Peak Load vs Estimated 1RM vs Top Set Output
Most apps show you a handful of numbers per lift. They are not interchangeable, two of them reward bad habits, and only one of them answers the question you're actually asking. Here's what each one measures and where it misleads.
The short answer
Estimated 1RM is the one to track over time. Peak Load tells you what you lifted on your best day and is easy to move without getting stronger. Top Set Output and Best Session Total are training-load measures that tell you about work done, not capacity built — useful for programme design, misleading if you read them as progress. If you can only track one number per lift, make it the estimated max.
The four records, defined
| Record | What it is | What it measures | As a progress signal |
|---|---|---|---|
| Peak Load | Heaviest weight logged for the lift, any session | Absolute load capacity on a single day | Weak — see below |
| Estimated 1RM | Best set projected to a single, via formula | Capacity normalised across rep counts | Strong |
| Top Set Output | Weight × reps on your highest-volume set | Work capacity in the heaviest-working range | Situational |
| Best Session Total | Summed volume across all sets of the lift | Total work done in one session | Volume, not strength |
Peak Load: the number that flatters you
Peak Load is the heaviest weight you have ever logged for a lift, and it is by far the most common "progress" display in strength apps. It is also the least informative as a measure of whether you are getting stronger, for a reason that is easy to miss.
Peak Load can go up in three ways: you got stronger, you did a single rep instead of five, or you were fresher that day. From the number alone you cannot tell which. A lifter switching from 5 reps to 1 rep at the same weight sees their Peak Load climb while their actual capacity is unchanged — or slightly worse.
Friday (fresh) 100 kg × 5
Same weight, same lift, very different days. Peak Load reads identically for both. What actually happened is visible only in the reps — and that is precisely the information estimated 1RM uses.
Peak Load is worth keeping as an all-time best marker. It is simply not a progress metric. Use it to know what you've done before, not to know whether you're improving.
Estimated 1RM: the one that survives comparison
Estimated 1RM takes your best set and projects it to an equivalent single, using a formula such as Epley: weight × (1 + reps ÷ 30). Because it normalises for rep count, sets at different loads become directly comparable.
The same two sessions from above, normalised:
- Monday, 100 kg × 1 → 100 × (1 + 1/30) = 103 kg estimated
- Friday, 100 kg × 5 → 100 × (1 + 5/30) = 117 kg estimated
Now the ordering is correct, and the gap — 14 kg of estimated capacity — is the actual difference between the two days. Peak Load hid that completely. This is the core argument for estimated 1RM over raw weight: it does not reward you for choosing a flattering rep count.
Two caveats worth keeping straight. It is an estimate, and it degrades at high rep counts — prefer your 2–10 rep sets for trend purposes. And it is sensitive to which formula you use, so pick one and never switch mid-series. Building a 1RM trend covers the method in detail, and the calculator compares six formulas.
Top Set Output: a work measure, not a strength measure
Top Set Output is the highest weight × reps product among your working sets — typically taken from your heaviest set that wasn't a true single. It exists to answer a question about work capacity: can you move meaningful volume at a meaningful load?
It is genuinely useful for programme design. If Top Set Output is climbing while estimated 1RM holds flat, you are likely getting stronger at work capacity rather than peak strength — often a desirable adaptation, particularly in phases where volume is the priority. It also tells you when you have genuinely progressed past a rep range.
Read as a progress signal on its own, though, it is misleading — it will climb for weeks while peak strength does not move at all, and then plateau while you are still getting stronger. Track it as a complement to estimated 1RM, never instead of it.
Best Session Total: volume, and volume is not strength
Best Session Total sums weight × reps across every set of a lift in your best session. It is a volume measure, and it answers a different question: how much total work did you do?
The reason it misleads as a strength metric is that volume responds to programme design, not just to capability. Add sets, add reps, drop the load — Best Session Total climbs while your actual strength is flat or declining. Many people experience this and read it as a good month, when it may reflect three weeks of volume accumulation before a deload.
It is the right number to look at when you're managing fatigue, planning a deload, or asking whether a training block did what you designed it to do. It is the wrong number to look at when asking whether you're stronger.
PR drought, and why it matters more than a new PR
One more measure worth tracking, because it answers a question the other four cannot: how long since this lift last improved?
A PR drought counter is simply days since the estimated 1RM for that lift last rose meaningfully. It's blunt and it will count a plateau you haven't noticed, but it does something none of the others do — it makes inaction visible. Most lifters notice a stall when performance drops; almost none notice a plateau that holds steady for ten weeks while they keep showing up and keep training.
Watch it per exercise rather than in aggregate. An aggregate PR drought across all lifts will be dominated by accessories you rotate and never improve, which tells you nothing.
What to actually track
Estimated 1RM as the primary signal, read in blocks of three sessions rather than daily. Session volume alongside it, to catch the fatigue pattern. PR drought per lift, to catch stagnation. Everything else is context. Four numbers is already more than most people maintain consistently, and consistency matters more than count.
Frequently asked
What is the difference between Peak Load and estimated 1RM?
Peak Load is the heaviest weight you've logged for the lift, regardless of reps. Estimated 1RM projects your best set to an equivalent single, which normalises for rep count. Peak Load can rise without you getting stronger — by lifting a single instead of five reps. Estimated 1RM cannot be moved that way.
Is Top Set Output the same as a PR?
No. Top Set Output is a work-capacity measure — the heaviest weight times reps on your highest-volume set. A PR is a peak measure. You can improve Top Set Output substantially without a new PR, particularly in a high-volume phase, and that is a real adaptation rather than a failure.
Should I track Best Session Total?
For managing fatigue and checking that a training block did what you designed it to, yes. As a strength metric, no — it responds to adding sets and reps, so it can climb while your actual strength is flat or declining.
Which single number best shows if I'm getting stronger?
Estimated 1RM per lift, compared in blocks of three sessions rather than day to day. It's the only one of the four that normalises for rep count and so cannot be flattered by choosing an easier rep scheme.
Why does my weight go up but my estimated 1RM not?
Almost always because the rep count dropped. Moving from five reps to a single at the same weight raises your heaviest weight and leaves your estimated capacity roughly flat. That's the pattern Peak Load hides and estimated 1RM is designed to expose.
Related
- Build an estimated 1RM trend from WHOOP logs
- Estimated 1RM calculator — six formulas compared
- How to spot a lifting plateau in your data
- Tracking strength progression on WHOOP
Sources
- Epley, B. (1990). Weightlifting predictors of one-rep max performance: a review. Journal of Strength and Conditioning Research.
- Schoenfeld, A.J. et al. on dose-response relationships in resistance training and volume metrics.
- ACSM position stand on resistance training progression models.