The measurement problem
Is your athlete
getting better, or
just getting older?
A thirteen-year-old will get faster over six months doing nothing at all. Which means almost every before-and-after number you have ever been shown by a training facility is partly just growth.
What everyone else measures
Two dots and
a hopeful arrow.
The standard model in this industry is a one-time assessment: you come in, you get tested, you get a profile of strengths and weaknesses, and you get a plan. That is a genuinely useful thing and we do it too — it is the first session of every athlete we take.
But it answers where are you now. It does not answer the only question a parent is actually paying to have answered: did this work?
To answer that, you need a second measurement, a third, and a fourth — and you need something to compare them against besides the first one.
The comparison that matters
Everyone gets faster.
Not everyone gains ground.
Illustrative shape, not one athlete's data. The bar at Week 12 is the test's own margin of error — a change smaller than that is not a change. Real figures live on the Results page.
We track their growth directly
Height and body mass are measured at every testing day, to a fixed standard. A growth spurt shows up as the change between sessions — measured on our stadiometer, not estimated from a questionnaire. Nothing invasive, nothing asked of anyone but the athlete.
We re-test on a fixed cadence
Every two weeks on the qualities that move that fast, and a full re-test at the close of every 12-week block. Same gates, same protocol, same order, same time of day — because a trend line is only real if the measurement never changes.
We report standing, not just the gain
Your report shows what changed by more than the test's own margin of error, and where that leaves your athlete against our tested reference set for their age. Both numbers, every block — including when one of them hasn't moved.
Growth is part of the data
We measure growth the same
way we measure everything.
Two fourteen-year-olds can be years apart physically. One has already been through his growth spurt; the other hasn't started. Judging their test results against the same expectation is the most common mistake in youth athletic development.
The method
Measured, not
estimated.
Height is taken at every testing day — to a fixed standard, three times, median recorded. Because the cadence never changes, a growth spurt shows up in the data as it happens: the change in height between sessions tells us when an athlete is growing fast, without estimating anything.
When an athlete is mid-spurt, two things change. We read their test scores more cautiously — limbs are lengthening faster than control adapts, and numbers get noisy through that window. And we adjust how they're loaded, because a rapidly growing body earns different programming than a settled one.
Every result is then read against athletes the same age, tested on the same protocol, over the same window — peers who are growing too. That comparison is what "growth-adjusted" means.
A rule we hold ourselves to
We report what we measured, not what we modeled. We don't estimate your child's biological age, and we don't predict adult height. Any facility quoting either to a decimal place is selling you precision the underlying methods do not have.
Precision-engineered performance
Nothing here
is a stopwatch.
Four pieces of testing equipment, one report. Every number your athlete is measured on comes off the same gear, in the same order, every single time — which is the only reason a two-week trend line means anything.
Force production
Force plates
Measures how much force your athlete puts into the ground, how quickly they can produce it, and how evenly each leg contributes. Left-right asymmetries show up here long before they turn into an injury.
- Countermovement jump
- Left–right asymmetries
- Max isometric outputs
- Peak propulsive & braking metrics
Speed
Dual-beam laser timing gates
Two beams per gate instead of one, so a swinging arm can’t trip the clock early. Splits acceleration from top-end speed — because an athlete who starts well and fades needs the opposite of one who builds late.
- 10-yd acceleration
- 10-yd fly
- Max velocity (mph)
Power
Jump mat
Contact time and flight time on every jump. That gives us jump height, reactive strength, and how efficiently your athlete stores and returns elastic energy — the quality that separates quick from merely strong.
- Max vertical jump
- mRSI (reactive strength)
Power at speed
Keiser pneumatic resistance
Measures power through the whole range of a movement, not just how much weight moved. Shows us where your athlete actually produces power and where it drops off — which decides how their programming gets built.
- Peak rotational power
All four feed one growth-adjusted report — not four printouts you have to reconcile yourself.
The protocol
Why every re-test
looks identical.
A trend line is only real if the measurement never changes underneath it. So every testing session at GPS runs the same way: the same warm-up immediately beforehand, the same tests in the same order, the same equipment and setup, the same rest between attempts, and the same time-of-day window.
