heel height
Introduction
High heel shoes ( HHS ) have been widely used among women in several centuries ; 37 % to 69 % of women wear HHS daily ( American Podiatric Medical Association , 2014 ). HHS are featured with heel evaluation , rigid heel cap and curved plantar region , which interfere with natural foot motion ( Cronin , 2014 ). A more plantar flexed and supinated foot position can alter the distribution of plantar pressure , affect muscle activities around ankle joints , and limit the range of motion ( ROM ) of the ankle during standing and walking ( Ko et al ., 2009 ; Luximon et al ., 2015 ; Simonsen et al ., 2012 ). A number of studies have documented that the effects of HHS are not localized to the ankle ; instead , a “ chain reaction ” of kinematic effects travels up the lower limb and disturbs the displacement of the center of mass ( COM ) ( Chien , Lu & Liu , 2013 ; Cronin , 2014 ; Schroeder & Hollander , 2018 ). These biomechanical alterations can decrease perceived stability , impair postural control , and increase the risks of falling among HHS wearers ( Luximon et al ., 2015 ; Wan , Yick & Yu , 2019 ). The rate of high heels-related injuries increased from 7.1 % to 14.1 % during the 11-year period from 2002 to 2012 . Most of the injuries were sprains or strains occurred to either the ankle or foot body regions ( Barnish & Barnish , 2009 ; Moore et al ., 2015 ).
One of the risk factors on high heels-related injuries is decreased postural stability among HHS wearers ( Wan , Yick & Yu , 2019 ). Postural control is the ability to stabilize and restore the body ’ s COM relative to the base of support ( BOS ) during self-initiated and externally triggered perturbations ( Horak , 2006 ; Winter ,
1995 ). To maintain postural stability , a complex motor skill based on the interaction of proprioceptive , visual , and vestibular system is utilized in this process ( Mancini & Horak , 2010 ). Wearing HHS can cause biomechanical constrains and disturb human movement strategies through reduced BOS and elevated heel height ( HH ) ( Chien , Lu & Liu , 2013 ). The HHS wearers tend to apply different movement strategies ( e . g ., ankle and hip strategy ) to maintain the stability of the body ’ s equilibrium with regard to elevated HH during standing , walking , and dynamic perturbations .
A number of studies found that different HH can influence postural stability through interfering with the stabilization of COM with respect to the BOS . Different sensory and movement strategies are also involved in the process of postural control in HHS wearers . Recent studies have examined that HHS wearers had significantly worse standing balance starting at seven cm HH by analyzing the center of pressure ( COP ) magnitude in quiet stance and limits of stability test ( LOS ) ( Choi & Cho , 2006 ; Gerber et al ., 2012 ; Mika et al ., 2016 ). During extrinsic perturbations , previous studies demonstrated that HHS can impair human balance ( e . g ., sinusoidal oscillations and waist pulling ) ( Choi & Cho , 2006 ; Sun et al ., 2017 ). When HH increased to 10 cm , increased use of ankle strategy , slow center of gravity ( COG ) movement velocity , and decreased body equilibrium were observed with increased HH ( Hapsari & Xiong , 2016 ; Truszczyńska et al ., 2019 ). However , no difference in the interaction of sensory systems was found in postural control among HHS wearers with increased HH ( Hapsari &
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