A five-day work trip will not undo your marathon build. Research suggests you can cut your running volume by a third to two thirds and hold your endurance for weeks, as long as you keep some intensity in the mix.
The real danger isn’t a short week. It’s the panic that turns a short week into a missed month.
How much fitness do you lose when you can’t train?
Start with the scary numbers, because they’re the ones you’ve read. In studies of complete detraining, VO2max (the size of your aerobic engine) fell about 7% after 12 days in trained runners and cyclists. Other studies found drops of 3.7% to 4.7% at two weeks and 4.2% at three weeks. At 56 days the loss hit 13%. These figures are pooled in a 2024 review in Frontiers in Physiology.
In short: stop everything for two to three weeks and you lose a noticeable slice of fitness.
Read that chart carefully. Every bar comes from athletes who stopped training entirely. Blood plasma volume also fell, by 5% after 14 days of inactivity and 12% over two to four weeks of full rest. Your heart pumps less blood per beat when plasma shrinks.
A travel week isn’t that. You’ll still run, walk and carry a bag through an airport.
Rest is the cliff. Reduced training is a gentle slope.
Marathon training while travelling: the minimum effective dose
Think of your fitness as a phone battery. Complete rest is leaving it unplugged for a month. A short week on the road is a slower charger. The battery still holds its level.
A 2021 review of minimal-dose research found endurance performance can hold for up to 15 weeks. You can cut training frequency to as low as 2 sessions per week, or cut volume 33% to 66%. The authors name one condition: intensity stays high. Translation: fewer miles are fine, but don’t make every run a shuffle.
Taper research backs this up. A meta-analysis of 27 studies found a 41-60% volume cut, with intensity and frequency held, worked best over two weeks. Athletes shed fatigue and kept fitness. A travel week is a mini taper you didn’t plan.
So what do you protect? Two sessions:
- One quality run. Tempo, threshold or intervals. Keep it short but honest.
- Your long run. Shorten it if you must. Don’t skip it.
Everything else is optional easy mileage. For deeper background on why easy running builds the engine, see how Zone 2 builds the aerobic base.
Keep the hard stuff. Trim the filler.
What to do by trip length
The table below is my own rule of thumb. It comes from the 33-66% volume window above, so you’d keep roughly 34-67% of normal mileage. It isn’t a prescription from any single study. Adjust it to your build week.
| Trip length | Volume kept | Structure | Jet lag note |
|---|---|---|---|
| 1-2 days | 67-100% | Run before or after travel. Keep the plan. | Ignore it under 3 zones |
| 3-5 days | 50-67% | 1 quality run, 1 shorter long run, 1-2 easy runs | Hard session on day 3 or later |
| 6-10 days | 40-60% | 1 quality run, 1 long run, strength twice | Wait out the adjustment before hard work |
| 10+ days | 34-50% | Same, plus a mini-week reset on return | Treat arrival like a recovery week |
Back at home, ease in. If a trip left you sick or sore, the same logic applies as in what to do after missing a week of marathon training: add load gradually, not all at once.
Jet lag and your workouts
Jet lag hits after crossing 3 or more time zones. A consensus statement from 26 experts estimates your body clock shifts about 1 day per zone flying east. Flying west, it’s about half a day per zone.
In short: six zones east means roughly six days of fuzzy. Six zones west is closer to three.
That changes your calendar. Don’t schedule intervals on day one or two. Go easy, get outside light, and save the hard session for when your sleep settles. The same panel recommends morning light of at least 2,500 lux around your body’s temperature low, plus short early naps. They also admit the evidence is thin, so treat these as sensible habits, not guarantees.
Sleep is the other lever. In a small study of 10 soccer players, sleeping 5 hours or less hurt aerobic performance, and a modest caffeine dose softened the hit. It’s a tiny sample, so don’t build a plan on it. Just don’t schedule your hardest run after a red-eye.
For hydration, no study gave a hard number. Sip regularly through the flight, skip the alcohol, and drink plain fluids.
The hotel treadmill and the 1% rule
A 1996 study by Jones and Doust tested 9 trained male runners at six speeds from 5:42 to 3:20 per km. A 1% incline matched the energy cost of level outdoor running. Level treadmill running underestimated that cost.
Treat 1% as a starting point, not an exact match. Treadmills differ, so run by effort and breathing more than by the number on the screen.
So set the belt to 1%, run by effort, and don’t obsess over pace. Treadmill numbers are close, not exact.
Hotel-room strength in 15 minutes
The same 2021 review says strength can hold for up to 32 weeks in younger adults. It takes one session a week with one set per exercise. A hotel floor is enough.
Do squats, lunges, a plank and single-leg bridges. Add Nordic hamstring curls if you can anchor your feet under a bed frame; here’s why Nordics protect runners’ hamstrings. Fifteen minutes, done.
A case study: Dana’s London week
Take a runner I’ll call Dana. She’s 41, aiming for a 3:45 marathon, and runs 45 miles a week. Her company flies her from New York to London for six days. That’s 5 time zones east, so expect about 5 days for her body clock to catch up.
Her old habit was to skip everything and “catch up” at home. This time she cut volume to about 22 miles, around half. She kept days one to four easy and did one tempo run on day five, once the jet lag eased. She ran a long run of 10 miles on the treadmill at 1% grade. Two hotel strength sessions filled the gaps.
Back home, she resumed full volume after two easy days. Her next 16-mile long run came in at her usual easy pace, with her heart rate within a few beats of normal. These are illustrative numbers, but the pattern matches what the research predicts: reduced training, kept intensity, no cliff.
How AthleteOS re-plans the week
Tell the AthleteOS AI coach which days you’re travelling and what you’ll have to work with, like a hotel treadmill or only your running shoes. It reshapes your training plan for that week and shows each change on your workout calendar with a plain-English reason. A fixed PDF plan can’t do that, which is why static training plans fail real life. Start a plan on AthleteOS and add the trip before you pack.
Your marathon is built over months. One week away won’t take it back.