The infamous Zone 2. Meme’d, argued over, and heralded—all at the same time.
Many people get it wrong though. It doesn’t matter what level of running economy/fitness you currently have; you’re probably running your easy runs too fast.
The problem with running is that is feels doable or easy enough up into the higher heart rates zones of 3-4, especially when compared to other forms of cardiovascular fitness. (Try hitting 155BPMs on the bike versus running—there’s a huge difference in effort needed).
But the problems still arise, no matter how “okay” you feel running most of your runs in the 150-165BPM heart rate range. The cracks in the dam form over time, as your body goes from slightly stressed to overstressed. It may take a few months for the effects to appear, but they will. As your body won’t be able to keep up with the repair needed of these higher HR efforts, injuries will come.
