1. Good info in this post. Thank you.

    You mention and link to “a 1996 study by Bogdanis et al., subjects performing 10 maximal effort sprints on a 6-seconds on, 30-seconds off cadence incurred a 27% drop in power output from the first sprint to the last (870W – 635W).”

    Did you mean to refer to Gaitanos et. al. (1993) who did the study on 10 x 6-second intervals? The Bogdanis study appears to be 2 sprints separated by four minutes.

    regards, neil

    1. Neil,

      I really appreciate the catch, man – the Gaitanos study is the one I intended to post. The error was entirely mine and I’ve sent Joel the correct paper to hyperlink in the Bogdanis paper’s place.

      Fantastic content on your site, by the way. I’ve thoroughly enjoyed everything I’ve read.



      1. I’ve updated the study in the article, everything should be correct now. Good overall review of some more current research on the zone5endurance site, the only thing I’d point out is that it’s not quite as simple as saying “everything we used to think was anaerobic is actually more aerobic, therefore this type of training will always improve aerobic fitness.” It’s easy to diminish aerobic fitness with prolonged high intensity efforts because even though aerobic may be contributing at a high level, it can also lead to mitochondrial destruction as well.

        1. Thanks for the update and the kind words guys. Joel, your comment is fair and well-taken. As you probably noticed, I’m not formally schooled or trained in this science – instead am an endurance athlete and occasional coach who likes to read and wants to better understand/explain this stuff. As such, mitochondrial destruction was not on my radar before, but I will add it to my list of topics to explore.

          Finally just a word of thanks to all of you. Much of the stuff on Zone 5 re: modern energy systems research (incomplete as it may be) derives from concepts that I first discovered here on 8 Weeks Out (e.g. Joel’s Energy Systems preso, Dave Tenney’s soccer articles, etc.). I’m not aware of anyone else that has taken the time to consistently piece together/explain the latest science on these topics and translate it into meaningful training terms like y’all have done. Many of us in the endurance community have found your work extremely valuable. So thank you!!

    2. Very interesting review/article Eric. Couple of comments thought:

      Soccer or any team sport is NOT repeat-sprint sprint sport, but rather HIIA – High Intensity Intermittent Activity. RSS or repeat sprint sequence is a SEQUENCE that happens now and then during the course of a game. If you take a look at this poster by Martin Buchheit, you will get data that RSS actually doesn’t happen that often in a competitive game.

      The research is still inconclusive (and that was actually said in the review articles on RSA you were referencing) about the role of glycolysis in the RSA (Repeated-Sprint Ability). Athletes with higher amount of glycolytic energy system activity actually had BETTER total times in RSA tests compared to the athletes whose glycolytic energy system decreased over the number of sprints. So, to improve RSA should we increase or decrease reliance on glycolytic system?

      Although these two point might seem to conflict the notion of alactic-aerobic, they actually support it. First, intermittent sports are NOT repeat-sprint sequences. RSS happens couple of times during the game and it is questionable how much specific RST should be done to improve it (if the athlete is doing sprint, power, strength and intervals/aerobic training anyway). Thus, game specific endurance is not solely RSA as we portray it, thus although glycolytic energy system is important in RSA and RSS it doesn’t mean HIIT should be done day in and day out, because RSA is not that actually important. So, for team sports alactic-aerobic is still the key to game specific endurance.

      Just my 2 cents…. Keep up the good work

  2. Just to clarify, for lactic development one would do 2-12 bouts of 20-30 s max effort, with about 10 min rest between each? The set and rep scheme in the article seems a bit vague.

    1. arumuko,

      I apologize for the ambiguity, but it looks like you’ve got it.

      Research has indicated that these longer rest periods (10-15 minutes) between bouts of high-intensity intervals are related to the greatest increases in glycolytic enzymes (as apposed to 3-4 minute rest periods).



        1. desearls,

          Would you believe that the NFL, quite possibly the richest sporting organization in the world, doesn’t collect time-motion research but Irish hurling does? Crazy …

          Between the actual reps of lactic power intervals, rest periods of greater than 4 minutes are recommended, with ~10-15 minute rest periods appearing to be optimal for PFK and phosphorylase augmentation. As arumuko mentioned above, I’d aim for 2-12 of these “reps” per session, depending on where you fall in your lactic system development progression.


  3. Great review Eric – I really liked seeing the graphs of energy contributions from 1st to last interval, never seen that before.

    I’ve got 2 questions:

    1) What did the studies describe in terms of what adaptations DO occur with the 30/90-240 work:rest interval methods? Do you have the references for these?

    2) For aerobic power style intervals (120/60), I coach my athletes to start out strong (but not a sprint) and gradually pick up the pace until they get to a hard steady state about halfway, then go as hard as possible while maintaining running form (not running like they’re about to die) for the last 50 m…

    I find we do approach max HR with this method by the end (can’t tell when it hit in the middle as I don’t have second-to-second HR vs. time data).

    I do this so as not to get them to start very fast then have to drastically reduce their speed.

    What are your thoughts on this and what methods do you use or would you say it doesn’t matter much and is more personal/athlete preference?

  4. Super article, I keep referring everyone to it.
    But one question, What are the options for length of block when periodizing. I was doing 4 week blocks but my aerobic fitness was dropping too much. I switched to undulating wave periodization and that worked well for about 4 months but then I started overtraining. Are my periods too short? and if they are too short, how do I keep my cardio high during the strength and power building periods?

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