Short answer: Group muscles by how they move: push muscles together, pull muscles together and leg muscles together — or split upper and lower body. Avoid training the same muscles hard on consecutive days.

The standard groupings

Most workout splits use one of a few logical groupings. Each has a reason behind it, which makes it easier to remember and to schedule.

Why overlap matters

Many exercises train more than one muscle. Pressing uses the triceps and front delts, and rows use the biceps. If you train chest and then shoulders on the next day, your triceps and front delts are working both days.

That is why push days group chest, shoulders and triceps: the overlap happens inside one session instead of across several.

Antagonist pairs

Some plans pair opposing muscles — chest with back, biceps with triceps — and alternate sets between them. This can save time because one muscle rests while the other works. The Arnold split is built this way.

Where do abs, calves and forearms go?

Smaller muscles fit wherever there is time and recovery. Core and calves are commonly added to leg or lower-body days, and forearms get plenty of work from pulling. Place them where they do not interfere with the main lifts.

Example arrangements by number of days

Two to three days: full body each session. Four days: upper/lower. Five days: push, pull, legs plus upper and lower, or one muscle per day. Six days: push, pull, legs twice.

How to avoid conflicts

Leave at least a day between hard sessions for the same muscle, avoid stacking heavy squats and heavy deadlifts back to back, and put the muscle you care most about early in the week when you are fresh.

FAQ

Can I train chest and back together?

Yes — they are antagonists, and many lifters train them together (as in the Arnold split). Sessions can be long, so keep exercise selection tight.

Should biceps go with back or with arms?

Either works. Biceps are involved in pulling, so many splits put them on pull day.

How often should I train each muscle?

Around twice a week is a practical default.

Keep going

General guidance, not personal coaching or medical advice.