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Are these formulas close to every ones one rep max on varies exercises? and

I would like to know how accurate this is for everyone and if you have anything better?

Formulas to find your one rep max (or 1rm)

2 reps- 1.06 x weight lifted= 1rm
3 reps- 1.09 x weight lifted= 1rm
4 reps- 1.12 x weight lifted= 1rm
5 reps- 1.15 x weight lifted= 1rm
6 reps- 1.18 x weight lifted= 1rm
7 reps- 1.21 x weight lifted= 1rm
8 reps- 1.24 x weight lifted= 1rm
9 reps- 1.27 x weight lifted= 1rm
10 reps- 1.302 x weight lifted= 1rm

Example on how to use-

I went to the gym today and benched 300 pounds for 5 repetitions so i apply the formula 5 reps- 1.15 x 300 pounds = 345 pounds for my one rep maximum

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3 Answers 3

That is one formula that will make a good estimate, but it's important to remember that it is just an estimate and individual milage will vary. The only way to know for sure is to try it.

  • These formulae are generally targeted towards experienced strength athletes; novices are unlikely to be able to lift the predicted 1RM because they haven't trained their nervous system to sufficiently stimulate their muscles.
  • According to Practical Programming, women can generally lift an intensity close to their 1RM more times than men can, so e.g. their 5RM is much close to their 1RM than a man's would typically be.

This online 1RM calculator lists a number of alternate formulae:

  • Brzycki: 1RM = W x (36 / (37 - R))
  • Epley: 1RM = W x (1 + 0.0333 x R)
  • Lander: 1RM = (100 x W) / (101.3 - 2.67123 x R)
  • Lombardi: 1RM = W x R0.1
  • Mayhew et al.: 1RM = (100 x W) / (52.2 + (41.9 x e-0.055 x R))
  • O'Conner et al.: 1RM = W x (1 + 0.025 x R)
  • Wathan: 1RM = (100 x W) / (48.8 + (53.8 x e-0.075 x R))
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Considering the many formulas available for predicting your 1RM (one rep max), the best way to know which is closer for you is to test it at least once. Many intermediate strength programs have a day to test your 1RM built in as part of the program, and you'll be testing it once or twice per program cycle (roughly 12 weeks on average).

When you get to the point you want to know for sure what your current 1RM is, you'll need to test it safely. Even if you have three spotters, a dropped barbell can happen so fast that they may not be able to catch it in time. So, proper equipment is necessary:

  • Power rack: this is a cage with safety rails.
  • Safety rails: the safety rails should be put low enough so that it won't interfere with the barbell while you are lifting, but high enough not to cause injury if you drop the bar.
  • Flat bench: If you are testing a bench press, you need a flat bench that can fit in the cage.

Now, the rest is about testing the actual 1RM. You will want to have multiple 1 rep sets slowly ramping up in weight. My suggestion, and feel free to customize for the way you want to work, is:

  • Start with the highest weight you've lifted so far. If it's your 5RM, that's the starting weight. (You want one good lift)
  • Use the lowest calculated 1RM from the equations above. (Brzycki formula: 337.5 in your case)
  • Use the highest calculated 1RM from the equations above. (Epley formula: 350 in your case)
  • Using your past experience of how you feel, add sets increasing what you think you can above that.

Essentially, you'll have a minimum of 3 sets. You may decide after your second set that you might want another set or so in between. For example, if you feel like 337.5 is pushing yourself to your limits, you might try a small increase of 2.5lb and see if you can do 340. The bottom line is you keep going until you just can't anymore.

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Make sure you are giving yourself sufficient rest and recovery time in between your warm up sets so you can get to your true 1 rep max. You should be able to figure it out after 3 tries.

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