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Coach Sheet

Glossary entry — methodology

Estimated One-Rep Max e1RM

A predicted maximum weight a lifter could perform for one rep, projected from a sub-maximal working set using a regression formula like Epley or Brzycki. 

median of Epley + Brzycki + Lombardi formulas

What e1RM means

e1RM (estimated 1-rep max) is what the lifter could likely lift for one rep, calculated from a sub-maximal working set without testing the 1RM. The estimate comes from regression formulas fitted to historical lifting data, not from any specific physiological principle.

Three formulas dominate practical use:

Epley:    1RM = load × (1 + reps / 30)
Brzycki:  1RM = load / (1.0278 − 0.0278 × reps)
Lombardi: 1RM = load × reps^0.10

Worked example

A lifter benches 100 kg × 5 reps with RIR 1 (could have done 6). Effective rep count = 6.

Epley:    100 × (1 + 6/30)            = 120.0 kg
Brzycki:  100 / (1.0278 − 0.0278 × 6) = 116.2 kg
Lombardi: 100 × 6^0.10                = 119.6 kg

Median: 119.6 kg

The 119.6 figure becomes the lifter’s e1RM for bench press. Coach Sheet’s Lifting Records tab auto-calculates this in a column next to logged sets.

Why e1RM and not 1RM

True 1RM is unreliable to test. Catch the lifter on a tired day and the number undershoots; on a fresh day it overshoots. Form degrades at maximum effort, inflating measured numbers. The psychological cost of weekly max attempts adds up.

e1RM uses sub-maximal sets. Typically 3-8 reps in the working range. To project upward. The projection has uncertainty, but the trade-off is that you don’t have to risk a near-max attempt to know roughly where the lifter’s ceiling sits.

How accurate is it

LeSuer 1997 tested four prediction equations against measured 1RMs in 67 untrained subjects. Average error across all formulas: ±5%. No single formula was uniformly best; Brzycki was tighter on bench, Epley tighter on squat. Showing all three and taking the median gives ±3% on average.

For a trained lifter, the formulas tend to slightly underestimate at low reps (1-3) because trained lifters have a flatter strength-endurance curve than the formula assumes. Above 10 reps, the formulas drift apart and accuracy degrades sharply.

The honest practical interpretation: an e1RM is a working ceiling estimate, not a measured value. Use it for prescribing percentages of 1RM and for tracking progression trends. Don’t treat it as a meet-day expectation.

When to recompute e1RM

Each time the lifter logs a set in the working range. Coach Sheet auto-recomputes on every log; manual systems recompute weekly during programming review.

Track the e1RM trend over time, not single readings. A flat e1RM for 4+ weeks signals stagnation; a steadily climbing e1RM signals progressive overload working as designed.

When e1RM lies

The estimate inflates when:

  • The lifter exaggerated reps (8 reps but rep 7 and 8 were grinders that violated form)
  • The lifter undershot RPE (rated RPE 8 but it was RPE 9.5)
  • The set was performed with technique compromised by spotter assist or cheat reps

The estimate deflates when:

  • The lifter has bad neural day (low coffee, poor sleep) producing reps below their real capacity
  • The set was conservative on RPE rating (rated RPE 8 but RPE 7)

The fix for both directions: track the trend across many sets. Outliers smooth out. Run the 3-test PR protocol periodically to triangulate against multiple data points.

In Coach Sheet

The Lifting Records tab auto-calculates e1RM via:

=MEDIAN(EPLEY(load,reps), BRZYCKI(load,reps), LOMBARDI(load,reps))

with RIR adjustment baked into effective rep count. The Strength Progress tab charts e1RM trends per main lift over time. Save Week reads the latest e1RM to inform next week’s load prescriptions.

Sources

  1. [1]
  2. [2]