The order isn't arbitrary — speed first, then jumps and reactive strength, then maximum strength, then mobility. Least fatiguing to most. Conditioning never runs before power, because a tired athlete tests like a slower athlete and you would read that as a regression.
Sprints and jumps are scored best-of-three, reactive strength best-of-five. New athletes get a familiarisation exposure before anything is logged as a real number, because the first time you do a test you are learning the test, not showing us your ceiling.
If a test can't be run under standard conditions on a given day, we don't log it. A contaminated number is worse than a missing one — it looks like data, and it will sit in your athlete's trend line lying to both of us.
Why two weeks
Test twice, twelve weeks apart, and you have a line with two points — and a line with two points can be drawn through anything. A bad night's sleep at either end moves it. Re-testing every two weeks, six times across a block, means no single session decides the story. You see a direction, and you see it early enough to change the plan while the block is still running rather than finding out at the end.
Reading the report
What a percentile is,
and what a good one
actually looks like.
A raw number tells you almost nothing on its own. Is a 4.9-second 30-yard dash good? It depends entirely on who's running it. A percentile answers that: it places your athlete against others their own age. At the 60th percentile, they are faster than 60 out of 100 athletes in their age band.
This is the mechanism that makes growth visible. If your athlete's raw sprint time improves but their percentile stays flat, they got faster at roughly the rate their peers did — the whole field is growing. If the percentile climbs, they moved up on athletes who were also getting older. That climb is a change in standing. It is not a measurement of what training contributed, and we won't dress it up as one — no honest test can separate those.
It also explains something that confuses parents: an athlete can post a personal best and still lose ground. Both facts are real, and we report both — the gain that cleared the test's margin of error, and the standing that hasn't moved yet.
Where this comes from
We didn't
invent this.
Reading a young athlete's results against age-group peers — instead of against a bare before-and-after — is established practice in long-term athletic development research, and professional academies have interpreted youth testing data this way for years.
What is unusual is doing it for a fourteen-year-old in Lake in the Hills, on a two-week cadence, and handing the parent a report that shows the gap in plain language.
Our claim is not that this science is ours. It is that we run it, on your athlete, and we put money behind the answer.
The honest boundaries
What this method
does not do.
Every measurement approach has limits. A program that won't tell you its limits is either not looking for them or not telling you.
A percentile move means nothing without its baseline
Athletes who start near the bottom of a ranking tend to drift up, and athletes near the top tend to drift down — that's statistics, not coaching. So we always report where your athlete started alongside where they moved, and we will never use a percentile drop alone to sell you urgency.
Standing is a diagnosis, not a verdict
Where your athlete ranks today explains why a result looks the way it does and what to train first. It is not a verdict on their ceiling, and it should never be used to decide who is worth developing. Late developers are the athletes this most often protects.
Our reference set is our own tested athletes
Percentiles place your athlete against the athletes we have tested in their age band — a training population, not a national census. That makes the comparison demanding, and we tell you exactly what it is rather than dressing it up as something bigger.
One re-test never decides anything
Sleep, illness, a heavy practice, exam week — all of it moves a number. Any single session can mislead. Only the direction across several re-tests is worth acting on, which is exactly why we test as often as we do.
Use this on us too
Five questions to ask
any facility — including this one.
Most advice for parents evaluating a training program stops at "make sure they measure something." That isn't enough. Measuring the wrong thing consistently still tells you nothing. These five questions separate a program that can prove its work from one that is asking you to take it on faith.
- 01
What exactly will you measure, and on what equipment?
"We'll track their progress" is not an answer. You want named tests on named instruments. A stopwatch has roughly a tenth-of-a-second human error in it — which is larger than the improvement a twelve-year-old will make in a month. If the measurement error is bigger than the effect, the number is decoration.
- 02
How often will you re-measure, and under what conditions?
Two tests twelve weeks apart give you a line with two points, and a line with two points can be drawn through anything. You want a cadence frequent enough to show a trend, run under standardised conditions — same equipment, same order, same time of day. A number collected differently is not comparable to the one before it.
- 03
What are you comparing the result to?
This is the question almost nobody asks, and it is the one that matters most. Compared only to their own starting number, every growing athlete improves. Compared to other athletes their own age, you learn whether they gained ground or merely kept pace. Ask which comparison you're being shown.
