Vi Trainer is an AI-powered fitness coaching app that uses adaptive audio coaching to guide users through runs, walks, and other cardio workouts. The AI adjusts in real-time based on your heart rate, pace, and fitness data, creating a personalized training experience that feels surprisingly interactive. The freemium model lets you explore basic features before committing, and at $7.99/month, the premium tier is competitively priced against alternatives like Freeletics or Aaptiv. Strengths include its natural-sounding voice coaching, solid integration with wearables, and progressive training plans that adapt as your fitness improves. The real-time feedback during runs is genuinely motivating and helps maintain proper intensity zones. However, Vi Trainer leans heavily toward cardio and running " strength training and flexibility are underserved. The app's ecosystem also feels somewhat limited compared to more comprehensive platforms. For dedicated runners and cardio enthusiasts seeking an affordable AI coach, Vi Trainer delivers solid value, though those wanting a full-spectrum fitness solution may need to supplement with other tools.