When it comes to endurance training, monitoring your heart rate has long been considered a fundamental practice. It's a metric that provides valuable insights into your body's response to exercise (Internal Load), helping you (or your coach) optimize your training regimen. However, like any tool, heart rate comes with its own limitations that athletes should be aware of. In this post, we'll delve into both the significance and the constraints of using heart rate as a guide in endurance training.