- 04
What happens if the numbers don't move?
A program confident in its measurement will tell you what it changes when the trend is flat — and what it costs you. A program that has never considered the question will reassure you instead. Notice which answer you get.
- 05
Can I see the raw numbers, not just a summary?
You are entitled to your athlete's actual data — the test values, the dates, the conditions. A summary with no underlying numbers cannot be checked, and anything that cannot be checked cannot be trusted.
We wrote these to be used on us. If GPS ever can't answer one of them for your athlete, that is a real problem and we'd want to hear about it.
Why we'd rather be measured
This is the standard,
not the upsell.
Every block you see two things: what changed by more than the test's own margin of error, and where your athlete stands against our tested reference set for their age. Every athlete, every block. We don't attach a refund to it, because we control it completely and always deliver it — and a promise you can't fail isn't a promise.
The guarantee that does carry risk is the 12-Week Improvement Guarantee: if Week-12 testing doesn't show measurable improvement in at least one of your athlete's three priority areas — with 90%+ attendance and tracking — you choose another 12-week block free, or a full refund of that block.
Guarantee terms are defined in the enrollment agreement · 90%+ attendance & tracking required
Straight answers
Questions parents
actually ask.
The five we get asked most about how any of this is actually measured.
01 What does growth-adjusted actually mean?
It means your athlete is read against the athletes they actually compete against — others the same age we have tested, who are growing over the same window your athlete is. Depending on the age band and the test, that group runs from a couple of dozen to close to a hundred athletes, and it is currently male baseball athletes; we always tell you which group a number was read against. What we do not do is claim to calculate how much of an improvement was training and how much was growth. That number requires a baseline nobody has for these tests, and any program quoting it is guessing.
02 Why isn't a before-and-after number enough?
Because a 13-year-old who does nothing at all will still get faster and stronger over six months. Any program can show a before-and-after improvement in a growing athlete and call it a result. A comparison group that is growing over the same window at least tells you whether your athlete moved relative to the athletes they compete against — which a before-and-after number on its own cannot.
03 How often do you re-test?
Every two weeks on the metrics that respond that fast, with a full re-test at the end of each 12-week block. That cadence is what makes the trend line real instead of two dots on a chart.
04 Is the growth-adjusted reporting a guarantee?
No, and we would rather be straight about that than dress it up. Every block you get both numbers: what changed by more than the test’s own margin of error, and where your athlete stands against our tested reference set for their age — currently male baseball athletes, and we always say which group a number was read against. It is written into the enrollment agreement as part of what the Program includes, not as a refund promise. Attaching money to something we control completely and always deliver would be theatre. The guarantee that carries real risk is the 12-Week Improvement Guarantee.
05 What is a percentile, and what counts as a good gain?
A percentile places your athlete against others their own age — at the 60th percentile they are ahead of 60 out of 100 athletes in their age band. Two things to know about reading it. A few points inside one two-week window is noise. And an athlete who starts low will tend to climb while one who starts high will tend to slip, for purely statistical reasons — so we always show you where they started next to where they moved. A climb that holds across a full block, from a starting point that was not already near the bottom, is a real change in standing.
06 Can my athlete post a personal best and still have lost ground?
Yes, and it is the most useful thing this comparison tells you. If the raw number improves but the percentile stays flat, your athlete got faster at roughly the rate their peers did — the whole field is growing. That is not a failure, and we will still show you that the gain cleared the test’s margin of error, because it did. What it means is that the gap to the athletes they actually compete against has not closed yet. Closing it is what more time in the program is for.
07 What happens if my athlete is a late developer?
Late developers are the athletes most often written off in youth sport — they test behind peers who are simply further through their growth spurt. Two things protect them here. Their height is measured at every testing day, so when the spurt arrives we see it directly and read the noisy window around it accordingly. And their report always shows their own baseline and trend next to the age-band standing, so a low percentile reads as a starting point, never a verdict.
08 Do we get the raw numbers, or just a summary?
The raw numbers — the test values, the dates, and the conditions they were collected under. A summary with no underlying data cannot be checked, and anything that cannot be checked should not be trusted. That applies to us as much as to anyone else you might train with.