That tension becomes especially clear with heart rate zone training, a popular five-tier system that endurance athletes use to measure effort and fine-tune performance. The well-known formula is ...

Not that it was ever unpopular, but it’s fair to say that running is going through somewhat of a renaissance right now. Data released by Sport England in April of this year revealed that 250,000 more ...

You likely know the importance of zone 2 training—low-intensity miles that are the foundation of distance running plans. The challenge? Finding your personal zone 2 range, and sticking to it. That’s ...