I'm afraid not. "For running you can use pace for interval training - it should correlate directly to power." - think about running the same pace for an interval (1) up a hill (2) on a flat (3) downhill. Same pace, 3 very different effort (and power) levels "Heartrate would work very well for managing running effort" - if used only by itself then no. Exactly the same theory as why you would use power numbers in cycling. A number of external factors can influence your HR including fatigue, sleep the night before, stress, cardiac drift over the course of a workout etc. All make HR relatively ineffective (when used solely by itself). If you combine HR, pace and RPE you can manage your interval efforts pretty well especially if you are an experienced runner
