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From Fellrnr.com, Running tips
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* There was no difference found in impact forces between two shod conditions where one type of shoe provided 50% more cushioning than the control shoe<ref name="ClarkeFrederick2008"/>.
* A study of 93 runners that compared three hardness shoes (40, 52, & 65 Shore) showed that the softer shoes had the greatest impact peak<ref name="Garcia AznarBaltich2015"/>. Based on my measurements of running shoes, the range of firmness in this test goes from somewhat soft to remarkably firm. The impact ranged from 1.70x Body Weight (BW) for the hardest shoe, to 1.64x BW for the medium and 1.54x BW for the hardest. The impact was measured using a force plate and used the impact peak, not the active peak (see diagram above) which is why the impact is much lower than other studies that report 2.0-2.4x BW. The study found that running increased their joint stiffness in the softer shoes, which may be the cause of the greater impact.
* Highly cushioned Minimax shoes and conventional shoes may result in more knee stress than minimalist shoes<ref name="Sinclair-2016"/>. The study looked at 20 male runners and measured impact with a pressure plate while filming the leg movement. The leg movement was then used to estimate knee stress based on a model that used knee movement and angle. The Minimax shoes were Hoka, the minimalist shoes were Vibram FiveFingers, but the conventional shoes were not specified. The runners were not familiar with the non-traditional shoes, and only had 5 minutes familiarization. The study also found greater contact forces in the non-minimalist shoes.
* Runners who normally run in shoes have greater impact forces when running barefoot, but this is reversed with as a runner becomes adapted to being barefoot<ref name="Robbins-1990"/><ref name="Divert-2005"/><ref name="Robbins-1987"/>.
* In a study somewhat related to shoes and impact, a study looked at impact and running surface and found there were not impact differences between concrete, synthetic track, natural grass, and a treadmill<ref name="FuFang2015"/>. The study used a pressure sensor in the shoe's insole and an accelerometer attached to the Tibia, with the runners wearing non-cushioned, minimalist shoes.
As noted above, the interaction of impact and injury rates is unclear.
=Running Shoes & Pronation Control=
* A study of 12 male runners looked at foot strike for shoes with 0mm, 4mm, and 8mm of drop, plus barefoot<ref name="ChambonDelattre2013"/>. The barefoot condition was midfoot strike rather than rear foot strike in the shoes. The different drop conditions were not significantly different, though there was a trend towards more rear foot strike with the 8mm drop than with 0mm and 4mm drops.
* A drop of 15mm or 7.5mm did not produce a significant reduction in Achilles tendon stress<ref name="Dixon-1998"/>.
* A study comparing the minimal Vibram FiveFingers with Hoka Minimax shoes suggests there may be more Achilles tendon stress in minimal shoes<ref name="SinclairRichards2015"/>. However, the group size was small (n=12), and there's no indication that the runners had experience with either type of footwear.
=Running Shoes & Injury Rates =
Several studies have found there is no evidence to support the idea that running shoes can reduce injury rates<ref name="RichardsMagin2009"/><ref name="van Gent-2007"/><ref name="van Mechelen-1992"/>. One 2015 study did show a reduced injury rate with motion control shoes.
* A study of 247 runners over 5 months showed no difference in injury rates between firm and softly cushioned shoes<ref name="TheisenMalisoux2013"/>.
* Three studies compared evaluated the idea that shoe type should be determined by arch height<ref name="KnapikTrone2014"/>. Runners were put into two groups, with one group assigned shoes based on the shape of the arch, and the other group just assigned a stability shoe regardless of their arch. These studies found no difference in injury rates. The studies were done by the US Army (2168 men, 951 women), Air Force (1955 men, 718 women), and Marine Corps (840 men, 571 women).
** The neutral runners had higher levels of pain in the neutral shoe than the stability shoe. The pronating runners had higher levels of pain in the stability shoe than the neutral shoe. This is the opposite of most recommendations for shoe and foot type.
** Note that while the overall sample size was reasonable (81), each individual subgroup was quite small (5 to 18 runners) and variation within subgroup of results was large. The subgroups also varied significantly in weight, BMI, age, and years of running experience.
* A study of 372 recreational runners assigned them randomly either a neutral or motion controlled shoe and found that those in the neutral shoe had a higher injury rate<ref name="MalisouxChambon2016"/>. The study is unusual in that it blinded both the subjects and the testers to the type of shoe used. The shoe type is not identified in the study, other than to say they were commercially available and modified so the runner would not know the brand or type. Both types of shoe were a 10 mm drop, and the motion control shoes had a [[Pronation| Medial Post]] made of both firmer foam and a plastic insert. The study found that those in the neutral shoe had nearly twice the injury rate of those in the motion control shoes. When the subjects were divided by their [[Pronation]], the study found that the injury rates were only different in those runners with Pronation (~25% of both groups). The study also noted that the greatest predictor of injury is a history of prior injuries, and both groups had ~75% of previously injured runners.
