why so much variation in my run times? - Couch to 5K

Couch to 5K
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why so much variation in my run times?

So, I graduated C25K with a 5k Park Run a coulple weeks ago, managing a very respectable time of 32 minutes. I've run 5K several times since, but come no where near this time (35-37 minutes is typical).

I often run on grass...is this slower than pavement/tarmac path? I also usually run in the evening after work...is this likely to be slower than running in the morning? I feel I'm working pretty hard on my runs (i.e. not holding lots back), so can't see how I can be 30-60 seconds slower per km than that first 5K. Is the Park Run experience just so magical that you're automatically 10% quicker?

I'm not complainig - I'm so pround of how far I've come, and just the fact I'm going out and running 5K three times a week is pretty amazing given where I was 3 months ago! Just wondering if others find some runs quicker than others...?

6 Replies

Firstly, congratulations with the great result of 5 km in 32 minutes. that's certainly something to be proud of!

I find that running on grass is slower than running pavement/tarmac. I run about 30 seconds slower per km on grass.

I also find that running later in the day tends to be slower than mid morning (which for me is where I'm fastests - fully awake, breakfast digested, but not yet dragged down by the trials and tribulations of the day).

And you should not discount the extra energy you find within yourself when you're running in a race-like setting. That can easily explain another 15-30 seconds per km.

So all in all... this doesn't sound unusual at all.

Enjoy your running :)

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Every run is different. All sorts of things can influence it - the weather, how you're feeling, what you've eaten, traffic and other obstacles etc., etc. - and grass is much harder than tarmac but will help with building stamina.

How are you timing yourself? 30 - 60 secs per km does seem quite a difference but again, it's not unusual to run a lot faster when you're surrounded by an enthusiastic crowd!

Maybe you're trying too hard. Pushing yourself too much will wear you out a lot quicker and you might not be able to maintain that pace over 5k. Try running slower at the beginning and gradually increasing speed to a comfortable level - you might surprise yourself!


Thanks tomas and dottiemay...I maybe need to build up more times over a few more weeks to really know what's happening...just interested that there can be such a difference.

RE maintaining pace...I've been quite pleased that my pace seems pretty consistent throughout (usually quickest in the last K when I know I will complete the run, but want to push a bit harder!). I'm using a Garmin Forerunner 10, and looking at the output, I trust the times...

Anyway, as I said before, the main thing is that I'm out running...I'll stick with the grass until the weather forces me onto tarmac...good to know the grass might be building up my stamina!


It's the 'pull' factor. It's harder to judge your pace and so much easier to go out too fast when surrounded by people running round you, my parkrun times are a good few minutes faster than my 'run on my own' times, at the same time of day as well.

Also, the organised 10ks I've done were a good 5+ minutes faster than my lonesome 10k times.

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I agree, the first (DNF) parkrun attempt I had completely pulled me away at the start and my times up until the point I had to stop were crazily quick, like nothing I had done before. My next parkrun attempt was also fairly speedy compared to my average runs and I've heard a lot of people say that race days often have a little something extra in the tank.


Hi Susie boots this happens to me all the time. I ran a 37 mins 5k and then did 32 mins at an event. I think its the momentum of being in a crowd that carries you along quicker. I think!!

Hoping this applies too when I do my next 10k as my time is not great for that.


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