Background
There is strong evidence that adherence to physical activity guidelines is associated with health benefits and reduced mortality in both healthy and chronic disease populations [
1,
2]. There is no specific evidence that physical activity is beneficial in bronchiectasis; however it is strongly related to mortality and lung health in other respiratory conditions such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis [
3-
5]. Promoting physical activity has been proposed as a key component of care in chronic respiratory disease [
2,
3,
6,
7]. International recommendations for the whole population promote a minimum of 150 minutes of at least moderate physical activity per week (accumulated in at least 10-minute bouts) and a restriction on extended periods of sedentary behaviour for promoting and maintaining health [
1]. The impact of bronchiectasis on sedentary behaviour and physical activity is unknown. It is important to explore this to identify the need for physical activity interventions and how to tailor interventions to this patient population.
Objective assessment of sedentary behaviour and physical activity using activity monitors has been recommended in preference to questionnaires [
7-
9]. In this study, we chose to use the ActiGraph activity monitor as it is one of the most studied activity monitors with demonstrated reliability and validity in respiratory disease populations [
10,
11]. The ActiGraph activity monitor measures many different physical activity dimensions but currently there is limited research to inform clinicians on which of these variables are most useful. Van Remoortel and colleagues have proposed that time spent in different physical activity intensities, energy expenditure and step counts should all be considered to provide a comprehensive assessment [
12]. The ActiGraph activity monitor also measures time spent in sedentary behaviours such as lying and sitting. Previous research has highlighted how sedentary behaviour has an important role on patients’ clinical progression [
13].
A range of clinical characteristics (disease severity, exercise capacity, health-related quality-of-life (HRQoL) and symptoms) have been shown to impact on sedentary behaviour and physical activity in other respiratory conditions [
13-
16]. However, their impact in bronchiectasis is unknown.
Additionally psychological and behavioural factors may also have an impact on sedentary behaviour and physical activity. An adaption of the transtheoretical model (TTM) of behaviour change can be used as a framework to identify why patients with bronchiectasis engage in physical activity or not, and when and how individuals are likely to change their physical activity behaviour [
17,
18]. The TTM constructs include the stages of change, self-efficacy, decisional balance and both cognitive and behavioural processes of change (more details included in Table
1 and Additional file
1). The TTM assumes that behaviour change is a dynamic process rather than an all-or-nothing phenomenon [
19]. However, specific data in patients with bronchiectasis using the TTM is not yet available [
18]. Understanding the links between physical activity and sedentary behaviour, and clinical and psychological characteristics will potentially inform the development of future physical activity interventions.
Table 1
Description of each component of the transtheoretical model (TTM)
Stage of change
| |
Pre-contemplation | No intention to engage in regular physical activity |
Contemplation | Intend to engage in regular physical activity in next 6 months |
Preparation | Immediate intentions and commitment to engage in regular physical activity |
Action | Initiated engagement in regular physical activity in last 6 months |
Maintenance | Maintained engagement of regular physical activity for longer than 6 months |
Self-efficacy
| Personal confidence towards physical activity commitment when: Tired/In a bad mood/Do not have time/On vacation/It is raining or snowing/Having respiratory symptoms* |
Decisional balance
| |
Pros | Perceived benefits of engaging in regular physical activity |
Cons | Perceived barriers to engaging in regular physical activity |
Cognitive processes of change
| |
Increasing knowledge | Finding information on the benefits of physical activity and the current recommendations for physical activity |
Being aware of risk | Concern for the risks of being physically inactive |
Caring about consequences | Realising social and environmental benefits that physical activity has |
Comprehending benefits | Assessing physical activity status and the values related to physical activity |
Increasing healthy opportunities | Awareness, availability and acceptance by the individual of physical activity in the society |
Behavioural processes of change
| |
Substituting alternatives | Substituting inactive options for active options |
Enlisting social support | Seeking out social support to increase and maintain physical activity |
Rewarding oneself | Providing rewards for being more active |
Committing oneself | Setting goals and making commitments for physical activity |
Reminding oneself | Controlling factors that have a negative effect on physical activity to prevent relapse and using stimuli to increase physical activity level |
The overall aim of this research was to explore sedentary behaviour and physical activity and correlates of these behaviours in patients with bronchiectasis. Specific objectives of this research were to explore patterns of physical activity in patients with bronchiectasis and determine if patients meet the current physical activity guidelines; and to examine the relationship between physical activity levels of patients with bronchiectasis and clinical characteristics (disease severity, exercise capacity, HRQoL and other symptoms of their disease) and constructs of the TTM (stages of change, self-efficacy, decisional balance and processes of change).
