I like to run for an hour with variable speeds. I usually jog at 5 miles per hour but every once in a while I get flooded with energy and go supercharge as fast as I can 10-12 miles an hour (more?).
I'd like to track this to see how on a chart the rate of intensity increase so I can track how long I'm in this state and get an more accurate calorie burned estimator. Apps and fitness trackers welcome.