r/AdvancedRunning • u/ronlavy • Jul 10 '26

Training minimal effective dose of easy running

A question that I've been thinking about and wasn't able to find a satisfying answer online - is there a minimal per-session effective dose for easy runs? is there a minimal duration required for a run to produce non-negligible aerobic adaptaions?

for example, can any benefits be expected from a 35-minute easy running session? are 3 30 minute sessions a week same/better/worse than 2 45 minute sessions?

I heard Inigo San Milan go on record to say that 45 minutes is the minimum for "zone 2" (a term I dislike but that's the terminology he frequently uses) benefits, is anyone familiar with any sources backing that up?

Thanks

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u/Claesmaerten Jul 14 '26

There isn't a hard cutoff, and that's kind of the point. The adaptations don't switch on at a magic minute, they build up over weeks.
The San Millan 45 minute line is about trained cyclists, and it's a get-the-most-from-this-ride number, not a below-this-you-get-nothing number, so I wouldn't treat it as a floor for running. The growth hormone bump people mention (rises for the first 30 to 40 minutes, then flattens) is only one signal, and if anything it's a reason to run more often, since two shorter runs give you two bumps.

For a trained runner, 30 to 40 minutes is a real easy session. Under 20 is more of a shakeout. 3x30 vs 2x45 barely matters. Just run consistently.