BALANCE OF HIGH-HEELED WOMEN: EFFECTS OF HEEL HEIGHT, HEEL CONTACT AREA, AND SHOE WEARING EXPERIENCE

Abstract

A study revealed that between 37% and 69% of women wear high heeled shoes (HHS) on a daily basis (The Gallup Organization 1986) and this number has recently increased (Schneider 2009; Jacobs 2013). The fact that HHS can artificially increase the attractiveness of women and has made these shoes remain popular despite the negative effects surrounding them. This study aimed to examine the effects of heel height and heel contact area as shoe design factors, and shoe wearing experience as human factor on human static and dynamic balance. Using questionnaires, human perceptions of balance and discomfort were also investigated in this study. In total, 60 young healthy females consisting of experienced and inexperienced high heeled shoes wearers participated in a series of balance tests when they wore shoes with four different heel heights: 0 cm (flat), 4 cm (low), 7 cm (medium), and 10 cm (high) with two different contact areas (A1, area = 1.33 cm² and A2, area = 0.80 cm²). In general, increasing heel height impaired human balance in terms of functional mobility and limits of stability especially starting from shoes with 7 cm heel height. However, participants were still able to keep their postural balance even with the highest heels in this study. To achieve this performance, they shifted the balance control strategy from the ankle to the hip, but still predominantly used the ankle strategy. Increased heel elevation caused the lower limb and lower back muscles to work harder, especially the calf muscles. Participants wearing higher heels also shifted the force and pressure distributed under the heel and mid foot regions to the forefoot and toe regions, and changed the center of pressure (COP) location more to the ball of the foot. During gait, increasing heel height caused them to have their center of mass (COM) of the body elevated and more fluctuated. They also had shorter COP path length, demonstrating an altered motion of the foot during walking. To compensate the restricted knee movement, they started to use an upper body control strategy with more flexible movements of the hips and elbow to maintain their balance when walking with higher shoes. Due to these unnatural positions, they had lower confidence in balancing their body and higher discomfort, especially on the lower leg and foot. Even though experienced wearers did not show significantly better balance performance, they had better stability limits in terms of maximum excursion and control of direction in the back and forward directions. They showed an adaptation effect, indicated by smaller loads and lower pressure under the forefoot region, and shifted their COP back to the heel as if they wore shoes lower than they actually were. They also used different muscle utilization and movement patterns that may provide them with better stability. Heel contact area did not affect the balance performance significantly. From our results, it is recommended for young females to wear shoes with heel height lower than 4 cm since these shoes are within a person’s ability to maintain their balance and can be considered safe. Shoes with heel height higher than 7 cm could cause significant challenges to human balance performance and thus are not recommended. Regular high heeled shoes wearers are recommended to stretch and strengthen their calves regularly to counteract the intense activities on the calf muscles as a result of wearing high heeled shoes. It is also recommended for them to mix up the footwear and wearing flat shoes on some days in the week to prevent the shortening of calf muscle fascicle and stiffening of Achilles tendon. For the designers, it is important to consider the shank curve to redistribute the force over a larger area of the plantar surface of the foot when designing the shoes. Additionally, shoe cushions, pads, inserts or insoles are recommended to reduce the foot discomfort, especially if the intended height of the heel is higher than 4 cm. The findings can enhance the understanding of imbalance challenges imposed on the human body while wearing high heeled shoes and help to further establish safety footwear recommendations for improving human balance and fall prevention.