intervals, including the very short ones of 30 seconds, to be run at VO2max pace and no faster to maximize the total time that can be spent running at VO2max during the session.

3) I agree that lactate, per se, is not a bad thing. Not only is it a product of working muscles, it is also a fuel for them.

How does lactate help to buffer acidity? Correct me if I am wrong. But, as I understand it, both lactate and acidity (H+ ions) are byproducts of the same process, namely the dissociation of lactic acid produced by working muscles. H+ acidity is buffered by sodium bicarbonate that is present in the body resulting in water (H2O) and carbon dioxide (CO2), which is expelled through the lungs.

The problem for a runner occurs when running becomes intense (anaerobic) enough for the rate of production of lactic acid to exceed the body's rate of utilization of lactate as fuel and rate of buffering and clearing H+ ions by sodium bicarbonate. The results are a rise in blood lactate level and a rise in muscle acidosis, which interferes with enzymatic metabolism of glucose to produce energy.

4) Depends on what you mean by "longer workouts". If you mean longer than 3 minutes, then I don't agree; although I don't think that's what you meant since you said in another post that 5 minutes should be the upper limit.

You can get the intensity high enough to drive VO2max for as long as you can sustain VO2max pace, which is longer than 3 minutes for all but the least developed runner. The problem with intervals longer than 5 minutes is the amount of blood lactate and muscle acidosis accumulation, which eventually reduces the total length of time that VO2max pace can be sustained throughout the entire workout.

5) Yep. You can push VO2max with 30-60 second sprints. But, I have two problems with such a workout. The first is, again, a pace that is unnecessarily much faster than VO2max pace. That pushes you well into the anaerobic zone and results in increased lactate/H+ accumulation, which will impose a lower limit on the workout duration than will a slower pace closer to or at VO2max pace. Of course, that assumes that VO2max development is the purpose of the workout. If the primary purpose is anaerobic metabolism development and VO2max is a secondary benefit, then I think it's an excellent workout.

The other problem I have with 30-60 second intervals, even at VO2max pace, is that so many of them have to be run to get an equivalent workout as, say, 4 minute intervals. The fundamental goal of a VO2max interval session should be to get about 20 total minutes, plus or minus a few minutes, of running at VO2max pace. That can be done lots of ways. For instance:

Four 5-minute intervals, which yields 20 minutes.
Six 3-minute intervals, which yields 18 minutes.
A ladder of two 3-minute intervals, two 4-minute intervals, and two 5-minute intervals, which yields 24 minutes.
A pyramid of one 3-minute interval, one 4-minute interval, one 5-minute interval, one 4-minute interval, and one 3-minute interval, which yields 19 minutes. (I like this one because of the variety it brings to the workout.)
Twenty 60-second intervals for 20 minutes total.
Forty 30-second intervals for 20 minutes.
For variety, Daniels suggests a workout that consists of 6x2-minutes with 1-minute recoveries, 8x1-minute with 30-second recoveries, and 8x30-second with 15-second recoveries, for a total of 24 minutes at VO2max pace and 12 minutes of recovery.
etc, etc, etc

I suspect that most long distance runners would quickly become bored with the very short intervals, although sprinters and middle distance runners might prefer them. I would probably lose count of them since they exceed the number of fingers that I have.

There used to be a guy on these forums named FrankS (aka Parrothead) who can still be found on the Merv forums. Denton knows him. Frank is an old guy, like me. Unlike me, however, in his youth he was an excellent track man....I think he set a couple of 440 or 880 school or county records in Florida. (I said we are old....we predate the shift to the metric system. ) Frank used to talk about a workout that his track team did that was especially tough....25x440. That makes for a very challenging VO2max workout. He used to tease forumites about "sentencing" them to a 25x440 session for comments with which he disagreed.

ExPhysRunner - I was stuck on this:

”The use of the word ‘interval’ can be confusing because it is often used generically to describe different types of workouts. However, the term is most commonly applied to a specific type of workout that is intended to improve aerobic capacity, or VO2max. A simple way to define this workout and to remember how it should be run is to think of it as ‘three times 3-5’.”

I read that to be a narrow definition. I re-read the post and noted that discuss other things (reps, cruise and such) and say that they are not often called intervals.

