While many introductions start with sharing your name and where you’re from, for the average gym-goer, the most common icebreaker is, “What’s your split?”. “Split” simply refers to your workout routine, typically by which body parts are being worked out weekly. Some of the most common splits are Push-Pull-Legs (PPL) or an “Arnold Split.” Push means any muscles that “Push” things like the triceps, shoulders, and chest, and pull similarly any muscles that “pull” things like the biceps and back. While the Arnold Split involves working out opposing muscle groups together, it utilizes a chest and back day, a shoulders, triceps, and biceps day, and a leg day. Within these splits are a variety of exercises with several sets and repetitions. The question is: What combination of sets per week are enough to build muscle?
What about a PPL split, 12 repetitions for 4 sets for 8 exercises at moderate weight? Is this overtraining? What about an Arnold Split, 10 repetitions for 1 set for 6 exercises, 3 times a week with heavy weight? Is this under training? There is endless discussion and online debate about what to do and not to do. For many listeners, it can be hard to choose the most efficient workout routine to build muscle. Is it better to train a higher volume of sets with lighter weight or a lower volume but heavier weight?
How Does The Body Build Muscle?
When skeletal muscle is exposed to mechanical stress during exercise, microscopic damage and tension within the fibers trigger pathways that recruit nutrients and activate protein growth. This process repairs and reinforces the muscle, leading to an increase in fiber size, which is known as muscle hypertrophy. Research suggests that hypertrophy is best stimulated by mechanical loading under stretch, where muscles experience high tension while lengthened, as this maximizes fiber recruitment and repair of the muscle. As stated by Korakais et al. (2023) in a review, this is most likely to occur during training with a range of motion that puts the muscle in its most stretched position while also using a repetition tempo between 2 and 8 seconds.
What Combination of Sets is Just Right?
Perfecting each repetition, maximizing sleep, and maintaining a balanced diet all can contribute to muscle growth. However, the most effective factor to build muscle is the frequency of loading the muscle, and how often you do so. Better described as sets of exercises based on a percentage of your max strength. The debate is whether to train “High Volume” (12-20 sets per muscle group per week) at moderate weight (60% of max weight) or “Low Volume” (Less than 12 sets per muscle group per week) at high weight (85% – 90% of max weight). Studies like Vann et al. (2022) have shown that training until failure at a lower volume sets improves strength better than high volume sets. But training until failure at a higher volume of sets stimulates hypertrophy better than training until failure at a lower volume of sets. This is primarily because of neural adaptations rather than differences in muscle size. Jenkins et al. (2017) showed that heavy-load training (80% of max weight) increased voluntary activation and enhanced motor unit efficiency by creating more efficient neural pathways. Thus, the nervous system becomes better at activating muscle fibers, coordinating movement, and generating maximum force. In contrast, the high-volume training maximizes fatigue and total work, which expands muscle size rather than force output.
In an effort to settle this ongoing debate, as recommended by Baz-Valle et al. (2022) in a systematic review, a range of training, 12-20 sets per muscle group weekly to failure, may be an appropriate recommendation for increasing muscle hypertrophy.
