Editing Running (section)

===Stride length, hip and knee function===
Biomechanical factors associated with elite runners include increased hip function, use, and stride length over recreational runners.<ref name="Cavanagh 1990"/><ref name="Pink 1994 541–549">{{cite journal|last=Pink|first=M.|title=Lower Extremity Range of Motion in the Recreational Sport Runner|journal=American Journal of Sports Medicine|year=1994|volume=22|issue=4|pages=541–549|doi=10.1177/036354659402200418|pmid=7943522|s2cid=1744981}}</ref> An increase in running speeds causes increased ground reaction forces, and elite distance runners must compensate for this to maintain their pace over long distances.<ref name="Weyand 2010 1991–1999">{{cite journal|last=Weyand|first=P.G.|title=Faster top running speeds are achieved with greater ground forces not more rapid leg movements|journal=Journal of Applied Physiology|year=2010|volume=89|issue=5|pages=1991–1999|doi=10.1152/jappl.2000.89.5.1991|pmid=11053354|s2cid=2448066|doi-access=free}}</ref>
These forces are attenuated through increased stride length via increased hip flexion and extension through decreased ground contact time and more energy being used in propulsion.<ref name="Weyand 2010 1991–1999"/><ref>{{cite journal|last=Mercer|first=J.A.|title=Individual Effects of Stride Length and Frequency on Shock Attenuation during Running|journal= Medicine & Science in Sports & Exercise|year=2003|volume=35|issue=2|pages=307–313|doi=10.1249/01.mss.0000048837.81430.e7|pmid=12569221|s2cid=23896334 |doi-access=free}}</ref><ref>{{cite journal|last=Stergiou|first=N.|title=Subtalara and knee joint interaction during running at various stride lengths|journal=Journal of Sports Medicine and Physical Fitness|year=2003|volume=43|issue=3|pages=319–326|pmid=14625513 }}</ref> With increased propulsion in the horizontal plane, less impact occurs from the decreased force in the vertical plane.<ref>{{cite journal|last=Mercer|first=J.A.|title=Relationship between shock attenuation and stride length during running at different velocities|journal=European Journal of Applied Physiology|year=2002|volume=87|issue=4–5|pages=403–408|doi=10.1007/s00421-002-0646-9|pmid=12172880|s2cid=26016865}}</ref> Increased hip flexion allows for increased use of the hip extensors through midstance and toe-off, allowing for more force production.<ref name="Hammer 2010 2709–16"/>
The difference even between world-class and national-level 1500-m runners has been associated with more efficient hip joint function.<ref name="Leskinen 2009 1–9">{{cite journal|last=Leskinen|first=A.|title=Comparison of running kinematics between elite and national-standard 1500-m runners|journal=Sports Biomechanics|year=2009|volume=8|issue=1|pages=1–9|doi=10.1080/14763140802632382|pmid=19391490|s2cid=25422801}}</ref> The increase in velocity likely comes from the increased range of motion in hip flexion and extension, allowing for greater acceleration and speed.  The hip extensors and extension have been linked to more powerful knee extension during toe-off, contributing to propulsion.<ref name="Cavanagh 1990"/>
Stride length must be appropriately increased with some degree of knee flexion maintained through the terminal swing phases, as excessive knee extension during this phase along with footstrike has been associated with higher impact forces due to braking and an increased prevalence of heel striking.<ref>{{cite journal|last=Lafortune|first=M.A.|title=Dominant role of interface over knee angle for cushioning impact loading and regulating initial leg stiffness|journal=Journal of Biomechanics|year=2006|volume=29|issue=12|pages=1523–1529|doi=10.1016/s0021-9290(96)80003-0|pmid=8945650}}</ref> Elite runners tend to exhibit some degree of knee flexion at footstrike and midstance, which first serves to eccentrically absorb impact forces in the quadriceps muscle group.<ref name="Leskinen 2009 1–9"/><ref>{{cite journal|last=Skoff|first=B.|title=Kinematic analysis of Jolanda Ceplak's running technique|journal=New Studies in Athletics|year=2004|volume=19|issue=1|pages=23–31}}</ref><ref>{{cite journal|last=Skoff|first=B|title=Kinematic analysis of Jolanda Ceplak's running technique|journal=New Studies in Athletics|year=2004|volume=19|issue=1|pages=23–31}}</ref> Secondly it allows for the knee joint to contract concentrically and provides significant aid in propulsion during toe-off as the quadriceps group is capable of producing large amounts of force.<ref name="Hammer 2010 2709–16"/>
Recreational runners have been shown to increase stride length through increased knee extension rather than increased hip flexion, as exhibited by elite runners, which provides an intense braking motion with each step and decreases the rate and efficiency of knee extension during toe-off, slowing down speed.<ref name="Pink 1994 541–549"/> Knee extension, however, contributes to additional stride length and propulsion during toe-off and is seen more frequently in elite runners as well.<ref name="Cavanagh 1990"/>