Joe Friel on Training With Power

Joe Friel, author of The Triathlete's Training Bible and The Cyclist's Training Bible among many other endurance training books, explains the benefits on training with power in this 3-part video series.  Power is the preferred way to measure training intensity due to its immediate feedback, which is unaffected by external factors.  Heart rate can change due to arousal levels, caffeine, cardiac drift, etc.  Power output will always remain constant under these varying conditions.  Therefore, it provides a more accurate measurement of the amount of work an athlete is performing.