Boost VO2 vs Intervalla

Boost your VO2 max and running performance with the Norwegian 4x4 interval training method. WHAT IS 4X4 TRAINING? The Norwegian 4x4 method consists of 4-minute high-intensity intervals followed by 3-minute recovery periods, repeated 4 times. This training protocol has been extensively researched and proven to significantly improve VO2 max and aerobic capacity. KEY FEATURES: Personalized Training Plans Create custom 4x4 training programs based on your fitness level Choose from 4-8 week plans with 1-4 workouts per week Get estimated VO2 max improvements for your specific plan Guided Workout Experience Audio coaching with clear interval timing and instructions Visual cues and haptic feedback during workouts Automatic phase transitions (warmup, intervals, recovery, cooldown) Voice coach selection for personalized motivation PERFECT FOR: Runners looking to improve aerobic capacity Athletes training for endurance events Fitness enthusiasts wanting to boost VO2 max Anyone following the Norwegian 4x4 method WHY CHOOSE BOOST VO2? Unlike generic interval training apps, Boost VO2 is specifically designed for the Norwegian 4x4 protocol. Our app provides the exact timing, structure, and guidance needed to maximize your VO2 max improvements through this proven training method. Start your journey to better aerobic fitness today with Boost VO2 - the ultimate 4x4 interval training companion.

Free. No ads. No account required. Intervalla is a precision interval timer built for serious training. Whether you follow the classic Tabata protocol, push through an AMRAP session, or design your own custom intervals — this app keeps you on pace with a clean, distraction-free interface. THREE TRAINING MODES • Tabata — 20s work / 10s rest with configurable rounds • AMRAP — As many reps as possible in one timed block • Custom — Set your own work, rest, rounds, warm-up and cool-down LIVE HEART RATE Connect any Bluetooth Low Energy heart rate monitor (Polar, Garmin, Wahoo, etc.) and see your BPM in real-time. Switch to HR mode for a live sparkline graph that tracks your intensity throughout the session. After your workout, get a full summary with avg/max/min BPM and time in each heart rate zone. WORKS WITH YOUR SCREEN LOCKED Put your phone in your pocket and train. Audio cues play reliably in the background, and your heart rate monitor stays connected — even with the screen off. DESIGNED FOR FOCUS • Circular progress ring with phase-specific colors • Distinct audio cues for work, rest, and transitions • Lock controls to prevent accidental taps mid-workout • Dark interface that's easy to read mid-workout SAVE YOUR FAVORITES Save up to 5 custom presets and start any workout with a single tap. Three built-in presets included to get you started immediately. AUDIO THAT WORKS Plays through the silent switch on iOS — never miss a cue. Different tones for work start, rest start, countdown, and workout complete. SHARE WORKOUTS Create a workout and share it with friends, training partners, or your community. One link opens a ready-to-run timer. COMPLETELY FREE No ads, no subscriptions, no account required. Just open and train. Built with care in Norway.