Improving endurance — don’t understand research paper

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  • #13808
    xcskier
    Participant

    I have come across this paper:
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5987183/

    In short, they have a insanely intense protocol of cycling for 6s at
    250% FTP (functional threshold power, so, it’s not quite all out), followed
    by 24s rest. You repeat this 90 times, for 45 minutes total. This was done
    3 times a week for 2 3 week blocks.

    The paper claims slow-to-fast fiber type transformation and improved
    endurance performance.

    Besides the brutality of the protocol, I fail to see why transforming your slow
    fibers to fast fibers improves endurance. Don’t we want slow fibers and
    perhaps increase mitochondrial density in fast twitch (IIa) fibers?

    Furthermore, wouldn’t event is 6s sprint generate a lot of lactate and
    would have hard time removing it in such a short time (24s)?

  • Keymaster
    Scott Semple on #13833

    I agree. I don’t know why converting ST to FT would be an advantage. Perhaps that’s not what’s happening, even if they think it is?

    For instance, that protocol wouldn’t produce near-peak lactate. It may be higher than aerobic threshold (~2 mM), perhaps even higher than ~4 mM or MLSS. But it would still be a mostly aerobic effort.

    To maximize lactate production, you need to use longer, passive rests. Something like 8-10x 8-12″ with 2-3′ passive rests will show peak lactate values. In a weekly progression, this type of workout also increases anaerobic capacity.

    The short rest periods in the protocol in the NCBI article won’t allow the FT fibers to recover, so I don’t think high lactate values would be observed. Although very intense, this seems like an aerobic protocol to me.

    Keymaster
    Scott Semple on #13834

    Also, from what I understand, a 5″ peak power effort is usually around 400% of FTP. The 250% that they used in the study is closer to a 45″-1′ effort level of power. To me, that supports the idea that the study protocol is mostly aerobic.

    If aerobic capacity increased after this protocol, my guess is that:
    * The FT fibers were exhausted pretty quickly because they didn’t have time to recover; so
    * The still-active ST fibers were forced to deal with the elevated levels of lactate;
    * Probably increasing their aerobic capacity as a result.

    To really see if there was “slow-to-fast” fiber conversion, did they measure maximal anaerobic capacity before and after the program?

    Also, it’d be interesting to try this on a treadmill.

    ===========

    Also, in my first response, I said:

    “To maximize lactate production, you need to use longer, passive rests.”

    I should have said:

    “To maximize lactate production, you need to use longer, passive rests AND NEAR-MAXIMAL SPEEDS.”

    Keymaster
    Scott Johnston on #13867

    This study does present some interesting results. But as will controlled studies that are designed to look at a narrow range of effects, I caution you to not read too much into them. I have no doubts about the validity of the tests or their results but other mitigating factors limit the usefulness of these studies for anyone other than other researchers.

    FIRST) There were 7 untrained subjects in this test and while the standard deviation in the endurance test results definitely show significant improvements in time to exhaustion at both 65 and 80% of peak power, we have not control group of similarly untrained subjects doing another training intervention to see how they would respond. What would this intervention have looked like if applied to well endurance trained athletes?

    SECOND) No athlete trains in 3 week isolated blocks. Athletes train all year of at least in season long blocks. What would this intervention look like if applied over a prolonged training block of months? Could it be sustained?

    Third) The lactate levels dropped through out the 2 three week training blocks which is what we see with your ME workouts. This indicates that the aerobic metabolic system is contributing more of the ATP yet the researchers admit to finding some of their results contradictory and suggest that some of endurance improvement may be do do hypervolumea (increase in blood volume). This would especially pronounced in untrained subjects but much less so in well trained.

    In short I suggest a heavy caution in trying to apply the results of lad studies to the real world. Instead, look at what the methods used by the best endurance athletes and coaches for guidance. The best laboratory in the world is the competitive arena. The best measurement is the stop watch. The pool of subjects numbers in the millions. The study lengths are measured in months and years. The natural evolutionary process of rejecting bad ideas and refining good ones using empirical methods naturally weeds out the field so that 100 years on we have very good consensus as to what works and what doesn’t.

    Taking studies out of context is exactly what has given us the fitness fads like CrossFIt, PX90, Boot Camp, Orange Theory Fitness, Tabata intervals etc, etc, etc.

    If these get fit quick schemes worked, the endurance athletes of the world would be flocking to them…….They’re not.

    Scott

    Participant
    xcskier on #13887

    Scott and Scott, thanks for your replies.

    I wouldn’t want to use this method (or other “sport science” training
    methods) for actual training. Instead, I was just trying to understand
    a possible mechanism for why performance improves despite seemingly
    non-intuitive fiber expression change.

    No elite (or highly trained) endurance athlete would be willing
    to try this method for a study.

    It seems that the endurance improvement may come just from a typical
    “anything will work for a few weeks” for untrained subjects.

    I am still somehow surprised by the amount of lactate that was
    generated. While 6s may be initially short enough to just use
    creatine-phosphate, 24s rest is way too short to replenish
    for the consequent sprints.

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