A single completion of an exercise movement, such as one push-up, is known as one repetition.
In strength training, repetitions—often shortened to “reps”—count how many times an exercise is performed in succession. One push-up from the starting position down and back up is one rep; doing ten push-ups means completing ten repetitions.
Repetitions are grouped into sets. For example, three sets of ten squats means performing ten repetitions, resting, and repeating that sequence three times. The number of reps and the resistance used can change the training emphasis: heavier loads commonly suit strength work, while lighter loads and more repetitions can support muscular endurance.
A repetition is not the same as an interval, circuit, or set. An interval is a period of work or rest, a circuit links several exercises, and a set is a group of repetitions. “One-repetition maximum,” or 1RM, means the heaviest load someone can lift for one complete repetition.