Changes

[[File:Paula Radciffe NYC Marathon 2008 cropped.jpg|right|thumb|300px|Paula Radcliffe, the holder of the women's world record for the marathon (2:15:25) has gained much of her improvement through greater Running Economy.]]

{| class="wikitable"

|- valign="top"

|[[File:PR Running Economy.jpg|none|thumb|300px|Paula Radcliffe's Running Economy (V̇O₂ consumption at 16 Km/hr, 6:00 min/mile)]]

|}

=Shoes=

The research on how shoes effect running economy is rather confusing, with many apparently contradictory findings in some areas. Some of the problems include:

[[File:Reeves-2014-ShoeMass-RE.jpg|right|thumb|300px|Shoe mass against running economy<ref name="Reeves-2014"/>.Even on a cushioned treadmill, it appears that shoe cushioning can provide an improvement in running economy. The tests were performed at paces corresponding to various percentages of [[VO2max|V̇O₂max]] (the shapes) and the vertical axis is the change in RE compared with barefoot. ]]

The results of studies that have compared barefoot and shod running (or running in un-cushioned and cushioned shoes) have provided conflicting information. Some studies show that running economy is worse when wearing shoes, with the bulk of the detrimental effect explained by the shoe weight. However, other studies have shown that the cushioning provided by shoes can compensate for the reduction in running economy due to shoe weight, and sometimes the shoes can actually be provide better economy than barefoot. I believe that the key to understanding this conflict lies in the type of running a surface that is used by the study. Not surprisingly, if a study uses a cushioned treadmill, the cushioning provided by the shoe does not confer any additional advantage over the barefoot condition. Of the 11 studies I found, 3 of the 4 studies using cushioned treadmills showed no improvement in running economy for shoe cushioning, while the 4 studies using un-cushioned treadmills and one using a cushioned treadmill showed an improvement for shoe cushioning. There were three studies that did not give sufficient information to determine the type of treadmill, and two showed no improvement while the remainder did. '''I conclude that a well cushioned running shoe can improve Running Economy by an estimated 2-3.5% compared with a weight matched un-cushioned shoe'''. In practice, most shoes will have a beneficial impact on Running Economy due to cushioning and a negative impact due to their weight.

** A thesis study showed that barefoot is more economic than shoed (New Balance M1500, 344-368g/shoe), but the same as shod when compensating for shoe mass<ref name="Flaherty-1994"/>. The barefoot condition had a greater [[Cadence]] than shod. The treadmill (Marquette model 1900) was cushioned.

** Habitually FFS runners are 2.4% more efficient in minimally shod (FiveFingers with) than cushioned (GEL-Cumulus 10) shoes at 9 min/mile pace and with weights to ensure equal mass<ref name="Perl-2012"/>. This study used a Vision T9250 treadmill that is cushioned, with a reputable reviewer rating as 6.8/10 for cushioning<ref name="treadmilldoctor.com"/>.

** A study compared barefoot (BFT), minimally shod (MS), and shod (SH) showed that BFT was 2.6-5.1% more efficient than SH<ref name="MooreJones2014"/>. The study also compared MS at the [[Cadence]] of BFT (165) and the cadence of SH (160), with an improvement only seen at the lower cadence. The participants had no prior barefoot or minimal running experience, and no adjustment was made for shoe mass. However, this study used a Woodway PPS treadmill with the manufacture claim that "Our patented Slat Belt running surface helps absorbs more of the impact than any other treadmill(<ref name="woodway.com"/>)".

** A study comparing barefoot running with the participants using their normal running shoes showed that barefoot condition had a 4.4% improvement in running economy<ref name="Reeves-2014"/>. However, 80% of the change in running economy could be explained by shoe mass. In fact, the slope of the line between shoe mass and running economy predicts that a shoe weighing 9.2oz/260g would have the same running economy has barefoot. The shoes used weighed between 8.5-15oz (239-430g). Interestingly while running economy improved, [[VO2max|V̇O₂max]] did not. The treadmill used was a WoodWay Pro-XL, a highly cushioned "slatted" treadmill similar to the one noted above.

** Running in lightweight (150g/5.3oz, Nike Mayfly) shoes was 2% more efficient than barefoot<ref name="Franz-2012"/>. The study used runners with a midfoot [[Foot Strike]] and an un-cushioned treadmill (Quinton 1860).

** A thesis study showed that running in lightweight shoes (Nike Mayfly) was 3.4% more efficient than weight matched barefoot, and 2.1% more efficient than barefoot<ref name="Wierzbinski-2011"/>. The study used runners with a midfoot [[Foot Strike]] and an un-cushioned treadmill (Quinton 1860). When the weight of the Nike Mayfly shoes was doubled using weights, the running economy was still better than barefoot. The study also added EVA foam to the treadmill surface, but this did not change the running economy of barefoot running. However, the cushioning was added in slabs, and participants noted that the gaps felt "like running on a trail".

