Tempo refers to the speed or rhythm at which an exercise is performed. In strength training, tempo is often expressed using a four-digit code that describes the timing of the four phases of a repetition: the eccentric (lowering) phase, the pause between eccentric and concentric (lifting) phases, the concentric phase, and the pause between concentric and eccentric phases.
The first number indicates the duration of the eccentric phase, the second number indicates the duration of the pause between eccentric and concentric phases, the third number indicates the duration of the concentric phase, and the fourth number indicates the duration of the pause between concentric and eccentric phases. For example, a tempo of 3010 means that the eccentric phase should last for three seconds, there should be no pause between the eccentric and concentric phases, the concentric phase should last for one second, and there should be no pause between the concentric and eccentric phases.
Tempo can be used in strength training to manipulate the time under tension (TUT) of an exercise, which is the total amount of time that the muscle is under load during a set. By slowing down the tempo, the TUT can be increased, which can increase the metabolic stress on the muscle and potentially lead to greater hypertrophy (muscle growth). Tempo can also be used to help develop motor control. It is commonly used at the start of someone strength journey as they develop positional awareness and control over a movement.
It is important to note that tempo should not be the only factor in designing a strength training program. Other factors such as intensity, volume, and exercise selection should also be considered.