Self-perceptions of aging and physical function
In recent years, a large number of studies have provided broad evidence for the impact of self-perceptions of aging (SPA) on physical and mental health and even mortality (1, 2). SPA refer to an individual’s overall expectation and attitude towards the aging process. Especially in old age, SPA also increasingly reflect a person’s own actual aging experiences (3). SPA are multidirectional which means a person can hold both positive or gain-related and negative or loss-related SPA at the same time. SPA are also multidimensional: they refer to different life domains, e.g. to health, self-development or social relationships. This means, individuals can concurrently have positive SPA that refer to gains such as personal growth and development, having time to make new plans and being able to pursue new ideas. Negative, loss-related SPA usually refer to physical or social losses, such as physical decline, illness or loss of social embeddedness.
By now, there is abundant evidence for the importance of SPA for the way people actually grow older (3, 4). For example, people with more positive SPA report better physical and mental health (5) and even live up to 7.5 years longer (1), while people with more negative SPA are at increased risk of physical decline or frailty (6, 7). However, most findings in this context rely on self-report data for physical function obtained by measures like the Short Form Health Survey (8, 9) or the Health Scale for the Aged (10). These might be subject to bias through social desirability or simply because some people over- or underestimate their actual physical performance, e.g. their ability to walk several blocks without a break. It is therefore important to accumulate additional knowledge about effects of SPA on objectively measured physical function.
So far, only few studies have addressed this question. In addition, we see a very limited range of outcomes in these studies – they either looked at composite measures of physical performance like the Short Physical Performance Battery (11) or at single gait parameters like gait speed (12).
Gait as indicator of physical function
Gait speed is a gait parameter that is relatively easy – albeit not trivial (13) – to measure and associated with a large range of health outcomes and has even been termed “the functional vital sign” (14). Modern technological devices allow the detailed recording of a large range of gait parameters that give additional information on specific gait features over and beyond gait speed such as step-width-variability or walk ratio. As some gait parameters change with gait speed, recording walking at different gait speeds is recommended (15). Participants complete the walk at their usual pace and at their individual maximum speed. This provides important indications of everyday functioning of older adults. Walking at a usual pace reflects everyday behavior, like the ability to go grocery shopping. Yet, when crossing a road at a traffic light, it is also important to be able to keep a stable gait while walking at increased speed. At maximum speed, limitations in walking capacity become more noticeable (15) .
However, most studies have focused on the role of single gait parameters e.g. for incident disability (16) or compared single gait parameters between groups (17). Since walking is a complex task that requires coordination of diverse motion sequences, looking at gait patterns as a combination of several different gait parameters might be of additional value. Some studies proposed methods to form gait patterns, e.g. through cluster analysis or latent profile analysis. However, these studies were interested in identifying gait patterns associated with specific illnesses like hemiplegia (18) or multiple sclerosis (19), and not among community samples of older adults. Furthermore, studies on gait have rarely considered potential psychological correlates, and if they have, they mostly focused on the role of personality (20).
Aims & Hypotheses
Taken together, as to our knowledge, this is the first study which regards the complexity of gait while taking multidimensional and multidirectional aspects of SPA into account. We aimed to investigate the role of loss- and gain-related SPA, which refer to two different life domains, for gait patterns in a community sample of older adults.
To reach this goal, we first explored gait patterns in a community sample, and then – in a second step – investigated associations of SPA with these gait patterns. Based on previous research on SPA and physical function, we developed two specific hypotheses for associations of loss- and gain-related domains of SPA with gait patterns.
First, the loss-related domain of SPA physical losses refers to the notion of aging as associated with decline in health, fitness and vitality. People who have this attitude usually report worse physical function (9) and more functional limitations in everyday activities (21) than those who do not have this view on aging. This means, SPA physical losses is closely related to the experience of actual physical losses, which is not surprising: Individuals often experience age-related physical decline and accumulating illnesses and many people tend to attribute this to aging (22). Since these limitations are noticeable in everyday behavior, we hypothesized:
H1: Higher SPA physical losses increase the likelihood to exhibit a functionally limited gait pattern when walking at usual gait speed.
Second, the gain-related domain of SPA ongoing development is a more motivational facet of SPA and is a sign of resources. Previous research that did not consider domain-specific views on aging but looked at overall positive SPA showed that these views can buffer the negative effect of precariousness on health and well-being (23) and promote healthy behavior (24). Positive SPA are also associated with a lower rate of overnight hospitalizations after four years (25). Furthermore, the association of positive SPA and better self-reported physical function in late life is mediated by self-efficacy (8): This means that positive SPA subsequently foster a person’s ability to cope successfully with aging-related challenges, which is then later reflected in better self-reported, and, presumably, also objective physical function.
H2: Higher SPA ongoing development increases the likelihood of exhibiting a more favorable gait pattern when walking at individual maximum gait speed.