What Is a Repetition in Weight Lifting?

When you’re weight training, your muscles push and pull against resistance provided by the weights. A key part of any regular weight-training program is deciding how many times to repeat each exercise. Some trainers, for example, recommend lifting heavier weights fewer times. Others may advise you to lift lighter weights, but to do so more often. To help decipher the differing opinions, it’s helpful to understand what a repetition means.

  1. Standard Definition

    • The term “repetition” can have two slightly different meanings in weight training. For most exercises, however, the definition is straightforward. Every time you return to the exercise’s starting position, you’ve completed one rep. If you’re bench pressing, for example, and you start with the barbell near your chest, one repetition consists of pressing the bar up, then lowering it to your chest.

    Right and Left Movements

    • You may count your repetitions differently if you’re moving one arm or leg at a time. For example, if you’re performing dumbbell curls with two dumbbells that you move simultaneously, you complete one rep every time you raise then lower the dumbbells. But if you alternate arms, then you must raise and lower both arms once to complete one repetition. If you do your curls with one dumbbell at a time, revert to the standard definition and count each full up-and-down movement as one rep. You’ll then perform the same number of sets with each arm.

    Concentric Phase

    • A repetition consists of two phases, each of which affects your muscles differently. When you’re lifting the weight -- pressing upward during the bench press, or moving downward during the lat pulldown, for example -- your muscles shorten, which is known as a concentric contraction.

    Eccentric Contraction

    • Eccentric contractions typically occur in the second half of a standard repetition, although some weight-training activities are performed in reverse. When you lower the weight in a dumbbell curl, for example, your biceps lengthens -- assuming you’re lowering the weight under control, as you should -- which is termed an eccentric contraction.

    Sets

    • A series of repetitions performed without rest is called a set. Opinions regarding the optimal number of reps to perform in each set vary. Dr. David Ryan, a former “Mr. World” bodybuilder, generally recommends higher reps and lighter weights for beginners, anyone with joint problems, exercisers older than 50 and exercisers who are overweight. He advocates performing fewer reps with heavier weights for more experienced exercisers who are either thin or muscular. As a very general guideline, Ryan states that 12 to 15 repetitions per set will help a regular exerciser achieve a “basic level of fitness.”