Pyffbo: Heart Rate Intervals

The gym solved progression long ago. Add a little weight each week and you get stronger. Cardio apps never copied it. They train you for an event, a 5K or a race day, and they end there. Pyffbo has no finish line. It trains the engine itself the way the gym trains strength: every session slightly harder than the last, from 20-minute walks up to hard 4-minute intervals and beyond. Your week is simple. Easy days, interval days, rest. Finish a session and the next one gets a little harder. Miss twice and it steps back down. When there's a heart rate, it has to be in the right zone. Without a sensor you rate the effort instead. You never program anything yourself. If you're starting from zero, your plan begins with 20-minute easy sessions. If you already train, you can jump straight into 4-minute intervals. If hard exercise is new to you, check with a doctor first. Best with Apple Watch on…