[Nick]

Catherine,

You are correct there is nothing that specifically defines an optimal length of time. I have found that for most presentations 5 min or less is enough to create a therapeutic effect and tends to be what I use most often.

Here is a link to a nice article written by Frank and Dave.
https://drmasintegrati.wpengine.com/appropriate-use-electrical-stimulation-dry-needling/

Here are two examples of ENS for low back pain I recently shared on instagram.

This was a chronic issue where she has had L5 distribution paint for several months and continued nerve tension. ENS done < 5 min
https://www.instagram.com/p/Br7bcb-H8OW/

This was a friend of mine who’s back tightened up the day prior more of an acute locked feeling that I suspect was discogenic in nature. <5 min
https://www.instagram.com/p/Br6Fte_nLhz/

Here is a published case study for low back pain where they applied for 20 minutes.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625794/