N4x4 vs Trellis

The best Norwegian 4x4 App on the App Store. Train the Norwegian 4x4 without watching the clock or guessing your effort. N4x4 reads your live heart rate — from Apple Watch, AirPods Pro 3, Garmin, WHOOP, Polar, or any Bluetooth monitor — and turns it into clear push, hold, and ease-off cues through every interval. When you finish, you see exactly how long you held the target zone, and how today compared with last time. Four 4-minute efforts, three easy recoveries. 33 minutes, warm-up and cooldown included. It trains VO2 max, the fitness marker most closely tied to how well you age, and it's one of the most studied ways to raise it. If you're going to invest time in your health, this is a strong place to start. HIT THE RIGHT ZONE • Target zones calculated from your own max heart rate • The number turns orange when you're below the zone and red when you're above, on both iPhone and Apple Watch • Spoken and haptic nudges when you drift out and stay out • A haptic countdown into every interval change: two taps, then the buzz USE THE SENSOR YOU ALREADY OWN • Apple Watch: install N4x4 on your wrist and heart rate streams automatically • AirPods Pro 3: the earbuds you're already wearing double as your heart rate monitor (iPhone on iOS 26) • Garmin (Broadcast Heart Rate), WHOOP (HR Broadcast), Polar, Wahoo, COROS, Powerbeats Pro 2, and any standard Bluetooth chest strap or armband • Wearing more than one? You choose which source wins • A built-in guide with exact, per-model setup steps EASY TO KEEP THE HABIT • Voice coaching through every interval, with the phone locked and your music ducked • Night-before, morning-of, and comeback reminders — each on its own switch • Weekly streaks, and a Live Activity on the Lock Screen and Dynamic Island FINISH WITH PROOF • Every interval charted against its target zone • Time in zone, time to zone, and a note per interval for your settings • Last session laid over today's, so progress is easy to see • Your usual workout — Cycle, Run, Kettlebells, and more — pre-selected when you save SEE THE PAYOFF • Your VO2 max trend from Apple Health • Training calendar, milestones, and full session history Works on the treadmill, rower, bike, stair climber, with kettlebells, or on the open road — any cardio that gets your heart into the zone. No account. No subscription. No ads. Your data stays on your device and in Apple Health. Start with one hard session a week. Add a second when you're ready.

Trellis is a habit tracker built around one idea: real life has rest days, busy weeks, and schedules more interesting than "every day." Trellis is designed to understand them — so your streaks, stats, and reminders finally match how you actually live. STREAKS THAT UNDERSTAND REAL LIFE The streak engine knows your schedule: a rest day never breaks a streak, today isn't "missed" while it's still pending, and skips can excuse a day. A 26-week heatmap and 12-week trends show the long game. ON-DEVICE INSIGHTS Your best and worst weekdays, habits at risk, and habit correlations — like "on days you meditate, you're more likely to exercise." Computed entirely on your device; nothing ever leaves it. FLEXIBLE SCHEDULES Daily, specific weekdays, N times per week, every N days, or N times a month. Check-off habits or quantity goals like 8 glasses of water. Log today — or catch up on the past week. SMART REMINDERS Per-habit reminders with quiet hours, skip-when-done, streak-risk rescues before a streak breaks, and a Monday summary. No reminder spam. SIRI & SHORTCUTS "Mark Meditation done." "How are my habits today?" Log and review by voice, from Spotlight, or with Shortcuts automations. WIDGETS EVERYWHERE Home screen, lock screen, and Mac desktop widgets with one-tap logging — the ring updates without opening the app. PRIVATE BY DESIGN No account. No server of ours. No analytics. Your data syncs through your personal iCloud and can lock behind Face ID / Touch ID. One app for iPhone, iPad, and Mac — built natively for each.