A workout split is how you divide your training days across the week: which muscles or movements get trained in which session. Full body hits everything each workout. Upper/lower alternates between the two halves. Push pull legs rotates through three movement patterns. The name matters less than the outcome it produces, which is how often each muscle gets trained per week.
Why it matters
People argue about splits like they argue about sports teams. And honestly, most of that arguing is wasted energy. The research keeps pointing at the same variables: weekly volume per muscle, and training each muscle at least twice a week. A split is just a container for those numbers. A good one fits your schedule so consistently that you never skip, spreads volume so no session turns into a two-hour slog, and gives each muscle enough rest between visits.
How to use it in training
Start with your real schedule, not your ideal one. Training 2 or 3 days a week? Full body wins, no contest. Every muscle gets hit every session, so frequency stays high even with few gym days. Four days? Upper/lower is the classic choice, and it's hard to beat. Five or six days? Now push pull legs or a body-part hybrid makes sense.
One warning. The old-school "chest day, arm day" bro split trains each muscle once a week, and that's leaving gains on the table for most people. If a muscle only gets touched every 7 days, consider redistributing.
Related terms
Go deeper
Want the studies on how often each muscle should be trained? Read our full breakdown: Training frequency research.