Benefit of multiple short intense efforts


New Member
Jan 20, 2011
Hi guys,

i have a coach friend who has just recommended i do a circuit of hills with 4 uphill sprints, durations are ~20sec, ~15sec, ~40-50sec, ~1min, but not far between. And we'd do this loop 4-5 times

His theory is we're working on power, sprinting form, and also yanking the heart rate up, recovering briefly and then going hard again. To get used to being able to attack the bunch hard and then recover and go again. Eg Cadel evans in worlds in geelong last year.

My question is, what do you guys think of this and what sort of adaptation do you think I could get from it? I know it's anaerobic and obviously more of a specific race preparation thing, but what benefit will i get from it?

I did find it useful for sprinting technique i must say. And i agree with the concept of recovering from hard efforts for racing.

Would i get similar benefits from doing V02 efforts, say 3min efforts with 3min recovery or something like that? or is this a separate type of training session?


Some time ago I asked practically the same question about 30 sec intervals but the answer was "we don't understand it, we don't use it, it's not worth a penny".

There is some research that shows that series of 25-30 sec practically all-out (like a "very long sprint") intervals with long recoveries of 3-5 minutes in between compound both aerobic and anaerobic development though they're probably just a tad less effective than typical 3-5 min VO2max work. Explanation I've got for this is that they are intense but brief, that is they involve large muscle mass including high-threshold type IIb fibers but short duration bars severe acidosis which might be detrimental for aerobic development but provides enough stimulus for high-threshold type IIb fibers involved for aerobic development. Going beyond 35-40 seconds at the same level of effort shift these efforts into completely anaerobic range because of significant lactic acid buildup.

When done in series with short recoveries in sets like 3-4 intervals 30 sec on/30 sec off they become pure anaerobic and VO2max work.

Joe Friel also mentions series of the latter (40sec work/20sec rest) as anaerobic/VO2max stuff in his bible.

I like both types of workouts because when training in the streets. there is no room for making long VO2max efforts on the brink of losing concentration at high speed let alone breaks from traffic lights. For 30 sec intervals I can get by with a stretch 1-1.5 km of more or less empty road.
Cool thanks Dot, that makes some sense.

I think they're good for sprinting practice, i haven't really done any 3min v02 intervals so i might try those also, maybe i can alternate between the two from week to week. we're lucky here in aus to have some fairly quiet long roads to do that kind of stuff on.

be interested to hear what others have to say. I'm interested in finding out the effect of the different duration / intensity intervals, ie difference between 30sec, vs 2min, vs 5min, vs 10min, vs 20min, vs 60min, etc. So if anyone has any comments on this be great to hear.
there is lots of stuff on longer intervals,
this article nicely sums everything up,-by-andrew-coggan.aspx
there only missing values in the second table but there are copies of it all over the internet.
Originally Posted by stowy .
I'm interested in finding out the effect of the different duration / intensity intervals, ie difference between 30sec, vs 2min, vs 5min, vs 10min, vs 20min, vs 60min, etc. So if anyone has any comments on this be great to hear..
The choice of interval duration allows you to target a primary energy delivery system assuming the interval is ridden near maximally for the chosen duration. By 'near maximally for the chosen duration' I'm talking about 90% or more of your best intensity for the chosen interval time. Rest periods between intervals can also be manipulated to alter the target systems somewhat, particularly if the rests are kept very short as in 30 seconds or less and can lead to some unusual protocols like Tabata intervals that leverage incomplete recovery between primarily anaerobic bursts.

One way to understand the way interval duration targets one physiological energy delivery system over another is to think about the typical time it takes to exhaust a given system and force the athlete to drop to a slower more sustainable energy delivery system:

- Neuromuscular efforts fueled primarily by Phosphocreatine, ~10-30 seconds
- Primarily anaerobic efforts fueled via anaerobic glycolysis (burning sugars without O2), ~30 seconds - 2+ minutes
-VO2 Max efforts fueled via sugars burned aerobically at maximal O2 exchange rate, ~ 2 - 6 or 8 minutes max
-Threshold efforts fueled via sugars and fats burned aerobically at sub maximal O2 exchange rate, ~7 to 60 or more minutes
- Tempo efforts fueled via sugars and fats but at a lower intensity, Up to several hours
- Endurance efforts fueled by a higher fat to sugar ratio and lower intensity, many hours

All real world efforts are fueled by more than one process, even sprinters rely heavily on power generated through aerobic processes and even in a full hour time trial you can't help but draw on anaerobic processes to supply some of your power. It's one reason why the term 'anaerobic threshold' has fallen out of favor. There is no discrete 'threshold' where you use or don't use anaerobic processes, instead you use a blend all the time but as you exhaust higher intensity systems you're forced to rely more and more heavily on lower intensity and thus more sustainable systems.

So looking at the list above in a different way you can ask what energy delivery system is being primarily targeted by choosing a particular interval duration:

- Up to 15-30 seconds, Neuromuscular
- 30" to 2' or so, Anaerobic Work Capacity
- 2' to 6-7' or so, VO2 Max
- 8-10' to 60' or so, Threshold
- 1 hour to several hours, Tempo (still works Threshold and sustainable power but also stresses increased glycogen storage in the working muscles)
- Long rides, Endurance (more emphasis on glycogen depletion and storage as well as long duration fatigue resistance but still has benefits in terms of sustainable power if you do enough of it.)

This all assumes the efforts are ridden up close to your best possible effort for the duration. So a two minute effort ridden at your Tempo pace doesn't yield either an AWC effort or really a Tempo effort as you're not going hard enough to heavily engage anaerobic energy production nor long enough to deplete the higher intensity systems and rely primarily on sustainable metabolic processes.

More complex HIIT intervals like Tabatas don't fall nicely into this way of understanding things and is part of the reason Tabata's results with speed skaters was so surprising. But for conventional blocked interval workouts it's a pretty good way to get your head around why the length and intensity of your intervals matters.

I'm not a racer and I don't track stats of my riding. However, I basically do this all the time during my commutes. Especially when stopped at a stoplight, I start off as fast as possible, go way into the red zone. Not too long ago I was feeling weak and took a few days off, when I got back on the bike I decided to NOT do any massive accelerations and just ride a good pace. I was amazed at how fast I could ride for hours. I credit all the times going into the red and I never realized how much it takes out of you (because I do it all the time -- it became normal). So now when I need to make some really good time I don't do the crazy accelerations and my average speed shoots way up.

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