Nobody Cares About Your One-Rep Max

Earlier this summer I found myself sitting in on an exercise prescription lecture for second-year Doctor of Physical Therapy students at my university. I’ll likely be delivering this lecture next year, so I wanted to have a look-see at the material that was currently being offered. Plus, I just love being that guy who sits in the back of the room interrupting the professor to add his two cents every so often.

One of the things that struck me during the lecture was the emphasis (or overemphasis, in my opinion) on the one-repetition maximum (1RM). For those not familiar, a 1RM is the heaviest weight you can lift one time for a given exercise.

(Note: if you’re feeling fussy, you can differentiate between a “true” 1RM and a “technical” 1RM. True would be the heaviest weight you can lift, form be damned, just get the weight up any which way. A technical max would be the heaviest weight you can lift with perfect form.)

Devoting lecture time to the 1RM isn’t unique to exercise prescription for physical therapy students. 1RM and the testing thereof gets a lot of attention in most exercise textbooks and kinesiology curricula. This thorough treatment of the 1RM isn’t without reason, of course. Tons of training parameters are based off of it.

Conventional training wisdom dictates that if you want to train for a particular adaptation (e.g. strength/power, muscle gain, or endurance), you do a specified number of reps that corresponds to a certain percentage of your 1RM. In addition, 1RM testing can be used to document performance gains over time.

That’s all dandy, but here’s my beef. Unless you’re a competitive powerlifter or an otherwise advanced trainee, the process of figuring out your 1RM is often unnecessarily painstaking, risky, and uninformative.

The number just isn’t that important.

Nevertheless, since the dawn of kinesiology instruction, many lectures and textbook chapters have been dedicated to the determination of the 1RM. The process usually goes like this:

1.    Start off with a weight you know will be easy, do a bunch of warm-up reps, and rest briefly.

2.    Add some weight, do a few more warm-up reps, and rest for a little longer.

3.    Add some more weight, do a couple last warm-up reps, and rest for a while.

4.    Choose your first test weight, and do one rep. If that was the absolute heaviest you could do, you’re done! Otherwise, rest completely and proceed to Step #5.

5.    Add a few pounds, and do one rep. If that was the absolute heaviest you could do, you’re done! Otherwise, rest completely and repeat this step.

See what I mean by painstaking? All told, we’re looking at around 6-8 sets and upwards of 10-15 minutes. Tack on another 5-10 minutes if you’re testing two sides separately (e.g. single-leg leg press). And that’s only for one exercise out of several that are presumably going to be trained. Not to mention exposure to relatively high loads for a person who may not tolerate them well. Is the risk versus reward really worth it? Let’s see.

As I mentioned above, the end-game of 1RM testing is generally to prescribe training loads. For example, say I want to hit my trainee with a weight they can do for 12 reps. (I could just hit them with my prosthetic leg, but they probably wouldn’t come back to me if I did that.) If I know their 1RM, there are at least half a dozen conversion formulas and tables out there I can use to figure out what percentage of their 1RM should allow them to perform those 12 reps.

The trouble is, these formulas are only theoretical estimates -- estimates that may be accurate on average across a large number of people but oftentimes not so much for the individual at hand. To boot, the estimates get worse as the target number of reps increases. The calculation might be decent for a set of 6 reps, but by the time you get to 12, it’s basically a crapshoot. Not only that, but the estimates are also for one set, and I’m often more interested in choosing a weight my client can handle for multiple sets.

The utility of these estimates even varies between men and women. Anecdotally, women can often perform a greater number of reps at a high percentage of their 1RM than men. Maybe women have more endurance than men. Maybe women’s nervous systems inhibit them to a higher degree as weights get heavy, causing them to underperform during 1RM testing unless they’re highly trained. Who knows.

What I do know is strength also fluctuates on a day-to-day basis for people regardless of their sex based on a myriad of factors (sleep, stress, time of day, mood, training status, etc.). This variability tends to make a 1RM from a previous day less relevant -- and potentially a fool’s errand to go chasing percentages off of.

All told, the time spent on 1RM testing could be better spent actually training or rehabbing and simply guessing loads. Anyone with half a brain and a few months of experience should be able to estimate an appropriate weight for sets of 8, 10, 12, or whatever for the person in front of them, plus or minus a few pounds.

Suppose you do over or undershoot the weight on the first set? You can easily adjust it for the second set based on how many reps the person achieved, how the reps looked, and how they felt (i.e. "perceived exertion").¹ Ask the person, "On a scale of 1-10, how difficult was that?" In general, for main lifts add weight if the answer is less than 8. For auxiliary exercises, add weight if the answer is less than 6. 

If your guess was way off, you can even decide to relegate that first set to warm-up, and you’ve only "wasted" about two minutes. Whoop-de-doo. Please, tell me again how important 1RM testing is for calculating training loads.

Now, if you’re using strength testing as a way to track performance gains, I’m totally on board. My primary recommendation here would be to choose an alternative that’s less risky than a 1RM, like a 10RM or 5RM (or maybe a 3RM, in some cases). Not only do you avoid unnecessary exposure to super heavy loads, but data points like these will also be a lot more relevant to people who train more in that 5-10 rep range.

For serious lifters or people who just like to geek out with numbers, I recommend making a table of all your main lifts and your repetition maxes, as shown below. Each time you train, endeavor to crush one of your previous bests.

Based on the above discussion, it may sound like I’m saying no one should ever max out. I’m not. I’m just saying you have to know when to do so (answer: infrequently; a few times per year at most) and for whom to do it (answer: advanced trainees and people who compete in lifting as a sport).

In a rehabilitation or training setting for a general population patient/client, there’s rarely a need for a 1RM. With any luck, educational paradigms will come around to this truth soon.

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1 I try to err on the side of undershooting. That way we're always adding weight rather than taking it away.^↩