Once you've signed up for a half marathon and done the necessary training, the next thing to consider is how to execute on race day. Knowing how to pace a half marathon can make the difference between a celebratory finish- knowing you've fulfilled your potential- and a painful slog just to finish.

In this article, we'll discuss various race strategies for a half marathon and help you find your best approach to pace your fastest half marathon. Specifically, this article will answer these questions:

• How should you pace a half marathon run?
• What should your half marathon pace be?
• What are common mistakes made with pacing in a half marathon race?
• What does half marathon race pace feel like?
• What should your heart rate be in a half marathon running race?

Pacing Strategies for a Half Marathon Run

There are generally three approaches to pacing a half marathon run:

• Running the second half faster than the first half (negative splitting).
• Running the same pace throughout the race (even splits).
• Starting fast and hanging on (the "Hold on for Dear Life" or positive split approach).

We'll discuss each of these strategies below.

Negative Split

Negative splitting means pacing so that the second half of the race is faster than the first half.

For example, a half-marathon runner may negative split a two-hour half marathon by running the first half (10.5 kilometers, or 6.55 miles) in 61 minutes and the second half in 59 minutes.

Negative splitting is an advanced technique, and many elite runners have used this strategy to set personal bests and records. For example, at the Chicago Marathon in 2022, Emily Sisson negative split the marathon to finish in 2 hours, 18 minutes, and 29 seconds, setting the United States national record.

For more novice runners, negative splitting can be difficult. To execute it well, you need to have a clear pacing plan and expectations of how you can finish. Creating and executing this plan requires a few skills that new runners need time to develop:

• Great discipline: It can be very difficult to keep an easier pace at the beginning of the race when adrenaline is high.
• Sense of pace: While GPS watches can help, a good negative split race requires a runner to have a great internal sense of how fast they are running, especially in the first half of the race. You can use your long runs to practice this, but the more experience, the better.
• Dialed-in race pace: While many elite runners can accurately predict precisely how fast they'll be able to run in a race based on years of training data, beginner runners often need time to determine their running capabilities.

Even Splits

An even split pacing plan is similar to a negative split race plan, except that instead of getting faster as the race progresses, you hold the same pace throughout. For example, a runner aiming to finish a half marathon in two hours, or 120 minutes, should run as close to 9 minutes and 10 seconds per mile (or 5 minutes, 42 seconds per kilometer) as possible.

Like a negative split plan, an even pace requires discipline to lock into your goal pace, an excellent internal sense of pace, and knowledge of your abilities.

The "Hold On for Dear Life" / Positive Split Plan

Finally, the "Hold On for Dear Life" / positive split half marathon race strategy is the most common (but ill-advised) approach for new runners.

In this approach, you run fairly hard from the start of the race and then dig deep to hold your pace later in the race.

The positive split plan can be a good pacing strategy at the right time, but it is high risk/high reward. If you start hard when the gun goes and can maintain your pace or limit the decrease in speed, you may be rewarded with a personal best or a finish time that exceeds your expectations. However, if you go out too fast, you may blow up early and struggle with the remainder of the race.

What's the Best Half Marathon Pacing Strategy?

Studies have shown that for most runners, the best half marathon race strategy, leading to the fastest race times, is to execute either an even split or a slight positive split (where the second half is just a bit slower than the first half).

With this approach, you'll need a good sense of your anticipated race pace. To figure out what pace you should aim for in a half marathon, consider the paces you've held comfortably in half marathon training during some of your tempo running workouts. For example, if you can complete a workout of 3 x 15 minutes at a 9-minute per mile pace, aiming for a 9-minute mile run pace over 13.1 miles would be reasonable.

Once you have a half marathon goal time in mind, you can use our pace calculator to determine your race pace:

Alternatively, if you've recently completed a 5k or 10k race, you can use the same calculator to estimate an equivalent half marathon pace.

Once you've determined a goal race pace, aim to start the event at or just a bit quicker than your goal pace but still at a controlled effort.

For example, if your goal race pace is 9 minutes per mile (5 minutes, 35 seconds per kilometer), aim to start at that pace or just slightly quicker (like 8:55 per mile or 5:30 per kilometer). You'll beat your goal time if you can maintain that pace for the entire half marathon. You'll likely still match your goal even if you slow down a bit.

