RepetitionRep · Reps
One complete movement of an exercise, from start position back to start position.
A repetition is one complete cycle of an exercise: the lowering phase where the muscle lengthens under load, usually a brief transition, and the lifting phase where it shortens. Reps make up sets, and sets make up the training week.
Rep ranges are the traditional way of organising training, with low reps at heavy loads for strength, moderate reps for size, and high reps for endurance. That framework is roughly right at the extremes and much looser in the middle than gym lore suggests.
The clearest finding of the last decade is that load matters less for growth than effort does. Meta-analysis comparing low load and high load training found similar muscle growth when sets were taken close to failure, with heavier work producing greater strength gains.
That is practically liberating. Sore elbows, a cranky back or a hotel gym with light dumbbells are reasons to change the rep range rather than to skip the session, and a set of 20 taken to the edge builds muscle much like a set of 8 does.
Rep quality is the part that gets neglected. Full range of motion generally beats partial range for growth, control on the lowering phase is where a large share of the stimulus sits, and adding weight while quietly shortening the range is not progress.
Counting reps also gives you the simplest form of progression. Adding a rep at the same weight, session after session, until the top of a range is reached and the load can go up, is the double progression method.
In practice, pick a range you can execute well, take sets close to failure, and let our double progression planner decide when to add load.