Will I hurt myself doing 13.1 without training

My wife had signed up for a 13.1 with her sister in law in California (we live in TN). Came out a few days ahead of time for mini vacation and while hiking around my wife hurt her leg and is going to be unable to run in the event. She is wanting to transfer the entry to me so it’s not wasted (because I’m “always exercising”), but I’m hesitant. I don’t have a running background as I’ve just never enjoyed it. I’m 27 and active outside of just biking, but with Leadville and other cycling events on my calendar this year I don’t want to derail with possible injury. What’s the chances I hurt myself if I run a half marathon cold turkey?

well, n=1 but the one time I tried that I got a stress fracture in my foot pretty much instantly…

Just take it slow and listen to your body and you will be fine.

You can do it but you will probably not enjoy the day after if you overdo it. Fuel well, listen to your body, take the pace appropriate for your skill level. Run-walk is fine.

I have done it some years ago without training but probably went a bit too fast (1:49) and had really sore legs. I could not really walk stairs for a couple of days and still felt it 2 weeks later. I think if you take it easy you should be fine though…

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Evaluate opportunity cost here. What’s the best case outcome for you doing this race? You finish and get a worthless medal?
Worst case, you’re hit by a bus and die. Realistically though you’re looking at injury and or fatigue that prevents you being able to train several days to a few weeks for the events you actually care about.

You two are already out the money for the race, so that’s not coming back. Did you pack real running shoes? Socks? Running gear?

I know the answer if it were me but to each their own.


I did one in my early 20s (when I was actually fit) on minimal training. I ran perhaps twice a week at the time. I actually got round fine, to my surprise, but it took me several months, iirc, to get rid of the plantar fasciitis that followed…

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OMG. My son is an ultra marathon runner, and a few years ago he said to me “hey Dad, do the little 5k thing with me next weekend.” I, being the supportive Dad and all-round-nice-guy, said “sure! let’s do it.”

Holy mother of terrible ideas. My knees hurt for the next two weeks and I could barely go up and down the stairs.

My $0.02 ? Without training, the only place you should run is away from this event.


If you are lean and spend time on your feet a good bit I believe you will be fine. If you have a lot of cycling fitness just make sure you don’t use all that fitness.


No run history whatsoever? Considerable, and for sure you won’t enjoy it. Plus you’ll suffer for days after.

Contact your local running club and donate the spot if it’s transferable. If it’s not transferable…don’t :slight_smile:

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I did something very similar to this about ten years ago. With good bike fitness but absolutely no running experience or sense of a proper running ramp rate, I started with a few 5 mile runs (which were fun but left me extremely sore) and quickly upped the load, culminating in a half marathon about a month later.

Midway through the run I started feeling some ankle pain, and in true cyclist form, I decided to ignore it. It got worse and worse and by the end of the run was really starting to hurt. Well, the next day I was unable to put much weight on the foot, and it turned into a serious case of achilles tendonitis that kept me off the bike for weeks (and kept me from running again for months).

As others have said, weigh your likely outcomes. Best case scenario, you’re going to be extremely sore afterwards and probably off-bike for a few days at least. Worst case you get injured and are off-bike considerably longer. Unfortunately an outcome resembling the worst case feels more likely to me, based on my own personal experience and mistakes.



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You’ll seriously run the risk of forgetting to wear socks. Are you willing to have that weigh on your soul?

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echoing what others have already said, short answer is yes. you have the aerobic engine to do the run but muscles, not so much. I try and do a ~5k run 2x a week (can’t be on the bike seven days a week + that whole load bearing exercise thing), if I miss more than a couple of weeks, the next run would be painful afterward. that is the kind of incentive I need to not to miss too many runs in a row. at best you can expect to be very sore afterwards.

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As a cyclist with a good aerobic base, you have the engine, but not the chassis for a 13.1.

In addition, your cardio fitness will allow you to run at a WAY faster pace than you should, further compounding the chance of injury.

If you have other goals this year, I’d avoid it……I guess you have to ask your self how much the entry fee is worth to you.


I think I won’t do it, can’t risk forgetting to wear socks when I bike.

All of you have good points. I did a quite technical 50 mile MTB race last weekend and then with the travel need to jump back into quality training ASAP when I return. Don’t want to risk being off the bike longer. I’ll just take this week as a rest week and jump back in fresh instead of sore (best case scenario). Thanks for the input.

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Last year I did exactly one run, and it was a trail 10k w/ 1500’ of climbing/descending.

I got 7th out of a couple hundred, which I thought was awesome for a 49 yo non-runner.

I also basically couldn’t walk for 4 days afterwards. I’d imagine that a half would only be so much worse, though I’m certain that it’s the downhill running that did me in. Turns out that’s an actual skill, and something one needs to train for :confused:

No way I would do this. On rare occasion I’ll run, but no more than 4 mi and even that hurts a few days. I’m sure I’d suffer injury, or at best, a week of aches and pains if I attempted a slow 13.1.

I think the key here is, are you na injury prone person.

If you don’t know if you are, then that probably means you aren’t. Some people can get off the couch and run a marathon. Maybe slow, maybe ugly, but no issues.

Me on the other hand. I used to have to build up from 10min runs very slowly week on week, and even then I couldn’t just go out and do a random run/adventure.

21km isn’t that far, and plenty of cyclists will do it fine. I’d say be cautious. I wouldn’t, but I know that I can’t and wouldn’t consider the equation.

All about expectations… Run and walk all the way to the finish line and you will be fine… Make sure you have proper running shoes…

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