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Cadence

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Cadence is a critical part of running, lowering the stress on ankles, knees, & feet, improving [[Running Economy]], reducing injury rates, and enhancing [[Running Form]]. Cadence is how often your feet touch the ground and it's easy to modify.
=Correct Cadence=
So what should your cadence be? It's generally accepted that a turnover of 90 stepsstrides/minute is optimum for most people (180 steps/minute if counting both feet). To start off, check your cadence when you are running and if the number is 90 or higher, pat yourself on the back. If the number is lower than 90 then you should look at changing your cadence. Your cadence does not have to be exactly 90, and is likely to change somewhat with your pace and terrain. A faster pace may have a higher cadence, as will up or down hill sections. <br/><br/>It's unclear if cadences above 90 strides/minutes are better or not. It's been observed that elite runners in a 5K have cadences of 95-100+<ref name="Treadlightly"/>, but those runners are moving at a much faster pace than most runners. The research discussed below suggests there is a "goldilocks zone" of optimal cadence, so it's reasonable that cadence could be too high for efficiency. It seems likely to me that the upper limit of efficient cadence is related to pace, but more research is needed in this area.
=Measuring Cadence=
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]].
* A review of the scientific studies showed consistently that an increased [[Cadence]] reduces shock at the hip, knee, and ankle, vertical oscillation, and ground contact time<ref name="SchubertKempf2013"/>.
* Barefoot running tends to have a higher cadence than shod<ref name="Divert-2005"/>.
* Leg Spring Stiffness increases with higher cadence<ref name="FarleyGonzález1996"/>.
* There is relatively little evidence concerning the height or leg length of athletes and their cadence.
** A study of 37 male senior elite triathletes indicated that height did not change Cadence, but taller athletes were faster and had longer stride lengths <ref name="Brisswalter-1996"/>.
[[File:Cadence and Impact.jpg|none|thumb|500px|This chart<ref name="Mercer-2003"/> shows the impact forces for three different cadences at the same speed. The thick line shows the Preferred Strike Frequency (PSF) and Preferred Strike Length (PSL), which was a cadence of 84. The thin line has the runners with a 10% slower cadence of 76 and shows increased impact. The dotted line shows 10% faster cadence of 93 and a reduced impact force.]]
[[File:Cadence and VO2.jpg|none|thumb|500px|A chart showing the oxygen cost and heart rate for different cadences. (Cadence values in red added)<ref name="Hamill-1995"/>. The highest cadence levels had impaired [[Running Economy]] but it should be noted the runners had relatively little time to adapt to the different values.]]
=References=
<references>
<ref name="Cavanagh-1989">PR. Cavanagh, R. Kram, Stride length in distance running: velocity, body dimensions, and added mass effects., Med Sci Sports Exerc, volume 21, issue 4, pages 467-79, Aug 1989, PMID [http://www.ncbi.nlm.nih.gov/pubmed/2674599 2674599]</ref>
<ref name="LiebermanWarrener2015">D. E. Lieberman, A. G. Warrener, J. Wang, E. R. Castillo, Effects of stride frequency and foot position at landing on braking force, hip torque, impact peak force and the metabolic cost of running in humans, Journal of Experimental Biology, volume 218, issue 21, 2015, pages 3406–3414, ISSN [http://www.worldcat.org/issn/0022-0949 0022-0949], doi [http://dx.doi.org/10.1242/jeb.125500 10.1242/jeb.125500]</ref>
<ref name="FarleyGonzález1996">Claire T. Farley, Octavio González, Leg stiffness and stride frequency in human running, Journal of Biomechanics, volume 29, issue 2, 1996, pages 181–186, ISSN [http://www.worldcat.org/issn/00219290 00219290], doi [http://dx.doi.org/10.1016/0021-9290(95)00029-1 10.1016/0021-9290(95)00029-1]</ref>
<ref name="Treadlightly">"Do All Elites Run at a 180 Cadence: None of the 5K Finalists at the US Olympic Trials Did" http://www.treadlightlybook.com/2012/07/do-all-elites-run-at-180-cadence-none.html</ref>
</references>