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