As a trusted coach and personal trainer, I assign my personal training clients workouts to complete on their own,
in addition to the primary workouts that I instruct them through beginning to end. When prescribing this “homework exercise”, a client may ask, “how many sets shall I do for that”, or, “how many reps“. Well, the best personal trainers and best coaches DO NOT simply give static answers and cookie cutter workouts. The best answer will depend mostly on the person asking the question. 
As a qualified, experienced coach, you must train the person standing in front of you. In addition, the best personal trainer or best coach will teach the client concepts and strategies that can be used in the long term and in the coach’s absence.
“How many reps?”, and “how many sets?” have been important questions since the beginning of weight training.
The answers in this subject area are a product of the work of thousands of athletes and hundreds of coaches. More specifically, the questions are,
- “at a given number of repetitions, what is the OPTIMAL number of sets?”
- “at a given intensity (%RM) level, what is the expected, or optimal, number of repetitions?”
- “what is the training effect of a specific number of repetitions (per set)?”
Fortunately, some very intelligent minds have taken on the task of providing concrete answers to these important questions. I have provided a brief overview of the most important work on this subject by 2 outstanding coaches; Prilepin and Poliquin.
Before I present a synopsis of the work of these 2 great coaches, I would like to point out the simple (and obvious) short answer to, “what is the relationship between reps and sets?”. The answer is, the number of sets/exercise and the number of repetitions/set are INVERSELY related. Meaning that, as the number of reps per set goes up, the corresponding number of (optimal) sets must fall. And, conversely, as the number of reps per set goes down, the corresponding number of (optimal) sets must rise. For example, if I am performing 10 repetitions per set, then I should probably only perform 3 sets. If I choose to do 15 reps/set, I only need to do 2 sets. If I choose to do only 2 reps/set, I should probably do about 12-15 sets.
Repetitions and Sets represent two of the six loading parameters in strength training. All six loading parameters are mathematically related.
So, now let’s present more detailed information on the subject –
1. PRILEPIN’S TABLE:
In the 1970’s A.S. Prilepin found a set of guidelines for how elite Olympic weightlifters trained to develop maximum strength. The results of his study are below.
We can see from the chart that when the athlete is working with loads that represent roughly 55-65% of his/her maximum lift weight, that the number of repetitions for that exercise ideally falls in the range of 18-30 total reps, with the optimal total number of reps being 24. Three examples: 5 sets of 5 reps, 4 sets of 6 reps, or 9 sets of 3 reps. Additionally, I would suggest that 3 sets of 10 reps would also be a good choice for working at this 55-65% load level, even though repetitions above 6 are not addressed in this chart.
From the next line we can see that when the athlete is working with loads that represent roughly 70-80% of his/her 1RM (1 Repetition Max), that the number of repetitions falls in the range of 12-24 total reps, with the optimal total of reps being 18. Three examples: 6 sets of 4 reps, 4 sets of 6-6-4-4, or 8 sets of 3 reps.
Now, 99% of people working out in the best gyms that are using primarily free weights will use loads that represent 55-80% – so we can concern ourselves, for the basis of this article, with just these first 2 lines of Prilepin’s Table. If you are a strength athlete, or advanced gym trainee, you are probably lifting loads more regularly in the area of 80%+ and have a decent understanding of the relationship between sets and reps already. Despite that, I guarantee you that I can take you to the next level. More than likely, you have only a faint idea of how strong you can actually be with the right training.
If all this stuff is like a foreign language to you, and you are interested in performing real strength training that will help you unlock your true potential, get some instruction from a qualified coach.
2. POLIQUIN’S CHART:
(Page 9 from The Poliquin Principles: Successful Methods for Strength and Mass Development
Table 1: Relationship between maximum number of reps, intensity and training effect (Poliquin,1990)
Relative Strength increases through enhanced neural drive:
1 rep = 100% duration of set(s): 0-20 seconds
2 = 94.3
3 = 90.6
4 = 88.1
5 = 85.6
Optimal compromise of maximal strength and hypertrophy gains:
6 reps = 83.1% duration of set(s): 20-40 seconds
7 = 80.7
8 = 78.6
Best hypertrophy gains leading to increased max strength:
9 reps = 76.5% duration of set(s): 40-70 seconds
10 = 74.4
11 = 72.3
12 = 70.3
Strength-endurance gains and lower hypertrophy gains:
13-20 reps = 68.8-60.6% (roughly 1.2/1.3% lower per rep) duration of set(s): greater than 70 seconds
This chart does a really effective job of illustrating what you are getting from your strength training efforts in regards to how your body is adapting to the stimulus (weight training). It also points out an important fact that I tend to stress often to PT clients: the body doesn’t really “see” reps, it sees, or responds to, the duration of the set.
If you look at the rep ranges and the corresponding duration of set, you can see that each rep range (and duration of set) delivers a specific message to the body. In the rep range of 1-5 reps, and a duration of set between 0-20 seconds, you can see that the body will respond to this stimulus with mostly neurological changes (relative strength increases through enhanced neural drive) – aka, the body is learning to use, more efficiently, the capability (muscle) it already has.
If we look down to the rep ranges of 9-12 repetitions (per set), with a duration of roughly 40-70 seconds per set, we can see that the body responds to this stimulus primarily through changes to the muscular system (body is encouraged to build more muscle).
At this point, inexperienced personal trainers might jump to the conclusion that “this is the only rep range I need for almost all my clients!”. And these inexperienced personal trainers would be wrong.
Thirdly, sets of 6-8 reps, or 20-40 seconds, is giving us a somewhat balanced blend of some neural AND some muscular adaptations (GAINS!).
Lastly, sets that last over 70 seconds per set are… wait for it… CARDIO.
And, that is a subject for a future article. Unfortunately, you see many inexperienced personal trainers having clients perform, almost exclusively, 15-20 reps per set. This is also an extremely naive approach. When these sets of 15-20 are performed on machines, it is just plain dumb.
An expert personal trainer or experienced, qualified coach will have his clients learning how to effectively employ ALL the repetition ranges (1-5, 6-8, 9-12, and 13-20) as part of a comprehensive program.
Thank you for reading. Best of luck in your gym efforts.
Paul Newt has a passion for learning in all its forms, and finds great enjoyment in conceptualizing, creating, and improving systems that lead to success. Paul spends his time training, coaching clients, being a great husband and father, consuming non-fiction books, tinkering with new technology, researching investments, and building on old, refining current, and discovering new successful methods to improve human health, performance, and appearance. Paul’s lifelong goal is to become the best version of himself, and add value to the world by assisting others in doing the same.