Eh, it’s kind of both depending on the context. Generally speaking volume means the total work performed, and usually on a weekly (or longer) macro scale. Not workout to workout
Volume = total work performed = reps x sets x weight
If your trainer said “today we’re gonna increase the volume!” you could interpret that, colloquially, to be your definition and assume it’s gonna be a high-rep session
As I said use whatever definition you want, as with most things in lifting there are always multiple ways to look at something. But criticizing someone for saying “that’s not volume” is wrong and kind of weird to expect everyone to go by one definition because you decided so
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