When working out with weights, what is the impact of the trade-off between

  • the amount of weights used
  • the number of times an exercise is repeated

For example, I can perform an exercise 3 sets x 10 reps with 20kg weights but only 3 sets x 7 reps with 25kg weights. What will be the difference of these two exercises on the body?

  • By 10x3, do you mean 10 sets of 3 or three sets of 10? Commented Sep 29, 2012 at 2:54
  • @DaveLiepmann 3 sets of 10
    – behzad
    Commented Sep 29, 2012 at 17:02

1 Answer 1


Your goals and your current level of progress determine the number of sets and reps.

Possible Goals

Training for strength, power, endurance and hypertrophy all require a different number of sets and reps:

  • Strength (how much weight your muscle can move) is best developed by lifting as much weight as possible. This is probably best achieved with 5 or less reps. Strength is expressed in how much you can lift one time, so the closer you train to 1 rep at a time, the more specific you are training for strength.
  • Power (how much your muscle can move quickly) is best developed by moving heavy weights very fast. This is best achieved with very few reps, something like 2 or 3 in a set, but you have to use slightly less weight so that you can move it faster.
  • Endurance (how long your muscle can keep doing its job) is best developed by lifting a weight many times, which requires many, many more reps: at least 15. You'll have to use a lot less weight in order for this to be possible.
  • Hypertrophy (how big your muscles are) is best developed by achieving momentary muscular failure, and with overall training volume. Moderate weight works best for this purpose, since it is heavy enough to quickly make one unable to lift it, but not so heavy that failure to lift is dangerous. Most people use 6-12 reps for this purpose, but there may or may not be anything special about this range. Multiple sets and exercises are useful for achieving high total workout volume.

This is well explained by a chart in the article I linked to:

Sets, reps, rest periods for different goals

Three sets of 7 at 25kg will demand and develop more strength than three sets of 10 at 20kg would. The sets of 10 would promote greater hypertrophy and require more strength-endurance and conditioning. The difference is not going to be terribly significant, however, since 7 and 10 aren't too far apart.

Doing fewer reps with heavier weights requires and develops more strength and less conditioning than more reps with somewhat lighter weights. Doing more reps with slightly lighter weights may, in some circumstances, for some exercises, produce more hypertrophy (mass gain). Fewer heavier reps is better for strength; more reps (but still as heavy as possible) is better for size.

Though the original on page 60 of Rippetoe & Kilgore's Practical Programming is better (the gradations from range to range are less stark) this chart from reddit does an excellent job explaining the effects of different rep schemes: Weight training repetitions table

Doing fewer repetitions with heavier weights builds strength most effectively. Doing more repetitions (circa 4 to 12), with weight that is still challenging, builds mass most efficiently. Doing more than 12 repetitions in a single set is generally best for endurance as opposed to strength. (See this answer for more information.) Does this mean that someone who is diligent with a 12-rep program can't get strong? Heck no! People get strong with 12-rep sets all the time. But if raw strength is their goal, they could probably achieve that goal faster with sets of, say, 3 or 6.

A novice generally does best with a focus on strength and some hypertrophy. Three sets of five or five sets of five are the two most common set/rep schemes. The weight must be heavy enough to make more than 5 sets very difficult.

Note that there is very little about these rep ranges in and of themselves that produces desired attributes. It is how these rep ranges relate to elements of training such as volume, intensity (that is, proximity to 1RM), and muscular exhaustion that determines the effects of training. Notice also that hypertrophy produces strength and power, and strength and endurance enable hypertrophy.

The following "map", from the Starting Strength site, explains the relationship of this volume-to-purpose relationship to sports. It refers to the three metabolic pathways: phosphagenic, glycolytic, and oxidative. The phosphagenic pathway is used when we do a very small number of reps in a set (3 or less, whereas higher-rep sets use the glycolytic pathway (approximately 4 to 12, though it depends on how vigorously one is working out). The oxidative pathway is for even higher rep ranges (e.g. 20), and is more commonly associated with longer duration, repetitive exercise like distance running or bicycling. It is explained in more detail in this article. sports-to-metabolic-pathway chart

  • 1
    @MikeS Uh, no, I just found the book to do its job in a way that resonated with me. I plug other programs and authors, too, in the appropriate contexts--Kurz on exercise science, GreySkull LP for upper-body enthusiast novices, paleo/Weston A. Price diets, and so on. If Mark Sisson would write a to-the-letter "do this if you're a novice" workout program, I'd probably plug that more than SS. Commented Dec 11, 2012 at 23:22
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    Actually, following the Reddit link gives you a much higher resolution version of the same image, and everything makes sense now: i.imgur.com/UrF1U.png Commented Aug 20, 2013 at 20:58
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    I must say I don't really understand this chart from reddit. Almost all of the dark (= optimum) areas are in the 1-5 range, so why would anybody ever train anywhere within the 6-20 range (as bodybuilders do)?
    – s427
    Commented Mar 10, 2016 at 11:56
  • 1
    @s427 A) if your goal is sarcoplasmic hypertrophy (that is, big muscles) or something else not served best by 1-5, B) if you have limitations on working in the 1-5 range, like you're using movements inappropriate for high-intensity/high-load work Commented Mar 10, 2016 at 12:07
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    @s427 1) "the original [chart] on page 60 of Rippetoe & Kilgore's Practical Programming is better (the gradations from range to range are less stark)" 2) just like doing singles and doubles is optimal for strength but sets of 5 or more are used in strength programs to get the benefits of hypertrophy, working in in 8-12 provides benefits other than pure hypertrophy. Commented Mar 12, 2016 at 19:32

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