Marathon Running and Race Support

Toxic 5k?

We have the well known "Toxic 10" mins, but I've noticed that about 5k is my own "hump" to get over! Looking at my heart rate data on Strava it seems it always climbs steadily and then reaches a plateau between 4.5 - 6 km. Is that then point at which everything is in back in balance finally after the initial disruption of the system heart/lungs and muscle demand? I'm usually as fresh as a daisy(ish) for the first 10 mins, only getting the gremlins later towards about 5k or 25-35 mins. After that I seem to get a bedded down into a good rhythm and get the feeling I can go on and on at the same pace.

Anyone else have this delayed kind of Toxic 10 effect?

Maybe if I went hell for leather from the gun it might be more of a normal toxic 10 mins response?

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When I have done marathon training, I found the I didnt get into my rhythm until after that first 5k.... I dont know why. I dont feel it now though as I'm not running that far at the moment.....

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I've noticed it hard to get settled until at least 3-4 k in on any distance run. Then, later on longer runs at 14-15k, there feels like another wall to get through. At least for now that's how it feels

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I don't have a delayed Toxic 10 (had to Google this), but like the others, on long runs it takes 4-5K before I settle into my run. The first 5K are pretty awful. Is this something we can translate into pushing past the wall for seriously long runs?

I certainly had a Toxic 10 at parkrun on Saturday, and then ran faster than I ever had.

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Decker/C3PO - Maybe Toxic 10 is only for full tilt exertion from the off then? The 5km barrier maybe due the mental scars of c25k? ;-)

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I have heard 5K racing described as an endurance sport, I agree with that definition!

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Maybe it just takes 5k for the whole shebang (legs, lungs and gremlins) to get the message " Yes, campers! We are doing this!!"

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That's what I've thought.

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Weird, isn’t it? I always dislike first 5k of any run. It takes me a few miles to settle down - people always joke that parkrun must be my worst nightmare and it’s kind of true. Just as I’m beginning to enjoy myself, it stops!

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Bazza1234 had a post about oxygen debt awhile back - I might guess this is closely connected... I can't figure out how to link to a specific post, but the gist was: "when you start exercising , you don't have enough oxygen in your blood to feed the muscles that you have started to use - so the heart and lungs have to race to catch up." Longer, more intense warmups seemed to be the conclusion to get the heart rate up before the task.

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Yeah, a good post that,

and it made sense. I suppose the 5k thing must just be psychological mainly, plus an element of equilibration to the longhaul?

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Yeah, I suppose?

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I think it's simpler than that. You know on the longer runs you are in for the long haul and that first 5k or so you know you still have a lot to do, so it's hard to settle till you have at least 5k under your belt.

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I get similar on a long run but no idea why either. I certainly get past 5k and feel the ryhthm in my running which usually goes to pot at 10 miles when the legs tire 😂

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funnily enough I am exactly the same - 4/5 kms in and it all seems a bit of an effort and then post 5km it improves, maybe as you do more long runs, your body re-sets the clock slightly?

I notice too that generally my pace doesn’t alter that much between short and long runs, which makes me think maybe I am more suited to longer, as the pace difference is not so great...

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Thanks for all the feedback! So it's pretty standard and I'm not weird! (Well maybe only a bit).

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