By Jennifer Copley (Last Updated 5 November 2016)
The ideal number of repetitions depends on your body type and strength training goals.
Most reliable sources say that beginner strength training goals can be achieved with 8-12 repetitions per set (if you can’t manage 8, try a lower weight, and if 12 is too easy, increase the weight). Research also indicates that one set per exercise or muscle group is sufficient for beginners.
If you’ve been training for awhile and want to accelerate your progress, you should lift heavier weights with fewer repetitions and do 2-4 sets per exercise
alternate between weights you can lift 8-12 times (better for increasing muscle size) and those you can only lift for 4-8 repetitions (better for developing muscle strength), either within the same workout or on different days.
If your priority is developing muscular endurance rather than strength, choose a weight you can lift 20 times and take shorter rests between sets (fewer than 90 seconds).
Strength training strategies should be customized for your body type
Keep in mind that bodies respond differently to strength training routines based on a number of variables including genetics and diet. One factor that has a major influence on how your body responds is your balance of Type 1 and Type 2 muscle fibers:
- Type 1 muscle fibers, also known as slow-twitch, have less power but more endurance (great for activities such as long-distance running or cycling).
- Type 2 muscle fibers, or fast-twitch, fatigue more easily but can produce more power (better for activities that require brief, explosive movements, such as sprinting and power lifting).
Low-rep sets (8 or fewer) with heavier weights encourage growth of Type 2 muscle, while higher-rep sets (12 or more) with lighter weights encourage growth of Type 1 muscle. Strength gains in both types of muscle are achieved in the 8-10 rep range, though heavier-weight/lower-rep sets are better for building Type 2 muscle, while lower-weight/higher-rep sets are more effective for building Type 1 muscle.
It will be easier to get big if you have more Type 2 muscle than Type 1 – just do high-weight/low-rep sets. If you’re having trouble bulking up but you have great stamina for endurance sports, you probably have more Type 1 muscle, so you may get better results with a lower-weight/higher-rep strategy. If you go with this option, take shorter rests between sets.
Will women bulk up if they use a high-weight, low-rep strategy?
Most men using the high-weight, low-rep, multiple-set approach not only gain strength, but also bulk up to varying degrees (genetics and diet also play a role in this). However, although women using this approach will also build strength rapidly, they won’t typically bulk up unless they take steroids or have unusual high testosterone levels.
Women have some testosterone, but far less than men, so it’s very difficult for them to gain size. Female strength trainers usually just lose fat and replace it with lean muscle. Muscle weighs more than fat, so their weight may stay the same or even increase as they lose inches and develop a more toned and streamlined appearance.
- American College of Sports Medicine. (2013). Resistance Training for Health and Fitness [PDF]. ACSM.org.
- Hutchinson, A., PhD. (2011). Which Comes First, Cardio or Weights? Fitness Myths, Training Truths, and Other Surprising Discoveries from the Science of Exercise. HarperCollins.
- National Strength and Conditioning Association. (2014). Foundations of Fitness Programming [PDF]. NSCA.com.
- Penney, S., MS, NASM-CPT, CES, PES, FNS. (2015). Fast-twitch, slow-twitch: what’s the difference and does it matter? National Academy of Sports Medicine. Blog.nasm.org.
- Westcott, W., PhD. (n.d.). How many repetitions? Healthy.net.