How Long Should Your Longest Run Be Before an Ironman?

The Short Answer:

Your longest run should typically fall between 2 hours 30 minutes and 3 hours, depending on your pace, durability, and training background.

If you're aiming to finish your Ironman strong, especially on the marathon, smart run training is essential — and that doesn’t mean running a full marathon in training.

Why You Don’t Need to Run a Full Marathon in Training

Many athletes assume they need to run 26.2 miles in training to prepare for an Ironman — but this is a big mistake.

For most amateur triathletes, running a full marathon in training carries more risk than reward:

😬 Increased injury risk

💤 Extended recovery time

📉 Disrupted training consistency

Only our most experienced athletes — who have built up years of volume — will ever run this distance in training, and even then, it’s rare and carefully programmed.

Instead, the goal is to simulate the demands of the Ironman marathon, not replicate the full distance in training.

What Should Your Long Run Look Like?

Recommended Peak Long Run:

Distance: 18–21 miles (29–34 km)

Duration: 2.5 to 3 hours

Pace: Easy aerobic (Zone 2) — not race pace

Frequency: 2–3 long runs in the final 6–8 weeks before taper

Remember: Time on feet matters more than miles.

Your focus is to build durability, not speed.

Why Brick Runs Matter

A standalone long run is important — but it’s not the full picture.

Brick runs (running immediately after biking) are essential to simulate race fatigue and prepare your legs for the Ironman shuffle.

🔁 Bike-Run Brick Example:
Long bike (4–5 hours) + 60–90-minute run at Zone 2 pace

These workouts are gold for mental and physical preparation.

Should You Walk in Training? Yes — Strategically.

Let’s be honest — many athletes walk during the Ironman marathon. Just watch the final hours of any race and you’ll see it’s common, not a failure.

That’s why strategic walk breaks during training can be a game-changer.

Use the aid station walk method (walk for 30–60 seconds every 2 km or aid station)

Practice taking nutrition and fluids while walking

Consider a run-walk strategy from the start — for many, this leads to faster overall times

The goal isn’t to run the entire marathon at all costs. It’s to keep moving, fuel well, and avoid a total shutdown.

Final Word: It's Not Just a Run — It’s a Run After 180KM of Biking

You’re not training for a standalone marathon — you're training for the final leg of one of the toughest one-day endurance events in sport.

Pacing, fueling, and mental strength will be far more important than the number of miles logged in a single run.

Key Takeaways:

✅ Longest run = 2.5 to 3 hours, not a marathon


✅ Practice fueling during your long runs


✅ Use brick sessions to simulate race fatigue


✅ Walk breaks are valid, even for experienced racers


✅ Respect the distance, but train smart — not just long

Need Help Structuring Your Ironman Plan?

At Alpha State, we’ve helped dozens of athletes prepare for and complete their first Ironman — and for many, it was just the beginning. Whether your goal is to finish, qualify for Kona, or simply not blow up on the marathon, we’ll guide you every step of the way.

👇 More Ironman Training Resources:

✅ How to Prepare for Your Ironman (Beginner’s Guide)

✅ How Long Does It Take to Prepare for an Ironman?

✅ A Beginner’s Guide to Triathlon Training

✅ Ironman Race Strategies