The formula
effective volume = weekly sets per muscle group
Where it comes from
Training volume is counted in effective sets per muscle group per week, not in hours or in kilos moved: it is the variable that best predicts hypertrophy in the literature. Ten weekly sets is the minimum that shows anything, twenty is where most people stop gaining from adding more, and past that recovery becomes the limiting factor. Tonnage — sets times reps times weight — is useful for tracking progress on one exercise, but it does not compare groups against each other.
How to work it out by hand
- Count the weekly sets for each group, adding up every exercise
- Compare each group against the ten-to-twenty range
- Divide by the sessions to see how many land in each workout
- Look at the ratio between the most and least trained group
What is worth knowing
Careful not to double count: a bench press works the chest but also the triceps and shoulders, and a row works the back and the biceps. The usual convention is to count a full set for the main group and half for the assisting ones. The imbalance between the most and least trained group is what deserves the most attention: above a factor of three there is usually a symmetry problem that eventually shows, almost always between what you see in the mirror and what you do not.