I am a sports medicine doctor and the Japanese walking method is one of the most evidence-backed cardio trends I’ve seen go viral. Developed at Shinshu University, it alternates 3 minutes of fast walking with 3 minutes of slow walking for about 30 minutes. A randomized trial of 246 adults found it significantly outperformed steady-pace walking for aerobic capacity, leg strength, and blood pressure. A 2024 review confirmed those results across multiple populations. Pair it with two days of resistance training and you have the minimum effective dose for longevity: cardio that builds your VO2 max, and lifting that protects your muscle, bone, and metabolism. Four days a week. No gym required for the walking. That’s a complete program.