Elsevier

Gait & Posture

Volume 60, February 2018, Pages 65-70
Gait & Posture

Full length article
Are there associations with age and sex in walking stability in healthy older adults?

https://doi.org/10.1016/j.gaitpost.2017.11.010Get rights and content

Highlights

  • The centre of pressure was measured during walking in 114 healthy older adults.

  • Stability was challenged more in females compared to males during terminal stance.

  • Lower COP velocity was associated for females.

  • Greater age was associated with increased centre of pressure variability.

Abstract

The variability of the centre of pressure (COP) during walking can provide information in relation to stability when walking. The aim of this study was to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking. One-hundred and fourteen older adults (age 65.1 ± 5.5 yrs.) participated in the study. A Kistler force platform (1000 Hz) recorded the ground reaction forces and COPs during walking at a self-selected walking speed. The stance phase was divided, using the vertical GRF, into four sub-phases: loading response (LR), mid-stance (MSt), terminal stance (TSt), and pre-swing (PSw). The standard deviations of the COP displacement (variability), the COP velocity, and COP excursion in the medial–lateral and anterior–posterior directions, as well as the resultant magnitude were assessed. When controlling for walking speed, a greater age was associated with a higher variability and excursion of the COP during LR only suggesting that stability is maintained during the majority of the stance phase. During LR lower COP velocity was significantly associated for females for anterior-posterior and total COP, which may be a strategy to facilitate stability before, and moving into, MSt and TSt.

Introduction

The trajectory of the centre of pressure (COP) represents the cumulative neuromuscular response that controls the movement of the centre of mass (COM) to help maintain forward progression and upright balance [1]. The anterior–posterior (AP) COP trajectory indicates the control of the forward progression of the COM during stance. The medial–lateral (ML) COP movement reflects the control process to regulate lateral stability, especially in single-support. COP excursion, COP velocity, and COP variability provide useful information about COP characteristics during walking [2], [3], with greater COP variability indicating possible difficulties in controlling stability during walking [2], [3].

Variability of gait measures during walking may reflect the underlying neural control of gait indicative of sensitivity to ageing and pathological processes [4]. Such data add to the understanding of gait and motor control in older age and assist in defining older adults who have an unstable gait and may be at a greater risk of falls. A view of gait variability may be a reflection upon the central neuromuscular control systems ability to maintain steady walking, thus measures of gait variability may indicate instability or falls risk [5]. For example, a more varied gait, indicted by COP variability, may predispose an individual to greater instability [5]. Although evidence suggests that falls in older adults mostly occur during dynamic movement rather than when standing still [6], little is known about the movement of the COP of older adults (55 years of age and over) under dynamic conditions such as walking. This indicates that there is a need to assess dynamic characteristics during activities of daily living among older adults and between sexes. Since walking is a common activity of daily living, this study considered walking. The COP during walking in older adults has not been reported in the literature. Nevertheless, this is an important variable to evaluate because almost half of the population over the age of 65 years report some difficulty with stability or walking [7]. This reduced ability to maintain balance is associated with a greater risk of falling [8] which, in the UK, accounts for approximately 14,000 deaths and costs the National Health Service £1.7 billion/year [9].

Gait differences between the sexes are seen for some kinematic and kinetic parameters during walking [10]. These differences may be further exacerbated, for falling, with females more prone to fall than males [11], and the differences in gait and balance between the sexes may be a reason for this [12], [13]. Despite these differences in gait, the association of sex to COP movement, and in particular variability, in older adults has not been reported in the literature.

Little is known regarding the natural history of COP movement variability of older adults during walking and even though females are more likely to fall, differences in COP variability between sexes have not been reported in the literature. Therefore, the aims of this study were to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking when controlling for walking speed.

Section snippets

Participants and experimental set-up

Following ethical approval, n = 131 community dwelling older adults (aged 55–84 years of age) recruited from the local area participated in this cross-sectional study. All participants lived independently. Eligibility criteria required all participants to be aged fifty-five years or over, to have no surgical procedures occurring in the last six months, and be able to walk at least 10 m unaided. These criteria were broad to capture a representative sample of this age range (55–84 yrs.). By

Results

The mean and standard deviation of the COP variability, COP excursion, and COP velocity for the whole group and split by sex is shown in Table 2. For the whole group only, a comparison between phases was carried out. The COP variables were significantly greater for the LR and PSW compared to MSt and TSt phases (Table 2).

The univariate analyses demonstrated that age was associated with COP variability and COP excursion (anterior-posterior COP and total COP) during loading response. There were no

Discussion

The objective of this study was to establish if COP parameters, which are seen as indicators of stability during walking, were associated with sex and age in a group of older adults. Since walking speed effects a number of biomechanical gait parameters [16] we also controlled for walking speed. For sex, regardless of walking speed, greater COP variability (anterior-posterior and total COP) during MSt and TSt was significantly associated with females. A similar association was seen for COP

Conflict of interest

None.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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