Treadmill vs Outdoors: So I completed the entire... - Couch to 5K

Couch to 5K

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Treadmill vs Outdoors


So I completed the entire C25K on a treadmill a few days back and decided it was time to brave it outside.

Since completing the program I have run outside a total of twice. Each time I’ve not managed to run the 30 mins and had to stop and do a little walk at around 20 mins. I though I might have been going too fast but when I checked my pace it’s between 11.15 and 11.30 miles per min. I’ve only managed a distance of 1.77 miles.

I can’t understand what’s happened, why am I so exhausted outside, it’s completely different to running on the treadmill and I’m starting to think I made a mistake doing the program indoors. Maybe I should start from week 1 again but outside this time?

I’ve also noticed I get major muscle ache in my thighs the following day, maybe I’m using different muscles outdoors due to the elevations?

I’m feel rather deflated, I had thought I’d be able to go outside and immediately run for 30 mins and perhaps beat my treadmill pace of 10 mins per mile but sadly not.

What’s wrong with me? 😧🤭

6 Replies

Nothing is wrong with you. Running on a treadmill is just different.

Running outside you have (sometimes imperceptible) changes in slope, exposure to the weather (especially wind and sun), street furniture or wild things to dodge etc.

This requires a different running style and requires a bit more effort (imo).

Should you go back to the start? Nah. But perhaps go back a week at a time until you find the run you can complete.

But also challenge yourself why you aren’t completing - can’t do it or giving up? The change to outside might be knocking your confidence so much that you let the gremlins take over.

Good luck with your next run.

BandahicupGraduate in reply to Jay66UK

Hi, I am doing the c25k on the treadmill with a slight gradient, it was on the recommendation of my physio. I know that when I get to the finish I won’t be able to run for 30 mins outside so I am planning now what I will do so I won’t be disappointed later. I am still on week 6 with the last run scheduled for Sunday. I have started this program so many times and gave up at week 3, this time my head is different although my body is less fit than the other times I tried it! Your head and your chimp have a lot to answer for!!!

A few things might be affecting you. The air temperature will different, and maybe there is pollution - depends when and were. Then there is the gradient, on the TM you are at a constant gradient, outside it may be changing (I find this, and in the car I can't tell there is a gradient at all), even a very small gradient can be a challenge. On top of this there is that fear and loathing of being thought a twit, as you run past your neighbour's house - that's why I run at 5:30....

It certainly wouldn't hurt to try a few of the week 4-6 style interval runs to build up the outside muscles a bit and gain confidence.

Run-Claire-RunGraduate in reply to theoldfellow

Yeah, I can definitely relate to the "twit" feeling :-)

You definetly don’t need to re start. Outside is different and Jay66UK has explained many of the reasons why. For me the heat has beaten me before and brings on fatigue much quicker. I now start quite slowly and build up. With the heatwave coming next week I’m just going to get out very early. You are doing brilliantly - just need to readjust to your new setting. 😊


Not to mention on the treadmill it's mentally easier to keep going. You literally have to unless you make a conscious decision to press that stop button. Outside you have don't have that so when it's tough it's a conscious decision to keep going!

In the past (I ran a few years ago and am getting back on it) i have done a below 30min 5k on the treadmill! outside on the flattest path I could find it was just over 32.5 min.

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