why are my 5k to 10k times not in line?

16:10 to 35:00 is not the worst conversion in the world! But with these things it always comes down to mileage. Spend a couple of years running 80mpw and your times will normalize. But that's easier said than done!

When you do your workouts weather tempos, Intervals or long runs gradually extend them. Longer tempo, more intervals and a longer run. Overall milage will likely make a difference for a 10K.

Reading about the "VO2 slow component" may give some clues. It's not fully understood. But practically speaking, the longer distance athletes tend to do more training volume and a pyramidal distribution.

Endurance. The things you can do to get a better 10k is probably going to be tempo runs with 30-40 mins at the pace you could run for one hour (prob slightly slower than 10 mile pace for you), 6x mile and 10x 1k at race pace, and mileage.

Why are you going out at 33:00 pace? Try going out at 3:24/k for the first 6k and maybe you won’t blow up trying to run 15-20 seconds slower than your all out 5k for the first half.

Yeah endurance & going out too fast are the obvious answers. 3:18/k for 10k is the target for someone who can hold their speed for the longer distances to a T. Add in some more mileage. Build workout volume/spend more time @ 10k & threshold. Switch up your race strategy. Go out slower through 6k & then make an intentional move from 6k-8k. Maybe that means you're just maintaining with more effort but then you've just got 2k to go.

It's not mathematical, workout Z x workout Y doesn't = time Q. You might just be wussing out after 5k. I feel like attention span at high effort is not a factor people consider very often.

It's because you're aerobically underdeveloped. You need a good 16-20 week block of high mileage (70+) at low intensity so you don't burn yourself out and so you're body can actually adapt.

i went out in 33min because i was told that would be around the pace i should be able to do with a low 16min 5k... like double the 5k plus a minute? the guys beating me are even under that
i always tried to go hard from the beginning like i do on the track
next 10k i will try a slower start like the posters here explained
i try more miles but the workouts must be more for short distances because i will run some 800m and 1500m in early summer

i dont know if i can handle that volume honestly
will try it out though

What’s your 800/1500/mile/3k? If you’re comparatively better at the shorter distances and speed side of things it’d make sense if your 10k is weaker. This is pretty common for younger and/or lower mileage runners.

you're trying to run the 10k too fast. assuming your 5k PB time is close to optimum, the 10k time pace you're running would be the absolute best you could hope for based on your 5k PB, if everything is in your favour e.g. temperature, good taper etc. so not impossible but unlikely to happen. try and get a 34:00 on the board first and then go for the 33:30 and eventually the 33:00. don't just jump straight to the 33:00.

with ~16:10 you should be able to run approximately ~33:30 if you pace yourself properly and very evenly. If you run the first half at 33:00 pace you're going to have a suboptimal race because those seconds faster matter a lot and you'll pay them with interest in the last few kms.

~33:30 would be a possible time for an experienced runner with decent volume; if you really are at 16:10 shape, I would suggest you running conservatively the first half in 17:00, if the race is flat it is nearly guaranteed you will break 34:00.

You are incorrect. That formula works for a 13:00 guy. Double and add 1:30 for your level.

The calculator I swear by says 16:15 indicates 33:45, and 34:00 indicates 16:22. Obviously it varies between individuals based on training and natural strengths/weaknesses, but I think it’s fair to say the OP should be able to target sub-34, but 33:00 pace is too fast. Kinda crazy that the OP makes it sound like he keeps trying the same thing, which is basically running a 4 mile race and then dying. Just try going out in 17:00 and hope to negative split, and if you still slow down after 8k then yeah, the training needs addressed.

Lose ten pounds. increase threshold work. run hills. run longer on long runs. its not that hard so go train

my pbs are 1:56/4:06/9:18
the poster below is right also... i need to learn patience because i always positive split
34 low is hopefully possible when pacing right
was pretty stubbern on 33 like i said because ive been told so by people that know more about long distance training than me
after reading all, next try will be going out in 17.15 and try to keep it up
ill see if i can handle higher volume workouts or miles

30-40 mins at 1 hour race pace? That's a race effort in a workout. Please tell me that's a typo cuz if not you don't know the first thing about training. No one does 40 mins at 1 hour race pace in a workout without it destroying them, if they can do it at all. And if you can, then your 1 hour race pace is wrong.

For years I was in the camp that Daniels was nuts with his 20 min tempos at 1 hour race pace. I think those "tempos" are finally unpopular now, but I used to get a ton of sh-t for that opinion back in the day. But 30-40 mins is laughable!

How many 10ks have you raced? There's a bit more of a learning curve compared to the 5k.