Runner's Dilemma #24 — One Month Out — How Many More Long Runs Do I Need?
Runner's Log | Runner's Dilemma #24
One Month Out — How Many More Long Runs Do I Need?
My full marathon is less than a month away now.
Two years ago, on my first attempt at the full distance, my knee gave out around the 30km mark and I couldn't properly run the rest of the way.
Someone heard about my training and said,
I don't actually know if that was the cause.
But since it might have been, this time I wanted to actually understand long runs before doing them.
A month out from race day:
What pace should I set it at?
Should I keep doing long runs every week, right up until race week?
And once I've done my last long run, do I stop running long distances entirely?
What else should I watch out for?
I asked AI.
1. The Longest Long Run by Race Distance
First, I looked into distance.
For a half marathon or a 30km-ish race, you cover a large chunk of the actual race distance in training.
But the full marathon is different. You don't run the entire 42.195km in training.
Because of injury and recovery concerns, the longest long run for a full marathon is typically capped around 32~35km.
| Race distance | Typical longest long run |
|---|---|
| Half (21km) | ~16-18km |
| 30-32km range | ~25-30km |
| Full (42km) | ~32-35km |
Rather than running the whole 42km in advance, what matters is finding a distance that builds the endurance you need while still leaving enough time to recover before race day.
From here on, I'll be looking at everything from the full marathon's perspective.
2. Long Run Pace by Goal Time
So how should I set my pace?
Long run pace should be set with plenty of margin from your goal marathon pace.
Sources vary somewhat, but roughly 20-60 seconds/km slower is a common starting point, with the ultimate benchmark being a comfortable, conversational effort.
| Goal time | Goal pace | Long run pace |
|---|---|---|
| Sub 3 | 4:16/km | 4:35-5:10/km |
| Sub 3:30 | 4:59/km | 5:20-5:55/km |
| Sub 4 | 5:41/km | 6:00-6:35/km |
| Sub 4:30 | 6:24/km | 6:45-7:20/km |
| Sub 5 | 7:06/km | 7:25-8:00/km |
Of course, none of this is an absolute formula. Weather, course, heart rate, and current condition all shift things around.
What matters is whether you have enough margin to sustain it over a long stretch.
3. Long Run Distance by Week — Tapering Down
So how should long runs change as race day approaches?
Rather than repeating the same distance right up to race day, the basic idea is to taper the distance down progressively.
For a full marathon, that typically looks like:
| Timing | Long run guideline |
|---|---|
| 4-3 weeks out (28-21 days) | Longest long run, 32-35km |
| 2 weeks out (14 days) | ~18-20km |
| 1 week out (7 days) | 8-13km, no long run |
| Race day (0) | 42.195km |
This varies depending on individual training level and weekly mileage.
The key point here is that overall training volume also decreases as race day approaches.
Marathon taper research has found that reducing total training volume by roughly 41-60% over the final two weeks tends to be the most effective strategy.
In other words, after your longest long run, the goal shifts from building up to backing off.
4. Training After the Long Runs Are Done
If you're cutting down on distance, does the pace need to come down too?
Not necessarily.
The general taper principle is to reduce volume while not eliminating intensity entirely.
You run less, but keep some of the necessary stimulus in there. For example:
· Short runs at goal pace
· Light intervals
· A few short, quick bursts (not a full sprint — roughly 80-100m at a comfortably fast effort, repeated a few times)
These keep the legs' running rhythm and sensation alive.
distance ↓ total volume ↓ fatigue ↓
but the feel of running stays.
5. Things to Watch Out for During Long Runs
It turns out distance and pace weren't the only things to worry about on a long run.
| Item | Guideline |
|---|---|
| Fueling | Regularly every 45min-1hr; find your own amount through training |
| Hydration | Drink on a plan, not just when thirsty — but avoid overdoing it too |
| Pace | Don't get dragged into someone else's pace |
| Judgment | Check perceived effort + heart rate + how your body feels, together |
Especially over long distances, fueling and hydration are part of the training too.
You shouldn't be trying this for the first time on race day. During your long runs, figure out — "how much do I actually need to eat?" "How much do I need to drink?" — ahead of time.
And above all,
If today's long run is about adapting to distance, don't get impatient and run it at your actual race goal pace. Run it in a way that fits its actual purpose.
So Here's How I'm Applying This to Myself
Here's my 35km run from two days ago.
① Distance
Since it's a full marathon, the longest long run should be around 32-35km. I've already done 35km. Distance-wise, I'm covered.
② Pace
My goal is sub-4. Goal pace is 5:41/km. The right long run pace is 6:00-6:35/km.
Setting this run aside, the long run pace I'd been training at was around 6:20/km — right in that range. My legs got stiff in the back half, but it wasn't unbearably hard.
But on this particular 35km, I ended up running alongside someone targeting a 3:20 finish. My average pace was 5:55/km, but the 20-29km stretch actually came in at 5:20-5:30/km.
In the final 3km, my pace dropped past 6 minutes and into the 7-minute range. I could grind through it, but it was genuinely hard.
Next time, I'm not chasing anyone else's pace. I'll stick to a long run pace that matches where I actually am.
③ Time remaining
I've already done my longest run at 35km.
My club president told me to do two more long runs — this weekend and next.
Based on everything I looked into, there's no need to repeat the same 35km.
But you know how it is. I still kind of want to do it properly, one more time.
So this weekend, I'm planning one more long run at around 32km.
This time, though, I'm really not chasing anyone's pace — sticking to my long run pace of 6:00-6:35/km.
Next week I'll cut back to around 18-20km, and the week after that, shorter still, tapering into race day.
④ Training beyond long runs
Long runs build endurance, but I'm still not sure I can hold 5:40/km for the full 42km at sub-4 pace.
To keep some ease at faster paces, I'm planning to keep one interval session a week.
Probably Tuesday, so it doesn't get in the way of the weekend long run.
The closer race day gets, the more I want to push both distance and speed at once — my mind's getting a little restless about it.
⑤ Things to watch out for
Thinking back on this 35km run again.
I only fueled once, at the 18km mark — one energy bar, two Oreo-style snack cakes, 700ml of water.
Maybe because I'd stopped briefly to fuel, the first km after was tough.
But things got easier from there, and I ended up covering the next 10km at around 5:30 pace.
Then past 29km, things fell apart quickly.
As for why:
I got thirsty at one point and just pushed through it instead of drinking.
And a long run is supposed to build endurance — but I ran the 19-29km stretch at 5:30, drifting from that actual purpose.
So this weekend, I'm going to try to actually do it right.
Fuel properly.
Drink the moment I'm thirsty, not after.
This time, I'm determined to let the 3:20 pacer go ahead of me.
I just don't know how to actually say no to him.
Every time I try to wave him ahead...
"I'll take it slow too, don't worry."
And then the pace creeps up and up, and I can't exactly get mad about it...
But if I stick with him, running too slow would mess up his pace too...
So I end up trailing behind, saying "please, go ahead" for what feels like the hundredth time.
So I can finally run my own pace.
