Does 5 g per day of creatine monohydrate for 21 days raise my countermovement jump by more than 1.2 cm over baseline?
+0.6 cm on the jump, +0.9 kg on the scale, and a power calculation that says I never had a chance.
Dates
Apr 21 – May 25, 2025
Duration
35 days
Pre-registered primary
Countermovement jump, best of 5 (cm)
FN-02 · 01
The question
Creatine monohydrate is the best-evidenced legal supplement in sport; the Truth Engine gives it the strongest verdict on that entire shelf, on the back of hundreds of group trials. But those are groups, over months. The question I can actually ask is smaller and more personal: with the measurement tools I own, could I detect anything in myself in three weeks?
Falsifiable form: 5 g daily, and my countermovement jump has to move more than 1.2 cm against a two-week baseline. The 1.2 figure is not from a paper; it is my own measured session-to-session spread, established during the baseline. Anything smaller than my own noise floor does not count as detected, by construction.
FN-02 · 02
Pre-registration
- Protocol
- 5 g creatine monohydrate (plain powder, third-party tested) dissolved in juice every morning with breakfast. No loading phase. Training, diet, and sleep continue unchanged.
- Duration
- Two-week jump-testing baseline (6 sessions), then 21 days on creatine (9 sessions). Daily body-mass log runs one week before and throughout.
- Primary outcome
- Countermovement vertical jump, best of 5 attempts, measured Mon/Wed/Fri before practice: chalk on fingertips, mark on the gym wall, standing reach subtracted, same warm-up every time.
- Secondary outcomes
- Morning body mass, daily: after bathroom, before breakfast, same scale, same spot on the floor
- Perceived heaviness in the final set of practice, 1 to 5
- Counts as null
- Jump change under 1.2 cm (my baseline session-to-session range) counts as not detected. I am writing 'not detected' rather than 'null' on purpose: see the power note in the write-up.
Saved as a dated, unedited note before day one. The goalposts above are the goalposts the data was judged against; nothing in this record was touched after the first measurement.
FN-02 · 03
The protocol
Compliance was 21 of 21 doses, which sounds virtuous until you remember it involves drinking juice. Monohydrate, because every fancier form on the shelf is the same molecule with better marketing; the Truth Engine audit covers that in detail. No loading phase, because 20 g per day is a well-documented way to spend a tournament weekend near a bathroom.
Jump testing was the strictest measurement routine I have run: same shoes, same 8-minute warm-up, same five attempts with 45 seconds rest, best mark kept. The wall-and-chalk method resolves about half a centimeter on a good day, and that number turns out to be the entire story of this experiment.
Dose
5g/day
Compliance
21/21doses
Jump sessions
15total
Mass log
28days
FN-02 · 04
The log
The actual daily data, charted with the intervention window shaded, plus the raw log as a table under each chart. Same arrays feed both, so they cannot disagree.
Axis spans 3 cm to make a 0.56 cm shift visible at all. The last three sessions are the three highest, which is also exactly what a practice effect looks like.
›View the raw log · 15 rows
| test session | Date | Phase | Jump height (cm) |
|---|---|---|---|
| 1 | Apr 21 | baseline | 42.1 |
| 2 | Apr 23 | baseline | 41.3 |
| 3 | Apr 25 | baseline | 41.9 |
| 4 | Apr 28 | baseline | 42.4 |
| 5 | Apr 30 | baseline | 41.5 |
| 6 | May 02 | baseline | 42 |
| 7 | May 05 | intervention | 41.8 |
| 8 | May 07 | intervention | 42.3 |
| 9 | May 09 | intervention | 41.9 |
| 10 | May 12 | intervention | 42.6 |
| 11 | May 14 | intervention | 42.2 |
| 12 | May 16 | intervention | 42.9 |
| 13 | May 19 | intervention | 42.4 |
| 14 | May 21 | intervention | 43 |
| 15 | May 23 | intervention | 42.7 |
The manipulation check I did not know I was running: creatine is osmotically active, intramuscular water rises inside two weeks, and the scale saw the molecule arrive even though the jump test could not.
