This app guides you through high-intensity interval training for VO2 max improvement. It uses your heart rate monitor to provide real-time cues and track your progress, making it easy to stay on track with your fitness goals.






177+ iOS apps & games curated and reviewed
The best n4x4 apps and games on iPhone average 4.1★ across 177+ titles — we've ranked them by what real users actually keep on their phones. Updated May 2026.
| # | App | Price | Rating | Ads | In-App Purchases | Updated | |
|---|---|---|---|---|---|---|---|
| 1 | Free | 4.5★ (20) | No | No | Oct 2026 | ||
| 2 | Free | 4.5★ (91K) | Yes | Yes | Nov 2026 | ||
| 3 | Free | 3.0★ (181) | No | No | Oct 2026 | ||
| 4 | Free | 4.6★ (5) | No | No | Oct 2026 | ||
| 5 | Free | 3.6★ (706) | Yes | No | Oct 2026 | ||
| 6 | Free | 4.8★ (30K) | Yes | Yes | Nov 2026 | ||
| 7 | Free | 5.0★ (1) | No | No | Oct 2026 | ||
| 8 | Free | 3.1★ (184) | Yes | No | Oct 2026 |






This app guides you through high-intensity interval training for VO2 max improvement. It uses your heart rate monitor to provide real-time cues and track your progress, making it easy to stay on track with your fitness goals.






Experience the ultimate offroad adventure with extensive vehicle customization, diverse open-world environments, and a powerful map editor. Engage in various jobs, roleplay scenarios, and multiplayer races with friends. Design your own trails or explore community-created maps.




Experience the most realistic off-road driving simulation with dynamic weather and terrain. Navigate challenging environments with advanced car physics and explore vast worlds with exciting missions.