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Thanks to Roland from the Netherlands for bringing up this topic!

Introduction

Very few trainees ignore the importance of sets and reps. Every bodybuilder worthy of that name knows that 8-10 reps is optimal for size development, that 6 reps or less is best for strength development and that 15 reps or more is better suited for the improvement of muscular endurance. Or is it...?

You see, not a lot of trainees are aware of the tempo-training variable and as a result they are likely to end up short-siding their muscle gains. How many bodybuilders do you see hammering those weights so fast that between your sets you go sit beside him just to benefit from the wind blowing from his motion? Well, that might be pushing it a bit far but nonetheless true. Trainees are so fixated on the number of reps they perform that most of them don't stimulate much growth by doing the reps too fast. Yeah but I'm doing 10 reps and 10 reps is the optimal number to stimulate size gains... Not necessarily so and this article will show you why.

Optimal Time Under Tension for maximum gains

To stimulate hypertrophy (muscle size gains) the optimal time under tension (TUT) for each set is between 40 - 70 seconds. Of course sets of 20-30 seconds can induce hypertrophy, but 40-70 seconds is optimal. The main reason why sets of 40 - 70 seconds seem optimal to stimulate hypertrophy is related to lactic acid release. Lactic acid (or lactate) is released as a by-product of anaerobic glycolysis (using glycogen for energy without the help of oxygen). Now, lactate has been associated with an increased release of testosterone and mainly growth hormone (GH) both of which are anabolic hormones that stimulate muscle growth. This could be termed the hormonal hypertrophy stimulation theory (HHST) and coupled with the superior protein degradation from sets of 40-70 seconds it explains why sets of this duration lead to more muscle gain.

Now, our average bodybuilder who do 10 reps in 20 seconds or so will not stimulate as much growth because the protein degradation he causes and the hormonal response he gets are inferior to that of a bodybuilder who uses a longer tempo.

So, to develop maximum muscle mass, the duration of a set should fall in the range of 40 to 70 seconds. This gives us a lot of variation so we can change tempo frequently, thus avoiding stagnation.

Tempo prescription

To better understand tempo, we use three digits. The first digit is the lowering (eccentric) portion of the lift, while the middle digit is the pause and the third represent the returning (concentric) portion. If someone would do a squat by lowering for three seconds, pause at the bottom for two seconds and then explode up in one second, it would read 3-2-1. If one of the portions are to be done as fast as possible, we would use an X.

A frequent question regarding tempo is that the eccentric portion (first digit) doesn't always come first in an exercise (lat pulldown for example). The answer to this problem is quite simple, don't think about the digits as fixed in place or as a plan, think of them as guideline to every part of the movement (in other word you take all the digits separately). This means that if you first do the concentric portion then arrange the digits so they conform to the flow of the movement. I.e. take the third digit (which is normally the concentric portion) and switch it with the first digit (which is usually the concentric portion). If you understand that the when we prescribe a tempo the first number always refers to the eccentric portion than you can manipulate the numbers if you need to. But when trainees get better at knowing when is the eccentric portion of a movement and when is a concentric portion, they don't need to move the numbers around. Again, the digits are simply "memory helper"; they don't tell you or decide for you how you start a movement. They tell you what the tempo is in every part of the movement, so when you start differently from the writer's sequence all you have to do is to adjust the sequence accordingly.

That having been said, we get back to the great variation possible because of the variability of the tempo variable. Remember that for maximum size gains each set should last between 40 and 70 seconds. So you can modify your tempo a lot, as long as it stays in that range. Below are some examples of possible tempos for different number of reps that are ideal for size gains:

If you do 12 reps: 111 , 201, 30X, 211, 202, 301, 40X, 41X, 212, 302, 31X, 401, 41X, 50X

If you do 10 reps: 211, 202, 301, 40X, 41X, 212, 302, 31X, 401, 41X, 50X, 303, 312, 411, 402, 42X, 501, 51X, 60X, 323, 413, 422, 511, 502, 52X, 601

If you do 8 reps: 41X, 212, 302, 31X, 401, 41X, 50X, 303, 312, 411, 402, 42X, 501, 51X, 60X, 323, 413, 422, 511, 502, 52X, 601, 404, 413, 422, 503, 512, 521, 53X, 602, 611, 62X, 701, 71X, 80X

If you do 6 reps: 303, 312, 411, 402, 42X, 501, 51X, 60X, 323, 413, 422, 511, 502, 52X, 601, 404, 413, 422, 503, 512, 521, 53X, 602, 611, 62X, 701, 71X, 80X, 414, 423,504, 513, 522, 531, 54X, 603, 612, 621, 62X, 702, 711, 72X, 505, 514, 523, 532, 604, 613, 622, 631, 64X, 703, 712, 721, 73X, 802, 811, 82X

Of course these are only a few possibilities, as long as the Time Under Tension (TUT) of each set is between 40 and 70 seconds you will stimulate maximum muscle gains. So in that regard a set of 1 repetition that uses a tempo of 30-0-30 (TUT = 60 seconds) would be better to develop size than a set of 10 repetitions that uses a tempo of 101 (TUT = 20 seconds).

Another possible tempo prescription

There is another way to prescribe tempo. Some trainees will choose to add a fourth digit after the first three. The fourth digit represents the time between the concentric part of the movement and the eccentric part, i.e. how much time you will pause between each repetition. This fourth digit serves many purposes and that's why more and more trainees and trainer choose to include it. Some of the purposes of this fourth digit include:

1. That portion of the movement (time between each rep) is there, so you might as well control it.
2. Playing with that fourth digit can lead to even more variation in your training.
3. Some training methods involve a longer pause or static hold at the end of each repetition thus you need to be able to quantify that portion of the lift. Examples of such method include the rest-pause method and functional isometrics among others.
4. For bodybuilders, it can help them improve their capacity to hold a pose on stage (a muscular pose is essentially a peak isometric contraction).

However the problem with adding a fourth digit is that it complicate things a bit. Even with three digits some peoples get confused, so a fourth digit is likely to add even more confusion for the less experienced trainee. Bottom line is that the prescription method you use is a personal thing, go with what you are comfortable.

The need for the pause

One of the first comment from trainees who look at a tempo prescription for the first time is: "Why do you quantify the pause between the eccentric portion and the concentric portion?" This is an understandable question since the most overlooked portion is the pause or the isometric portion. If you pause for a few seconds, all the plyometric effect (or myotatic reflex) is eliminated. This will force your muscles to contract harder since you cannot use your elastic energy to lift the weight. The opposite is the dude who bounces the bar on his chest in the bench press. Slowing down your movements (like 4-2-3) will produce better muscle mass and strength gains. This is due to the fact that the Type IIa fibers get more stimulation while it will bring increased muscle glycogen and CP, ATP, ADP, creatine, PFK, and Krebs cycle enzyme activity.

Last words

The important thing to remember is that for muscle size gains you need to maintain an intense muscular effort for 40-70 seconds. For most trainees that mean that they'll have to slow down. However, to get the best development, we need to change tempo from time to time. For bodybuilding, the lowering portion could fall in the range of 2 to 8 seconds. The pause should always be a second or longer (although this is debatable). And the returning/concentric portion could be in the range of 1 to 6 seconds. Variation is the key. And if you're after explosive strength, you should direct your training more towards explosive (as fast as you can) concentric portions.

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