10K as a predictor of HM

I think the 10k converts decently well to the HM. Given your low mileage and relative lack of experience I suspect a direct conversion is pretty optimistic though. I would get in some HM specific workouts over the next 2 weeks... things like 3-4x2 mile and a 6 mile tempo effort where you start at 6:50 pace and see if you can work down into the 6:30s. I would also recommend starting out at 6:50 pace in your race, working down to the low 6:40s through 7 miles and then re-evaluate. If you can wind it down from there then great.

Much better to run strong and feel like you left some time on the course in your first HM than completely blow up which I would say I likely if you head out at 6:30 pace.

1:30 would be too slow. 1:25 might be ok, depending on your endurance. Shoot for 1:27 initially, then pick it up if feeling good at halfway. It's only 21k, you can't really die there in the marathon way of dying.

Are you sure the course was actually 10k? 37:20 definitely predicts faster than 1:25 even with your relatively low mileage. If you can run a 10k at 6min/mi, a half at 6:25 pace should be very doable.

Positive the course was 10k, it was the major marathon event for my city and my watch read 10.1 km. I appreciate your positivity, but also cautious of what the other posters have mentioned, my lack of lifetime mileage/HM workouts at true goal pace may come back to bite me.

Make sure that the 10k was a real 10k. If it's just a Strava 10k, you didn't actually run 10k.

Other than that, I would not overthink it.

If you want to be cautious, go out with a 1:26 finish pace and see what happens.

The calculators are great but you still have to run it and there are so many factors on race day why things could go different.

But that's why we race. To find out what we actually can do.

Good luck!

There's no reason to be in a hurry. Spend another year running 10Ks and then you'll have a better idea of a good target pace for a HM and it will be less likely to be a miserable experience.

I had a very similar trajectory to you when I began to take running more seriously. About a year ago after 9 months of roughly 50 mpw, I ran 36:47 for 10k and 2 weeks later ran 1:24:13. So I'd say with your experience and volume, 1:25 is probably a good goal time. I wouldn't be too worried about your training paces for your longer tempos. When I ran those times, I didn't do any longer tempos at all, only 3-4 mile Daniels style threshold runs. My advice is to start out running a bit slower than 1:25 pace and work down in the second half if you're feeling good.

In that case, if you're going to be happy with sub 1:25, then go for it. Go out at that pace and if you feel good at 15k, pick it up. It'll be nice to pass people in the last 5+k. Good luck!

Nothing wrong with crashing and burning.

The tables are not a one size fits all.

Most of your terminology is outdated.

Go for the 1:25 and run it out, see what you have.

Meanwhile, do the work. You can get there, but the legs may be lagging. The other approach would be to drop your 5km and mile which will also translate to a faster half marathon.

The 10k translates closer to a 1:22-23 HM. Personally I'm ramping up for a HM at end of May and hope to run a low 37s 10k and 1:23 HM, which all my workouts indicate as realistic.

Agree with other posters, not having a long running history and lack of workouts near pace makes a ~1:25 more realistic than the equivalent from your 10k. But that 10k time is a good sign you'll be faster than you think.

The 10k is a fairly good predictor but won't pan out if you train for a half marathon like a 5k/10k runner. A lot of people have PRs at 10k & under that would show better potential in the half & full. What prevents that from panning out can be a lot of things but mileage and longer workouts/tempos are a good place to start. So much more can go wrong in a long distance race. If you do your homework, and train for the distance, you should be able to run close to what a calculator predicts.

NewbieRunner1,

Your progress is very good, congrats.

I think you should not worry about (relatively) low mileage. With 37+ at 10K you can break 1.25 no doubt.

I always was a "low mileager" (very rare reached 50 mpw, usually stood about 40-45) but did not suffer at longer distances, And at your age I was about 1.11-1.12 at HM.

Just select the right (comfortable) pace.

OP, with specific work you can break 1:25. Good workouts in the suggestions above.

I broke 37:30 and 1:25 around the same time, and had never ran over 40 mpw in my life at the time.

Thanks for all the advice. I'll do some more specific work for the next couple of weeks and then shoot for 1:25, starting out a bit slower as suggested and picking up in the second half.

Thanks!

I think a 10K time translates quite well to HM, and the training is not necessarily that different. Even 5 years ago, good coaches/training plan just used either 10K or marathon training and adapted it slightly.

I ran 1:25 in my first HM. At that point, my only race longer than 5K was a 15K in right around an hour (roughly equivalent to 39 flat in a 10K). And I only had 6 weeks to train for the HM after several months of iffy training.

Stay in control for the first few miles (like 6:40-45), but be prepared to feel like you're jogging. It will feel ridiculously easy. I think it's okay to let your pace gradually get faster after that, but keep it around 6:35 +/- 5 seconds until mile 7. Make sure you know the course well, too. Depending on the race, you might have big gaps around you after halfway.

I just went through my old training logs and regardless of age etc, the factor 10k x 2.223 seems to be a good predictor if (!!!) you did some 15 mile workouts. The HM does not require a overall volume, but some easy long runs will definitely help.

Ideally you should do some longer runs with the last 5 miles close to target pace, but you can do thast prior to your next attempt (please don't do this know ahead of your May HM).

And don't worry, you don't crash in a HM. If you go out too fast you may suffer a bit during the last 2-3 miles, but this is not a "marathon suffering". I would go out at 1:26 pace and then give it everything you have in the last 4 miles.

Thanks for he tips, I built up to a 17-mile long run workout with 5 mile tempo towards the end a couple of weeks ago. Probably got a bit carried away on that one.

The idea of setting out at 1:26 pace and bringing it down (if I can) as the race progresses seems to be the consensus so I'll give that a crack in May.

Hi OP,

First of all, congrats, you've come a long way quickly and you've got a lot of potential.

A few years ago, I ran 36:50 on a hard course and then 1:19:50 a few months later. So I think 1:25 is a fine goal. I had been running for about 10 years at that point.

OTOH, a 1:28-1:29 HM would also be a fine accomplishment (and to the general population, the distinction between 1:24 and 1:28 won't mean much). And you're pretty sure you can do that, so why not?

In the scheme of things, 1:25 is an ambitious goal for a first-timer (and in general). If you want to set an ambitious goal, that's fine, just if it doesn't work out, it would be a shame to lose steam on a promising career because of an early-on setback.

Either way, good luck.

I had lifetime PRs of 36:44 and 1:18:59, run a few months apart and both on fast but honest courses. I was the most extreme "all slow-twitch" runner there ever was. However, your 1:25 goal seems very reasonable, particularly given long runs of up to 17 miles.

As others have noted, if you go out too fast in a HM you'll struggle over the last few miles, but it's nothing like going out too fast in a marathon. Usually you'll only have 2-3 miles at the end that are bad and you can make it through on willpower.

Good luck!