** Running barefoot and in Nike 3.0 shoes had no difference in running economy on an un-cushioned treadmill (Quinton 1860)<ref name="Tung-2014"/>. However, adding 10mm of cushioning to the treadmill improved barefoot running economy by 1.9%<ref name="Tung-2014"/>. Using 20mm cushioning made no further improvement over 10mm. The cushioning was provided by EVA foam used in running shoes. (The EVA foam was fairly soft, measuring 52-58 on the Asker Type C scale<ref name="Tung-2014-PC"/>. That's about 27-33 on the Shore A scale.)

** A comparison of barefoot and shoes weighing 150g and 350g showed the same running economy in barefoot and 150g shoes, but 3.6% lower running economy in 350g shoes<ref name="Divert-2008"/>. The treadmill used (ADAL 3D, HEF-Tecmachine) appears to be un-cushioned. This study also showed that compared with barefoot, shoes reduced the total energy required to run (work) without changing V̇O<ref name="Divert-2008"/>, suggesting that barefoot is using more elastic energy, further suggesting that the barefoot condition in this study uses forefoot strike<ref name="Ardigò-1995"/>.

** Barefoot was 2.0% more economic than shod on a treadmill and 5.7% more economic on an indoor track<ref name="Hanson-2011"/>. However, the type of treadmill and indoor track was not described and may have been cushioned. No indication was given of the type or weight of the shoes used.

** A study using Nike Air shoes showed an average 2.4% improvement in running economy compared with firmer shoes of a similar weight<ref name="Frederick 1986"/>. The improvement in running the economy varied by individual, between 0.5% and 6%, SD=1.8%. No details of the type of treadmill used were recorded.

==Heel Rise (drop)==

=Glycogen depletion & Fat Burning=

Because burning fat requires more oxygen than carbohydrate, the switch to fat burning due to [[Glycogen]] Depletion means more oxygen is required. This does not directly change running economy as the energy required remains similar<ref name="KyrPullinen2000"/>. However, breathing rate becomes higher to supply the required oxygen, and the amount of oxygen extracted in each breath is lower, further driving the breathing rate.

* '''Balance and step width'''. Maintaining side to side balance is estimated to cost 2% of the energy of running<ref name="ArellanoKram2011"/>. This may be due to step width, as increasing step width can reduce running economy by 11%<ref name="Arellano-2011"/>.

[[File:Step Width.jpg|right|thumb|200px|The blue line is the center line of the body and the red line indicates the center of the foot placement. The distance between the two lines is the step width.]]

* '''Arm Swing'''. While it obviously costs energy to swing the arms while running, this arm swing actually improves running economy<ref name="ArellanoKram2011"/><ref name="Arellano-2011"/>, probably by improving balance.

* '''Body Mass'''. Greater body mass is associated with better running economy<ref name="Bourdin-1993"/><ref name="Bergh-1991"/>. This may be because larger individuals can store more elastic energy on each step to reduce their energy consumption<ref name="Taboga-2012"/>.

* '''Body Fat'''. Perhaps surprisingly, obese individuals have similar running economy as leaner individuals<ref name="Taboga-2012"/>. Remember that running economy is energy used divided by weight. So the heavier you are, the more energy required overall, and more body fat results in a lower power output. So being overweight reduces your fitness (aerobic capacity) but not your running economy.

=DOMS=

=Flexibility=

[[File:Standing External Hip Rotation.jpg|right|thumb|200px|Greater Standing External Hip Rotation reduces running economy.]]

* '''Stretching Programs'''. Most studies show that [[Stretching]] programs do not reduce running economy<ref name="Nelson-2001"/><ref name="Godges-1993"/>.

* '''Stretching before running'''. One study<ref name="Wilson-2010"/> has shown that stretching directly before running reduces performance and running economy, but most studies indicate no impact<ref name="AllisonBailey2008"/><ref name="Hayes-2007"/>, even though the stretching impairs other muscular functioning. (One study on subjects with limited hip range of motion showed that stretching before running improved running economy<ref name="Godges-1989"/>, but the subjects were only tested with 4 minutes of running, and a steady state requires 4-15 minutes<ref name="Morgan-1989"/>).

=Gender =

Women may improve their running economy in response to training more effectively than men<ref name="Bourdin-1993"/>.

=Framework for Factors Effecting Running Economy=

[[File:Factors affecting running economy.jpg|none|thumb|500px|A schematic of the factors effecting running economy<ref name="Saunders-2004"/>.]]

=References=

<references>

<ref name="GuLi2013">Effect of Shoes' Heel Height on the Energy Cost during Jogging, Y.D. Gu and Z.Y. Li, Research Journal of Applied Sciences, Engineering and Technology July 15, 2013</ref>

<ref name="Brown2013">The Acute Effect of Heel to Toe Drop on Running Economy. Brown, Harrison and Silva, Robert (2013). Undergraduate thesis, Fort Lewis College</ref>

</references>