Legs after hill sprints

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  • #54221

    I am finding that after the 10 second all out hill sprints workout in the big vert plan my legs feel really tired and heavy the next day.

    I am pretty sure I am slow twitch dominant (both from experience – i am NOT a sprinter at all) and from genetics.

    The first time I thought it could be the weather suddenly getting much hotter but it has now been 3 weeks of trying to do my normal long Saturday run and finding that my legs feel really super heavy but not sore at all.

    Based on the workout commentary and people’s comments I was expecting the workout to feel super easy because I haven’t done hardly any sprinting before (and I read that people who haven’t won’t engage the FT muscles and therefore it will feel like it’s too easy) I actually find it fine. Not super easy but not super hard. At the end my legs feel a bit tired but not at all sore.

    My presumption is that it is glycogen depletion. I have tried to be a bit more aggressive about refueling after the last 2 sessions although I still didn’t notice much difference the next day. My guess is I’m just still not refueling enough but wondered if anyone else had found the same.

    I also find that by Sunday (2 days after) they are generally feeling better (although after feeling heavy on Saturday I have generally been making a concerted effort to add more carbs during the day) and the rest of the week is pretty fine.

    Am I right to assume that these 10second all out hill sprints could seriously deplete muscle glycogen or could it be the neuromuscular fatigue as well?

    For more background I don’t have ADS (~7% between AeT and AnT and my fat adaption is pretty good. I do the hill sprints on a 37% rocky hill. I do do my Saturday run fasted but have done fasted runs like that for a long time and not seen an issue. Very noticable difference after starting hill sprints the day before.

    Interested in any thoughts/experiences.


Posted In: Mountain Running

  • Participant
    Dada on #54226

    The anaerobic alactacid pathway (ATP) lasts about 8-10s. Maybe, yours last not so long an anaerobic lactacid jumps in which could cause heavy legs.

    Can you test 8s of sprinting?


    Thomas Summer, MD on #54239

    Great that you are sprinting!
    For a slow-twitch guy that’s a normal reaction. The fatigue is mostly neuromuscular. With these all-out sprints, you recruit muscle fibers that you haven’t used in a long time. That’s quite a challenge for your nervous system. And that makes you tired. You probably don’t get sore, because you can’t produce the force to damage your muscles enough.
    Glycogen depletion is playing, if any, only an insignificant role. The duration of the sprints is too short to burn a big amount of calories. But you ramp up your metabolism, so you burn more after. Being aggressive with refueling is a good idea because that helps with recovery. And after the sprints, you have heightened insulin sensitivity. So the muscles really suck up the sugar. I would also recommend getting a good amount of protein after the sprints or even supplement with BCAAs. What I also found helpful for the sprints is supplementing with creatine. This way you support the anaerobic alactacid pathway and get more out of the sprints.
    Dada’s recommendation is something to consider. Especially if you find it hard to hold the pace until the end of the sprint!? It’s all about maximal power output.

    Keep doing the sprints! As a slow-twitch guy, you will see great improvements!

    ST (Summer Thomas, but synonymous with slow-twitch)

    Anonymous on #54307

    What Thomas said!

    dan.k on #54379

    Thanks everyone! Makes sense now. I have actually used low dose (5g per day) creatine before and at that dose I didn’t notice large weight gain that I think you get with the super loading of 20g per day that people sometimes use. I will add that back in and continue to be aggressive with the refueling after.

    Thomas Summer, MD on #54382

    For creatine, the loading phase is not necessary. Just consume 3-5g per day. If your muscles don’t get heavy and stiff with that, then I would continue to use it. It’s one of the few supplements that actually work. But more important is to continue to work on your speed and power. As I said: you will see great improvements if you wake up your slow legs;-)

    dan.k on #54430

    Ok great. Thanks.

    One other question. I presume if I do have super heavy legs from neuromuscular fatigue I shouldn’t be pushing through a long workout and should adjust/cut it short to avoid overtraining?

    Thomas Summer, MD on #54446

    Let’s say: “it depends”;-) The important word here is “pushing”. You should not push, but a long and easy (really easy) training session can be good for (mental) recovery. But that’s more about being in nature and enjoying the scenery. Could be a long walk or an easy hike. But the golden rule is: If there is only a little bit of doubt, DO LESS!

    Anonymous on #55308

    But the golden rule is: If there is only a little bit of doubt, DO LESS!


    (I tried to post a thumbs up, but the forum won’t accept the image…)

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