Training Concepts
What is a
Long Run?
The long run is the single most important session in any endurance training plan. It builds the aerobic engine, trains your body to burn fat as fuel, and prepares your legs for the demands of race day. Here's exactly how to do it right.
What Makes a Run "Long"?
A long run is your longest run of the week, done at an easy, conversational pace. It's not defined by a fixed distance — for a beginner running 20km per week, a long run might be 8km. For an experienced marathon runner doing 70km per week, it might be 30km.
What defines it is the duration and relative effort — typically 90 minutes to 3+ hours at genuinely easy effort. The goal is time on feet and aerobic adaptation, not speed.
The golden rule: You should be able to hold a full conversation throughout your long run. If you can't speak in complete sentences, you're running too fast. Slow down — the benefits come from the duration, not the pace.
Why the Long Run Works
Extended easy running triggers a cascade of adaptations that hard training simply cannot produce. Your body develops more capillaries to deliver oxygen to muscles, increases mitochondrial density for better energy production, and improves its ability to burn fat — preserving precious glycogen for when you really need it late in a race.
For marathon runners, the long run is particularly critical. Running 30km+ in training teaches your body to cope with glycogen depletion, prepares your connective tissue for the pounding of race distance, and builds the mental resilience to keep moving when tired.
How Far Should Your Long Run Be?
- 5K training — peak long run 8–10km. Don't need to go much further for a short race.
- 10K training — peak long run 12–15km. Builds the aerobic base that underpins 10K performance.
- Half marathon training — peak long run 18–22km. Get close to race distance but don't exceed it.
- Marathon training — peak long run 28–35km. Most coaches cap it here — the recovery cost of going further outweighs the benefit.
What Pace Should You Run?
Easy. Genuinely easy. A rough guide: 60–90 seconds per kilometre slower than your goal race pace. For a runner targeting a 2-hour half marathon (5:41/km), the long run should be around 6:30–7:10/km.
This will feel embarrassingly slow, especially early in a run when your legs feel fresh. Resist the urge to speed up. The adaptation you're seeking happens at low intensity over long duration — not from running fast.
Long Run Day — Practical Tips
Fuel from the start: Eat a light breakfast 60–90 minutes before. For runs over 75 minutes, take a gel or sports drink every 30–45 minutes — don't wait until you feel hungry or tired.
Run on tired legs sometimes: Deliberately scheduling your long run after an easy midweek run teaches your body to run efficiently when fatigued — which is exactly what the end of a race feels like.
Recovery matters: The long run creates fatigue that takes 48–72 hours to fully clear. Schedule an easy or rest day the day after. The adaptation happens during recovery, not during the run.
Long Runs Built Into Every Plan
Long Run Progression
PaceLab builds your long run distance progressively each week — capped to safe maximums for your race distance.
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