How to Pace Your Fastest Half Marathon

Your Mile by Mile Guide for How to Pace Your Fastest Half Marathon

Have you ever endured that moment in a race where suddenly your legs cannot run any faster? The sensation of defeat overwhelms you, as your pace slows down and the finish line is still miles away. Many runners are familiar with the crash-and-burn experience in the half marathon distance. They start out fast since they feel good, but then fall off pace with just a few miles to go. You do not have to make that mistake! Keep reading to learn how to pace your fastest half marathon and enjoy a breakthrough race.

Why does pacing matter for the half marathon? For most runners, half marathon pace is not much slower than your lactate (anaerobic) threshold. When you run faster than your lactate threshold, you accumulate lactate at a much more rapid rate. Now, lactate isn’t the big bad we once believed; your body can actually shuttle it from the bloodstream to cells and use it for further energy production. However, a by-product of lactate production are hydrogen ions and other acidic metabolites. These cause a burning sensation in your muscles and a resulting fatigue of the muscles. Your breathing also increases, as you both attempt to consume more oxygen for energy and as your body regulates its acid-base balance.

Essentially, you fatigue at a much quicker rate when working above your lactate threshold than when you run slower intensities. When you start out a half marathon too fast – faster than goal pace – you fatigue more rapidly than you would at goal pace or slightly slower. That’s why the last 3-5 miles of a half marathon feels so difficult when you do not pace appropriately. You sabotaged your race by starting out too fast.

These tips are what I have found that worked for me in running my half marathons, including my PR of 1:34 (here’s how I took 12 minutes of my half marathon time).  I have used these strategies on hundreds of runners as I have coached them to half marathon PRs. Of course, every runner is different, but these strategies can help you pace your fastest half marathon.

How to Pace Your Fastest Half Marathon

Before the Race:

Warm up with 5-15 minutes of very easy running, three or four strides at race pace, and dynamic stretches. The warm-up elevates the temperature of your muscles, which allows greater force production, and increases blood flow which enhances energy production. 

Miles 1-2:

Take these miles steady and slightly controlled. You are tapered, so that will equate to a pretty quick pace. Even if you warmed up before the race, you do not want to jump right into goal pace just yet. Aim for 10-15 seconds slower than your goal pace. Do not weave around other runners. The lateral movements will fatigue muscles you don’t normally use in running. Additionally, weaving will add extra distance to your race and affect your finish time. Let people pass you in that first mile.

Miles 3-9:

Settle into a steady pace. You should have practiced your half marathon pace enough in training where you know how this pace will feel on race day. The effort should feel moderate to moderately hard and relateively sustainable. Don’t obsess over your watch. Check in at your pace but trust yourself and trust your training. Take most of your fuel at this point, so that your body can continue to produce energy.

If you feel tempted to slow down or speed up too much at any point, focus on a few runners around you who are running your speed and pace with them. In How Bad Do You Want It?, Matt Fitzgerald describes the group effect as being how running with others reduces your perceived effort – thus making it easier to run faster than you would on your own. Take advantage of this effect if you find others running your goal pace.

Miles 10-12:

A half marathon will get hard at this point. If you started out conservatively, you should still have fuel in your tank. Maintain your goal pace as best as you can or increase it by 5-10 seconds per mile if possible. If you do pick up pace, do not increase it rapidly, as this costs more energy than a more gradual acceleration. 

This is when the race becomes a mental game. You will feel comfortable, but with the proper coping strategies you can run at this effort. This segment of the race is when you should try to pass other runners: focus on one runner, work towards passing them, and then repeat. Passing will distract you from the discomfort. The accompanying surges that come with passing temporarily use a different energy pathway, so they are possible even when you are tired. 

Miles 13-13.1:

Push your pace more and more – you are almost done and you are not about to crash and burn at this point (unless it is psychological). I like to count down by tenths of a mile from 12.1 and tell myself to push just a bit harder with each tenth that passes. Give your hardest effort over the final tenth.

Final Notes on How to Pace Your Fastest Half Marathon:

  • Focus on the mile you are in. Don’t worry about how you will feel in the next mile or at the end of the race.
  • Don’t stare at your GPS instant pace (trees and skyscrapers can throw it off). Instead, set it to show lap pace and check in on your mile or km laps to determine if you are running on pace.
  • Bad miles and good miles alike occur in a race. Don’t stress over a mile split that is too fast or too slow – simply get back to goal pace and focus on the next mile.
  • Make sure you have a solid nutrition plan to support the energy pathways needed to finish strong!
  • If this is your first half marathon, use a similar strategy but do not worry about your finish time as much. Make it a goal to start controlled and finish strong!

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25 Responses

  1. I really struggle with the weaving early in a race. I think I often times end up starting too far back and cant go anywhere near my goal pace without weaving. I think I need to work on lining up more appropriately so that I don’t waste energy passing other runners!
    I generally do pretty well with pacing half marathons- its the 5ks that I go out too fast or to slow for!I guess with a half its a long enough race that I feel comfortable holding back a bit in the beginning.

    1. It does make a difference where you line up – especially in big races! I try to line up near the pacer for my goal time, although they usually go out faster. I haven’t run a 5K race but I can imagine the pacing is very hard with those!

  2. It took me years and years and years to learn to not start out too fast. Actually, truth be told, I STILL start out too fast. There’s just something about the adrenaline on race day that gives my legs the speedies!

  3. Love these tips Laura! I have definitely crashed and burned more times than I care to count. Then, the last miles are such a painful struggle. It can be so hard to dial it back in the beginning. The best races I have run are ones where I dialed in my pace at the beginning perhaps on the slow side and then worked towards negative splits!

    1. Thank you! I think crashing and burning is a rite of passage for a distance runner – we’ve all been there! Negative splits are hard to run but so rewarding when we do.

  4. Thank you so much for writing this post!! My last half marathon was a crash and burn….the last 5 or 6 miles were miserable because I started out too fast without even realizing it. I don’t want to make that mistake again, and as I have a 10 miler this weekend, I’ll remember your advice!

  5. This is a fantastic post and exactly what my coach tells me and what I tell my clients.

    Also, you’re so adorbs in your race pic. Look at that smile!!

  6. Any suggestions on trying to maintain an even pace during those middle miles? I don’t struggle so much starting out fast, but my pace isn’t as even as I’d like it to be in those middle miles. Training for my second and third half (one week apart), but have ran quite a few 10k’s. I even get 0.25mi updates from my running app just to try and keep tabs on my pace-it’s a pain, but I feel it’s the only way to have any idea.

    1. I would recommend doing lots of continuous tempo runs at half marathon in training to help you know what race pace feels like and know how to hold it for several miles. I’d also recommend trying to focus more on effort and getting the tabs on your pace less often – about every mile – since instant pace can vary and the 1/4 mile updates may cause you to surge or slow down, rather than settling in at the steady pace.

  7. My half-marathon PB is also 1:34 – we should have run it together!
    Great tips, Laura. I like the idea of setting the watch to a lap pace. That information is so much more reliable than the current pace reading.

  8. It’s been so long since I ran an in-person half-marathon. These are great tips. I do remember having races where I went out too fast and then tired at the end. I’ve also gone out too slow for too long and then had a hard time getting back on pace!

  9. I have had a bad habit of sometimes going out too fast. It’s been so long since I’ve run a half marathon in-person I’ll probably feel like a newbie again so I’ll be saving these tips for the future.

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