If you have a half-marathon looming in the near future, you have likely considered what pace you should run on race day. This is a critical question that may determine whether you run the faster race you ever have, or whether you run out of gas in the final few miles.
This can often be a difficult question if this is your first half marathon. However, if you have run multiple half-marathon before this becomes much easier to determine. The key to finding your best half marathon race day pace is to listen to your body during training runs, and to complete at least one or 2 prep races.
This topic is a particular concern of mine right now, because I happen to be running a half-marathon in just over a month (Labor Day Half Marathon in Redmond, WA on Sept. 2nd). In addition, I will be using my time on this half marathon to determine my pace for my full marathon in 2 months (Leavenworth marathon on October 5th).
Testing Your Pace During Training
The key to being more accurate in your race day predictions is to have solid workouts. There are many different half marathon training plans out there, but most of them will consist of some long runs, tempo runs, and speed/interval training. Each of these workouts have their place in developing the strength needed to finish well.
However, tempo runs are the most important run to help you determine what your pace should be.
A tempo run, can be described in several different ways, but for the most part its around a 3 to 5 mile steady pace run at your 10k to half marathon goal pace. The 10k pace would only be used if you are training solely for a half marathon. Since, I’m personally “really” training for a full marathon, I run my tempo runs at slightly faster than my half marathon goal base, but never quite at my 10k pace.
For example, I am running a half marathon in about a month. My goal is to get 1:37:35 or a 7:27 per mile pace. As such, I try to run my tempo runs at a pace between 7:20 to 7:27 per mile. However, this is really my training for a full marathon. If my half marathon was my end goal; I may actually train a bit faster and run my tempo runs between 7:10 to 7:20.
If you are not about to run 3 or 4 miles at this pace; you should start to be concerned that you’ve set too ambitious of a goal!
So, is your body telling you that you are running your tempo runs too fast? If you are struggling to run 3 to 5 miles at just a little faster than half marathon pace, you should consider revising your goal.
On the other hand, if you are able to breeze through your tempo runs; perhaps you should adjust your goal and train a bit harder!
Using Tune-up Races to Find Your Pace
However, even better than just using a tempo run, is to use another race. So, if you are preparing for a half-marathon, a 10k race would be great to run about a month before your half.
Then you can take your finishing time from this 10k and plug it in to the McMillan calculator or other calculators to help you determine what your half marathon goal pace should be.
For example, I am running the Railroad Days 10k Race on August 17th to help me determine what kind of shape I’m in and at what pace I should run my half marathon. If I run the 10k race at a 7:10 pace (44:31 finishing time), the McMillan calculator predicts that I could run a half marathon at 1:39:15.
Obviously a lot of different factors go into determining the final outcome of a race; but using a tune up race can really help you get a good feel for where your goal pace should be.
So, if I can only run a 10k in a time of 44:31, the chances of running below 1:37:35 becomes pretty slim. However, a time of 1:39:00 would be very realistic. I would be able to predict that most likely I am going to finish a half marathon between 1:37 and 1:39.
In this particular case, I would probably set a pace at a 1:38:00 finishing time and let the last 5k dictate whether I speed up towards the end.
So, if you have run a 10k “tune up” race about a month before your half marathon, you can usually predict within a couple of minutes what your half marathon finishing time will be. I personally would not try to go much more than 2 minutes faster than what the McMillan calculator predicts – until the end of the race. If you are feeling great the last 5k, then by all means give it what you have and finish faster!
But you don’t want to make the mistake of going out faster than your body can handle only to dramatically slow down about half way through, and finish MUCH slower than you wanted or expected.
If you are looking to run a half marathon under 2 hours, I’ve written some similar analysis for getting that pace.
Overall, this is the type of process that I go through to find my half marathon pace time. I highly recommend that you run a 10k or other race before your official half marathon. This will be your best predictor. However, if you are unable to do so, you can also use tempo runs to determine your overall fitness level.
Then as you run more and more half marathons, you will be able to look at your past racing history and know how you run to predict an even more accurate time than any online calculator ever could do.
If you have anything that you would like to add to the discussion, I would love to hear your thoughts in the comments section below!