Obesity is a pervasive public health issue that affects individuals of all ages, including older adults [1]. In older adults, obesity is associated with a higher risk of chronic diseases [2], multimorbidity, functional decline [3], increased risk and severity of falls [4], and diminished quality of life [5]. Effectively prevent and manage obesity in older adults, it is crucial to adopt a physically active lifestyle that helps maintain muscle mass and increase energy expenditure.
During the past decade, a more comprehensive approach for describing a physical active lifestyle has been advocated, addressing various movement behaviours throughout the day, including physical activity, sedentary time, and sleep [6]. These behaviours are naturally interrelated and optimizing the balance between them in 24-hour cycles is essential for health and well-being [7].
Prior articles focused on 24-hour behaviour primarily from the perspective of intensity. This entailed distinguishing between Sedentary Behaviour (SB), Light Physical Activity (LPA), and Moderate-to-Vigorous Physical Activity (MVPA), and sleep. However, these intensity-specific classifications fail to accurately account for the postures in which these behaviours are performed. For instance, assessing sedentary behaviour based solely on intensity might overlook postures like sitting, reclining, or even quiet standing. Yet, specific postures significantly influence energy expenditure, muscle function, and metabolic responses. In contrast to the traditional intensity-based approach, posture-specific analyses offer a more adaptable strategy, catering to the unique abilities and limitations of older populations. This makes such an approach especially valuable when designing interventions for seniors, as it addresses the challenge of incorporating physical activity within their capabilities.
Moreover, focusing on posture-specific behaviour also helps reduce the bias inherent in the intensity-based approach. Accelerometers, commonly used in intensity-based studies, do not distinguish between sitting and standing still, leading to measurement bias for SB and LPA [8]. This bias can skew results in favour of the relative contribution of MVPA over other movement behaviours. By employing posture-specific measurements, future studies can provide a more accurate and unbiased representation of all movement behaviours, improving the overall quality of evidence [9].
As the global population continues to age, with the number of individuals aged 60 and over projected to double by 2050 [10], this approach becomes increasingly justified. Older individuals often have varying degrees of mobility and different physical limitations compared to younger or more active populations [11]. Additionally in older populations, it is crucial to monitor walking, alongside other activities as it is a fundamental activity that significantly impacts overall health, mobility, and independence in seniors [12]. By focusing on posture and ensuring that walking is adequately incorporated and monitored, healthcare providers can tailor physical activity recommendations and interventions that are both safe and effective for older adults.
This paper seeks to delve into the interplay among lying down, sitting, standing, moving, and walking. Specifically, we will analyse posture-specific behaviours and their connection to obesity risk in younger and older groups of elderly. Through three compositions with 4, 5, and 6 components, each progressively detailing specific activities, we can comprehensively assess variations in daily activities and their health implications. The first composition looks at lying, sitting, standing, and any form of movement. The second composition further breaks down movement into non-walking movement and walking. The third composition then differentiates walking into slow and fast walking. This approach allows for a nuanced understanding of how each specific activity impacts BMI and obesity risk.
Through compositional and isotemporal substitution analyses, we intend to provide insightful perspectives for crafting targeted interventions tailored to the distinct needs of seniors. Therefore, the aims of this study are to:
A) describe posture-specific behaviours (lying, sitting, standing, moving and slow and fast walking) in younger and older seniors;
B) examine the compositional associations between the 24h posture-specific behaviours and BMI; and
C) investigate the differences in BMI associated with replacing time spent in lying, sitting and standing with moving or walking.