Building muscle: where to start

Is a full-body workout or a split better?

By GyroscopeUpdated November 15, 20267 sources

Neither wins once the weekly sets are the same, so pick the one that fits your week. Two or three days a week, train your whole body each time. Four days, split it into upper and lower body, twice each. Five or six days, a body-part split works if every muscle still gets enough hard sets. For most people, two or three full-body days is the best place to start.

Bodybuilding magazines made the split famous. You did chest on Monday, back on Tuesday, legs on Wednesday and arms on Friday, and each muscle got hammered once a week. Then the internet swung the other way, and full-body training became the smart choice because each muscle gets trained more often. People still argue about it in every gym. When researchers matched the total work, both came out about the same.

The head-to-head trial

One of the cleanest tests is a 2022 trial in Norway. Researchers took 50 young women, about 22 years old, who had never lifted, and paired them up by strength. Half trained their whole body twice a week. The other half did four sessions a week, two for the upper body and two for the lower body. Both groups did the same ten exercises and the same number of sets, 3 of each, starting with a weight they could lift 12 times and working down to 8 over 12 weeks.

At the end, the full-body group’s leg press was up 29% and the split group’s 28%. Their bench press rose 26% and 30%, and their muscle mass 1.9% and 1.7%. The researchers found no real difference between the groups on anything they measured. Muscle was estimated with a body composition scale, which is a rough tool, and the women were young beginners, so the result fits people starting out best.

A 2024 analysis pooled 14 studies with 392 people that compared split and full-body routines. Strength on the bench press and on leg lifts rose about the same, and so did muscle size in the arms, the thighs and lean mass overall. The authors concluded that people can pick a routine based on their personal preferences.

What trained lifters found

Two small trials in experienced men pointed in opposite directions. In 2015, 20 trained men did either a split that hit each muscle once a week or full-body sessions three times a week. The full-body group grew more muscle at the front of the upper arm, with no difference in strength. In 2021, 21 trained men did 10 weeks of either routine, and this time the split group grew more thigh muscle, while the full-body group did better on one of the bench press tests. Small trials like these bounce around, which is why the pooled analysis of 14 studies is the better guide.

The weekly total does the work

A 2018 analysis of 22 studies found people who trained more days a week got stronger, but when the total weekly sets were matched, the number of days made no difference. The 2026 position stand from the American College of Sports Medicine (ACSM) found the same for size. Muscle grew the same whether people trained once a week or more than five days a week, as long as the total volume was matched. Strength did better with 2 or more sessions a week.

Weekly sets work like reading a book. Read 50 pages on Saturday and Sunday, or 15 pages every night, and you finish the book in the same week. The one catch is that 50 pages in one sitting gets hard to focus on, and so does the twelfth set for one muscle in one session. A 2020 analysis of 111 studies found that more sets packed into a single workout went with a little less growth.

Pick by your week

A body-part split can still give each muscle 10 or more hard sets a week. It packs them into one or two long sessions per muscle, so watch how many you stack on a single day. The program lays out the 2, 3 and 4 day versions with every exercise.