The long run is the most important single session in your week — and also the one most runners overthink. How far is far enough? How fast should you go? When do you increase? When do you stop increasing?
The answers depend on where you are and what you’re training for. But the principles are universal.
How Long Is “Long”?
Your long run should be your longest run of the week — but it shouldn’t dominate the week. Pacewright caps the long run at 30% of your total weekly volume. This ensures that one session doesn’t consume so much of your recovery capacity that the rest of the week suffers.
For a runner doing 20 miles per week, that’s a 6-mile long run. For someone at 30 miles per week, it’s 9 miles. For 40 miles per week, 12 miles. The number scales with your total volume — not with an arbitrary distance target.
If you’re training for a marathon and wondering about the classic 20-mile long run, here’s the math: to support a 20-mile long run at the 30% cap, you’d need to be running roughly 65-70 miles per week. Most recreational marathon runners don’t do that — and most don’t need to. Long runs of 16-18 miles, combined with consistent weekly volume, are sufficient for the vast majority of marathon finishers.
How Fast Should You Go?
The long run is an easy effort — RPE 4-5. You should be able to hold a conversation throughout. The purpose isn’t to practice running fast. It’s to accumulate time on your feet at an aerobic intensity that builds endurance-specific adaptations.
Those adaptations include:
- Improved glycogen storage and utilization. Your muscles learn to store more fuel and burn it more efficiently during sustained effort.
- Enhanced fat oxidation. At easy effort, your body increasingly relies on fat as fuel, sparing glycogen for when you need it.
- Mental endurance. Running for 90+ minutes teaches you how to manage boredom, discomfort, and the urge to stop — skills that translate directly to race day.
- Structural resilience. Extended time on your feet strengthens the connective tissues — tendons, ligaments, fascia — that absorb impact.
Running your long run too fast turns it into a different workout: one that accumulates fatigue without providing the aerobic benefits you’re after. A long run at RPE 7 isn’t a better long run. It’s a badly paced tempo that you’ll need extra recovery from — and that recovery cost means your other workouts suffer.
How to Progress
Your long run follows the same spike guard as every other run: no single session exceeds 110% of your longest run in the past 30 days. If your longest recent run was 8 miles, next week’s long run caps at 8.8 miles. The progression is gradual because the tissues that absorb impact — bones, tendons, cartilage — adapt slower than your cardiovascular system.
A practical progression for a runner building from 6 miles to 10 miles:
| Week | Long Run | Notes |
|---|---|---|
| 1 | 6 miles | Baseline |
| 2 | 6.5 miles | Small increase |
| 3 | 7 miles | Building |
| 4 (recovery) | 5 miles | Planned cutback week |
| 5 | 7.5 miles | Resume from new baseline |
| 6 | 8 miles | Building |
| 7 | 8.5 miles | Building |
| 8 (recovery) | 6 miles | Planned cutback week |
| 9 | 9 miles | Resume |
| 10 | 10 miles | New peak |
Notice the pattern: 3 weeks building, 1 week recovery. The recovery week drops your long run to roughly 60-70% of your recent peak. This isn’t wasted time — it’s when your body consolidates the adaptations from the build weeks.
When to Hold Steady
Not every phase of training calls for longer and longer runs. There are good reasons to keep your long run at its current distance:
- You’re in a base-building phase and the focus is on increasing total weekly volume, not single-run distance
- Your weekly mileage doesn’t support a longer long run (the 30% cap would be violated)
- You’re focusing on speed — 5K or 10K training plans emphasize intervals and tempo work, with a moderate long run that maintains endurance without chasing distance
- You’re in a recovery or deload period and the plan has deliberately pulled the long run back
A 10-mile long run every weekend for 8 weeks straight is excellent training. You don’t have to increase it just because you successfully completed it last week.
Walk Breaks on Long Runs
Walk breaks are a legitimate strategy on long runs, not a sign of weakness. Taking a 1-minute walk break every mile or every 10 minutes reduces cumulative muscle damage, helps manage heart rate drift, and allows you to cover more total distance than continuous running at the same perceived effort.
Many experienced runners use walk breaks specifically on long runs while running their shorter sessions continuously. It’s a tool for managing the demands of extended time on your feet — not a substitute for fitness.