Ramp4x4 vs Stellar Intervals

Train your VO2 max with guided Norwegian 4x4 interval workouts. Ramp4x4 handles the timer, heart-rate guidance and coaching so you can focus on the effort. Four 4-minute hard intervals. Three-minute active recoveries. Warmup and cooldown included. Start the classic workout for free on iPhone or Apple Watch. KNOW WHAT TO DO NEXT See your next session, recent workouts and cardio fitness in one clear Today view. Follow a structured 8-week plan with Ramp4x4+, progressing through Build, Overload, Peak and Taper. STAY WITH YOUR TARGET See whether your heart rate is below, within or above your target. Follow interval countdowns, voice cues and haptics without constantly watching the clock. Apple Watch is optional: use a compatible Bluetooth heart-rate monitor, supported heart-rate earbuds on iOS 26 or later, or Timer Only on iPhone. TRAIN WHERE YOU LIKE Run outdoors, use a treadmill, ride a bike, or train on a rower, elliptical, stair climber or SkiErg. Run a workout directly from Apple Watch, even when your iPhone is unavailable. MAKE EVERY INTERVAL COUNT Review completed intervals and your latest workout summary. Ramp4x4+ adds full workout history, interval breakdowns, time in target, heart-rate recovery and workout-quality insights to help you understand each session. FOLLOW YOUR CARDIO FITNESS See your latest available VO2 max estimate from Apple Health. Ramp4x4+ adds available Cardio Fitness history and workout trends. Ramp4x4 displays Apple Health estimates; it does not directly measure VO2 max or guarantee improvement. Indoor workouts do not generate Apple Watch Cardio Fitness estimates, and a new estimate is not guaranteed after every outdoor workout. START FREE - Unlimited classic Norwegian 4x4 workouts - iPhone and Apple Watch workout guidance - Standard voice cues, haptics and interval countdowns - Apple Health workout saving with permission - Your latest workout summary and available Cardio Fitness estimate GO FURTHER WITH RAMP4X4+ - Complete 8-week training plan - Full workout history and detailed interval analysis - Available VO2 max history and workout trends - Custom interval, recovery and warmup presets - Advanced heart-rate alert and coaching settings Ramp4x4+ is an optional auto-renewing monthly or annual subscription. Price and duration are shown before purchase. Manage or cancel your subscription in your Apple account settings. No account or login required. Heart-rate features require a supported source. Apple Health features require permission and available data. Supported heart-rate earbuds require compatible hardware and iOS. Ramp4x4 provides general fitness guidance, not medical advice. Build up gradually and speak with a clinician before high-intensity exercise if you have a health concern. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://rampworkout.com/privacy/

Most Norwegian 4x4 timers count the clock. Stellar Intervals counts what matters: the time your heart is truly in the zone — and how fast it recovers afterward. THE PROBLEM WITH CLOCK-BASED 4x4 The Norwegian 4x4 protocol calls for four 4-minute intervals above ~85% of your max heart rate. But it takes time to climb into that zone — often 60 to 90 seconds. A standard timer counts that ramp-up as "work," so you get an uneven, watered-down dose every session. Two workouts that look identical on the clock can be completely different efforts. TRUE TIME IN ZONE Stellar Intervals fixes this with a heart-rate-gated timer. The interval clock starts only when you cross your 85% threshold — and pauses the instant you drop below it. No more junk time. Every session delivers a true 16 minutes of high-intensity stimulus. Repeatable, predictable, honest. A CLEAN SIGNAL: HEART-RATE RECOVERY Here's what true time in zone unlocks. Heart-rate recovery (HRR) — how many beats per minute your heart drops in the first minute after an interval — is one of the most studied markers of cardiovascular fitness. But it's only meaningful if the effort before it was consistent. Because Stellar Intervals standardizes every interval to the same load, your HRR becomes a clean, comparable number you can trust. Track it interval to interval and week to week, and watch your fitness improve in a metric measured from your own training. THE SCIENCE The Norwegian 4x4 protocol is the gold-standard interval method for improving VO2 max — and VO2 max is one of the strongest predictors of long-term health and longevity. Stellar Intervals helps you execute the protocol precisely and follow your progress through HRR, a marker researchers have long tied to heart health and aerobic fitness. FEATURES Heart-rate-gated timer — counts only true time in zone Auto-pause when you fall below 85% HRmax Per-interval heart-rate recovery (HRR) tracking Long-term HRR and time-in-zone trends Works with Apple Watch and Bluetooth chest straps Sport-agnostic: run, bike, row, ski, or elliptical Apple Health integration Clean, distraction-free workout screen HONEST BY DESIGN Stellar Intervals does not estimate or claim to measure your VO2 max — no app can do that accurately from your wrist. What we do measure, we measure for real: your true time in zone and your heart-rate recovery. Two numbers you can trust, both improving as you train. WHO IT'S FOR Runners, cyclists, and rowers chasing VO2 max gains. Longevity-minded people who already track HRV, sleep, and biomarkers. Anyone who wants their 4x4 done with precision instead of guesswork. Requires a heart rate source (Apple Watch, Apple Airpods Pro 3 or Bluetooth HR monitor). Start your first true interval today.