30 sec on 30 sec off was used by Veronique Billat with runners. It could be a fartlek workout for instance. Just another way to skin the cat. Sprinters would actually do an all out effort with a full recovery, not a very incomplete one.

How fast do you run a mile? The mile, even at world class pace, is still predominantly an aerobic activity. I will take a moment to clarify: The actual pace is based on an all out 6 minute effort (for me that often comes out to be around a mile). That correlates very well with the pace of vVO2max--that is the minimum pace that elicits VO2max. The longest that I have seen reported that a person can run at VO2max is 8 minutes. So 5K pace is nowhere close to VO2max pace--it is too slow.

So run the 6min run. You cover 1600m. Your 3min effort is then 800m. 3 minutes is still very aerobic at this pace. Also, each subsequent one is more aerobic than the one before it (just as it is with the 30/30's.

Why do you fear lactate? Have you not been following the discussions about it and how it is an excellent fuel source? Acidosis may not be all that bad. I suggest you read Cairns review in a recent issue of Sports Medicine. Acidosis has some positive benefits at the temperatures in the body during exercise where the blood gives up more O2 (Bohr effect).

Oops, I see that you know it is a fuel substrate.

Each lactate molecule takes up a proton. Go to http://www.sportsci.org and find Robergs' paper on Metabolic Acidosis. I cannot get a direct link, but there is a search function if you want the whole process.

You need to separate out lactate from the protons (H+). Also see Cairns about how acidosis may not be a bad thing. A lot of this is based on research done on frogs and (as I learned) amphibian muscles are different than mammalian muscles in regard to response to acidity. Also many experiments were not done at muscle temperatures that an exercising human would reach.

I did mean longer as in longer than 5 or so minutes. My issue with intervals longer than 5 minutes (and it could be longer for some people) is that the intensity is not high enough to get as much bang for your buck--that is improving VO2max or vVO2max. You seem to contradict yourself. Intervals longer than 5 minutes are going to produce less acidosis and less lactate since they have to be more aerobic.

The reason one does intervals for VO2max (or anything else) is that you cannot maintain that pace for as long so you shorten it, add recovery and you can do more work. If you can maintain VO2max pace for 15 minutes (using 3-5K) then why not run for 15 minutes at that pace? Because you cannot do it--no one can do it for that long. 5x3 or 3x5 amounts to the same thing--15 minutes at VO2max (assuming you get the pace right).

You are patently wrong about the 30 or 60 second sprints when done repetitively. Here is how a workout might go using 30 seconds.

Warm up
30 sec "all out"
30 sec rest (it could be standing or walking)
30 sec all
30 sec rest
(Continue for 8 to 15 minutes depending on ability)

The first one and even the second one is going to be highly anaerobic; however after that the aerobic contribution increases with each subsequent rep. The reason is that ATP-PC cannot be fully restored in 30 seconds so you increasingly have less and less.

I have a slide from Putnam's 1995 it shows that the first such sprint is 59% energy from lactate production, 15% from PCr breakdown and 26% from oxidative; the next one is 51/15/33 and the third one is 21/26/63.

Billat has similar findings:

Very short (15s-15s) interval-training around the critical velocity allows middle-aged runners to maintain VO2 max for 14 minutes.

Billat VL, Slawinksi J, Bocquet V, Chassaing P, Demarle A, Koralsztein JP.

Laboratoire d'etude de la motricite humaine, Universite de Lille II, Faculte des Sciences du Sport, Ronchin, France. veronique.billat@wanadoo.fr

