Tempos are constantly changing, but the order of the letters will always have the same meaning.
The first number, 4 in this example, is always used for the eccentric part of the movement, or in most cases the lowering of the movement.
For example in the shoulder press, the number 4 tells us that once the bar has been pressed overhead I must take 4 seconds to lower the bar back to the starting front rack position. In the squat, this would tell us that I need to slowly lower into the bottom of the squat for 4 full seconds.
The second number then tells us how long we will pause before beginning the concentric (shortening of a specific muscle or muscle group) part of the movement. If the number is 0, like in the above 4020 tempo, you will not pause in this position, but go immediately into the next part of the lift.
For example, in the shoulder press this would be the time in the front rack position, and for the squat, this number would represent how long you will be holding the bottom of the squat.
The third number represents the time it will take you to complete the concentric part of the movement (the shortening of a specific muscle or muscle group). In most cases this is the upward movement, like standing up from the squat, pulling your body over the chin up bar, and pressing the bar overhead. When you see the letter X in place of the third number, this means the concentric part of the movement is meant to be explosive.
Remember that it is the brain’s intent, not the actual bar speed that will determine the effect of being “explosive.”
Lastly, the fourth number explains how long you will pause at the top position. For example, how long will you be holding the barbell overhead in a locked out position for the press, or how long you will be standing at the top of your squat before you begin the next rep. Now take the number 3121. Three seconds down, 1 second at the bottom, 2 seconds to drive up, and 1 second pause at the top. Just think EPCP (eccentric, pause, concentric, pause) Easy enough, right? Just remember some movements such as the press and deadlift will start with the concentric part of the movement which will represent the 3rd number of the tempo format, rather than a squat where you will start with the eccentric portion, or the first number in the tempo. Practicing with tempos will only make reading and understanding this number more natural.
Why are tempos important?