This article was made possible through the generous support of our voluntary subscribers. If you would like to see more articles like this one, please support FasterSkier with a voluntary subscription. I’ve been using Heart Rate Variability (HRV) to guide endurance training for nearly 20 years. As with every innovation, we do research and test it extensively before we introduce the use with athletes. I was introduced to HRV by Tiina Hoffman the former skier and...