The purpose of this study was to compare the effectiveness of three very short interval training sessions (15-15 s of hard and easier runs) run at an average velocity equal to the critical velocity to elicit VO2 max for more than 10 minutes. We hypothesized that the interval with the smallest amplitude (defined as the ratio between the difference in velocity between the hard and the easy run divided by the average velocity and multiplied by 100) would be the most efficient to elicit VO2 max for the longer time. The subjects were middle-aged runners (52 +/- 5 yr, VO2 max of 52.1 +/- 6 mL x min(-1) x kg(-1), vVO2 max of 15.9 +/- 1.8 km x h(-1), critical velocity of 85.6 +/- 1.2% vVO2 max) who were used to long slow distance-training rather than interval training. They performed three interval-training (IT) sessions on a synthetic track (400 m) whilst breathing through the COSMED K4b2 portable metabolic analyser. These three IT sessions were: A) 90-80% vVO2 max (for hard bouts and active recovery periods, respectively), the amplitude= (90-80/85) 100=11%, B) 100-70% vVO2 max amplitude=35%, and C) 60 x 110% vVO2 max amplitude = 59%. Interval training A and B allowed the athlete to spend twice the time at VO2 max (14 min vs. 7 min) compared to interval training C. Moreover, at the end of interval training A and B the runners had a lower blood lactate than after the procedure C (9 vs. 11 mmol x l(-1)). In conclusion, short interval-training of 15s-15s at 90-80 and 100-70% of vVO2 max proved to be the most efficient in stimulating the oxygen consumption to its highest level in healthy middle-aged long-distance runners used to doing only long slow distance-training.

Note that the lactate levels were LOWER in the Billat study along with the Putnam study. Astrand has shown similiar findings with 60/60 intervals.

In the Billat study they spent 14 min at VO2max. Closely in alignment with your idea of 20 minutes or my thought of 15 minutes being about it. So you can do 60/60 for 30 minutes and get there.

The issue I have with very short efforts is that few people race like that and I think there is something to learning to "gut it out" for a period of time. Now if someone is really "racing" that is going to head to head for a win, the ability to surge and recover can be a great tactic.

The way to keep track is to do them on a track or some watches allow you to set up such repeats. Having done them in cycling, I had no problem keeping track. I did not count, I just did the on/off for X amount of time.

I also ran on Imperial tracks. In fact I ran the last event ever on my high schools imperial track before we converted it to a metric one (since I ran the 4x440).

25x440---I have done a few of those. Talk about a mind numbing and ball busting exercise!

Denton – Billat’s report concluded, "….short interval-training of 15s-15s at 90-80 and 100-70% of vVO2 max proved to be the most efficient in stimulating the oxygen consumption to its highest level in healthy middle-aged long-distance runners used to doing only long slow distance-training."

I always have concerns over studies that use the 'sample 'group as the definitions can vary. For example, how is a 'healthy middle aged' runner relevant to someone else (not saying it isn't but the question arises). But some healthy aged runner may have no relevance to who I train or my own training. On another note, this sort of '15s-15's' you mention would help to explain one of my taper sessions (had an achilles injury and couldn't go on the track so ran on the roads and in my trainers) that involves 3 minutes of alternating 30s-30s, then 3 minutes of 20s-20s and then 3 minutes of 10s-10s….therefore around 9mins total of alternating speeds.

ExPhysRunner - Good point, you do need to look at the population tested. Of course that description is spot on for a lot of folks on this site
At the same time, totally discounting it is not a good idea either. It was just one of many studies that show the same concept at work.

Jim2 - Thanks for your detailed reply. You are so proliferate on these forums that, probably out of necessity, your posts are usually very concise. I was hoping that you would go into detail on this one....and you did.

If Billat considers 6 minutes to be the max that one can sustain vVO2max, then she is in sharp disagreement with other physiological experts, such as Daniels and Martin/Coe.

Daniels, who(according to Martin/Coe) coined the term vVO2max to illustrate the combined the effects of VO2max and running economy on running and who pioneered its use as a training tool, says:

I define VdotO2max I intensity as a speed of running that could be kept up for 10-15 minutes in a race situation. For an elite athlete this is about 5000 meter pace, but for most people it is closer to 3000-meter to 4000-meter race pace. Using the pace of a current 5k race to approximate I pace is acceptable for less gifted or unfit runners, even though they take more than 15 minutes to race a 5k, because the pace factors in a more conservative intensity, which may not be a bad idea for this population of runners.

The interval (I) paces that Daniels lists in his VDOT tables are consistent with that. For instance, his I pace for a 6:00 miler (VDOT 48) of 4:03/1000 meters (6:31/mile)is just 8 sec/mile slower than that runner's 5k pace, but no where near his/her mile race pace.

