Split or Full-Body Training for Lean Muscle?

Do you know what is better for building lean muscle: split routines or full-body training?

In the beginning, in the early days of bodybuilding, athletes routinely trained using full-body routines. The idea was that regular stimulation of muscles throughout the week was the best strategy to increase lean muscle without overtraining.

However, by the 1960s, training philosophies started to change. Full-body routines gave way to training splits, where you work a muscle using multiple sets and exercises, and then allow the muscle to recover for a certain period of time before it’s directly trained again.

woman weight training

Higher training volume per muscle group

The idea of a split routine training is that it lets you to increase your total weekly training volume per muscle group, while also giving the muscles more time for recovery and growth. Besides, working a muscle with a high-training volume in a given session increases intramuscular metabolic stress, which in turn is said to improve the hypertrophic response. The combo of these factors is believed to ultimately result in greater long-term muscular gains.

Even though a case can be made for using either split- or full-body training session to build lean muscle, an evidence-based opinion can only be given by first evaluating the results of controlled research. Given that training frequency is one of the most important training factors, you would probably think there would be thousands of studies carried out on the topic, right? Well, this isn’t the case.

Until some time ago, only one study compared the muscle-building effects of training muscles one day in comparison to three days a week. Participants either executed three sets per exercise in a single weekly session, or one set per exercise spread out over three sessions a week over twelve weeks. When the study was at its completion, results showed greater increases in lean body mass among participants who had trained three times a week, meaning it’s more effective to train muscles more frequently.

The study is intriguing, but there are some inherent limitations that hinder the ability to reach practical conclusions. Firstly, participants performed only three sets per muscle group a week—far less than the majority of serious fitness enthusiasts usually include in their training programs. Secondly, muscle mass was measured by the skin-fold method, which lacks precision in identifying true changes in hypertrophy over time. The applicability of the study to serious lifters wanting to maximize muscle building is therefore limited.

barbell workout

Split training vs full-body training

To examine the topic in detail, recently a controlled study was carried out which compared muscular adaptations in a classic split in comparison to a full-body routine in trained lifters. Both programs consisted of 21 different exercises that engaged the major muscle groups using multi-set routines. Those in the split routine performed chest and back on day one, lower body on day two and shoulders and arms on day three. And the full-body routine comprised one exercise for all the major muscle groups during each session. Training was carried out three days a week for two months. Total volume was equated between routines in order that any differences in muscle development could be attributed directly to the consequences of training frequency. Changes in muscle size were assessed by ultrasound to provide direct hypertrophic measurements. All participants had more than four years of lifting experience, which excluded any issues from the beginner effect. The results were fascinating.

The surprising results challenge today’s training practices. The participants performing the full-body routine experienced considerably greater increases in biceps growth compared to split-body training (6.5% vs 4.4%, respectively). Although differences in the other muscles examined were not statistically different, the increases favored the full-body routine for both the triceps (8.0 vs 5.0%, respectively) and the quads (6.7 vs 2.1%, respectively).

What is more, determination of effect size—a statistical gauge of the meaningfulness of results—showed a clear advantage for the full-body program in all of the muscles measured. These results suggest a greater benefit to training a muscle more often throughout a week.

doing crunches

Should we ditch the split?

There’s a logical basis to training muscles more often each week. This is consistent with the fact that muscle growth is regulated by the dynamic balance between muscle protein synthesis (MPS) and protein breakdown. In other words, when MPS is greater than breakdown, there’s a net accumulation of skeletal muscle mass; the more you can maintain high levels of MPS over time, the greater your gains.

Studies suggest that the time course of muscle protein synthesis (MPS) takes about 48 hours or so after a lifting session. For this reason, one can conclude that training a muscle every few days would keep MPS consistently elevated, and therefore have a positive effect on muscular development.

However, before you ditch the split, it’s important to consider a few things. Firstly, split training is great because of the novelty factor. Prior to the study, interviews with the participants about their training history were done. During these interviews, 16 of the 19 participants reported regularly following a split-training program, with each muscle group trained once a week. Research suggests that just by changing program variables so that a new stimulus is provided can improve muscular adaptations. This increases the possibility that those in the full-body training group benefited from the new stimulus of training muscles with a higher weekly frequency.

weight lifting

Train muscles more often to maximize growth

What may be more important is that the study should be taken in the context that training volume was equated between groups.

The main benefit of split training is that it allows you to pack more volume into workouts throughout a week. Assuming 48 hours is afforded between training a specific muscle group—a generally accepted tenet—then you’re limited to three weekly sessions of full-body training. On the other hand, splitting the routine allows you to increase the frequency of sessions a week, and therefore allows you to achieve more volume per muscle, per session. Given that higher training volumes are strongly connected to greater lean muscle growth, the potential value of training splits shouldn’t discounted.


Research proves a benefit to training muscles more often over the course of a week. Even though evidence is somewhat limited, it appears that working a given muscle at least twice a week is beneficial to maximize lean muscle growth.

This can be achieved with an upper body/lower body split performed four times a week (for example, two days on / one day off, two days on / two days off) or a three-way split (for example, push/pull/legs) carried out six times a week (for example, three days on / one day off).

It’s also possible that periodizing exercise frequencies could provide a means to maintain the novelty of the training stimulus. Accordingly, think about integrating full-body exercise routines into your plan over the course of a training cycle to improve the hypertrophic response.

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Written by Sarah Johnson

Sarah Johnson is a woman who lives and breathes fitness and healthy lifestyle. She is a regular visitor to the gym and has gained wealth of experience in toning and strengthening the body. In the evenings she likes to read a good detective novel.


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