Changes

The cheapest way is to measure your cadence is to simply count how many times your foot touches the ground in a minute. However, it's much easier to use a [[Best Running Watch| running watch]] that displays cadence. Some watches will use a small [[Footpod]] attached to your shoe, but others make use of an internal accelerometer. (There's also more advanced options, such as [[RunScribe]] which make Footpods that measure a wide range of biomechanical data in addition to pace and [[Cadence]], including Braking G's, Impact G's, Ground Contact Time, [[Foot Strike]], and more.)==The accuracy of these approaches is covered in my [[Comparison of Cadence Monitors==]]. [[File:Cadence Comparison.jpg|none|thumb|1000px500px|A comparison of cadence monitoring devices during See my [[High Intensity Interval Training]].]]The graph above is from a [[High Intensity Interval Training]] session, which is a challenging test Comparison of Cadence monitors. The [[WarmupMonitors]] and [[Cooldown]] sections of the run are not included, just the intervals. You can see the cadence rise to above 100 during the fast, high intensity intervals, then drop back to my for more normal 90, then a further drop as I walk for a short period before commencing details on the next interval. I don't normally walk, but I wanted to challenge the cadence monitors a little extra. I avoided looking at any device during the run, as that can prevent the internal accelerometer based systems from operating without the normal arm swing. * I wore five watches, two accuracy of [[Footpod]]s and the Garmin HRM Run sensor for the run. * The blue line is from a [[Polar M400]] with the Polar Stride Sensor [[Footpod]]. The Stride Sensor is huge, but it seems to provide the best data. The Polar data is smoother (greater sampling frequency), and reflects the changes in Cadence a little better than other sources. For instance, I stood stationary for a few seconds around the 7:30 mark, and the Polar reflects this drop better. * The purple line is from a [[Garmin 920XT]] with a Garmin Footpod. This is very nearly as good as the Polar data, and matches the changes fairly accurately. * The green line is from a [[Garmin Epix]] with the Garmin HRM Run heart rate strap Best Running Watches| watches that also monitors measure cadence. This matches the Garmin Footpod nicely, showing a similar sampling frequency. * The red line is from a [[Garmin 225]] that is relying on its internal accelerometer. The Garmin 225 is firmly strapped onto my wrist to ensure its optical heart rate monitor is effective. This is rather tighter than I would like, and mostly it does okay. You can see it's a little delayed in some of its responses, and at the 5:00 and 6:30 minute marks it misses the rise completely. While it's far from perfect, it does a reasonable job. * The orange line is from an [[Suunto Ambit3]] using its internal accelerometer. The Ambit3 was reasonably firmly strapped to my armll find more detail, but nowhere near such as tight as the Garmin 225. I suspect it's this looseness that causes the poor data for the Ambit3. You can see that on the fast intervals the Ambit3 loses the plot completely and assumes that my cadence drops to zero. [[File:Cadence Comparison3.jpg|none|thumb|1000px|A second comparison of cadence monitoring devices during [[High Intensity Interval Training]].]]The graph above is another test during a [[High Intensity Interval Training]] session, and again, the [[Warmup]] and [[Cooldown]] sections of the run are not included. You can see that under steady state conditions, all the watches do reasonably well, but not during the interval section. * I wore five watches, only one with a [[Footpod]] and the others with just their internal sensors. * The orange line is from a [[Garmin 920XT]] with a Garmin Footpod. This is the gold standard for this run and I'm assuming it's accurate based on the tests above. * The purple line is from the [[Suunto Ambit2]] and matches fairly well with the Footpod. * The red line is from a [[Garmin Epix]] which does nearly as well as Ambit2, but there are a couple of drop outs where it thinks the cadence has dropped rather than gone up. * The blue line is from a [[Garmin 225]] and it does quite poorly, not really following the interval session at all. * The green line is from an [[Suunto Ambit3]] where again you can see it loses touch with reality completely and assumes that my cadence drops to zero. [[File:Cadence Comparison2.jpg|none|thumb|1000px|A comparison of cadence monitoring devices during a [[Long Run]].]]The graph above is the comparison of a [[Garmin 920XT]] with a [[Footpod]] (red line) with a [[Garmin 225]] using its internal accelerometer (blue line). You can see the internal sensor is far noisier, but worse, it has an overall bias. The Footpod showed an average cadence of 91.1 while the internal sensor was 89.3. That's not a huge difference, but it's far from ideal. [[File:CadenceV800.jpg|none|thumb|1000px|The [[Polar V800]] cadence compared with a Garmin as a reference.]]The [[Polar V800]] provides reasonably good tracking of Cadence, though it is biased a little high. For this example run it had an average of 95.5 rather than 94.6. The V800 tracks the walking break at 20 minutes, the faster pace at 30 minutes, and the [[Fartlek]] beginning at 50 minutes. I plan to perform further tests of the internal accelerometer based devices as time allows.