Martin and Coe describe a treadmill test performed under lab conditions to determine vVO2max. However, recognizing that it's unrealistic for most runners (even competitive ones) to undergo such a test, they say:

As a practical suggestion for coaches, athletes should perform a track time trial lasting somewhere between 10 and 12 minutes (this is about the longest period of that VdotO2max can be sustained). Knowing the distance covered and the elapsed time will permit a field-test estimation of vVO2max.

In the 1988 edition of his book, Bob Glover said to run intervals at the pace you can sustain for 10-11 minutes, which he generalized as about 10 sec/mile faster than 5k race pace. In the 1999 edition, he modified his guidelines somewhat to say to run slightly slower than sprint pace for 220s to 5% slower than 5k race pace for longer intervals up to a mile.

Actually, according to Owen Anderson, even Billat says that the period of time that runners can sustain vVO2max ranges from as little as 3 minutes to 13 minutes. Her 13-minute top end is within Daniels suggested range and a little above the top end and Martin/Coe's range.

I think all this just shows, like on so many running subjects, that even the "experts" don't always exactly agree. One reason might be differences in the audiences they are intending to address. The best us mortal folks can do is use our best judgment based on the info that we have to work with....and, if we are going to err, do it on the conservative side, at least until we become very experienced runners.

Bottom line, I think, is that the object should be to run VO2max intervals at the pace at which one just reaches VO2max, and no faster. Following either Daniels' guidelines or Martin/Coe's might put some folks a little short of true vVO2max. However, using 1-mile race pace is more likely to put the average person beyond it and risk compromising the quality of their workouts as measured in total work expended and time spent running at or near VO2max.

Billat's guidelines might be more appropriate for elite and other highly advanced runners. However, for the average Joe and Jane, I think Daniels guidelines are best. And they are more readily available via Daniels book. Said another way, to risk erring on the high (fast) side might be OK for folks on the High Performance Forum. But a slightly more conservative approach is probably better for most of us mortal beings who frequent the other forums.

For instance, if 1-mile race pace is "optimum" as you suggest, that might be 6-minutes for you. But, for this 67 year old, 40 pound overweight guy who hasn't been running for the last 5 years, it's within Martin/Coe's range for me and my 5k race pace is outside their range, but within that of Daniels'.

One way to really simplify this subject is to just run a set intervals totaling 15-20 minutes with equal recoveries at the slowest pace at which one cannot converse, even in short phrases, 1-4 times/month, depending on one's overall training program. That will benefit just about any runner.

Concerning the 30-60 sec all out sprint intervals, I might be “patently wrong” about them, as you said. But, then so are Daniels, Martin/Coe and Glover.

The report of the Billat test with the older runners that you included in your post was interesting. It demonstrated that an I pace that is faster than vVO2max produced higher blood lactate level than does a pace at or 10% below vVO2max, despite a correspondingly slower recovery pace. I think you would agree that sprint pace is faster than vVO2max. I think that supports the opinion that I stated re the 30-60 sec sprint intervals. And the advisability of erring on the conservative side of vVO2max.

This is a good discussion! I haven't been so energized over a thread since the one we had about treadmill incline a few months ago and some that hillrunner and I used to have on the Marathons Forum a couple of years ago. You are very knowledgeable about exercise physiology and I'm learning a lot from you, along with the research I have to do to try to discuss the subject halfway sanely. And learning (along with camaraderie) is what this place is all about!

ExPhysRunner - Yeah, it is all rather confusing and there is a consideration on the ability to measure such things as well. As technology has improved we have figured out that things are not as they once were thought to be.

I have a book by Joe Vigil (and some USATF stuff from their level 1 course) that is flat out wrong in terms of anaerobic contribution in middle distances. Why? At the time the technology did not exist to measure things so finely.

It makes perfect sense that the faster the person is the longer he/she can maintain VO2max. The Billat work is nice in that she actually checked on the correlation with VO2max. Remember when VO2max is measured in the lab, the velocity at the end of the test includes some anaerobic contribution. There is a slower pace that elicits VO2max.

The problem I have with Daniels is that he makes the assumption that everyone has the same running economy in his VDOT tables. Running economy that differs by 5 percentage points can really mess that up.

How bizarre...I was looking for a paper and found a review on training distance runners for Vo2max. Gonna read it now.

I have enjoyed your posts for a while.

Gotta go.