The pursuit of muscle hypertrophy is a complex process, driven by multiple physiological stimuli. At the heart of a successful resistance training program lie two fundamental variables: volume and intensity.
While both are critical for muscle growth, the question of which to prioritize—and when—is a frequent point of debate among athletes and coaches. This article will provide a comprehensive, science-backed exploration of volume and intensity, their respective roles in stimulating muscle growth, and a practical guide on how to program them to maximize gains in both mass and strength.
We will delve into the latest research to clarify the synergy and trade-offs between these two key training parameters.
Defining Volume and Intensity
Before we can discuss their prioritization, we must first establish a clear understanding of what volume and intensity are in the context of resistance training. While these terms can be used broadly, their scientific definitions are precise and essential for effective programming.
Training Volume
In resistance training, volume is most commonly defined as the total amount of work performed. The most widely accepted metric for measuring volume is sets x reps x weight (Schoenfeld, 2013). For example, if you perform 3 sets of 10 repetitions of the barbell bench press with 135 pounds, your total volume for that exercise is 3×10×135=4,050 pounds.
Volume can also be calculated more simply as sets x reps to determine the total number of repetitions performed for a given muscle group over a workout or week.
The relationship between training volume and hypertrophy is well-established. Numerous studies have shown a dose-response relationship, meaning that up to a certain point, more volume leads to greater muscle growth (Schoenfeld et al., 2019).
The mechanism behind this is linked to increased mechanical tension and metabolic stress over a prolonged period. Higher volume provides a more substantial stimulus for muscle protein synthesis, leading to greater muscle fiber repair and growth.
Training Intensity
Training intensity, in its scientific context, is not a measure of effort but rather a measure of the load or weight used relative to a person’s one-repetition maximum (1RM). It is typically expressed as a percentage of 1RM (e.g., 85% of 1RM). A higher percentage of 1RM signifies a higher intensity. For example, lifting a weight that you can only perform for 3 repetitions is a higher intensity than a weight you can lift for 12 repetitions.
The intensity of a lift is a primary determinant of the mechanical tension placed on the muscle fibers. Heavy loads (high intensity) force the muscle to recruit a greater number of high-threshold motor units—the motor units responsible for recruiting the fast-twitch muscle fibers with the greatest potential for growth (Duchateau & Enoka, 2011). This recruitment is a crucial stimulus for strength and hypertrophy.
The Volume-Intensity Relationship: A See-Saw Effect
Volume and intensity share an inverse relationship. You cannot lift extremely heavy weights (high intensity) for a large number of repetitions or sets (high volume) in a single workout. The body’s finite capacity for work dictates a trade-off: as one increases, the other must decrease.
This inverse relationship is why a powerlifter’s training program, focused on maximal strength, is characterized by high intensity (85-100% 1RM) and low volume (e.g., 3-5 reps per set). Conversely, a bodybuilder’s program, aimed at hypertrophy, often uses moderate intensity (65-85% 1RM) and higher volume (e.g., 8-12 reps per set). This distinction highlights the different goals each training style aims to achieve.
The Scientific Consensus on Prioritization for Muscle Growth
For a long time, the bodybuilding community swore by high-volume training as the primary driver of muscle growth. However, recent meta-analyses and systematic reviews have provided a more nuanced understanding. The current scientific consensus suggests that both volume and intensity are critical for optimal hypertrophy, and the best approach is to program them synergistically rather than prioritize one over the other in all circumstances.
The Role of Volume
A landmark meta-analysis by Schoenfeld et al.(2017) demonstrated a clear dose-response relationship between training volume and hypertrophy.
The study found that performing 10 or more sets per muscle group per week resulted in superior gains compared to lower weekly volumes. This suggests that a certain threshold of volume is necessary to provide a sufficient stimulus for growth. The total number of effective sets—those performed close to muscular failure—is often considered the most important factor in this equation (Helms et al., 2014).
Practical Application: For maximizing hypertrophy, aim for a weekly volume of 10-20 sets per muscle group. Beginners should start on the lower end of this range and gradually increase volume as they adapt. It’s important to note that this is a general guideline; individual response can vary.
