Load–velocity profiling
The central idea in velocity-based training. What the profile is, how to build one, and how to read it for 1RM, readiness and progress.
A load–velocity profile is a simple linear function: as the load on the bar goes up, the maximum velocity an athlete can produce comes down. The slope is consistent within an athlete but differs between athletes, which is what makes it useful. Build one and you can predict 1RM, daily readiness, and target loads from a few sub-maximal sets.
The relationship holds on virtually every strength exercise, and it’s stable and consistent enough to track progress, flag weaknesses, and monitor fatigue without scheduling a single testing day. It is, however, unique to each individual and each exercise: no two lifters share the same profile in absolute or relative terms, which is exactly why you build one per athlete, per lift.
Build your load–velocity profile
What it tells you
Three things, in order of how often you’ll use them:
- Estimated 1RM, in real time, from the workout that already happened. Where the line crosses minimum velocity threshold (the slowest a maximal effort rep ever moves for that lift) is the load the athlete could have hit on the day. No max attempt required.
- Daily readiness. The same load on Monday and Friday should sit on the same line. If Friday’s point sits above the Monday line, the athlete is moving faster than usual at the same load, so they’re recovered and primed. Below the line means fatigue or a technique drift; either way, ease off the gas.
- Programming intensity. Decide on a target velocity for the day’s intent, read against the athlete’s own profile rather than a universal chart, and the line tells you the load that produces it. The number on the bar follows the speed you want, not the other way around.
How to build one
The best part about load velocity profiling is that the only thing different you need to do is collect barbell velocity data. No extra set, no specific testing days booked. That makes it an attractive tracking method you can apply at any time of the season, without any extra fatigue or interruption to training flow.
Even better, if you use the Metric app the data collection and profiling is done fully automatically. Start a workout, record velocity on your preferred exercise, and once you have three or more sets completed Metric delivers your load velocity (and load power) profile. It even shows today’s profile against last session’s. If you use a different VBT device or app, the next best option is to input the data for each set into the free profiling calculator.
Load–velocity profile generator
Because the analysis and storage happen automatically, you can profile every single workout and accumulate enough data to trend with precision. Every workout becomes a low-stakes testing event: train as you normally would and collect velocity from all your sets, warmups included.
For a profile to be valid and reliable, the following criteria need to be met:
- At least 3 sets across a range of loads. Easily done by collecting velocity data from both warmup and work sets on a given day.
- One set above 75% of 1RM. This moderately heavy set is important to keep the profile valid. Without it, a weaker athlete can post inflated profiling scores.
- Use best-rep velocity/power from each load. Metric does this automatically; otherwise just scan the set for the highest mean velocity value.
- When coaching, be ready to eliminate cheat reps. Bouncing or flicking the bar, shortening ROM, and other reps with poor technique should be removed from the profiling data set.
As an example, a back squat profile (e1RM of 135kg) collected from a normal ramp-up might look like this:
- Set 1: 20kg x12, no data collected (warm-up)
- Set 2: 40kg x4, best rep 1.02 m/s
- Set 3: 80kg x4, best rep 0.83 m/s
- Set 4: 100kg x4, best rep 0.61 m/s
- Set 5: 115kg x4, best rep 0.46 m/s
If you prefer specific testing days, you can absolutely still run them as a way to collect profiles and create a motivating milestone in your program. Structure them however you like, and use the criteria above as your starting point.
Applications for the load velocity profile
While profiling a single session is fun and interesting, profiling really shines when we start comparing profiles over time, or between athletes, to highlight changes in performance.
This is why I’m such a big fan of high-frequency profiling. You can capture an accurate picture of how an athlete’s performance is changing in regular training and how they’re responding to their program. The ability to flag trends early and make adjustments is a monster advantage.
Competition and comparison
The load velocity profile is a great way to create fair competition between your athletes and build a motivating, challenging gym culture. You can do it by comparing the shape of two athletes’ profiles side-by-side, or, as you’ll see below, calculate a profile score like the e1RM and run a leaderboard on that.
It’s important, when competing on profiles, to take note of how you determine the x-axis. There are three options: percentage of one rep max, relative to bodyweight, or absolute load lifted. The one you choose determines what quality you’re highlighting.
When comparing between athletes, particularly field-sport athletes, I find multiples of bodyweight is the best way to go. Charts that use percentage of 1RM tend to be the most deceptive, especially when comparing different individuals.
Fatigue monitoring
A really simple, effective use of the load velocity profile is to track fatigue levels specific to each exercise. We do this by looking at the shape of today’s profile compared to your last workout.
Ideally, your profile should be slightly bigger every session: the same weights moving slightly faster, or heavier weights at the same velocity. When we’re fatigued, bar speed is one of the first things to suffer, so any time today’s profile sits below last session’s, that can indicate residual fatigue and reduced performance. Which might present an opportunity to apply autoregulation.
Tracking strength progress
Just as the profile lets us compete between athletes, it lets us compete with ourselves, trying to best a previous version of ourselves and build a bigger, better profile. The simplest way is to overlay the shape of your chart today against last session, last month, or last year.
Load velocity profiling scores
Beyond visually comparing profile charts, the other way to track strength progress is with a profiling score: take the raw data from the profile, apply some calculations, and find a single number that quantifies performance across all loads on that exercise. There are a few options, including the e1RM, Vzero/Lzero, and a performance index.
Estimating one rep max
The most commonly used calculation taken from the load velocity relationship is the estimated 1RM: getting a 1RM without having to complete a maximal set. It’s found at the intersection between the profile and a horizontal line drawn at the speed of your last rep before failure, also known as the minimum velocity threshold (MVT). For the full method, see the 1RM estimation guide.
