Set, Reps & Why It's All So Confusing

As a fitness professional, people are constantly asking me, "How many reps? How many sets?" There is more than one answer to these questions, depending on your goals. Yup, this is another long-winded answer. Smile, you're learning something...

Before I even get into it though, I need to make a point I will make throughout the post. No matter how many repetitions you are prescribed, your goal within each set is to reach momentary muscular failure. Even if you feel tired or uncomfortable, your muscle may still be capable of more work for that set. When people are lifting weights, I often hear them say things like:

"Oh, I can feel it!"
"This is hard."
"That's working!"

These are all comments from the brain saying that it would be more comfortable if you stopped doing that exercise. But you're not trying to fatigue your brain; you're trying to fatigue your muscle. When the muscle you are exercising is incapable of completing another repetition, it has truly spoken. When you hear trainers say things like, "Push yourself," or "One more...," they are trying to help you override your brain's messages to give up, because you don't reach your goals if you give up.

Now, on to the science behind sets and reps. To improve muscular strength and endurance, the American College of Sports Medicine (ACSM) recommends one set of exercises for 8-10 large muscle groups performed on 2-3 days/week. Improvements can be seen within a variety of repetition ranges 6-8, 8-10, or 12-15. Strength improvements may be more notable at a lower rep range while endurance gains will result from a higher range.

No matter what repetition range is chosen, the goal of each set is to reach momentary muscular failure - i.e. you couldn't do another rep if you tried.

Blah, blah, blah, right? So here's an example of how this prescription is typically applied, and where it goes wrong. You might be even be familiar with it. A woman joins the gym and gets one free personal training session so she can learn how to use the machines. She tells the trainer she wants to build strength and endurance in her muscles. The trainer shows her how to use 8 different circuit pieces at the gym (leg press, chest press, lat pulldown, etc.) and tells her to do 1 set of 10-12 repetitions for each exercise. In most cases, the trainer sets the initial weight for each exercise lighter than it ultimately should be. Lighter weights enable the client to learn proper form, develop self-efficacy with a new program, and give the connective tissue time to adjust to a new stimulus without injury. So the trainer tells she needs to increase the weights once she is able to complete 12 or 13 repetitions smoothly. This will probably mean she can only complete 9 or 10 repetitions with the new weight, but as her strength improves, she will soon be able to do 11 or 12 with the new weight, and so on. Great. There's nothing wrong with this advice. But here's how it plays out...

The client, knowing very little about momentary muscular failure, and having very little experience in life of working a muscle to absolute fatigue, comes into the gym and goes through the circuit with the initial weights the trainer has set, probably completing sets of 12 across the board. Even that's ok. But 9 times out of 10, this client will come in the second time around and go through the circuit with the same exact weight - which is too light - and perform the same number of repetitions (12) for each exercise. It may seem absurd in light of what I've talked about, but this is what really happens.

What this woman needs to be asking herself at the 12th repetition of every set is, "Could I do one more?" If the answer is yes, the weight needs to be increased. Sometimes, not only could someone do one more with the weight they think is right for them, they could do 8 more or 15 more. A weight that light is not pushing the muscle to reach momentary failure and it will not improve strength and endurance. Period.

ACSM's guidelines speak to enhancing muscular strength and endurance in the general population. The problem with these recommendations is that most people don't actually care too much about muscular strength and endurance - what they desire is muscular hypertrophy, or increased muscle size.

The National Strength and Condition Association puts forth a more detailed compilation of sets/reps to achieve muscular hypertrophy.

Hypertrophy
8-12 reps
4-6 sets
30-90 sec rest btw sets

The sets and reps here are referring to one muscle group. Therefore, if I wanted to increase the size of my quadriceps muscle on the front of my thigh, I might perform 3 sets of lunges and 2 sets of leg extensions, completing 8-12 repetitions of each exercise to momentary muscular failure.

I would have to use this formula for every single muscle group whose size I wanted to improve - chest, back, shoulder, triceps, biceps, abdominals. Obviously, this can't all be done on one day so often times, people will exercise certain muscle groups one day (i.e. legs, shoulders, back) and others on another (i.e. chest, biceps, triceps). There is no quick circuit for muscular hypertrophy. It's a lot of hard work. But whether your goal is a more moderate increase in muscular strength/endurance or a very visible increase in muscle size, the principle of momentary muscular failure has to be applied to every single set.