VO2 Max Trainer vs 4x4 Timer Interval Training

Boost your VO2 max, one of the strongest predictors of endurance performance and of how long and how well you live. Measure your true VO2 max in 15 minutes or less, raise it with Zone 2 and HIIT workouts, and beat the rest of the world on a verified global leaderboard. iPhone and Apple Watch. NEW: GHOST RACE Race a ghost during your Cooper test, Balke test or 1.5 mile (2.4 km) run. Pick your best run, your 12-week goal, the athlete 10 places above you on the leaderboard, the #1 of your age group, an Olympic record, or any VO2 max you choose. The gap shows live in meters or yards, green when you lead and orange when you chase, with voice cues when you pass or get passed. Follow the race on the Lock Screen, in the Dynamic Island and on your Apple Watch, even without your iPhone. The result saves as a normal test, and you can share a "Me vs ghost" card. MEASURE YOUR VO2 MAX - Beep test 20 m and 15 m (bleep test, PACER test, multistage fitness test, Leger shuttle run) - Yo-Yo Intermittent Recovery test, levels 1 and 2 (YYIR1, YYIR2) - Cooper test (12-minute run) - Balke test (15-minute run) - 1.5 mile / 2.4 km run test Results are compared with age and sex norms. FIND YOUR TRUE MAX HEART RATE AND LACTATE THRESHOLD The 220 minus age formula can be off by 10 to 20 beats per minute. Run a beep test with a heart rate monitor and the app records your real maximum heart rate and estimates your lactate threshold from how your heart rate responds as the pace rises, with no lab and no blood test. Your Zone 2 and HIIT zones are then built from your own threshold. TRAIN TO IMPROVE IT - Zone 2 training with personal heart rate limits and Apple Watch haptics when you drift out of zone - HIIT and interval workouts: Norwegian 4x4, Tabata, Gibala, 30/30, EMOM, Myoreps - Free mode to log any session - Custom workout builder: work, rest, repeat blocks, warm-up and cool-down - A 12-week training plan built from your current fitness level - An AI coach on the Plan tab that tells you what to do today and why GLOBAL LEADERBOARD WITH VERIFIED RESULTS Compare your VO2 max with athletes worldwide by age, sex, country and job. A score only reaches the leaderboard after anti-cheat checks: GPS, heart rate (Apple Watch or a chest strap), cadence and vehicle detection. Verification badges show how each result was checked. O2 POINTS AND RANKS VO2 max moves slowly, so O2 Points show the work you put in every day. Every minute with heart rate earns points, harder zones earn more, and 80/20 training, following your plan and retesting give boosts. Climb 7 ranks, from Reserve Duty to Norwegian Cyborg. LIVE ACTIVITIES AND WIDGETS Every test, Zone 2 session and interval workout shows on the Lock Screen and in the Dynamic Island: level, time, heart rate and zone without unlocking. Home Screen and Lock Screen widgets show your next workout, readiness, fitness age, VO2 max progress, Zone 2 minutes, O2 rank and leaderboard position. KNOW YOUR BODY - Training readiness score (1 to 100) from HRV, resting heart rate, sleep and recent load - Fitness age, from your VO2 max and other health markers - Race time predictions from 5K to marathon - Post-workout analysis: effort score, time in each zone, pace, intervals - Editable history with monthly and yearly charts APPLE WATCH AND HEALTH Leave the phone at home: tests, Zone 2 and intervals run on the watch with haptics and audio. Workouts sync with Apple Health, and workouts from other apps can be imported. WHO IT'S FOR Athletes and runners who want to go faster for longer. Soccer, rugby, basketball and hockey players. People preparing for military, police or firefighter fitness tests, PE teachers, students and coaches. And anyone who wants a stronger heart and lungs, a younger fitness age and more healthy years. Built by one independent developer. Questions? Message me in the app. Terms of use (Apple standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

4x4 Timer Norwegian Intervals is a simple, distraction-free interval timer designed for the Norwegian 4x4 training protocol, a well-known aerobic workout used to improve cardiovascular fitness and VO₂ max. The method is straightforward: 4 minutes ON. 4 minutes OFF. Repeat x4. This app guides you through the full session with clear visual timers and optional sound cues so you can focus on the workout, not the clock. Why Norwegian 4x4? The Norwegian 4x4 protocol has been widely studied in exercise physiology research as an effective way to train aerobic capacity and endurance. In recent discussions about longevity and brain health, Louisa Nicola highlighted this interval method as a powerful cardiovascular training approach used in performance and health optimization. This app simply helps you run the protocol consistently. Features • Simple 4x4 interval timer • Clear ON / OFF phase guidance • Optional sound cues for interval changes • Large easy-to-read timer for workouts • Session progress tracking and streaks • Minimal interface designed for training No accounts. No complicated setup. Just start when you're ready. How it works Tap Start Push hard for 4 minutes Take 4 minutes full rest Repeat for 4 rounds Total session time: about 32 minutes. Ideal for • VO₂ max interval training • Running intervals • Cycling workouts • Treadmill training • Stepper or rowing workouts • HIIT cardio sessions Research context The Norwegian 4x4 method has been studied in exercise science for its ability to stimulate high aerobic workload during short intervals. The app references this training approach discussed by neuroscientist and performance expert Louisa Nicola in conversations around cardiovascular fitness and long-term health. This app does not provide medical advice and is intended only as a simple training timer.