The research hypothesis was that patients with bronchiectasis would have high levels of sedentary behaviour and low levels of physical activity and these would be related to clinical characteristics and constructs of the TTM. More specifically, it was hypothesised that lower sedentary behaviour and higher levels of physical activity would be related to greater exercise capacity, greater lung function, better HRQoL and higher self-efficacy, perceiving more benefits of physical activity and using more processes of change.
Discussion
This is the first study to report patterns of sedentary behaviour and physical activity in bronchiectasis. The results demonstrate a more sedentary and less active profile for people with bronchiectasis compared to the recommended guidelines for physical activity. These findings are important as recent research has suggested a link with inactivity and decreased survival, poorer HRQoL and increased healthcare utilisation in chronic disease populations such as COPD and diabetes [
3,
4,
33-
36]. Furthermore, there is increasing evidence that a high level of sedentary behaviour is associated with adverse health outcomes in chronic disease populations [
36-
38].
To contextualise these study findings, we have compared our bronchiectasis data to similar ActiGraph data available for English, Swedish and USA healthy populations [
39-
43] and to another respiratory population [
16] (see Additional file
2). Albeit the healthy data sets are more heterogeneous in terms of age and ethnicity, some important contrasts emerge. Patients with bronchiectasis appear to have similar levels of sedentary behaviour and physical activity compared to the English healthy population [
42]; both populations fall well below recommended guidelines for physical activity [
1]. Patients with bronchiectasis appear to be more sedentary and less physically active compared to healthy Swedish and USA populations [
39-
41,
43]. USA population-based ActiGraph data is available in COPD. Patients with bronchiectasis appear to have a similar sedentary behaviour and physical activity profile; despite being younger in age [
16]. When designing physical activity interventions in bronchiectasis, researchers may need to consider the impact of patients’ baseline sedentary behaviour and physical activity levels as well as current and new symptoms.
We hypothesised that lower levels of sedentary behaviour and higher levels of physical activity would be related to greater exercise capacity, greater lung function, better HRQoL and higher self-efficacy, perceiving more benefits of physical activity and using more processes of change. FEV
1% predicted and BSI score did not correlate with sedentary behaviour time or physical activity variables highlighting that neither of these assessments should be used clinically as indicators of either sedentary behaviour or physical activity. Whilst MST did not predict sedentary behavior, MST consistently correlated with physical activity variables. This association between physical activity and exercise capacity has previously been demonstrated in bronchiectasis [
44] and highlights the potential importance of exercise interventions, such as pulmonary rehabilitation, to improve physical activity levels in patients with bronchiectasis. Based on positive findings from five key pulmonary rehabilitation studies in bronchiectasis [
45-
49], recent British Thoracic Society Guidelines for Pulmonary Rehabilitation recommend referral to pulmonary rehabilitation for patients with bronchiectasis who have breathlessness affecting their activities of daily living [
6]. The most recent of these studies by Lee et al. [
49] recruited patients with a very similar demographic profile into a quality randomised controlled trial of eight weeks of pulmonary rehabilitation versus control and demonstrated that pulmonary rehabilitation was associated with short-term improvement in exercise capacity, dyspnoea and fatigue; although these improvements were not sustained at 12-month follow-up. The positive effects of pulmonary rehabilitation on exercise capacity across chronic respiratory conditions have been shown to consistently diminish over time [
6]. With limited access to maintenance programmes, alternative strategies to reduce sedentary behaviour and/or increase and sustain physical activity may be important. Unfortunately, as with earlier studies, physical activity was not included as an outcome measure and further research is needed to establish whether changes in exercise capacity translate to changes in physical activity or whether physical activity needs to be specifically targeted in bronchiectasis.
