"How many sets should I do?" is usually the wrong question, because a set of leg extensions and a set of squats are not interchangeable units. The question that actually predicts whether a muscle group is getting enough training stimulus is narrower: how many hard sets is that specific muscle getting, added up across every exercise that hits it, over a full week. Get that number and you can actually compare weeks to each other. Skip it and "I trained legs twice this week" tells you almost nothing.

Why the week is the right window

A single session is too small a window to judge volume by. One heavy squat day says nothing about whether your quads are undertrained or overtrained, because the same muscle might show up again on a leg press day, a lunge-focused day, or as a secondary mover on a running-heavy week. Volume is a weekly accounting problem, not a per-session one: add up every set that trains a muscle across every day you trained it, then look at that weekly total instead of any one workout in isolation.

This is also why "sets per week" beats "workouts per week" as a volume metric. Two people who both "hit legs twice" can have completely different weekly set totals depending on how many exercises and sets landed in each of those sessions. The session count is a scheduling detail. The set count is the training stimulus.

Rough landmarks, held loosely

Most lifting programs and coaches land somewhere in the range of ten to twenty hard sets per muscle group per week for a trained lifter chasing hypertrophy, with beginners often seeing results from the lower end of that range and more experienced lifters needing to push toward the upper end to keep progressing. Above that range, more sets tend to produce smaller returns for a given muscle, and at some point added volume just adds fatigue and recovery cost without adding much stimulus.

Treat that range as a starting point, not a target to hit exactly. It moves with how many other muscles are competing for the same recovery budget that week, how close to failure each set is taken, how experienced the lifter is, and how well the person actually recovers between sessions. A useful number for programming purposes is still a wide range, and the honest use of it is as a sanity check: if a muscle group is sitting at two or three sets a week for months and progress has stalled, volume is a reasonable first thing to look at. If it is already north of twenty sets and joints are cranky, that is worth a look too.

Why counting by hand goes wrong

The obvious way to count is to add up sets on "leg day" or "push day." That undercounts almost every muscle group that is not the headline exercise of the day, because most compound lifts train more than one muscle at once. A set of barbell squats is a quad set, but it is also training glutes and, to a smaller degree, the muscles stabilizing the lower back. A pulling day's rows train the back but also load the biceps as a secondary mover. None of that shows up if you only count sets under the exercise you think of as the "target."

The other common miss is training volume that happens outside the labeled strength days. Interval running sessions and long runs load the same lower-body muscles a squat or lunge session does, just through a different pattern. If those sessions are not part of the weekly count, the total looks lower than what the muscle is actually absorbing, which matters most for anyone mixing lifting and running in the same week.

How Zirv reads it from your log

This is the part a spreadsheet does badly and an app that already has the data can do for free. Zirv's volume analysis, a Pro analytics feature, pulls your completed sets for the current week and groups them by muscle group using the same muscle tags attached to each exercise in the library, the same tags a compound lift like a squat or a row carries for every muscle it trains, not just the one you'd call the "main" one. A completed set counts fully toward every muscle group tagged on that exercise, so a squat set adds to your quad total and your glute total in the same week, instead of being split between them or credited to only one. Next to the weekly muscle group breakdown, it also compares this week's volume for each exercise against the previous week and flags whether it is trending up, holding flat, or dropping, so the direction is visible without pulling up a spreadsheet.

What it will not do is tell you the "right" number for your body. It reports what actually happened, at the exercise-tagging granularity the library already tracks, and leaves the interpretation to you, which is the same honest limitation the landmarks above have. A number that looks low next to a general range might be exactly right for a muscle group that is also getting real work from your running volume that week.

Reading the trend, not the single week

One week's total is noisy the same way a single body-weight reading is noisy. A missed session, a deload week, or a plan that happened to lean heavier on isolation work one week can all move the number without meaning anything changed about how you are actually training. What is worth paying attention to is the shape of the trend across several weeks: a muscle group that has been quietly sitting at the bottom of your weekly totals for two months is a real signal, and so is a number that has been climbing every week for a month straight with no deload in sight. Both of those only show up once you are looking at weeks, not workouts.

Volume is also only one input to whether training is working. It has to sit next to whether the numbers on the bar are actually moving, because progressive overload is still the thing that has to happen for a muscle to keep adapting. A muscle group can be sitting inside a reasonable weekly set range and still stall out if the weight or reps on those sets have not moved in a month. Volume tells you how much work happened. It does not by itself tell you whether that work was hard enough to matter.

The takeaway

Count sets per muscle group per week, not per session, because that is the window training volume actually operates on. Ten to twenty sets a week is a reasonable starting range for a trained lifter, held loosely and adjusted to how you actually recover. Counting by hand tends to undercount secondary movers and non-lifting training, which is exactly what a log built around exercise-to-muscle tagging can do for you instead. Read it as a multi-week trend, next to whether your actual working weights are progressing, not as a single number to hit and forget.