Can You Estimate 1RM Without Maxing Out? Load-Velocity Profiling With a Smartphone

1RM is the anchor for prescribing training intensity, but true max testing takes time and puts real stress on athletes. A 2019 study showed that 1RM can be estimated accurately from submaximal lifts by measuring lifting velocity — even on a machine exercise, using nothing more than a smartphone app.

What the study looked at

Balsalobre-Fernández and colleagues tested 15 men with at least two years of resistance training experience (mean age 33.6). Each performed an incremental test up to 1RM on the leg extension, both bilaterally and unilaterally.

Velocity was measured by filming the weight stack at 240 fps with an iPhone app and calculating how far and how fast the plates moved. The researchers built an individual load-velocity line for each athlete, estimated 1RM using only loads below 90% 1RM, and compared it with the measured 1RM.

Key findings

Load and velocity formed a near-perfect line: individual fits were very high (bilateral R² = 0.96, unilateral R² = 0.93) with small errors
Estimated and measured 1RM agreed closely: correlations were r = 0.88–0.96 with no significant difference
Bilateral and unilateral profiles differ: at the same %1RM, unilateral velocities were different from bilateral ones, so one profile cannot be swapped for the other

The authors conclude that load-velocity profiles can be built not only for barbell lifts but also for machine-based single-joint exercises, simply by tracking the weight stack.

How to read this in practice

You may be able to update training intensities without frequent max testing, which is helpful in congested competition periods
Load-velocity profiles are specific to each exercise and to bilateral vs unilateral work; build them for the movement you plan to use
The data only mean something when conditions are standardized: maximal intent on every rep and a consistent range of motion

This was 15 trained men on a single machine exercise. Whether the findings hold for free-weight lifts, women or youth athletes is not known.

Using ATHCON

ATHCON automatically estimates 1RM from the weights and reps your athletes log — no max test needed — and lets you set intensity as %1RM. That means you can keep daily training loads on target without repeatedly testing true maximums.

Takeaways

1RM was estimated accurately from submaximal lifting velocity (r = 0.88–0.96)
A smartphone app was enough to build load-velocity profiles on a machine exercise
Profiles are exercise- and limb-specific; small sample of men, one exercise