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!