What is a one-rep max?

How do you know how much weight to lift when you start a resistance-training program? Most programs are designed around lifting a percentage of your maximum strength, so it’s important to know what that is so you can push yourself in the gym.

The one-repetition maximum test (1RM) is one of the most common measures used to find out the heaviest weight you can press just once (but not twice). You can also do multiple-repetition tests. (A 5-rep test seems to be accurate, but more than 10 reps becomes an unreliable test for maximum strength.)

This instructional video demonstrates the American College of Sports Medicine’s (ACSM) protocol for a 1RM test.

  • Start by getting a good warm-up by lifting 5–10 reps of about half the weight you think your 1RM might be; make sure you lift with good form.
  • Rest for a minute, then lift 3–5 reps of 60–80% of what you think your 1RM is.
  • Next, add 5–10 pounds and do the lift. If you’re successful, wait 3–5 minutes, add another 5–10 pounds and try again.
  • Continue that process until you fail to complete the lift; the last weight you successfully complete is your 1RM.

ACSM’s protocol also can be applied to a multiple-repetition test. For example, for a 5-rep max test, determine the most weight you can lift 5 times, but not 6 times. If you choose a 5RM test, you can use this training load chart from the National Strength and Conditioning Association (NSCA) to figure out what your 1RM would be. If you have doubts about whether this is the right test for you, consult a strength and conditioning professional.

To determine your training load (the amount of weight as a percentage of your 1RM), you need to set your workout goals to figure out what percent of your 1RM you should lift. To improve muscular strength, you should lift a lower number of reps (typically 6–8) at 60–80% of your 1RM; to improve muscular endurance, lift a higher number of reps (12–15) using about 50% of your 1RM.

Now that you’ve figured out your training load, you can set your long-term workout goals and put together a periodized plan to really optimize your time in the gym.

Happy lifting!

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American College of Sports Medicine. (2017). ACSM Guidelines for Exercise Testing and Prescription (10th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.

Reynolds, J. M., Gordon, T. J., & Robergs, R. A. (2006). Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. The Journal of Strength and Conditioning Research, 20(3). doi:10.1519/r-15304.1

Scofield, D. E., Sauers, S. E., Spiering, B. A., Sharp, M. A., & Nindl, B. A. (2017). Evidence-Based Approach to Strength and Power Training to Improve Performance in Tactical Populations. In B. Alvar, K. Sell, & P. A. Deuster (Eds.), Essentials of Tactical Strength & Conditioning. Champaign, IL: Human Kinetics.