The body-part split: does one muscle a day still work?

The body-part split gives each muscle group its own day: chest Monday, back Tuesday, legs Wednesday, shoulders Thursday, arms Friday. It's how many bodybuilders have trained for decades, and it still fills gyms on a Monday. So does it work?

What the research says

When the weekly sets are the same, training a muscle twice a week tends to build a little more muscle than once a week, and spreading sets out makes each session shorter and fresher. The difference is modest, though. A body-part split with enough hard sets still builds muscle; it's just not the most efficient way to spend five days.

The pros

• Lots of variety for one muscle. You can fit several angles and exercises into one session.
• Long recovery for each muscle. A full week between hard sessions.
• Simple to plan. Each day has one job.

The cons

• Missing a day costs a whole muscle for a week.
• Very high sets in one session. After about 6 to 8 hard sets for one muscle, each extra set does less.
• Overlap you might not expect. Chest day works the front of the shoulders and triceps, so shoulder and arm days pile on top.

How to make it work better

1. Cap each muscle at about 8 to 10 hard sets per session.
2. Pair muscles so each gets two days: for example chest and back, then legs, then shoulders and arms, repeated.
3. Put legs away from back day so the lower back gets a break between deadlifts and squats.
4. Count indirect work. Rows train biceps; presses train triceps.

• Barbell bench pressChest
• Incline barbell pressChest, Front delts
• Cable flyChest
• Barbell rowUpper back, Lats
• Lat pulldownLats
• Dumbbell lateral raiseSide delts

Who it suits

People who enjoy long sessions on one area, have five or more days, and rarely miss one. If your week is unpredictable, a full-body or upper/lower plan is more forgiving. Still unsure? See how to choose a workout split.