POLAR RS 800 SD - Manual (Page 15)

Running Index
Combining aerobic fitness (VO
2max
) and exercise economy (how efficient
your body is at running), Running Index offers an easy way to measure
performance (how fast/easily you run at a given pace).
By recording your Running Index over time, you can monitor progress.
Improvement means that running at a given pace requires less of an
effort, or that your pace is faster at a given level of exertion.
You can improve your Running Index results by improving your fitness
level and running technique.
Running Index tells you more about your performance level because,
unlike a VO
2max
test, it factors in running technique. It is the equivalent
to performing a Cooper test every run!
15