When it comes to increasing muscle size, one of the biggest questions I see is, “What is the best rep range for mass?” Many people misunderstand this, and one of the main problems is the word-of-mouth myth that has been doing the rounds in the gym for centuries. Whoever coined the phrase, “You need to lift heavy to build muscle,” was dead wrong. In fact, I’m not going to sit here and give you more science.

Today, I want to tell you about the best repetition range to build muscle mass. However, I’m not going to sit back and give you a rep range. I’ll also tell you why the rep range I’m about to share with you is correct, why it’s effective, and how it’s backed by scientific research. Finally you will learn how many repetitions you need to complete to build muscle size.

I will also teach you about time under tension and rep tempo; These are often the two most overlooked aspects of building muscle. In fact, they are so overlooked that when I approached a personal trainer at my gym and asked him about TUT and repetition tempo, he had a huge smile on his face and was quite surprised that I even knew what these things really were. Everything I’m going to teach you goes together, so make sure you absorb all the information here and take notes if necessary.

How many repetitions to build muscle mass?

Before you can answer this question, you must first understand that there are 3 different types of muscle building. You can build muscle strength, size, and stamina.

Where most people get confused is the difference between muscle strength and muscle size. If you’re training for strength, you need to lift heavy with low repetitions. Strength training will increase your muscle density (strength), without increasing the actual size of your muscle. Size training will increase the size of your muscle, add some strength, but allow your body to harness more strength in the future. That is, the bigger you are, the stronger you can be.

The best rep range for mass is 8-12 reps for beginners and 6-12 reps for intermediate to advanced lifters. I know this may come as a surprise, but it comes directly from the National Strength and Conditioning Association personal training program. If you don’t believe me, feel free to get the book and see for yourself.

What about time under voltage?

Lifting in the proper rep range is of no use to you if you’re not also lifting in the correct time range for time under tension. Some of you may be asking, “Well, what is time under stress?” Time under tension is the amount of time it takes you to complete 1 full set of any given exercise.

For example: If you do 12 reps of bicep curls and it took you 45 seconds to complete those 12 reps, then your time under tension would be 45 seconds. You may be wondering, “Why is Time Under Tension, also known as (TUT) important?

Jim Stoppani, a bodybuilder with a PhD in exercise physiology, says that if you’re trying to put on size, you want a 40-60 second TUT. Anything less than 40 seconds, and you’re focusing more on strength; Anything over 60 seconds, and you’re focusing more on stamina. The fact is that if you can keep your muscles under tension for 40-60 seconds, the more the growth process will be stimulated.

Rep Tempo is another key to building mass.

Have you ever seen guys lift with horrible shape? Of course you have. The key to building mass is to stick to a good repetition rate. A good repetition pace can be defined as someone who takes 2 seconds on the concentric (against gravity or machine) part of the lift, performs a 1 second isometric hold, and then takes 3-4 seconds on the eccentric (with gravity or machine) part of the lift.

For example: If you were to bench press, you would lift, slowly drop the weight toward your chest on a 3-4 second count, and then push the weight back up on a 2-second count, and repeat. Why is repeat tempo important?

A study conducted at East Carolina University found that a test group of people built 46% more muscle if they focused on a slower repetition rate on the eccentric (gravity or machine) portion of the lift. In layman’s terms, you actually build more muscle on the negative (eccentric) part of the lift.

Next time you go to the gym, try this.

The next time you go to the gym, try reducing the amount of weight you normally lift. Don’t let your ego get to you. Lower the weight, use a rep range of 8-12 or 6-12 depending on how long you’ve been lifting, take 40-60 seconds to complete each set, and stick to a good repetition rate.

As a final tip, you can adjust the tempo of your repeats based on how many repeats you are doing. If your goal is to get bigger and you’re lifting more weight for 6 reps, for example, then your rep rate will be slower than someone lifting less weight for 12 reps. Remember, for size, your building muscle mass, your goal is always to fall in the 40-60 second rep range.