Conclusiones generales

Prochaska and DiClemente developed the Transtheoretical model (TTM) in the late 1970s, and it is interchangeably referred to as the Stages of Change model [101-103]. The TTM is a model of intentional change and focuses on the decision making of an individual. It operates on the assumption that people do not change behaviors quickly and decisively. Instead, the

behavior change process is cyclical and occurs continuously over time. This is especially true for habitual behaviors like physical activity [101-103]. The TTM suggests that those adopting physical activity as a behavior progress through five stages of change: precontemplation, contemplation, preparation, action, and maintenance [104]. Each of these stages will be defined in the context of physical activity in older adults, followed by a discussion of the literature supporting application of the TTM to this area of the disablement pathway which will reveal the importance of studying perceived barriers and facilitators related to this extra-individual mechanism.

In the precontemplation stage, older adults do not intend to take action in the foreseeable future, defined as within the next 6 months. People in this phase tend to believe the cons of engaging in physical activity outweigh the pros. These people may be unaware that their current behavior or inactivity in this case, is problematic or has negative consequences.

Older adults in the contemplation phase recognize that their inactivity may be unhealthy and start to place equal and practical emphasis on the pros and cons of engaging in physical activity. People in this stage intend to start engaging in physical activity in the foreseeable future (within the next 6 months). Ambivalence toward behavior change is still common in this phase.

The preparation stage is also considered the determination phase. Older adults in this stage are ready to become physically active within the next 30 days. These people typically believe that being physically active can lead to positive outcomes, such as improved physical function and mobility.

During the action stage older adults recently changed their behavior within the past 6 months and intend to continue being physically active. People within this stage can begin to

acquire new healthy behaviors in addition to engaging in physical activity. Additional modifications of behaviors associated with physical activity continue during the action stage.

The maintenance phase of the TTM occurs when older adults sustained their physical activity for more than 6 months. In this stage people intend on maintaining physical activity and work to prevent relapsing to earlier stages. Entrance into the TTM occurs at the precontemplation stage, and an individual can exit and re-enter at any stage.

The TTM identifies ten processes of change that result in strategies that assist an older adult in progressing through the five stages, engaging in physical activity, and maintaining the change: consciousness raising, dramatic relief, self-reevaluation, environmental reevaluation, social liberation, self liberation, helping relationships, counter-conditioning, reinforcement management, and stimulus control. Some of these processes are associated with barriers to and facilitators of physical activity in older adults, providing theoretical support for the importance of these intra-individual mechanisms and their influence on physical activity and functional limitations in the disablement pathway.

A number of studies employ the TTM to physical activity in older adults and through this application uncover the importance of perceived barriers and facilitators associated with this extra-individual mechanism [105, 106]. Yang and colleagues recognized that forming and maintaining regular physical activity habits is challenging for older adults, especially those that are inactive [107]. These investigators demonstrated that the TTM can be applied to interventions and used to successfully engage older adults in physical activity that they can maintain [107]. This study population consisted of older adults in the contemplation and preparation stages of the TTM and acknowledged that different strategies of facilitating behavior change may be needed for older adults in other stages of change.

Other studies used the TTM to examine factors that may be perceived barriers to or facilitators of the adoption of physical activity by older adults. Cheung and colleagues report that baseline self-efficacy predicts exercise behavior after a 16 week walking program in community-dwelling older adults [108]. Several longitudinal studies used the TTM to show that self-efficacy and perceived barriers to exercise were associated with physical activity participation in older adults [109-111]. Additional research utilizing the TTM discovered that perceived social support directly influenced older adults’ motivation and ability to be physically active [112-114].

In summary, the TTM can be used as a guide for understanding behavior change. Research supports the use of the TTM as a theoretical foundation for focusing on perceived barriers to and facilitators of physical activity, and how this impacts physical function and mobility disability in older adults. Discovering the factors, like perceived social support, influencing stages of change for physical activity could have a significant impact on the risk of physical disability in the growing population of older adults.

The disablement pathway does not assume that every older adult with impaired physical function or mobility disability becomes physically disabled, and it acknowledges that psychological and environmental contexts surround biological decline in the form of intra- and extra-individual mechanisms. This underlies the importance of studying the specific intra- and extra-individual mechanisms supported by the TTM, perceived barriers and facilitators and physical activity, and how they may be associated with physical function and mobility disability. The evidence base for perceived barriers to and facilitators of physical activity in older adults can be broken into two categories: quantitative and qualitative studies. The following sections will review the literature within each of these categories.

4.1.3 Quantitative Evidence for Perceived Barriers and Facilitators to Physical Activity in