There were important differences in the predictors of sedentary behaviour versus physical activity. In fact, decisional balance ‘pros’ score was the only correlate of sedentary behaviour suggesting that sedentary behaviour in bronchiectasis could be influenced more by psychological factors rather than physiological factors. The data shows that it is important to assess patients’ sedentary behaviour and physical activity levels directly. We also propose that it may be important to focus on behaviour change techniques and other behavioural strategies such as motivational interviewing [
50] rather than exercise training alone if targeting a decrease in sedentary behaviour as well as improved physical activity levels in patients with bronchiectasis.
Although activity energy expenditure was estimated using equations developed for healthy populations, an interesting relationship emerged with QOL-B Respiratory Symptoms scores. Patients with higher activity energy expenditure appeared to have worse respiratory symptoms. Patients with chronic respiratory disease potentially have an increased oxygen cost of breathing compared with healthy populations due to respiratory dynamics [
51].
In COPD, recent research suggests that higher physical activity levels are associated with higher self-efficacy and less depressive symptoms in patients with COPD [
52]. We have shown that patients with bronchiectasis perceived a range of barriers to participation in physical activity, with those who were more sedentary perceiving more barriers. They employed a range of cognitive and behavioural strategies to modify their physical activity behaviour. The most employed strategies were: realising benefits of being physically active, making commitments to be physically active and replacing inactive choices with active choices. Future intervention studies could focus on optimising frequently used strategies as well as considering the value of less commonly used strategies to support patients in altering their physical activity behaviour.
A major strength of this study was the use of validated instruments to assess physical activity, exercise capacity and HRQoL in a bronchiectasis population. This facilitated rigorous exploration of the correlates of sedentary behaviour and physical activity in bronchiectasis. One limitation may be that due to the exploratory nature of this study, no sample size calculation was performed. Nevertheless, this exploration has provided a useful insight into understanding correlates of sedentary behaviour and physical activity in bronchiectasis.
Conclusions
In summary, many patients with bronchiectasis demonstrated a largely inactive lifestyle and few met the recommended physical activity guidelines. FEV1% predicted and disease severity were not correlates of sedentary behaviour or physical activity. Exercise capacity was the strongest correlate of physical activity, and dimensions of the QOL-B were also important. Despite patients understanding the benefits of physical activity, many reported low levels of self-confidence in physical activity in certain situations, particularly when experiencing respiratory symptoms. This study highlights the need for physical activity interventions in bronchiectasis and provides information to tailor interventions to this patient population.
Acknowledgements
The authors would like to express their thanks to: patients recruited from the Northern Ireland Regional Respiratory Centre at Belfast City Hospital, Belfast Health and Social Care Trust (BHSCT); Craigavon Area Hospital, Southern Health and Social Care Trust (SHSCT); and Altnagelvin Area Hospital, Western Health and Social Care Trust (WHSCT) in Northern Ireland; patient representative (E Cosgrove); NICRN staff (S Gilpin, A McDonald, J Ratcliffe); WHSCT staff (D Todd); SHSCT respiratory physician (D Comer); and BHSCT respiratory physicians (D Downey, P McKeagney, J Rendall, S Rowan).
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
JB had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. JB, JW, KH, LK, SMcD, MT, IB, AK, JSE, BO’N contributed substantially to the concept or study design, data acquisition, data analysis and interpretation, and the writing or revision of the manuscript. DC, RC, MK contributed to data acquisition and revision of the manuscript. All authors have approved the final manuscript.
Judy M Bradley and Jason J Wilson were joint first authors. J Stuart Elborn and Brenda O’Neill were joint senior authors.