There is a lot of talk about hypertrophy training, but what it is and what the science says about it is unclear. In this article, we break down the different types of training, optimal rep-ranges for hypertrophy, when, and why to incorporate hypertrophy programming into your training.

Different Variation in the Types of Training:

  • Strength – *High resistance, near-maximal muscle contractions for a small number of repetitions with a full recovery in between each set.
  • Hypertrophy*Moderate loads and high volume with short to moderate resting periods that allow for the athlete to perform more repetitions than is typical of a strength training program, but heavy enough loads to elicit concentric or eccentric contraction failure (6-12 reps). Rest periods are short so that the muscles are not fully recovered before the next set begins. This contributes to the muscles ability to reach contraction failure. (reference book)

Hypertrophy is the result of individual muscle fibers experiencing mechanical loading and subsequently increasing in volume. Hypertrophy is the process of increasing the size of the cells/fibers that are already there.

For muscles to grow, two things have to happen:

  1. stimulation
    1. Dormant cells called satellite cells, become activated by trauma, damage or injury — all possible responses to the stress of weight training.
  2. repair
    1. An immune system response is triggered, leading to inflammation, the natural clean up and repair process that occurs on a cellular level.

Concurrently, a hormonal response is triggered, causing the release of hormones that help regulate cell activity such as, growth factors that help stimulate muscle hypertrophy, cortisol, and testosterone that increases protein synthesis.

Furthermore, satellite cells found in the muscle multiply and their daughter cells migrating to the damaged tissue. Here, they fuse with skeletal muscle and donate their nuclei to the muscle fibers helping them thicken and grow. This results in larger muscles with improved tolerance of larger loads.

Why Hypertrophy? The Prevailing theory:

The thought is that if the size of the muscle increases, then the more force that muscle can exert (i.e. increase in strength). The force-velocity relationship is the observation that muscle fibers produce more force when they are able to shorten slowly, compared to when they shorten quickly (think a bodybuilding style of training vs. Olympic weightlifting).

This is part of why Olympic weightlifters don’t have as big of muscle size as powerlifters, traditionally.

However, some analyses suggest that muscle size and strength don’t necessarily always have a positive correlation. In fact, one study in particular noted that muscle size itself is not a good indicator of overall strength. However, it is important to note that while they don’t always correlate, hypertrophy blocks are likely essential for longevity in lifting. Meaning they give your body, specifically your neuromuscular system, a much needed break.

Rep ranges for adequate hypertrophy:

It used to be thought that 6-12 reps was the ideal rep range for muscle hypertrophy. However, The American Society of Sports Medicine recommends 8-12 reps at 60-70% of a 1RM, but it appears that when reps are performed to failure (or near failure, 1-2 reps in the tank), you could train rep ranges of 30-40 reps at 30% of a 1RM with the same gains in hypertrophy as training 8-12 reps at 80% of a 1RM according to a landmark study published in the Journal of Applied Physiology (1).

When & Why:

Hypertrophy is best used away from competition with limited amount of sport-specific movement or practices. In beginner athletes, an increase in muscle size can be observed after 6-8 weeks of a true hypertrophy phase and in strength trained athletes, the changes are a little less obvious. The hypertrophy phase can last anywhere from 1-6 weeks, although if we’re talking about strength training, we would likely not see a 1 week cycle, but are more likely to see athletes complete 4, 6, 8 and even 12 week cycles. The length of cycle depends on a couple things:

  1. When is your next competition?
  2. How long have you been strength training. Will a 12 week cycle be better for you or would you be better off on a 6 week hypertrophy followed by a 6 week strength cycle.
  3. Are you injured? If you’re injured, a hypertrophy cycle will do wonders for your strength. Think of it as a time to really work on everything that is your weakness.

The goal of this phase is to increase lean body mass (LBM) and develop a muscular endurance (muscular and metabolic) base for more intense training in later phases or cycles. Think of hypertrophy as a necessary stepping stone, a foundation.

Frequency of training each muscle group:

“It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.”

According to the review quoted above, they found that training a muscle group twice a week opposed to once a week resulted in a higher desired hypertrophic effect. The difference, however, between two and three sessions per week is still to be determined (2).

American College of Sports Medicine Recommendations for Hypertrophy Training (3):

For novice (untrained individuals with no resistance training (RT) experience or who have not trained for several years) training, it is recommended that loads correspond to a repetition range of an 8-12 repetition maximum (RM). They also recommend a training frequency  of 2-3 days a week.

For intermediate (individuals with approximately 6 months of consistent RT experience) to advanced (individuals with years of RT experience) training, it is recommended that individuals use a wider loading range from 1 to 12 RM in a periodized fashion with eventual emphasis on heavy loading (1-6 RM) using 3- to 5-min rest periods between sets performed at a moderate contraction velocity (1-2 s Concentric; 1-2 s Eccentric). It is recommended that intermediate to advanced lifters train 3-4 days per week for intermediate training and 4-5 days per week for advanced training.

When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number.

Ready to incorporate hypertrophy into your training? Check out our 10 week strength program.

Want to learn how to incorporate proper nutrition into your life to optimize strength gains? Check out our Eat for Strength Online Course.

*Definitions found in:
Essentials of Strength and Condition (2nd Edition). National Strength and Conditioning Association (2000). Editors: Thomas R. Baechle & Roger W. Earle


  1. Mitchell CJ, Churchward-Venne TA, West DWD, et al. Resistance exercise load does not determine training-mediated hypertrophic gains in young men. J Appl Physiol. 2012;113(1):71-77. doi:10.1152/japplphysiol.00307.2012
  2. Schoenfeld BJ, Ogborn D, Krieger JW. Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sport Med. 2016;46(11):1689-1697. doi:10.1007/s40279-016-0543-8
  3. American College of Sports Medicine. Progression Models in Resistance Training for Healthy Adults. Med Sci Sport Exerc. 2009;41(3):687-708. doi:10.1249/MSS.0b013e3181915670


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