* An intriguing study suggests of 264 runners preparing for a marathon found that runners who swapped between multiple shoes had lower injury rates than those who only used a single pair at a time<ref name="MalisouxRamesh2015"/>. However, the data is self-reported and there were other differences between the groups, such as the multiple shoe runners having run more half-marathons than the single shoe group.
=Shoes and Running Economy=
''Main article: [[The Science of Running Economy]]''
Studies have consistently shown that heavier shoes reduce running economy<ref name="LussianaFabre2013"/><ref name="Burkett-1985"/><ref name="Sobhani-2014"/><ref name="Wierzbinski-2011"/>. Each 100g/3.5oz added to the weight of each shoe reduces running economy by about 1%<ref name="Franz-2012"/><ref name="Wierzbinski-2011"/><ref name="Frederick 1985"/><ref name="Frederick-1984"/>. Studies of cushioning and Running Economy have provided conflicting information. I believe this conflict is due to some studies using a cushioned treadmill to compare barefoot and shod conditions. 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. Analyzing the research, 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<ref name="Franz-2012"/><ref name="Wierzbinski-2011"/><ref name="Tung-2014"/>. Note that running shoes provide less cushioning in colder temperatures<ref name="DibSmith2005"/>. There are indications that a highly flexible shoe that is modified with a springy carbon fiber plate might be more efficient than a highly flexible shoe on its own<ref name="OhPark2017"/><ref name="Roy-2006"/>.
=Heel Counters=
The [[Heel Counter]] is intended to link the heel of the foot to the shoe,
* A study looked at bone marrow edema in 36 experienced runners transitioning to Vibram FiveFingers (VFF) shoes<ref name="RidgeJohnson2013"/>. The runners were randomly assigned VFF or their normal running shoes, with the VFF runners gradually transitioning based on the recommendations of Vibram at that time. Only 1 of the 17 runners in the control group showed signs of a bone marrow edema, compared with 9 of the 19 VFF runners.
* In 2014, Vibram settled a lawsuit that they made false and unsubstantiated claims that their FiveFingers shoes could reduce injury rates.
=Personal Observations=
While this page is dedicated to the current scientific research, I do want to add a few personal observations as a counterpoint.
* My testing of [[Running Sensors]] has made me realize how many ways there are of measuring the impact forces of running. I believe that this warrants much deeper scientific research.
** Impact can be measured as simple acceleration, or as "jerk" which is the rate of change of acceleration. In some situations, the human body can adapt to a continuous level of acceleration much better than it can to a rapidly changing level of acceleration. This can be observed when an aircraft takes off, and the initial buildup of acceleration seems quite dramatic, but after 10-20 seconds the steady acceleration is harder to notice.
** The impact forces can be measured on the ground, on the shoe, on the tibia (lower leg), or on the torso. Each location is likely to have a different result.
* I've observed some potentially interesting patterns during my initial testing using [[TgForce]], [[RunScribe]], [[MilestonePod]], [[Moov Now]], and [[Wahoo TICKR Run]].
** When use a forefoot foot strike the impact measured on my shoe is typically a little higher than when I heel strike. However, the impact measured on my tibia is vastly lower. When heal striking, the impact on my shoe is typically in the 7-9g range, and 5-7g on my Tibia. When I land on my forefoot the impact on my shoe is 8-12g but the Tibial impact is 2-4g.
** When comparing [[Maximalist]] shoes with minimally or cushioned shoes I'm typically finding that the impact measured on my shoe is a little higher with the more cushioned shoes, but the Tibial impact is virtually the same regardless of cushioning. (There is a very slight suggestion that more cushioned shoes have fractionally lower Tibial impact.)
