How Long Should Your Longest Run Be for a Half Marathon?

Not all half marathon training plans are the same, and long-run distances can vary. This leaves many runners asking: How long should your longest run be before a 13.1-mile race?

At Coopah, we recommend your longest run is no more than 10 to 12 miles (or 2.5 hours of running), whichever comes first.

While running the full 13.1 miles in training might seem like a good idea, the injury risk often outweighs the benefits. Here are the three key reasons why we cap the long run at 10-12 miles

Increased Injury Risk

At Coopah, our main goal is to get you to the start line healthy, recovered from your peak training, and ready to race.

• Diminishing Returns: Running much beyond 12 miles (or 2.5 hours) in a single training session brings a much higher risk for developing injuries, burning out, and peaking too soon.
• The “Test Run”: A 10-12 miler is the perfect distance to test your fueling strategy, race day kit, and pacing, all while building crucial endurance.
• Avoid “Fear Miles”: We don’t want you adding extra mileage out of fear that you’re not doing enough. This can lead to you leaving your best run on the training ground, not for race day when it counts.

THE NEED FOR RECOVERY

Pushing your body for longer than 2.5 hours or further than 12 miles for a half marathon can significantly impact how fast your body can recover.

Progressive Overload: A training block should be a progressive overload, which means you are gradually (and safely) increasing mileage up to your peak weeks. We aren’t looking to fatigue the body to the point of exhaustion where there isn’t enough time for recovery.

The Goal is Consistency: You should be able to complete your other runs during the week. If one long run pushes you to an unsustainable limit, your body won’t recover in time. This means you may have to skip other key sessions, which hurts your overall fitness.

“But How Will I Run the Last Few Miles on Race Day?”

This is the most common fear we hear: “How will I be able to run the last 1-3 miles if I’ve only run 10-12 in training?”

It’s a valid question, but here’s the crucial difference:

Your 12-mile long run is completed as part of a peak mileage week, on already tired legs.

Your 13.1-mile race is completed on rested, tapered legs in a race environment, fueled by adrenaline!

Your mind, your taper, and your consistent pacing practice will carry your body through those final miles. Trust the process—you don’t need to run the full distance in training to succeed on race day.

Get Your Half Marathon Pacing Right

If you find you are struggling to get through your long runs, you may be running at an unsustainable pace and should consider slowing down.

Download or open the Coopah app and chat with a coach for further advice