Effects of shoe inserts and heel height on foot pressure, impact force, and perceived comfort during walking

Abstract

Studying the impact of high-heeled shoes on kinetic changes and perceived discomfort provides a basis to advance the design and minimize the adverse effects on the human musculoskeletal system. Previous studies demonstrated the effects of inserts on kinetics and perceived comfort in flat or running shoes. No study attempted to investigate the effectiveness of inserts in high heel shoes. The purpose of this study was to determine whether increasing heel height and the use of shoe inserts change foot pressure distribution, impact force, and perceived comfort during walking. Ten healthy females volunteered for the study. The heel heights were 1.0 cm (flat), 5.1 cm (low), and 7.6 cm (high). The heel height effects were examined across five shoe-insert conditions of shoe only; heel cup, arch support, metatarsal pad, and total contact insert (TCI). The results indicated that increasing heel height increases impact force ($p<0.01$), medial forefoot pressure ($p<0.01$), and perceived discomfort ($p<0.01$) during walking. A heel cup insert for high-heeled shoes effectively reduced the heel pressure and impact force ($p<0.01$), an arch support insert reduced the medial forefoot pressure, and both improved footwear comfort ($p<0.01$). In particular, a TCI reduced heel pressure by 25% and medial forefoot pressure by 24%, attenuate the impact force by 33.2%, and offered higher perceived comfort when compared to the non-insert condition.

Introduction

Surveys of shoe choice have shown that 37–69% of women wear high-heeled shoes on a daily basis (The Gallup Organization, 1986; Frey et al., 1993). Wearing high-heeled shoes modifies gait kinematics and kinetics (Esenyel et al., 2003; Snow et al., 1992; Mandato and Nester, 1999; Voloshin and Loy, 1994; Kerrigan et al., 1998). Previous studies have demonstrated that walking in high-heeled shoes alters lower-extremity joint function (Esenyel et al., 2003), raises the peak pressure in the forefoot (Snow et al., 1992; Mandato and Nester, 1999), and shifts peak pressures from the third, fourth and fifth metatarsal heads to the first and second (Soames and Clark, 1985; Snow et al., 1992; Eisenhardt et al., 1996). In addition, wearing high-heeled shoes for walking generates a force spike at the initial ground contact (i.e., impact force) and the force is then transmitted up to the skeleton as a “shock wave” (Voloshin and Loy, 1994). This shock wave appeared to damage soft tissues, which may result in leg and back-pain complaints (Wosk and Voloshin, 1981; Voloshin and Wosk, 1982) and eventually lead to degenerative joint disorders (Kerrigan et al., 1998). Despite concerns regarding their adverse effects on human musculoskeletal system, employment criteria and/or fashion customs encouraged the continuous use of high-heeled shoes. Studying the impact of high heels on kinetic changes and perceived discomfort provide a basis for designs that minimize adverse effects.

Engineering efforts to reduce foot loading caused by peak pressure and impact force, and to improve shoe comfort, involved designing shoe inserts with different shapes (Light et al., 1980; Chen et al., 1994; Hodge et al., 1999; Lee et al., 2004). The use of inserts is effective in redistributing the pressure beneath the foot and absorbing energy in terms of reducing impact force. Various inert designs demonstrate different kinetic modification during gait. For example, a heel pad is effective in reducing heel pressure and the magnitude of the heelstrike impact (Light et al., 1980; Jorgensen and Ekstrand, 1988). An arch support was designed to resist depression of the foot arch during weight bearing through skeletal support, thereby decreasing tension in the plantar aponeurosis (Kogler et al., 1996). A metatarsal pad has been found to reduce forefoot pressure and transfer weight bearing to the longitudinal and metatarsal arches (Lee et al., 2004). Finally, a total contact insert (TCI) provided pressure relief in the heel and forefoot regions (Lord and Hosein, 1994; Chen et al., 2003). These studies, however, focused on inserts in flat or running shoes. No study, insofar as we have examined, attempted to identify insert effectiveness in high heels.

The purpose of this study was to determine whether increasing heel height and the use of various types of shoe inserts would result in changes in foot pressure distribution, impact force, and perceived comfort during walking. The types of shoe inserts used in the current study included heel cup, arch support, metatarsal pad, and TCI.