=References=
<references>
<ref name="OhPark2017">Keonyoung Oh, Sukyung Park, The bending stiffness of shoes is beneficial to running energetics if it does not disturb the natural MTP joint flexion, Journal of Biomechanics, volume 53, 2017, pages 127–135, ISSN [http://www.worldcat.org/issn/00219290 00219290], doi [http://dx.doi.org/10.1016/j.jbiomech.2017.01.014 10.1016/j.jbiomech.2017.01.014]</ref>
<ref name="RichardsMagin2009">C E Richards, P J Magin, R Callister, Is your prescription of distance running shoes evidence-based?, British Journal of Sports Medicine, volume 43, issue 3, 2009, pages 159–162, ISSN [http://www.worldcat.org/issn/0306-3674 0306-3674], doi [http://dx.doi.org/10.1136/bjsm.2008.046680 10.1136/bjsm.2008.046680]</ref>
<ref name="Clement-1980">DB. Clement, JE. Taunton, A guide to the prevention of running injuries., Can Fam Physician, volume 26, pages 543-8, Apr 1980, PMID [http://www.ncbi.nlm.nih.gov/pubmed/21293616 21293616]</ref>
<ref name="HamillRussell2011">Joseph Hamill, Elizabeth M. Russell, Allison H. Gruber, Ross Miller, Impact characteristics in shod and barefoot running, Footwear Science, volume 3, issue 1, 2011, pages 33–40, ISSN [http://www.worldcat.org/issn/1942-4280 1942-4280], doi [http://dx.doi.org/10.1080/19424280.2010.542187 10.1080/19424280.2010.542187]</ref>
<ref name="Garcia AznarBaltich2015">Jose Manuel Garcia Aznar, Jennifer Baltich, Christian Maurer, Benno M. Nigg, Increased Vertical Impact Forces and Altered Running Mechanics with Softer Midsole Shoes, PLOS ONE, volume 10, issue 4, 2015, pages e0125196, ISSN [http://www.worldcat.org/issn/1932-6203 1932-6203], doi [http://dx.doi.org/10.1371/journal.pone.0125196 10.1371/journal.pone.0125196]</ref>
<ref name="SinclairRichards2015">J. Sinclair, J. Richards, H. Shore, Effects of minimalist and maximalist footwear on Achilles tendon load in recreational runners, Comparative Exercise Physiology, volume 11, issue 4, 2015, pages 239–244, ISSN [http://www.worldcat.org/issn/1755-2540 1755-2540], doi [http://dx.doi.org/10.3920/CEP150024 10.3920/CEP150024]</ref>
<ref name="MalisouxRamesh2015">L. Malisoux, J. Ramesh, R. Mann, R. Seil, A. Urhausen, D. Theisen, Can parallel use of different running shoes decrease running-related injury risk?, Scandinavian Journal of Medicine & Science in Sports, volume 25, issue 1, 2015, pages 110–115, ISSN [http://www.worldcat.org/issn/09057188 09057188], doi [http://dx.doi.org/10.1111/sms.12154 10.1111/sms.12154]</ref>
<ref name="FuFang2015">Weijie Fu, Ying Fang, David Ming Shuo Liu, Lin Wang, Sicong Ren, Yu Liu, Surface effects on in-shoe plantar pressure and tibial impact during running, Journal of Sport and Health Science, volume 4, issue 4, 2015, pages 384–390, ISSN [http://www.worldcat.org/issn/20952546 20952546], doi [http://dx.doi.org/10.1016/j.jshs.2015.09.001 10.1016/j.jshs.2015.09.001]</ref>
<ref name="Sinclair-2016">J. Sinclair, J. Richards, J. Selfe, J. Fau-Goodwin, H. Shore, The Influence of Minimalist and Maximalist Footwear on Patellofemoral Kinetics During Running., J Appl Biomech, Mar 2016, doi [http://dx.doi.org/10.1123/jab.2015-0249 10.1123/jab.2015-0249], PMID [http://www.ncbi.nlm.nih.gov/pubmed/26959346 26959346]</ref>
<ref name="MalisouxChambon2016">Laurent Malisoux, Nicolas Chambon, Nicolas Delattre, Nils Gueguen, Axel Urhausen, Daniel Theisen, Injury risk in runners using standard or motion control shoes: a randomised controlled trial with participant and assessor blinding, British Journal of Sports Medicine, volume 50, issue 8, 2016, pages 481–487, ISSN [http://www.worldcat.org/issn/0306-3674 0306-3674], doi [http://dx.doi.org/10.1136/bjsports-2015-095031 10.1136/bjsports-2015-095031]</ref>
<ref name="Roy-2006">JP. Roy, DJ. Stefanyshyn, Shoe midsole longitudinal bending stiffness and running economy, joint energy, and EMG., Med Sci Sports Exerc, volume 38, issue 3, pages 562-9, Mar 2006, doi [http://dx.doi.org/10.1249/01.mss.0000193562.22001.e8 10.1249/01.mss.0000193562.22001.e8], PMID [http://www.ncbi.nlm.nih.gov/pubmed/16540846 16540846]</ref>
<references/>
[[Category:Science]]
[[Category:Injury]]
