Fitness wearable data,
actually analysed
Most comparisons of fitness trackers are written by people who own none of them, quote no sources, and describe testing they never did. StrengthInsight is the opposite: every guide is compiled from vendor documentation, published research, or arithmetic you can check yourself.
We cover what WHOOP, Fitbit, Garmin, Oura and Apple Watch actually measure — and how each metric is derived, including where the derivation is proprietary or estimated rather than measured.
- Research guides published
- 25
- Platforms compared
- 6
- First-party device testing
- 0
- Uncited claims permitted
- 0
- Free tools
- 1
Most read
Hevy + WHOOP: do they actually connect?
No — and the reason is structural rather than an oversight. What the API asymmetry means and how to run both in parallel anyway.
App integrationsHevy integrations: what connects to what
A capability matrix for every major pair — who syncs, who exports, and who needs manual work.
Strength dataTracking strength progression on WHOOP
What Strength Trainer records, what it leaves to you, and the one derived number that makes a trend visible.
EvidenceDoes WHOOP recovery predict your lifts?
The effect sizes are smaller than the marketing implies. What the research actually supports, and what it doesn't.
Reading your own training data
Improve your strength using data
The five-rule framework: log completely, derive one number, read in blocks, separate volume from strength.
Build an estimated 1RM trend
Turn logged sets into a progression line — formula choice and accuracy limits included.
Peak Load vs 1RM vs Top Set Output
Four records that look similar and mean very different things.
Spot a lifting plateau
A numeric definition, the three things that mimic one, and what to try in order.
Sleep consistency and your data
Which sleep metrics are actionable — and why your stage percentages are decoration.
Free toolEstimated 1RM calculator
Six formulas plus a programming percentage table. No signup, no account.
Google Health & Fitbit data
Where your Fitbit data goes now
Google deleted the web dashboard. What replaced it, and why iPhone and Android need completely different setups.
Recreating WHOOP on Google Fitbit
The API inputs, the published scoring methods, and where a Fitbit reimplementation stops short.
Google Health alternatives: 7 dashboards
What to use now the web dashboard is gone, compared on cost, hosting and data path.
Getting your Fitbit data into ChatGPT
Four routes that work. iPhone and Android need completely different answers.
Wearables compared
WHOOP strain vs other wearables
How the 0–21 strain score compares with Fitbit Cardio Load, Garmin Training Load, Apple and Polar — and why the numbers don't transfer.
Sleep and recovery with no subscription
Which wearables track sleep and recovery with no monthly fee — and the two big names that still charge.
Best tracker for recovery 2026
WHOOP, Oura, Garmin, Apple Watch and Fitbit on what they measure and where each falls short.
Fitbit Air vs WHOOP
Full comparison of the screenless tracker against the recovery-first alternative.
WHOOP vs Hevy
A logger and a readiness system. Which one you actually need.
The 2026 wearable landscape
Screenless bands, rings, and where the category is heading.
Using the WHOOP AI Coach
What the coaching features do, who they're for, and where the limits are.
New WHOOP features in 2026
Which of this year's releases change anything for a strength athlete.
What we don't do
- Claim to have worn devices for a fixed test period
- Report correlation figures we can't trace to a source
- Present an illustrative example as though it were a measurement
- Give medical advice — wearable scores are not clinical measurements
- Accept payment for coverage of any product
- Collect personal data. No accounts, no newsletter, no data sales
Our editorial standards set out the full method and how corrections work. Our disclosure explains exactly how the site makes money — and what that does and doesn't affect.
Frequently asked
What is StrengthInsight?
An independent research publication covering fitness wearables and the data they produce — what each platform measures, how its metrics are derived, how the platforms compare, and how to read your own strength training data.
Do you test the wearables you review?
No. Guides are compiled from vendor documentation, published research, or stated arithmetic, and each says which. Where we use a threshold or convention of our own — such as the plateau definition — we label it as our heuristic rather than presenting it as a published finding.
We also do not run the software, dashboards and open-source projects we write about. That coverage is desk research from official documentation, README files, licence terms and commit history. We have not installed those projects, connected a wearable, or verified a sync end to end, and our editorial standards spell out exactly what that does and does not cover.
Are you affiliated with any of the brands you cover?
No. Not affiliated with, endorsed by, or sponsored by WHOOP, Fitbit, Garmin, Apple, Oura, Hevy, Strava, Amazon, or any other company whose products we cover.
How does the site make money?
Affiliate commissions on a small number of product links. No sponsors, no subscription, no advertising network, no data sales. Guides with affiliate links say so before you reach them, and every link is marked.
Our coverage of software, dashboards and open-source projects carries no affiliate links at all. Where we list a paid service we state its cost and its free alternative rather than earning from it.
Do I need a wearable to use the methods here?
No. Estimated one-rep max, plateau detection and progression trends are arithmetic on a session log. A wearable adds recovery and readiness context, which is useful, but it isn't what turns a log into progress data.
How do I get my strength data out of my tracker?
It depends on the tracker, and it's usually the harder half of the problem. Hevy publishes a developer API and CSV export, which makes it unusually open. WHOOP's public API covers recovery, HRV, sleep and strain but does not expose per-set Strength Trainer data. We retired our own data-extraction guides in October 2026, because the tool they described no longer exists. We now cover the same problem editorially instead: where Google Health and Fitbit data can go in 2026 and what you can build from it.