The one-repetition maximum, or 1-RM, refers to the maximum amount of weight that can be lifted one time. The 1-RM is a standard index to quantify muscle strength. A 1-RM determination can be made for any dynamic constant external resistance (DCER; formerly known as isotonic) strength exercise, such as the bench press, leg extension and flexion, leg press, squat, or power clean. In addition, 1-RM testing can be performed using free weights or machine exercises. The procedure is a trial-and-error method where, after a warm-up period, progressively heavier weights are lifted one time until the subject cannot successfully complete the lift of a given weight. 1 The weight is then reduced until the heaviest successful weight is determined.