Q&A: Is Intensity Or Volume More Important?

Question: I’ve received similar questions from several readers recently about the relative importance of different training factors for stimulating increases in muscular strength and size. Will increasing intensity or volume produce better results? What matters more, reps and sets or time under load? Does it matter how I distribute the volume of work?

Answer: While many of these factors contribute to the stimulation of muscular strength and size gains, intensity of effort is the most important by far. Your results from training have more to do with how hard you train than how much training  you do or any other factor.

If exercise volume really is the most important factor, as some trainers claim, we would see a significant difference in strength and size gains between groups performing single and multiple sets. However, this is not the case. The majority of research shows it makes little difference whether you perform one set or many. It does, however, show that your intensity of effort – how hard you are working relative to your ability – makes a difference. If you do not train with a high intensity of effort no amount of exercise will stimulate significant improvements in muscular strength and size. If you do train with a high intensity of effort the amount of exercise you perform must be limited to avoid overtraining. The higher your intensity of effort the less work you can perform, the less you need to perform.

If you want better results from exercise you must push yourself to work harder on each exercise, not do more exercise. As high intensity training pioneer and innovator Mike Mentzer once wrote, “Anything that you do to make your workout harder will be a step in the right direction.”

Mike Mentzer backstage at the 1980 Mr. Olympia competition

There is a practical minimum, however. For optimum muscular development it is necessary to perform at least enough exercises to effectively work all the major muscle groups. If any major muscle groups are neglected your physique will not be well proportioned (for example, the odd, top-heavy, chicken-legged physiques of people who invest significant effort in training their upper body while neglecting their legs). However, the volume of exercise performed during each workout should not be so high that you are unable to maintain a high intensity of effort throughout. Reducing your intensity of effort for the sake of performing more exercise will give you worse results, not better.

Intensity of effort is also more important than load and tension. As long as an exercise is performed to the point of momentary muscular failure within a reasonable amount of time it appears to make little difference what percentage of one’s one repetition maximum load is used, and if an exercise is not performed to momentary muscular failure it will fail to produce the same results even if a heavier weight is used.

Time under load is more important than reps and sets for muscular strength and size gains. Consider it is possible to increase muscular strength and size significantly with isometric contractions involving no movement, no mechanical work at all, provided you are contracting with a high enough intensity of effort for sufficient duration to recruit and fatigue all the motor units in the target muscles. It doesn’t matter how many times you make the weight go up and down, or whether it even moves at all.

In a nutshell, if you want to get as big and strong as your genetics allow, you do not need a high volume of exercise, but what little exercise you do needs to be done as hard as possible. As I explained elsewhere it probably makes little difference how this  volume is distributed, however since time under tension is more important than mechanical work and a slower speed of movement is safer you’re better off performing one longer set with fewer, slower repetitions or isometrically than multiple shorter sets with more repetitions at a faster pace.


Fisher J, Steele J, Bruce-Low S, Smith D. Evidence Based Resistance Training Recommendations. Medicine Sportiva Med Sport 01/2011; 15:147-162.

N.A. Burd, C.J. Mitchell, T.A. Churward-Venne, and S.M. Phillips. Bigger weights may not beget bigger muscles: evidence from acute muscle protein synthetic responses after resistance exercise. Appl. Physiol. Nutr. Metab. 37(3): 551-554, 2012.

Jürgen Giessing, , James Fisher, James Steele, Frank Rothe, Kristin Raubold, Björn Eichmann. The effects of low volume resistance training with and without advanced techniques in trained participants. Pre-print (this reference will be updated after this study goes into print)

Carpinelli RN, Otto RM, Winett RA. A Critical Analysis of the ACSM Position Stand on Resistance Training: Insufficient Evidence to Support Recommended Training Protocols. Journal of Exercise Physiology Online 2004;7(3):1-60

Smith D, Bruce-Low, S. Strength Training Methods and The Work of Arthur Jones. Journal of Exercise Physiology Online 2004;7(6): 52-68

Westcott WL, Winett RA, Anderson ES, Wojcik JR, Loud RL, Cleggett E, Glover S. Effects of regular and slow speed resistance training on muscle strength. Journal of Sports Medicine and Physical Fitness. 2001 Jun;41(2):154-8

Cameron J. Mitchell, Tyler A. Churchward-Venne, Daniel W. D. West, Nicholas A. Burd, Leigh Breen, Steven K. Baker, Stuart M. Phillips. Resistance exercise load does not determine training-mediated hypertrophic gains in young men. Journal of Applied PhysiologyJul 2012,113(1)71-77;DOI: 10.1152/japplphysiol.00307.2012

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