Your one-repetition maximum, sometimes annotated as 1 RM, is a measure of the maximum amount of weight you can lift only once. A qualified fitness professional can walk you through a one-repetition maximum test, in which you literally attempt to lift the maximum amount of weight just once. But you can calculate your own one-rep max, with considerably less risk, based on your current workout routine and a number known as the Brzycki coefficient. Once you know your one-rep max, you can recalculate it periodically to determine your progress in building muscular strength.
Step 1
Perform five to 10 minutes of cardiovascular exercise that involves your upper body or entire body, if you're going to calculate your 1 RM for the bench press or chest press. Examples include the elliptical trainer or an upper-body ergometer, sometimes called an arm cycle. If you're calculating a leg press/squat 1 RM, do lower-body cardiovascular exercise such as a stair stepper, elliptical trainer, treadmill or exercise bike. This warms your muscles and reduces your risk of injury.
Step 2
Skip static stretching if it's a part of your normal warm-up routine. Static stretching before you strength train can decrease your performance.
Step 3
Do one or two warm-up sets of your chosen exercise, resting for one to two minutes between if you do multiple sets. The best exercises for submaximal strength tests are the leg press or squats to measure lower-body strength, or chest press or bench press to measure upper-body strength.
Step 4
Attempt a personal-best number of repetitions with a set amount of weight, based on your usual training program. So if you normally do eight repetitions with 250 pounds on the leg press, see if you can do more than eight repetitions during your personal-best attempt. Note that your target number of repetitions should be 10 or fewer.
Step 5
Try again, with a slightly heavier weight, if you succeeded at your last attempt. Note how many repetitions you successfully lifted with how much weight on your best attempt, even if you didn't hit your target number of reps.
Step 6
Multiply the amount of weight you lifted by the appropriate coefficient. The resulting number is your predicted one-repetition maximum. Finding the appropriate coefficient depends on how many repetitions you did of which exercise. For the leg press or squats, coefficients based on the Brzycki formula include five repetitions, 1.2 coefficient; six repetitions, 1.242; seven repetitions, 1.284; eight repetitions, 1.326; nine repetitions, 1.368; and 10 repetitions, 1.41. For the bench press or chest press, coefficients include five repetitions, 1.15 coefficient; six repetitions, 1.18; seven repetitions, 1.22; eight repetitions, 1.255; nine repetitions, 1.29; and 10 repetitions, 1.325. So if you successfully completed nine bench presses with a total weight of 95 pounds, your predicted one-rep max is 95 x 1.29 = 122.55 pounds.
References
- "ACE Personal Trainer Manual" Fourth Edition; Cedric X. Bryant, Ph.D., FACSM, and Daniel J. Green; 2010
- Mayo Clinic: Weight Training: Do's and Don'ts of Proper Technique
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