Biomechanical approach in facilitating long-distance walking of elderly people using footwear modifications

Highlights

• Heel lifts and silicon insoles facilitated long-distance walking of older adults.

• They improved subjective perception of physical exertion, pain and fatigue.

• They also improved gait measured by force plates and a motion analysis system.

• They might be solutions for healthcare workers to prompt walking of older adults.

Abstract

Background

Long-distance walking is a convenient way for prompting physical activity of elderly people. However, walking ability declines with aging.

Research question: This study assessed if silicone insoles with heel lifts (named here the prescribed insoles) could facilitate long-distance walking of older adults.

Methods

Fifteen adults aged over 65, who did not have obvious lower-limb problems, walked on a treadmill for totally 60 min in two separate walking sessions: 1) with the prescribed insoles, and 2) with original insoles of the standardized shoes. Gait tests using force plates and a motion analysis system, and subjective evaluation using visual analog and Borg’s CR10 scales were conducted at different time points of the treadmill walking.

Results

Objective gait anaylsis showed that without using the prescribed insoles, there were significant reductions (p < 0.05) in stance time, vertical ground reaction force, ankle dorsiflexion angle and ankle power generation of the dominant leg after the 60-minute treadmill walk. Such significant reductions were not observed in the same group of subjects upon using the prescribed insoles. Meanwhile, significant improvements in subjective perception of physical exertion, pain and fatigue were observed.

Significance

Heel lifts and silicone insoles are generally used to relieve plantar pain and reduce strain of plantar flexors in patients. This study showed they might also be solutions to facilitate long-distance walking of older adults, an approach which could prompt their physical activity.

Introduction

Improving health and preventing disease in the elderly population are among the top priorities in health-care policy of many governments. Evidence suggests that regular physical activity can reduce fall-related injuries [1], cognitive declination [2] and mortality rates [3] among older adults. Long-distance walking is a safe and convenient way of exercise for older people [4], which can easily be integrated into their daily routine [1]. Walking for over an hour per day was found to be able to reduce the risk of mortality [3] and disability [5] of the elders. However, walking ability clearly declines with advancing age [6]. A meta-analysis of 42 studies indicated that adults aged over 65 walked only an average of about 3000 steps per day [7], less than a total 30 min of walking per day.

Muscle weakening and fatigue could be the major reasons for the difficulty faced by the healthy elders walking long distances. Over the age of 60, muscle strength decreases by an average of 3% per year [8]. In addition, older people have even greater relative force loss than young adults and slower return to resting levels, after the muscles become fatigued [9]. Plantarflexors were found to be more susceptible to fatigue than other lower-limb muscles [10]. Fatigued plantarflexors could lower the abilities of shock absorption and motion generation [10], which potentially affect the ability of long-distance walking.

Discomfort and pain at the plantar surface of the foot could also account for the lack of walking among elderly people. The pain may not occur at the beginning of the day, but it may be perceived after some walking [11]. This could be explained by the hysteresis of the soft tissue at the plantar foot reducing its stiffness upon repeated loading [12]. A previous study suggested that after a long-distance walk the gait of the young adults changed to reduce loading at the forefoot which could be a response of avoiding pain and discomfort [13]. There is a lack of studies investigating the changes in level of pain at the lower-limb upon long-distance walking of older people. However, it was documented that older people have lower shock absorption ability of the soft tissue at the plantar foot [14], potentially bringing them more susceptible to foot pain upon repeated loading at the feet.

Modifying the forces applied to the lower limbs might address the biomechanical problems. Traditionally, orthopedic insoles are used to treat patients with foot pain. Silicone insoles were found effective in relieving foot pain in patients [15], inducing a significant reduction in peak plantar pressure [16] and soft tissue strain [17]. In addition, a wedge lifting the heel has been used to reduce the stretching of plantarflexors during lomoction, reducing further strain and fatigue [18]. Advantages of heel lifting in amputee population included a reduction in power generation of plantarflexors and a facilitation to walk longer distances [19]. Footwear modification has been used with success to treat a variety of foot problems [[15], [16], [17], [18]]. However, little attempt has been made to use such approach to facilitate long-distance walking of older people.

This study examined whether modification of shoe inserts, with the use of a full-length silicone insole and a heel lift, could facilitate long distance walking of the elderly. Gait tests measuring spatial–temporal, kinetic and kinematic parameters as well as evaluation of perceived level of physical exertion, fatigue and pain were conducted in the same group of older adults who walk for one hour with and without the shoe inserts modifications. It was hypothesized that such footwear modifications reduced pain and fatigue, producing noticeable improvements in perceived exertion and gait patterns of older people walking long distances.