Delta: Strength Training Log

Delta reads your recovery so you train at the intensity today calls for, progresses each lift by the method it responds to, and shows you which lifts are actually getting stronger.

Most workout trackers record what you did. The question a lifter actually has is whether that beat last time, and whether it beat it at a comparable load. Delta is built around that question.

READINESS, FROM YOUR OWN BASELINE Every morning Delta reads your overnight signals from Apple Health: resting heart rate, heart rate variability, respiratory rate, wrist temperature, and sleep. It scores today against your own baseline, where 50 is your normal. No universal thresholds. Readiness calibrates over your first 14 nights, and it needs an Apple Watch worn overnight. The rest of the app works fully without one.

A LOGGER BUILT FOR THE GYM FLOOR Sessions start on your iPhone, and the watch wakes as the logger: your last comparable set on screen, big targets, no fumbling. Straight sets, myo-reps, rest-pause, drop sets, top and back-off. Everything you log is saved the moment you enter it. Four templates to start from, including Push / Pull / Legs, or build your own, or import a program another Delta user shares with you.

SEE WHAT ACTUALLY MOVED Delta splits what you have actually gained from what you are re-establishing after a break, side by side, never averaged into a flattering number. An all-time PR list never expires; Delta tells you what you have genuinely got back. Estimated 1RM trends, per-muscle volume, consistency, and body composition from your scans.

COACH, WITH DELTA PLUS An AI coach that reads your logged training and readiness and gives specific, in-scope answers: swaps, push versus deload, recovery. It only sees what the screen says it sees, it never edits anything without your explicit confirmation, and it is training guidance, not medical care. You can turn its automatic session notes off on their own. Coach comes with Delta Plus. If you're on a trainer's plan, you can add it by upgrading to Plus.

JOINT-FRIENDLY, WHEN YOU NEED IT A picker filter for machine and cable movements, for the days or the years when barbells are not the answer.

YOURS, AND PRIVATE Yours. On your device, in your iCloud backups, synced to your Delta account, and exportable as JSON. No ads, no tracking, no third-party analytics. Delete your account from inside the app.

DELTA PLUS The full app, Coach included: $12.99 a month, or $99.99 a year with a one-month free trial. Subscriptions renew automatically through your App Store account and can be cancelled anytime in your Apple subscriptions.

Terms: https://deltafitness.app/legal/terms Privacy: https://deltafitness.app/legal/privacy

Discovery signals