Vzero & Lzero
These two scores take the profile and extend it out to its theoretical limits. By extending the line all the way to each axis, we can find the maximum load that would occur at 0 m/s (Vzero), or the maximum velocity at 0kg load (Lzero).
While both are theoretical, increases in each, relative to each other, can indicate performance on that exercise.
- An increase in Vzero suggests your maximum strength potential is improving: better force production, and likely a rising 1RM.
- An increase in Lzero suggests your explosive power and rate of force development is improving.
I quite like Vzero as an alternative to e1RM for measuring max strength when finding a reliable MVT isn’t practical. I tend to use Lzero less often, opting for the power curve and maximum power expression instead.
Performance index
This is my favourite progress-tracking score of them all. The performance index takes the total area of your load velocity profile and puts a single number on your performance, by calculating the area of the triangle created by the profile, the y-axis and the x-axis.
The equation is really simple: it’s Lzero times Vzero, divided by two. You can calculate it in absolute terms (a number usually in the hundreds), but the best way to use it is relative to bodyweight: divide the raw index by the athlete’s bodyweight for a relative score, usually somewhere between 2 and 5.
The relative performance index is great for competition between athletes (run a monthly leaderboard) and for tracking a single athlete through a changing bodyweight, which makes it ideal for athletic development and weight-class sports.
Load–velocity profile vs force–velocity curve
These two get conflated constantly, and the confusion is the root of a lot of misused velocity-zone theory. They are not the same thing.
The load–velocity profile is the practical, lift-specific line you measure in the gym: real data from a test or workout for one athlete on one exercise, capturing their ability at a moment in time. The force–velocity curve (or force–velocity profile) is a theoretical concept describing power-generating potential across all movements, derived from isolated-muscle physiology rather than a single session.
| Load–velocity profile | Force–velocity curve | |
|---|---|---|
| Description | Relationship between weight on the barbell and the speed of the barbell. Almost perfectly linear for most lifters. | Theoretical concept describing power-generating potential across all movements. |
| Data basis | Real data from a test or workout, specific to an athlete and exercise. | Theoretical; not based on single-session performance data. |
| Individuality | Unique to each athlete and exercise. Requires individual profiling. | A general model applied to all athletes. |
| Application | Track progress, flag weaknesses, monitor fatigue, measure performance. | Understand the balance between force and velocity in power generation. |
The force–velocity curve: more a theoretical concept than an actual test.
The load–power profile
A close sibling worth knowing: the load–power profile plots load against power produced (in watts) rather than velocity. Like the load–velocity relationship it’s stable and useful for prescription, but its shape is a curve, not a line. Power peaks at a moderate load, somewhere between roughly 30 and 80% of 1RM depending on the exercise and the individual, then falls off at both the light and heavy ends.
The load–power profile: parabolic, peaking in the mid-load range.
Where the line breaks down
Below ~30% of 1RM, velocity ceiling effects kick in (you can only move an empty bar so fast) and the line bends. Above ~95%, small load changes have outsized velocity costs and the linear assumption gets shaky. Inside 30 to 95% it’s clean.
The lift matters too: squat profiles are flat and reliable, bench less so, deadlift the noisiest. Each lift gets its own profile.
Getting started
Thanks to barbell velocity tracker apps like Metric and free tools like the load velocity profile calculator, regular profiling has never been easier. Experiment with these methods in your own training, track a few sessions, and let your profiling habits slowly evolve. Two guidelines to get you started:
- Pick the key lifts you really care about. You don’t have to, and probably shouldn’t, profile every exercise in your plan. At any given time I’m usually only focusing on two or three.
- Pick only one score per exercise. For me that’s relative max power (W/kg) for power cleans and trapbar jumps, and performance index (relative to bodyweight) for bench, trapbar deadlift, or safety bar squat.
Build your load–velocity profile
Articles in this topic
A complete guide to 1RM testing & strength estimation
Breaking strength personal records with VBT
How to find your 1RM — the 5 most accurate methods compared
Estimating 1RM with velocity-based training — the e1RM guide
Tracking progress in the gym with velocity based training (VBT)
Managing your bar speed data
Applications and example uses of velocity based training (VBT)
Charts in this topic
Load–velocity profile
The load-vs-speed function for a given lift and athlete. Plot a few sub-maximal sets and you can read 1RM from the line, compare lifts side-by-side, and see why a single percentage of 1RM lands different athletes in different velocity zones.
Force–velocity curve
The hyperbolic relationship between contractile force and shortening velocity. Theoretical, derived from isolated-muscle physiology — distinct from the load–velocity profile.
Load–power profile
Mechanical power output across the working load range, plotted in watts. The parabolic shape peaks at an intermediate load — typically 30–50 % 1RM for the squat.
Minimum velocity threshold by lift
Minimum velocity threshold values for back squat, front squat, bench, all three deadlifts, barbell row, and overhead press — by training level (novice / elite) and by effort tier (max out / tough / moderate).
Load–velocity vs force–velocity curve
The load–velocity profile is the practical, lift-specific line you measure in the gym. The force–velocity curve is the theoretical Hill hyperbola from in-vitro muscle physiology. Plotted on the same axes, they don't match — and that mismatch is the point.
Load–velocity and power curves
Linear LV profile (descending) and parabolic power curve (peaking mid-load) overlaid on the same load axis, dual y-axes. Shows why peak power lives between heavy strength loads and light speed loads.