4x4 Timer Interval Training

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.