One Month Left to Train for a Half Marathon

Hello, I'm running a half marathon in one month. I recently got sick with bronchitis and couldn't run for 3 weeks. I was only up to 5 miles at that point. With only 4 1/2 weeks left to train, what is the recommended training schedule? It's my first half, and my goal is to finish in the allotted time. Any advice is welcome. – Amelia

Hi Amelia,

Bronchitis with four and a half weeks to go — that's rough timing, but this situation is far more manageable than it feels right now.

Here's what we'll cover:

1. What bronchitis actually does to your running fitness — and what it doesn't
2. A simple four-week build-up from where you are now
3. The walk-run maths that make finishing very achievable
4. Race-day strategy and the final week

1. What bronchitis does — and doesn't do — to your fitness

Here's the reassuring part first: three weeks off running does not erase the aerobic base you had built. You'll lose perhaps 10-15% of your peak fitness — so if you were comfortably running five miles, you're sitting at roughly four miles' worth of fitness right now. That's a nicer starting point than most people in your situation realise.

The less comfortable truth is that bronchitis specifically irritates the airways, and that inflammation can linger for two to four weeks after you've otherwise recovered. What this means in practice: your first few runs back may feel harder than the effort level warrants. You might find yourself breathing more heavily than you'd expect for an easy jog. That is not a sign that you've lost all your fitness — it's residual airway irritation, and it settles down within a week or two of easy running.

This matters because it affects how you read your own body when you start back. Don't judge your fitness by how your lungs feel on the first two or three runs. Judge it by how your legs feel, and by whether you can sustain an easy pace for the planned duration without your heart rate going through the roof.

The second thing to say: your aerobic base from your pre-illness running is still largely there. The cardiovascular adaptations — a stronger heart, improved oxygen delivery, better fat burning at easy pace — take months to fully fade. Four and a half weeks is actually enough time to rebuild your running legs and arrive at the start line in reasonable shape. I've seen runners complete halves from a worse starting point than this.

2. A simple four-week build-up

Amelia, the goal here is not to cram fitness in — it's to rebuild your running legs steadily and arrive healthy. Here is a sensible week-by-week progression:

Week 1 — Easy return (this week): Three or four runs of 3-4 miles each at a genuinely easy, conversational pace. Total: 12-15 miles. Your longest run this week should not exceed 5 miles. If your lungs feel tight, shorten the run rather than pushing through. A 30-minute easy jog that feels comfortable is worth far more than a 50-minute sufferfest right now.

Week 2 — Building steadily: Increase to four runs, with your long run reaching 5-6 miles. Keep everything else at 3-4 miles easy. Total: 16-20 miles. You should start feeling more like yourself this week as the airway irritation settles.

Week 3 — Peak week: This is your most important week of preparation. Get one run of 7-8 miles in — that's your "long run" for this cycle. Keep it easy and steady, and use the walk-run pattern (more on that shortly) to protect your legs. Three shorter easy runs round out the week. Total: 20-24 miles.

Week 4 — Taper: Reduce volume significantly. Two or three easy runs of 3-4 miles, nothing longer. This is not the time to suddenly decide you need one more big effort. Your fitness is set by now. Rest, sleep well, and let your body consolidate.

Keep all runs at easy pace for now — the kind of pace where you could hold a conversation without gasping. That applies even to the tempo-style work you might read about in a standard half marathon programme. For training for a half marathon in normal circumstances, there's time for tempo work. In your situation, easy running and one weekly long run are the only tools you need.

3. The walk-run maths that make finishing very achievable

This is where the numbers are genuinely encouraging. Most half marathons have cutoff times of three to three and a half hours — that works out to roughly 13-16 minutes per mile. A steady walk-run approach gets you well inside that margin with comfort to spare.

Here's the simple maths: if you run at a relaxed 11-12 minute per mile pace and walk at a brisk 15-16 minute per mile pace, using a 3-minute run / 1-minute walk pattern, your average pace works out to around 12-12.5 minutes per mile. That puts you across the line in approximately 2 hours 38 minutes to 2 hours 44 minutes — well within a three-hour cutoff, and with energy to spare at the finish.

The trick with walk-run is to start the walking intervals from the very beginning of the race, not when you're already tired. This is counterintuitive but important. Walking from mile 1 feels almost silly when you feel fresh — but those early walk breaks are what preserve your legs for the final four miles, which is where first-timers typically fall apart.

Practise this pattern in your long runs — especially the 7-8 mile effort in week 3. Get comfortable with the rhythm of 3 minutes running, 1 minute walking. By race day it should feel completely natural. Beware the temptation on race day to skip your walk breaks because you feel good in the first half; this is almost always regretted by mile 10.

You can check the specific cutoff time for your event on the running races page or directly with the race organisers — but three hours is standard for most events.

4. Race-day strategy and the final week

Amelia, the final week is simpler than you might expect. Keep running — don't go dark — but keep it very easy and short. Three runs of 3-4 miles, with the last run two days before race day. No heroics. No sudden urge to test yourself with a long effort because you're feeling good.

Race morning: eat a light, familiar breakfast two to three hours before the start — whatever you've eaten before training runs is fine. Nothing new on race day. Lay your kit out the night before and double-check everything.

At the start line, position yourself at the back of your wave. Let the crowds thin out before you find your rhythm. Start your walk-run pattern immediately, even if it feels premature. The patience you show in the first four miles is what you'll spend in the final four.

One last thing worth saying plainly: a goal to "finish in the allotted time" is a completely sensible, entirely honourable race goal. Many beginner runners feel embarrassed about it, as though finishing without a fast time doesn't count. It absolutely counts. Covering 13.1 miles on foot after an illness setback, with four weeks of preparation, is fantastic progress — and I genuinely mean that.

You can find more on structuring a first half in the beginner running tips section. And if you'd like to read about what other runners in similar situations have managed, there's a lot of useful perspective there.

Go and enjoy it, Amelia. You've got this.

Kind regards,

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