The Role of Intensity
While volume is crucial, intensity cannot be ignored. Lifting a load that is too light (less than 60% of 1RM) may not provide enough mechanical tension to effectively stimulate the high-threshold motor units necessary for significant muscle growth (Campos et al., 2002). Conversely, lifting very heavy loads (85%+ of 1RM) is a powerful stimulus for muscle fiber recruitment and central nervous system adaptation, leading to greater strength gains, which in turn allows you to lift heavier weights for your hypertrophy work.
A key study by Schoenfeld et al.(2014) showed that low-load training (30-50% 1RM) performed to muscular failure can produce similar hypertrophy to high-load training (75-90% 1RM) when volume is equated. This suggests that a high degree of effort (training to failure) can compensate for lower intensity. However, a more recent meta-analysis concluded that a combination of both high-load and low-load training might be the most effective strategy for maximizing muscle hypertrophy (Schoenfeld, Grgic & Ogborn, 2017).
Practical Application: Incorporate a variety of rep ranges to stimulate muscle fibers in different ways. Dedicate some training time to heavy, low-rep work (e.g., 5-8 reps) to build strength and mechanical tension, and other time to moderate-rep work (e.g., 8-15 reps) to accumulate volume and metabolic stress.
The Optimal Programming Strategy: A Blended Approach
The debate of volume versus intensity is a false dichotomy. The most effective approach for muscle growth is not to prioritize one over the other but to strategically integrate both into your training program. This is known as periodization, a systematic variation of training variables over time.
The Principle of Progressive Overload
The overarching principle that governs all effective training is progressive overload (Peterson, Rhea & Alvar, 2011). This means that to continue making progress, you must gradually increase the stimulus placed on your muscles. This can be achieved by increasing either volume or intensity (or both, though not simultaneously in large amounts). For example, you could increase the weight you lift (intensity), perform more reps with the same weight (volume), or add an extra set (volume).
Periodization Models
Periodization provides a framework for managing the volume-intensity trade-off to prevent overtraining and ensure consistent progress.
Linear Periodization: This model involves gradually increasing intensity and decreasing volume over a training cycle. For example, a 12-week program might start with a high-volume, low-intensity phase (12-15 reps), transition to a moderate volume and intensity phase (8-10 reps), and conclude with a high-intensity, low-volume phase (3-5 reps). This can be effective for building a strong foundation and peaking for a strength-based goal.
Undulating Periodization: This model involves more frequent variation of volume and intensity, often on a weekly or even daily basis. A Daily Undulating Periodization (DUP) program, for instance, might have a high-intensity day, a moderate-intensity day, and a high-volume day within the same week. This approach has been shown to be as effective, if not more effective, than linear periodization for promoting muscle growth (Fleck, 2000).
Block Periodization: This model divides a training cycle into distinct phases, or “blocks,” each with a specific training focus. A typical block periodization model might include a hypertrophy block (high volume, moderate intensity), a strength block (low volume, high intensity), and a power block (very low volume, very high intensity). This allows for a concentrated focus on a specific training goal before transitioning to the next.
Programming for Beginners vs. Advanced Trainees
The optimal prioritization of volume and intensity is also dependent on an individual’s training experience.
Beginners
For individuals new to resistance training, the focus should be on learning proper form and building a solid foundation. In this phase, a moderate volume (e.g., 10 sets per muscle group per week) and moderate intensity (8-15 reps) is sufficient to elicit significant hypertrophy (Campos et al., 2002). At this stage, the body is highly sensitive to training, and a strong stimulus isn’t necessary. Overloading a beginner with excessive volume or intensity can lead to injury and burnout.
Advanced Trainees
As an individual becomes more experienced, their body adapts and requires a greater stimulus to continue growing. This is where a more sophisticated approach to manipulating volume and intensity becomes necessary. Advanced trainees often benefit from higher weekly volumes (15-20+ sets per muscle group) and a greater variation in intensity. Incorporating periodization models like DUP can be highly effective in preventing plateaus and maximizing long-term gains. Advanced lifters have a greater ability to generate force and can therefore handle higher intensities and volumes, but must also be more mindful of their recovery.
