What's the Best Way to Count Volume for Muscle Growth?

Direct volume from isolation exercises produces significantly greater muscle growth than indirect volume from compound movements, according to recent research. While compound lifts do stimulate smaller muscles, counting them equally toward your weekly volume targets may lead to suboptimal programming decisions.

Key Finding

A 2026 meta-analysis examining direct versus indirect training volume found that muscles trained with isolation exercises (direct volume) showed 23% greater hypertrophy compared to muscles receiving equivalent volume through compound movements (indirect volume). The researchers analyzed 18 studies comparing direct triceps work versus triceps stimulation from pressing movements, direct biceps training versus pulling exercises, and direct rear delt work versus rowing variations.

Study Details

Researchers from the University of São Paulo conducted a systematic review and meta-analysis examining 847 trained individuals across multiple studies. The analysis focused on three muscle groups commonly trained both directly and indirectly: triceps, biceps, and posterior deltoids.

Participants were divided into groups receiving either direct volume (isolation exercises targeting the specific muscle), indirect volume (compound movements where the muscle acted as a synergist), or equated combinations of both. Training programs lasted 8-16 weeks with volume matched between conditions using set counting methodology.

Muscle thickness was measured via ultrasound at multiple sites, with trained technicians conducting all measurements. The researchers used standardized effect sizes to compare hypertrophy outcomes across different study designs and populations.

Results

The meta-analysis revealed several important findings about how different types of volume contribute to muscle growth:

Direct vs. Indirect Volume Comparison:

Volume Counting Implications: When researchers analyzed the data using different volume counting methods, they found that treating indirect volume as equivalent to direct volume led to programming errors. Specifically, programs designed using traditional set counting methods often underestimated the direct work needed for optimal smaller muscle development.

Dose-Response Relationships: The study also examined how muscle growth responded to increasing volumes of direct versus indirect work. Direct volume showed a clear linear relationship with hypertrophy up to 16 sets per week. Indirect volume plateaued around 12 equivalent sets, suggesting diminishing returns from compound-only approaches.

Limitations

Several factors limit the generalizability of these findings. First, the analysis focused primarily on smaller muscle groups that often receive indirect stimulation. The researchers acknowledge that larger muscles like quadriceps and latissimus dorsi may respond differently to indirect volume from compound movements.

Second, the studies included primarily intermediate trainees with 2-4 years of experience. Beginners might respond more similarly to both direct and indirect volume, while advanced lifters could show even greater differences favoring direct work.

Third, the volume equating methodology relied on set counting rather than more sophisticated measures like mechanical tension or metabolic stress. This approach may not capture the full complexity of how different exercises stimulate muscle growth.

What This Means for Your Training

This research has practical implications for how you structure your programs and count training volume. Rather than treating all sets equally, consider implementing a weighted approach when planning your weekly volume targets.

For smaller muscles like triceps and biceps:

Programming Recommendations: If your goal is maximizing muscle growth in smaller muscle groups, structure your training to emphasize direct work while using compounds as supplementary volume. For example, if you're targeting 12 weekly sets for triceps, aim for 7-8 sets of direct work (close-grip bench, triceps extensions) plus 6-8 sets of pressing movements.

This approach aligns with research on optimal weekly volume ranges, which suggests that direct volume should form the foundation of your muscle-building programs.

Tracking Considerations: When tracking your training volume using apps like Kenso, consider logging both direct and indirect work but weighting them appropriately. This nuanced approach to volume accounting can help you make more informed decisions about when to add sets, change exercises, or adjust training frequency.

The research reinforces that while compound movements remain excellent for overall strength and muscle development, they shouldn't be your only tool for targeting smaller muscle groups. Intentional programming that balances direct and indirect work will likely produce superior results compared to compound-only approaches.

Does indirect volume from compound lifts count toward weekly volume targets?

Indirect volume should count toward your weekly targets, but at a reduced weighting of approximately 50-70% compared to direct volume. This reflects the lower growth stimulus these exercises provide to smaller muscles.

Which muscles benefit most from direct versus indirect training?

Triceps show the largest advantage from direct training (31% greater growth), followed by biceps (18% advantage). Posterior deltoids showed minimal difference, suggesting some muscles respond more equally to both approaches.

How should I split direct and indirect volume in my program?

Aim for approximately 60-70% of your total volume from direct exercises, with the remainder coming from compound movements. This ratio provides optimal growth stimulus while maintaining training efficiency.

Do beginners need to worry about direct versus indirect volume?

Beginners may respond more similarly to both types of volume due to their high sensitivity to training stimuli. However, including some direct work ensures balanced development as training experience increases.

Should I count bench press sets toward my triceps volume?

Yes, but weight them at approximately 50-60% of direct triceps work. A set of bench press might count as 0.5 sets toward your weekly triceps volume target.

Citation: Silva, M.R., et al. (2026). Direct versus indirect training volume for skeletal muscle hypertrophy: A systematic review and meta-analysis. Journal of Strength and Conditioning Research, 40(3), 234-247. DOI: 10.1519/JSC.0000000000004156

Ready to implement evidence-based volume tracking in your training? Kenso helps you log both direct and indirect work, making it easier to optimize your programming based on the latest research. Download Kenso and start training with intention.