Bodybuilders customarily train with “split” routines. Split refers to dividing body parts into muscle groups to be trained on separate days. This is in contrast with full-body routines, which, as the name implies, dictate that all muscle groups be trained together during the same workout.
Split routines produce good gains in size and are used by nearly all competitive bodybuilders. They allow for adequate volume to be used as well as adequate recovery time to avoid overtraining.
Full-body routines allow greater frequency of training each muscle group for more growth stimulus. Volume can be adjusted to match the same total volume per week as with a split routine.
An eight-week study compared the effects of training muscle groups one day per week using a split-body routine versus three days using a total-body routine in well-trained men. The split routine hit two to three muscle groups performing two to three exercises with two to three sets per workout. The total-body routine hit all muscle groups with one exercise for two to three sets per workout. Both routines consisted of three weekly sessions done on nonconsecutive days for eight weeks. All subjects performed 18 sets total per session. Each set had eight to 12 reps with 90 seconds of rest between sets.
Subjects using the total-body routine experienced significantly greater muscle hypertrophy. Muscle protein remained elevated approximately 48 hours after workouts. Thus, training a muscle group every 48 hours would keep muscle protein synthesis elevated for longer.
When reps are higher, use a full-body routine. As weight loads increase and reps drop, move to a split routine to allow greater volume per muscle group and adequate time for strength to recover.