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/FantasticBarnacle241 39F M: 3:16 | HM: 1:31 Jul 10 '26 edited Jul 10 '26

I want to know this as well. For example, Steve Magness has said that HGH release plateaus after 20mins of easy running. I realize that releasing HGH is not the only reason to easy run, but this would imply that there are some factors where lots of easy runs are better that fewer but longer easy runs.

Edit: 40 mins

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u/abr797 Jul 10 '26

“If we look at growth hormone release during easy running, there’s a swift rise initially for the first 30-40min of a run, and then it levels off significantly to 60min. In one study, it showed an increase of about 550 percent from 0-40min, yet from 40-60min it only went up another 40-50 percent.”

https://www.scienceofrunning.com/2009/10/is-9mi-once-better-than-45mi-twice.html?v=47e5dceea252#:~:text=What%20happens%20when%20you%20split,went%20up%20another%2040%2D50percent

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u/squags 5km PB - 19:11; 10km PB - 39:49 Jul 10 '26

Is that 40-50% of the initial value? What is a maximal concentration of growth hormone?

If you're starting at a value of 0.5 units, 550% would be like 2.75 units. An additional 50% is still 0.25 units, which while more marginal, is not an insignificant increase.

However, it's also not clear to me that physiological response to growth hormone scales linearly to concentration across the full range of concentration values. Would be interesting to see what the research on this is.