The first number is the most important, it relates to how many seconds you take to lower the weight (eccentric phase).
If there is 4-5 then you should really focus on slowly lowering the weight with maximum control!
The second indicates how long you should hold the weight in a pause at the bottom of the movement.
If there is 1-2 then you should pause at the bottom to avoid momentum!
The third number represents the time taken to lift the weight to the original starting position (the contraction phase)
If this number is higher than 1 then you have to learn the movement with slow and controlled contraction highly focusing on the muscles and form you want to work on.
The fourth number is how long you should pause with the weight at the top of the movement.
It shows you how much time should you keep the movement in the top contraction, flex position.
X means as fast as possible in an explosive movement. Even if a movement starts with an upward motion, such as a pull-up, begin counting the rep with the downward component.
Examples:
Back squat with the tempo of 30X0 would
look like this:
3 – Moving smoothly, use 3 seconds to squat to full depth
0 – Hold for 0 seconds at the bottom (do not pause)
X – Explode up as quickly as you can
0 – Start the next rep after 0 seconds (do not pause between reps)
Be sure to count each second fully.
Using a Bench Press with a 3010 tempo as an example:
3 - Take 3 seconds to lower the barbell to your chest (eccentric phase)
0 - Do not pause with the weight resting on your chest (first pause phase)
1 - Raise the weight at speed using one second to return the barbell to the starting position (concentric phase)
0 - Do not rest before starting the next repetition (second pause phase)