Common Mistakes Made in Pacing a Half Marathon

Starting Too Fast

By far, the most common pacing mistake many runners (including experienced runners) make is starting the half marathon too hard.

A successful half marathon race effort should be raced entirely under your lactate threshold. Your lactate threshold is an exercise intensity at which your muscles produce more lactate than the body can clear.

Once you exceed your lactate threshold, things get much more difficult. In particular:

• Your breathing becomes labored
• Your muscles begin to burn
• You start to feel like your legs are failing
• The effort feels much greater
• Your pace slows

Many beginner runners start half marathon runs so quickly that they exceed their lactate threshold within the first mile. It soon becomes difficult to breathe, the muscles become fatigued, and the runners must slow down or walk. This is not an enjoyable way to complete a half marathon!

To avoid this outcome, it's always a good idea to hold back a bit at the beginning of the race. A good way to think of a half marathon is to break it into three segments:

• Start through Mile 3 (or Start to Kilometer 5): Hold back a bit, gradually building effort, getting warmed up, and finding a good rhythm. This part of the race should feel relatively comfortable, with controlled breathing and little strain. You should be confident that you can increase your pace and, in fact, feel like you are actively holding back.
• Mile 3 to Mile 9 (or Kilometer 5-15): Hold your race pace or the tempo effort you've practiced in training. You should be working fairly hard and finding a rhythm but still feeling under control.
• Mile 9 (or Kilometer 15) to finish / Mile 13.1: Increase the effort again, really digging in to stay strong. The last 4 miles (or 6 kilometers) will feel tough - that's part of the game when running a half marathon! Lean into your training, maintain good running form, focus on turning the legs over quickly, and power all the way through the last mile.

Starting Too Slow

A less common pacing mistake is starting too slow. This may happen if you're faster than you thought, nervous about the distance, or just got caught up in the crowds.

If you start a half marathon too slow, you'll likely finish wondering if you could have had a faster time. No worries! Find another half marathon to enter, and see if you can start the race a touch faster and still finish strong.

The best way to avoid the pacing error of starting too slow is to know and trust your abilities before the race. Incorporate faster intervals and tempo runs into your training plan and see how your body handles certain paces. By the time you get to a race, you should have practiced your race pace so often that it feels almost automatic.

Also, to avoid the crowds in the first few minutes of larger events, get to the starting area early and position yourself closer to the starting line as you feel comfortable.

What Does Half Marathon Pace Feel Like?

There's no way to sugarcoat it: half marathons, done right, will be painful at the end! But up until the last four miles, they should be "comfortably uncomfortable."

For a half marathon, you should run at a brisk but controlled pace, building towards your threshold and finishing the last five kilometers, or three miles, at your highest effort.

More specifically, a half marathon effort should:

• Feel relatively easy for the first 3 miles (or 5k), like you're holding back.
• Be a moderate to strong, sustained effort for the next 6 miles (or 10k). The effort should feel like a slow burn, gradually getting tougher but always in control.
• Be difficult between 15k and 20k as you continue picking up the pace and increasing the effort. You should be breathing hard and feel the muscle burn, but feel like "controlled speed" with your running form staying smooth.
• Hurt a lot for the last 1k, as you run faster to finish strong.

What Should Your Heart Rate Be During a Half Marathon?

If you watch your heart rate during a half marathon race, you should see it rise gradually in the early miles. Once you reach about 20 minutes into the race, your heart rate should settle mostly in Zone 3. As you reach the finish, you'll likely see your heart rate rise to within ten beats of your maximum heart rate.

Wrap-Up

A half-marathon is a challenging endeavor, no doubt. But if you nail the pacing, you'll be able to finish knowing that you maximized your potential. That's a great way to feel on race day!

In this article, we discussed:

• A few different pacing approaches
• The smartest pacing strategy for most amateur runners: starting at or a bit faster than your goal pace and holding on
• How to find your race goal half marathon pace
• Some of the most common half marathon pacing errors
• What your heart rate should be during a half marathon as the race goes on

Before lining up for your first half marathon, it's a great idea to sit down and plan out your race. Then, use your discipline, experience, and technology to follow that plan. Trust us, there's nothing better than crossing a half marathon finish line knowing you executed the race to the best of your ability!