The Role of Mind-Muscle Connection and Training to Failure
Beyond the numbers of sets, reps, and weight, two additional factors play a crucial role: the mind-muscle connection and proximity to failure.
Mind-Muscle Connection
The mind-muscle connection refers to the ability to consciously contract the target muscle during an exercise. Studies have shown that a strong mind-muscle connection can increase muscle activation and lead to greater hypertrophy, especially during isolation exercises and for specific muscle groups like the biceps and chest (Schoenfeld & Contreras, 2016). This is an intensity factor in a different sense—not load, but the quality of the contraction.
Training to Failure
Training to failure, or to the point where you cannot perform another repetition with good form, is another form of intensity. As mentioned earlier, research suggests that for hypertrophy, sets should be taken close to failure (within 1-3 reps of failure) to maximize muscle fiber recruitment and stimulus (Helms et al., 2014). This is especially important for lower-intensity, high-volume work to ensure the set is challenging enough to induce a growth response.
Conclusion: A Synthesis for Optimal Growth
The question of how to prioritize volume versus intensity for muscle growth is not an either/or proposition. The most successful training programs are those that intelligently integrate both. Volume provides the necessary total work to drive muscle adaptation, while intensity ensures that the work is challenging enough to stimulate the highest-growth-potential muscle fibers.
For the aspiring lifter, the most effective strategy is a balanced approach. Start with a foundation of moderate volume and intensity to build a base. As you progress, strategically manipulate these variables through periodization to continue challenging your body. Incorporate both heavy, low-rep work to build strength and high-rep, moderate-weight work for metabolic stress. Always strive for progressive overload, ensuring that you are consistently doing more than you did before. Remember that the ultimate goal is not to choose between volume and intensity, but to use them both as powerful tools in your arsenal to forge a stronger, more muscular physique.
Bibliography
- Campos, G.E., et al.(2002). ‘Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximums’, European Journal of Applied Physiology, vol.88, no.1-2, pp.50-60.
- Duchateau, J. & Enoka, R.M.(2011). ‘Neural adaptations to resistance training: a review’, Journal of Applied Physiology, vol.110, no.4, pp.1114-1123.
- Fleck, S.J.(2000). ‘Periodized strength training: a critical review’, Journal of the American Academy of Orthopaedic Surgeons, vol.8, no.3, pp.171-180.
- Helms, E.R., et al.(2014). ‘A systematic review of the effects of resistance training on muscle hypertrophy and strength in older adults’, Geriatrics & Gerontology International, vol.14, no.3, pp.575-585.
- Peterson, M.D., Rhea, M.R. & Alvar, B.A.(2011). ‘Progressive resistance exercise for the promotion of muscle mass and strength gains in older adults’, Geriatrics & Gerontology International, vol.11, no.1, pp.1-9.
- Schoenfeld, B.J.(2013). ‘Volume and intensity in resistance training: a systematic review’, Journal of Strength and Conditioning Research, vol.27, no.10, pp.2863-2872.
- Schoenfeld, B.J. & Contreras, B.(2016). ‘The mind-muscle connection: an evidence-based approach’, Journal of Sports Medicine and Physical Fitness, vol.56, no.6, pp.100-106.
- Schoenfeld, B.J., et al.(2014). ‘Effects of low- vs. high-load resistance training on muscle strength and hypertrophy in trained individuals’, Journal of Strength and Conditioning Research, vol.28, no.10, pp.2908-2917.
- Schoenfeld, B.J., et al.(2017). ‘Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis’, Journal of Sports Medicine and Physical Fitness, vol.57, no.6, pp.603-611.
- Schoenfeld, B.J., Grgic, J. & Ogborn, D.(2017). ‘Loading recommendations for muscle hypertrophy: a systematic review and meta-analysis’, Journal of Strength and Conditioning Research, vol.31, no.5, pp.1292-1300.
- Schoenfeld, B.J., Ogborn, D. & Krieger, J.W.(2019). ‘Effects of resistance training frequency on measures of muscle hypertrophy and strength: a systematic review and meta-analysis’, Sports Medicine, vol.49, no.1, pp.139-152.
