The effects of angled insoles on short radius flat-track running mechanics

Abstract

While indoor track allows athletes to compete during the winter period of December to February, injury rates during the indoor track and field season are 16% higher than the outdoor season. Increases in injury rates are often attributed to the shorter turn radii experienced by athletes when competing on a 200m indoor track as opposed to the longer turn radii of a 400m outdoor track. A common method of counteracting these asymmetries is to bank the turns of a 200m indoor track. Aligning the athlete's resultant force vector perpendicular to the running surface can alleviate many of the running form abnormalities caused by turn running. However, the high cost of implementing a banked indoor track can be prohibitive to many programs who currently have a flat track facility. To this end, we have developed two experimental insoles designed to alleviate the asymmetries experienced during turn running: a physically angled foam insole and an insole containing an angled stiff mid-plate. Insole function was tested through human participant running trials to identify their effects on indoor flat track running mechanics. 12 NCAA Division 1 track and field athletes (6 male, 6 female, age: 21 + or - 2 years, mass: 61.4 + or - 11.4 kg, height: 1.77 + or - 0.17 m) who specialize in distance and mid-distance running provided informed consent to participate in this Institutional Review Board-approved protocol. Kinematics, muscle activation, and ground interaction variables were monitored during running trials and used to compare the effects of the insoles on running biomechanics. The physically angled insole produced positive results for ankle joint angles and ground interaction variables for turn running. The angled plate insole positively affected right-side ankle joint angle positioning and did not significantly impact straight running mechanics. Both insoles produced higher levels of muscle activation asymmetry, indicating that this may be a required effect of turn running regardless of joint angle positioning and ground interaction. While the angled plate insoles showed almost no impact on straight or turn running mechanics, the wedge insoles functioned effectively to alleviate several asymmetries related to turn running.