Repetitions are the basic building blocks of any strength or muscle building program but it is something that many lifters take for granted.
The first thing to note is that a repetition consists of three elements – namely lower, pause and lift.
The speed at which this is achieved depends on the desired outcome, but to maximize muscle growth a slow, controlled tempo is required.
The process should never be rushed, jerky or bouncy but instead should be controlled and smooth.
The second consideration relates to how many reps need to be performed. Once again, this depends on what you hope to achieve but you can use the following as a basic rule of thumb:
1. A single repetition maximum (1RM) increases muscle strength.
2. A six to eight repetition maximum increases muscle size.
3. A higher number of repetitions will have more effect on muscle endurance and little impact on size or strength.
Most of your training should be to complete six to eight reps of a load equivalent to 75-80% of your 1RM primarily with your compound movements such as squats, deadlifts, cleans, etc.
This will maximize your muscle building potential, provided you complete each lift with perfect form in a smooth controlled manner.