The Rep Theory

One of the most frequently asked questions in the fitness industry is: “How many repetitions should I perform for any given exercise?” If you are expecting a simple, straight-forward answer, forget it.

Bodybuilding great Mike Mentzer was an advocate of performing one to two well-performed sets to failure for a given exercise, and kept his workout limited to only about five exercises per body part, with a strict focus on two main body parts per workout. This philosophy of brief, infrequent and intense workouts was the basis of Mentzer’s impeccable physique, which won him the heavyweight title in the 1979 Olympia. Arnold Schwzenegger, on the other hand, forged his infamous physique by working each body part through a large volume of repetitions and sets, focusing on numerous body parts per workout. His belief was in high volume workouts and minimal rest, training each muscle group every other day.

Two of the greatest bodybuilders of our time with two contrasting training techniques, both of which extremely effective in their own right! So here is the real question: “Is there really an ideal rep range for muscle growth?” Consider these five essential variables before deciding on the rep range that suits you best.

1. Training Effect:

The training effect refers to the desired training goal you are trying to achieve such as hypertrophy, strength, speed, etc. Research has shown that number of repetitions performed often correlate with an optimal training effect. While the exact repetitions may vary between individuals, these ranges give an accurate understanding of how many to perform.

a)  1 to 5 Reps: This focuses primarily on the development of strength and explosive power, and is hence the repetition range commonly utilised in powerlifting and weightlifting training. Lifting much heavier weight with few repetitions works to dramatically increase strength, but not necessarily significant muscle size.

b)  6 to 8 Reps: This range focuses on functional hypertrophy. This kind of hypertrophy is great for athletic strength development as it builds functional strength without the athlete having to put on too much muscular bulk.

c)  8 to 12 Reps: This rep range is best for optimal hypertrophy and muscle growth, and is the range of choice for most gym goers and bodybuilders. However, studies has also shown that faster-twitch individuals respond better to the hypertrophy at lower end of this range, and that may even extend to as low as 5 to 6 repetitions.

d)  13 and above: Generally speaking, performing above 13 repetitions is more muscular endurance based, and is best used to get the heart racing and the lactic accumulating. This range creates more of a metabolic effect, increasing growth hormone production for optimal fat burn and generally can range from 13 to 25 reps for a given exercise.


2. Individual muscle variability

Individuals who are more fast-twitch dominant tend to hypertrophy and mentally respond better to training at lower rep ranges such as 5 to 8 reps. These individuals have a larger proportion of type 2A and 2B fibers, typically put on muscle quickly and gravitate towards more explosive movements like sprinting rather than long distance running.

Slower-twitched individuals, on the other hand, perform better, and get better hypertrophy results with higher rep ranges of 12 to 15. These individuals have less type 2A and 2B fibers, find it harder to put on muscle and often choose endurance sport like rowing and marathon running over sprinting.

3. Duration

If you have been keeping to a particular repetition range for longer than 3 to 4 weeks, then it’s best to change this range. Often the body can adapt to a given rep range quite quickly, especially if that is associated with the same exercises as part of a program. Furthermore, studies have indicated that upper body requires more variability than the lower body for continual improvements and gains. As such, choosing to either increase or decrease your range regularly is an effective way of breaking plateaus and will help your muscular development greatly.

  1. Muscle CompositionThe different muscles within our body respond better to specific rep ranges. This is because of it’s muscle fiber composition, specifically the proportion of fast or slow twitch fibres within that given muscle. For example, the hamstring muscles which comprise of 70% fast-twitched fibers, tend to respond better to lower rep ranges of 5 to 8 for optimal hypertrophy, whereas the quadriceps muscles which has less fast twitched fibers in general, tend to build more quickly on a regime of higher number of repetitions e.g, 8 and above, and higher overall volume.Similarly, the gastrocnemius of the calves are faster-twitched, and more suited to lower rep ranges and heavier weights, whereas the soleus which is targeted more during a bent-knee calve raise, is predominantly slower-twitched and responds better to higher reps and lower weight.
  2. Athletic PeriodisationIf you are an athlete training to be fast and explosive in a sport like basketball, rugby or judo, it’s best to keep the rep ranges lower and the weights heavier and more explosive during the lead up to game season. This helps with conditioning your nervous system to be more explosive and is less likely to result in muscle damage and Delayed Onset of Muscle soreness (DOMS) over the proceeding days. Higher rep ranges are generally kept to off-season work and for increasing muscle mass.

    Written by
    Benjamin Siong
    Founder and Master Strength Coach Australian Strength Performance

    To learn more on the topic of training for hypertrophy, you do not want to miss Ben’s Hypertrophy Level 1 course, which he will be teaching here at FIT Singapore on October 7-8 2019.

    Find out more about the course content and register directly here