In the ever-evolving world of fitness, few approaches have garnered as much scientific support and real-world results as Zone 2 training. This cardiovascular sweet spot, characterized by moderate, ...

MARTIN: Did you get a workout in this weekend? How'd it go? MARTÍNEZ: I got two. One was an easy one, and the second one was I put myself through the ringer. MARTIN: (Laughter) Excruciating. OK.

When it comes to fitness, there's always something new (and fun!) to learn about – and right now, zone 2 training is a hot topic of conversation. But what actually is zone 2 training, which exercises ...