4x4 HIIT vs n=1

Transform your cardiovascular fitness with the Norwegian 4x4 HIIT protocol - the scientifically-backed method used by elite athletes and researchers to dramatically improve VO2 max and heart health. WHAT IS 4x4? Four intervals of 4 minutes at high intensity (85-95% max heart rate), separated by 3 minutes of active recovery. That's it. WHY IT WORKS Developed by Norwegian exercise scientists, this protocol has been proven in clinical studies to: - Increase VO2 max faster than traditional cardio - Improve cardiovascular health - Boost endurance and athletic performance - Deliver maximum results in minimum time SIMPLE TO USE - Clear visual timer with audio cues - Tracks your intervals automatically - Works with any activity: running, cycling, rowing, or body weight exercises - No complicated setup - just hit start PERFECT FOR - Runners looking to improve race times - Athletes building aerobic capacity - Anyone wanting efficient, science-backed cardio - People with limited time for training The Norwegian 4x4 protocol is one of the most researched and effective HIIT methods available. Stop guessing. Start training with proven science. Download now and take the first step toward your best cardiovascular fitness.

Stop eyeballing trends in Apple Health. HONEST ABOUT RIGOR n=1 is for self-experimentation — unblinded, uncontrolled, sample size of one. Results screens say so in plain language. The point isn't proof; it's a structured way to see whether the thing you're trying actually moves your numbers. THE CORE LOOP • Pick a curated protocol or design your own (intervention + duration + tracked metrics) • Log adherence and optional energy / sleep quality / mood scores in a 15-second daily check-in • HealthKit data is fetched on demand: sleep, HRV, resting heart rate, weight, VO2 max, glucose, body temperature, workouts • When the protocol ends, see a baseline-vs-protocol chart per metric with the % change called out PROTOCOL LIBRARY 12 curated experiments across sleep, circadian, cardiovascular, recovery, and lifestyle — creatine, magnesium glycinate, Zone 2 cardio, morning sunlight, and more. Every protocol ships with a falsifiable hypothesis, an honest evidence summary, explicit cautions, and a difficulty rating. No fabricated effect sizes. SHARE A RESULT When a protocol ends, share a clean image card with the headline metric, supporting numbers, and a link back to the app — for your group chat, journal, or wherever you log your experiments. PRIVATE BY DEFAULT n=1 works fully offline. Your HealthKit data stays on your device — no ads, no analytics, no third-party tracking, no account required to start. n=1 is a self-experimentation tool, not medical advice. Always consult a qualified healthcare provider before starting any new health protocol.