Journal

Measurement notes · Sources cited · No oracle

Notes on recording your own physiology at full resolution — nights from the Polar Loop, raw RR intervals from chest straps, Concept2 sessions, and the files that hold it all. What we record, why it stays on your iPhone, and what a record you own makes possible.

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One number, or the whole night

Your body produces about 25,000 heartbeats a night and most apps hand you one number. What the full record looks like — and why one bad beat can quadruple it. 2026-09-18

A Polar Flow alternative for Loop and H10 owners

Run the Loop directly from your iPhone — setup, sync and full nights without an account — and keep the raw record in your own files. What ampulse does and what we stand for. 2026-09-15

Endurance training without the cloud

Recording, analysis, storage, sharing: which parts of a training setup genuinely need a server — and how a local record survives outages, shutdowns and lapsed subscriptions. 2026-09-15

Fitness data privacy: Oura, Whoop, Garmin — and the no-cloud option

Where health data lives with cloud wearables, why you rarely get to see the raw signal behind your own night, and what architecture without a server changes. 2026-09-15

“Privacy compliant” is not the same as private

Three questions no cloud wearable can answer — where is last night stored, who owns the company, which law applies — and the direct connection that makes them answerable. 2026-09-15

The loudest request in fitness software right now is an MCP connector

861 votes on a competitor's public board, official servers from Strava and COROS — assistants reading training data became the loudest demand in fitness software. Hosted vs local, and what ampulse ships. 2026-09-15

Plan your next race with Claude on your own record

Marathon, half or 10k: the local MCP connector puts your nights and sessions in Claude’s hands — and the plan comes back as structured weeks and .zwo workout files. 2026-09-15

Recording raw RR intervals from a Polar H10 during training

Every beat interval at millisecond resolution, banked on your iPhone: what the strap sends, why it is reference grade, and the export path to FIT, CSV and Kubios. 2026-09-15

Concept2 RowErg and SkiErg sessions, on record

PM5 watts and pace on one timeline with raw RR from the strap — the most repeatable training environment there is, turned into files you own. 2026-09-15

Using the Polar Loop without Polar Flow

How direct Bluetooth setup, sync and firmware updates work without a Polar account — and what the raw night files contain. 2026-09-15

Nightly HRV vs the morning spot check

What the peer-reviewed comparisons actually found: reliability numbers for both protocols, the one head-to-head overload study, and why a single reading is noise either way. 2026-09-15

RMSSD vs SDNN: why HRV numbers differ between apps

Two apps, two “HRV” values, same body. Most of the gap is the statistic itself — what each one summarises, what Apple Health stores, and the one rule that keeps trends honest. 2026-09-15

DFA alpha 1, explained

The heart rate variability index behind live intensity thresholds: what the 0.75 and 0.50 markers estimate, what the method needs from a chest strap, and where its limits are. 2026-09-15