Long run
Sustained easy running to build the aerobic base a marathon sits on.
Also called: easy long run, LSD.
The single most important session in a marathon build, and the one where discipline pays most. Easy means easy: conversational, comfortably aerobic, slow enough that you could hold a phone call. Running long runs a little too hard is the most common training error in recreational marathoning, because it converts a low-cost aerobic stimulus into a session that needs real recovery. Duration is capped around two and a half hours in this library — beyond that, injury risk climbs faster than fitness does.
The session
Shown at a 4:00 marathon reference — 1 h 57 total, about 16.7 km, including 2 min of quality work.
Session
- 1 h 51 easy (6:43–7:24/km)
- 6 × 20 s strides, jog back between
Why this session works
The plain long run remains the backbone: mitochondrial density, capillarisation, fat oxidation, and durable connective tissue all scale with time on feet at easy effort.
Source: Seiler 2010; Casado et al. 2022. Training phase: build.
Run it at your own paces
Open the workout generator and enter a recent race time — every rep length, recovery and target pace is recalculated for your fitness, and the session exports to .fit for a Garmin watch.
Frequently asked questions
What is a long run?
Sustained easy running to build the aerobic base a marathon sits on. The single most important session in a marathon build, and the one where discipline pays most.
How long is this session?
At a 4:00 marathon reference it comes to 1 h 57 and about 16.7 km, of which 2 min is prescribed quality work. The generator scales both to your own paces, so a faster runner covers more ground in the same time.
Who is this workout for?
It is written for the build phase of a marathon build. The distances shown suit a 4:00 marathoner; enter your own recent race time in the generator and every rep length and target pace is recalculated for you.
More long runs sessions
- Progressive long run — A long run that gradually accelerates, finishing at or near marathon pace.
- Long run with marathon-pace inserts — Blocks of goal marathon pace embedded inside a long easy run.
- Long run with surges — A long easy run broken up by short faster efforts.
- Steady-state run — Sustained running between easy and marathon pace — harder than a recovery run, easier than a workout.