Is 20 to 30 Training Miles Enough to Run a Half Marathon

by Terese
(Ogden, Utah. USA)

I have been a committed runner for a year and a half now and have completed two half marathons with over a dozen 10k races! With the snow and winter cold I have been averaging 20 to 30 miles per week and I am only just coming out of hibernation... and I have signed up for a half marathon in three weeks in California!

Do you think my weekly average right now will be enough to get me through the half marathon well? I am pretty confident I will do ok but not sure that I am putting in enough miles per week like I normally do in the warm weather months!

During the summer I average 50 miles a week!!!

Answer by Dominique:

Hey there,
Congratulations on that amazing running track record over the past year and a half. Great to see that you have done so many races. And it's fantastic to see you staying committed to your fitness goals despite the chilly winter months.

Now, to your concern about whether or not 20 to 30 miles per week is enough to prepare yourself for an upcoming half marathon, let's tackle this as follows:

1. Understanding your Training
2. Trusting your running history
3. Adjust your half marathon goal
4. So, how fast to go?

Understanding Your Training

Now, generally I would say: "Yes, 20-30 miles is sufficient to finish a half marathon.".

But, then it got me thinking... how are you dividing up those 20 miles?

Are you doing 5 x 4 miles each? Or 2 x 5 miles + 1 x 10 miles? Both ways you get to 20 miles.

But, I'd back the runner who is doing the three longer runs over the runner who is doing a maximal long run of 4 miles only!

So, you haven't given me that detail, but as long as you have got a long run in your schedule that is 8-10 miles in length, I think you are going to be fine.

Have your long runs been much shorter in the last three months? Then you might be in for a tough day!

Trusting Your Running History

You have done a year and a half of very regular running. You have done 50 mile weeks. When you reduce your mileage, you lose some fitness, but that history counts for something.

With a year and a half of consistent running behind you, I think you are more than able to finish a half marathon.

It may not be your fastest performance. It might even be really difficult towards the end. But, I am sure you can do it based on what you have told me.

Adjust Your Half Marathon Goal

Because your training has been reduced over the past three months or so, I would recommend you adjust your half marathon goal.

Your goal needs to reflect your current fitness. Not the fitness you may have had when you were covering 50 miles per week.

Starting off too fast can be a painful experience in the half. It can make a half feel like an ultra...

Believe me, been there done that quite a few times. It can really take the enjoyment out of running the half.

So, How Fast to Go?

To work out how fast you can go in your half, you have a few alternatives:

Goal Pace
Firstly, It would not be a bad idea to test yourself with a goal pace workout.

Training Paces
Secondly, if you have a reasonably good understanding of your training paces, you could use the Running Pace Calculator to approximate your race time.

Recent Race
Thirdly, if you have very recently done one of those 10k races, you could use that to estimate your performance in the half using my Race Conversion Calculator.

It is a bit tricky, because a half marathon relies on a strong endurance and with the lower mileage you will have lost a bit of that. The calculators may be a little bit too positive about your future half marathon performance, so keep that into account!

That's where I'll leave it. Best of luck with the remainder of your half marathon prep. Enjoy and I hope you keep on enjoying running and racing as much as you have been doing in the past couple of years!

Kind regards,
Dominique