Recent research has identified a dose-response relationship between training volume and hypertrophy (muscle gains). Unfortunately, most people make the mistake of adding junk volume. As the name implies, junk volume is training volume with little to no benefit and is just a waste of time and effort. All it does is eat into your ability to recover and grow.
A meta-analysis by Wernbom and colleagues found that there was an upper limit to muscle growth stimulated per workout. This finding was consistent with both low and high-frequency training.
It turns out that regardless of how hard you train within a session, there's only so much muscle you can build as a consequence of that workout. Trashing a muscle simply doesn't cause more growth. As bodybuilder Lee Haney once said, "Stimulate, don't annihilate."
Current research indicates that anything between 3-10 sets per body part, per session, is sufficient to maximize muscle protein synthesis (MPS). Now, this is a broad range, but it's impossible to establish an exact number as the difference between one person and another is just too great.
This is why research should act as a compass to guide your training, rather than as a map with an exact route to your destination. But we can determine some approximate upper limits based on the available data. It seems that most people benefit from up to a maximum of 10 sets per body part, per workout. As far as hypertrophy goes, diminishing returns will occur after this point.
To add volume, most folks just maintain their existing training split and add sets to each training session, i.e., junk volume.
A much more effective approach would be to increase your training frequency for each muscle. Instead of training it once a week with 18 sets (which is way too much for one workout), do three workouts of 6 sets. In fact, you could probably tolerate three sessions of 8 sets.
This significantly increases your weekly training volume (24 sets vs. 18 sets) while more evenly distributing your training. You end up maximizing muscle protein synthesis three times a week rather than once. More muscle-building workouts each week adds up to more gains.
Think of it this way: With a once a week frequency, a muscle has 52 growth opportunities per year. With a three times a week strategy, you get 156 muscle-building stimuli per year. Which do think will cause more growth?
- Train each muscle group 3 times per week.
- Use 1-2 exercises (2 for bigger muscles) per session, per muscle group.
- Perform 40-70 total reps per muscle group per session.
- Achieve this rep range across 6-10 sets.
- Follow a push/pull split.
- Hackett DA et al. Training practices and ergogenic aids used by male bodybuilders. J Strength Cond Res. 2013 Jun;27(6):1609-17. PubMed.
- Kumar V et al. Muscle protein syntheticr esponses to exercise: effects of age, volume, and intensity. J Gerontol A Biol Sci Med Sci. 2012 Nov;67(11):1170-7. PubMed.
- Schoenfeld BJ et al. Effects of resistance training frequency on measures of muscle hypertrophy: a systematic review and meta-analysis. Sports Med. 2016 Nov;46(11):1689-1697. PubMed.
- Schoenfeld BJ et al. Influence of resistance training frequency on muscular adaptations in well-trained men. J Strength Cond Res. 2015 Jul;29(7):1821-9. PubMed.
- Wernbom M et al. The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans. Sports Med. 2007;37(3):225-64. PubMed.