›View the raw log · 28 rows
| study day | Date | Phase | Body mass (kg) |
|---|---|---|---|
| 1 | Apr 28 | baseline | 63.4 |
| 2 | Apr 29 | baseline | 63.2 |
| 3 | Apr 30 | baseline | 63.5 |
| 4 | May 01 | baseline | 63.3 |
| 5 | May 02 | baseline | 63.6 |
| 6 | May 03 | baseline | 63.4 |
| 7 | May 04 | baseline | 63.3 |
| 8 | May 05 | intervention | 63.5 |
| 9 | May 06 | intervention | 63.6 |
| 10 | May 07 | intervention | 63.8 |
| 11 | May 08 | intervention | 63.7 |
| 12 | May 09 | intervention | 63.9 |
| 13 | May 10 | intervention | 64 |
| 14 | May 11 | intervention | 63.9 |
| 15 | May 12 | intervention | 64.1 |
| 16 | May 13 | intervention | 64 |
| 17 | May 14 | intervention | 64.2 |
| 18 | May 15 | intervention | 64.1 |
| 19 | May 16 | intervention | 64 |
| 20 | May 17 | intervention | 64.2 |
| 21 | May 18 | intervention | 64.3 |
| 22 | May 19 | intervention | 64.2 |
| 23 | May 20 | intervention | 64.4 |
| 24 | May 21 | intervention | 64.3 |
| 25 | May 22 | intervention | 64.2 |
| 26 | May 23 | intervention | 64.4 |
| 27 | May 24 | intervention | 64.5 |
| 28 | May 25 | intervention | 64.4 |
FN-02 · 05
What happened
Jump, baseline
41.9cm
Jump, creatine
42.4cm
Delta
+0.6cm
Body mass
+0.9kg
Jump: baseline mean 41.9 cm (range 41.3 to 42.4), creatine mean 42.4 cm (range 41.8 to 43.0). The change is +0.56 cm, under the 1.2 cm bar. There is an upward trend, and the last three sessions were the three highest of the whole study, but 'the last measurements are the highest' is precisely the signature of a practice effect in a repeated test, so it buys nothing on its own.
Body mass: 63.4 kg baseline to a final-week mean of 64.3 kg, a gain of roughly 0.9 kg with a visible ramp over the first two weeks and a plateau after. This is textbook creatine pharmacology: the molecule is osmotically active, water follows it into the myocyte, and the scale registers the loading of the phosphocreatine pool. The compound demonstrably arrived. Whether it did anything to my jump is a different question, and here is why mine cannot answer it.
The power note, which is the real result. The literature's expected effect on power tasks after saturation is roughly 1 to 2 percent, which on my 42 cm jump is 0.4 to 0.8 cm. My baseline session-to-session standard deviation is about 0.4 cm, and my measurement method resolves half a centimeter at best. I pre-registered a detection bar of 1.2 cm that the true effect, if present at full literature strength, would probably fail to clear. That is not creatine failing. That is my experiment being deaf at the frequency creatine sings at, and I can prove the deafness with my own baseline data.
The scale saw the molecule arrive. The jump test never had the resolution to.
FN-02 · 06 · Mandatory in every entry
Why this is weak evidence
This section is the module’s actual thesis. The result above is the least important thing on this page; the list below is why.
01
Underpowered by construction
Expected true effect: 0.4 to 0.8 cm. My noise: 0.4 cm per session, 0.5 cm instrument resolution, nine post-baseline sessions. An effect the same size as the noise cannot be resolved in nine samples; I could have computed this before starting, and next time I will.
02
No blinding, and jumps are motivational
I knew what I was taking and what it is famous for. A countermovement jump has a genuine effort component, and 0.5 cm of extra intent is entirely within my gift. Hope can jump higher than that.
03
Practice effect on the primary
Jump technique improves with repeated testing, and my baseline was likely still drifting upward when the intervention started, which inflates any before-versus-after comparison in the direction I wanted.
04
The mass gain is confounded too
Sodium, glycogen, hormones, and three ordinary weeks of a growing seventeen-year-old can move a scale by a kilogram. The timing and shape of the ramp fit creatine loading, but fit is not proof.
05
One instrument, made of chalk
The entire primary outcome ran through fingertip chalk marks on a wall, read by the person doing the jumping. There are force plates in the world. I did not have one.
FN-02 · 07
What I would do differently
- 01A jump mat or force plate, borrowed from anywhere, so the instrument resolves millimeters instead of guessing at half-centimeters.
- 02An 8-to-12-week timeline with a washout block, sized so the expected effect is at least twice my measured noise. Power first, enthusiasm second.
- 03Blinding: a friend fills identical capsules (creatine versus flour), holds the key, and does not tell me the order until the log is closed. Cheap, and it removes the motivation problem entirely.
- 04Pre-register the body-mass ramp as an explicit manipulation check instead of discovering afterward that it was the only unambiguous measurement I made.
FN-02 · 08
The verdict
The verdict, for me
InconclusiveInconclusive, and I am keeping the creatine. That looks like exactly the goalpost-moving this module exists to prevent, so the reasoning goes on the record: my decision is not based on my data. It is based on the group literature, which is unusually strong and unusually consistent, plus a manipulation check showing I absorbed the compound. My three weeks of chalk marks were never capable of overturning that prior, and the pre-registration said so before dose one.
The non-verdict, for you
This entry tells you nothing about whether creatine will do anything for you; the trials it rests on are summarized in the Truth Engine audit, which is where that question actually lives.
What it does tell you is transferable and slightly embarrassing: before you self-experiment, check whether your measurement can even see the effect you are hunting. Mine could not, I half-knew it going in, and the honest name for that is theater with a spreadsheet.
FN-02 · Cross-references
Where this entry leads
The group evidence, the mechanism, and the instruments behind this experiment live in the other modules.
Education, not diagnosis. This is a student-authored science platform. Nothing here replaces a physician, a physical therapist, or an athletic trainer. Sudden severe pain, numbness, an inability to bear weight, or visible deformity means stop reading and get seen.