Interval Work in Half Marathon Training: Yes or No?

I ran my first half marathon nine months ago and haven't been on a training routine since. I would go on spurts of trying to get back into it over the summer, but it was just very sporadic. Some weeks — no running at all, and other weeks would run 3 or 4 days of the week. My question is if I'm now starting training for a half in 3 months' time (the same one), should I classify myself as a "Beginner" and not do interval training? Or more of an intermediate runner, and do the speed work as a part of my training? Thanks! – Matt

Hi Matt,

You're in a classic in-between position — not a complete beginner, but not in the consistent shape you were nine months ago either. The good news is that three months is enough time to prepare well, if you approach this sensibly.

Here's what we'll cover:

1. Building your aerobic base first — the non-negotiable phase
2. The honest truth about intervals and half marathon training
3. Better speed work for your specific distance
4. A practical phased plan for your 12-week build

1. Building Your Aerobic Base First

Before we even talk about intervals or tempo runs, I want to be clear: the first 4–6 weeks of your training should be entirely easy running. No intervals. No tempo sessions. Nothing fancy.

You've finished a half marathon, so you're not starting from zero — your body knows what it's like to run distance. But after a summer of sporadic training, your aerobic system has lost some of its base. Tendons, ligaments, and connective tissue need time to re-adapt to regular running before you add intensity. Rush this and you'll pick up a niggle that derails the whole plan.

Follow some of the core beginner running tips for this phase — not because you're a beginner, but because the principles apply: run 3–4 days per week, all at an easy conversational pace. If you can't chat without huffing, slow down. That's genuinely the most important instruction I can give you right now.

Aim for 70–80% of your weekly running at this easy effort. Your body will come back faster than you expect, since you're rebuilding rather than starting from zero — but there's no fixed number of weeks that applies to everyone here, so let how you feel guide the pace of the base phase rather than a calendar date. Focus on time on your feet rather than pace or distance, and trust the process.

2. The Honest Truth About Intervals and Half Marathon Training

Let me be direct: you don't need intervals to run a solid half marathon. Full stop.

Intervals — short, fast repetitions with recovery — are outstanding for building VO2 max and top-end speed. They're brilliant for 5K and 10K preparation. But the half marathon is a different beast. You're sustaining a controlled effort for 13.1 miles; the primary physiological demand is lactate threshold, not raw speed. Intervals don't address that particularly well.

What does? Tempo runs. That's where the half marathon is won and lost in training.

If intervals appear in your plan at all — and they don't have to — use them sparingly. Once a fortnight at most, and only after you've established a solid base. Something like 6 x 2 minutes at 10K effort with 90-second recovery is enough. Generous recoveries, not track-session brutality.

The bigger risk for you right now is adding intensity too soon. Your tendons and bones haven't fully re-adapted after a sporadic summer. High-intensity work before that foundation is in place is one of the most reliable routes to injury I know — and an injury now, with only 12 weeks to race day, would be genuinely costly. So: base first, always.

3. Better Speed Work for the Half Marathon Distance

Once your base is established, the quality session to prioritise is the tempo run. A tempo run sits at roughly your half marathon training threshold effort — comfortably hard, not all-out. You can speak in short phrases, but not hold a full conversation. This is the effort level that teaches your body to clear lactate efficiently, which is exactly what you need to sustain goal pace for 13.1 miles without blowing up.

Start with 15–20 minutes of sustained tempo running. That might be a continuous effort or two 8-minute blocks with a short recovery — whatever gets you there comfortably at first. Build progressively to 25–30 minutes over weeks 7–10.

Then add goal-pace work in the final phase. This is running at your actual target half marathon pace — not faster, not easier. Start with 3 x 1.5 miles at goal pace with 2-minute jog recoveries. The purpose isn't to get fitter in the traditional sense; it's to engrain the rhythm and feel of your race pace so it becomes automatic on race day.

The beauty of both tempo runs and goal-pace segments is that they're less stressful than hard intervals — so you can fit them into a modest weekly structure without accumulating too much fatigue. For a returning runner with your background, that's the right balance. And it's the work that actually transfers to half marathon performance on race day. Base running drills during easy sessions can help reinforce good form throughout.

4. Your Practical 12-Week Plan

Here's how I'd structure your three months, given everything above.

Weeks 1–6: Base Phase. Run 3–4 times per week, all easy conversational effort. Keep your long run at a comfortable distance — perhaps 8–9 miles — and build it gradually to around 9–10 miles by the end of this phase. No quality work yet. Your sole objective is getting consistent miles in the legs without getting injured. If you feel a niggle, listen to your body and back off immediately rather than pushing through.

Weeks 7–10: Introduce One Tempo Run Per Week. Everything else stays easy. The tempo session replaces one of your mid-week easy runs — it doesn't add to the load. Start at 15–20 minutes of threshold effort, build toward 25–30 minutes. Your long run should reach 10–11 miles by the end of this phase.

Weeks 10–12: Add Goal-Pace Segments. Keep your tempo session, and add some goal-pace running to a second mid-week run. Think 3 x 10 minutes at race pace with easy jogging between. Your longest training run should reach 11–12 miles. Then taper — cut mileage by about 40% in the final week, keep a couple of short goal-pace efforts to stay sharp.

The trick is patience in those early weeks. The urge to train at the level you were at nine months ago runs strong — but your body isn't there yet. Let the base weeks do their quiet work. By week 7, you'll feel more like yourself again, and the tempo runs will feel earned rather than forced.

You have plenty of time to be ready for this race, Matt. Build it sensibly and you'll be standing on that start line in much better shape than you think.

Kind regards,

For a fuller explanation of where interval training fits in half marathon preparation, I recommend Daniels Running Formula by coach Jack Daniels.

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