Fitness and Performance
This is your speed at your maximum aerobic pace, on flat ground, after you've warmed up but before you begin to experience fatigue-induced cardiac drift. At this pace, you can comfortably hold a conversation with a training partner, sing outloud to yourself, and/or breath entirely through your nose. Our calculations are essentially a machine-learning implementation of Dr. Phil Maffetone's Maximum Aerobic Fitness test.
As the vast majority of your running event will take place aerobically, this offers an accurate snapshot of your overall fitness and performance. Day-to-day variations are usually caused by fluctuations in temperature, diet, sleep, and/or fatigue from a previous training session. Weekly and monthly variations reflect underlying changes in fitness. Keep an eye out for multiple slow readings in a row--you might be overtraining.
This is your mileage in the last week adjusted for intensity and decayed exponentially over time. It's an estimation of the accumulated load you're carrying around in your legs at any given moment.
Our calculations are an implementaion of Dr. Eric W. Banister's impulse-response model, in which hard, recent efforts receive more weight than easy, distant efforts. We've normalized the output to weekly mileage to make it more comprehensible.