WalkFit: 3x3 Interval Walking

Why does walking 10,000 casual steps a day often hit a fitness plateau?
Clinical exercise physiology shows that the key to walking efficiency is not raw step count alone, but alternating aerobic intensity.

WalkFit is purpose-built for the 3x3 Interval Walking Training (IWT) protocol developed by Prof. Hiroshi Nose's team at Shinshu University School of Medicine:
Alternate 3 minutes of brisk, wide-stride fast walking (>=70% Heart Rate Reserve, ~130 SPM) with 3 minutes of recovery slow walking (40%-50% HRR, ~100 SPM) for 5 sets (30 minutes total) to boost aerobic capacity (VO2peak) while keeping knee impact low.

KEY FEATURES:
- 48kHz Hardware-Clock Metronome, Ambient Synth & Trilingual Voice Coach (Free): Real-time voice prompts and 48kHz woodblock metronome ticks guide your stride cadence with smart background music ducking.
- 6 Cockpit Dials, 8 Themes, Free Latest Replay & HD Poster: Includes Obsidian Lime, Nordic White, and Shinshu Hinoki themes, Classic Dual Ring, Classic Chrono Dial, and Giant Type views, plus 1x-30x synchronized trajectory replay and 3x HD shareable workout posters for your latest workout completely free.
- 18 Altitude & Biomechanical Metrics: Track steps, SPM cadence, dynamic stride, fused distance, pace, Grade-Adjusted Pace (GAP), heart rate, %HRR, METs, VO2, calories, net fat crossover, barometric climb, and Borg RPE, plus 4 Pro lab-grade metrics (GLUT4 CHO, HRR-60s vagal recovery, Gait CV%, and 6MWD aerobic decoupling).
- 2.5s Stationary Auto-Pause & 4-Step Auto-Resume: Automatically pauses at traffic lights after 2.5s and resumes after 4 confirmed steps, with inline Pocket Anti-Mistouch Lock (double-tap or hold 0.75s to unlock).
- WalkFit Pro Upgrades: Unlock AI Cadence Auto-Follow, AI Physiological Smart Tempo, Apple Watch Live HR & BLE 0x180D Heart Rate Strap connection, unlimited historical archive 1x-30x replay, and full-screen zoomable clinical charts. Includes a 24-hour free Pro trial (no card required).

WALKFIT PRO SUBSCRIPTION & TERMS:
- Options: Monthly Pro ($2.99/mo), Annual Pro ($14.99/yr), or Lifetime Pro ($24.99 one-time purchase). Prices may vary by region as displayed via StoreKit in the app.
- Auto-Renewal: Payment will be charged to your Apple ID account at confirmation of purchase. Subscriptions automatically renew unless canceled at least 24 hours before the end of the current period. Manage or cancel anytime in Account Settings.
- Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
- Privacy Policy & HealthKit Disclosure: https://github.com/fly699/i2cdevlib/blob/walkfit-legal/PRIVACY_POLICY.md
- Technical Support & FAQ: https://github.com/fly699/i2cdevlib/blob/walkfit-legal/SUPPORT.md

SCIENTIFIC REFERENCE & DISCLAIMER (Guideline 1.4.1):
- Reference: Nemoto K, et al. Mayo Clinic Proceedings, 2007; 82(7): 803-811 (PMID: 17605959) and 14 peer-reviewed PubMed citations linked inside the app.
- Medical Disclaimer: Intended for general fitness and wellness only; not a medical device and does not provide medical diagnosis or treatment advice. Consult a physician before starting any exercise program.