I do not have a long history of racing, but in the past couple of years, I have been wearing a chest strap heart rate monitor for both training and racing. I display my heart rate on my watch. I find it very helpful for keeping me from pushing too hard at the wrong times. I have found the HR data from some 40k nordic ski races to be really helpful in determining how long I can stay above my lactate threshold in an effort that lasts over 2hrs.

There is also something comforting about walking up a hill and being able to see that I’m still working as hard as I was while running the flats.