O6.4 Physical activity and sedentary behavious

Physical activity (PA) is defined as any bodily movement generated by skeletal muscle that results in energy expenditure above resting levels and is often classified as light, moderate or vigorous intensity according to the energy level required (Garber 2011). In its broadest form, PA encompasses exercise (PA that is planned, structured and repetitive, undertaken with the aim of improving or maintaining physical fitness and for health benefits), sports, and PA done as part of daily living, work, leisure and transportation.

It is well-established that people with COPD participate in low levels of PA during daily life. Data from meta-analyses indicate that, on average, people with COPD participate in 57% of the total duration of PA undertaken by healthy controls (Vorrink 2011). Reductions in PA commence early in the COPD disease trajectory (Waschki 2015). Over time, levels of PA substantially decline across all severity stages of COPD and this decline is accompanied by deterioration in lung function and health status (Waschki 2015).  Levels of PA are reduced further during hospitalisation for an exacerbation of COPD (Pitta 2006).  An Australian study assessed PA in 50 individuals during hospitalisation for an exacerbation of COPD, and at one and 6 weeks following discharge (Tsai 2016). Although there was a significant improvement in PA at one week following discharge when compared to activity levels during admission, the level of PA at 6 weeks post-discharge showed no further significant improvement (Tsai 2016).

Low levels of PA are associated with increased mortality and exacerbations in people with COPD (Gimeno-Santos 2014) [evidence level I]. In one cohort study of 341 patients hospitalised for the first time with a COPD exacerbation, regular PA was related to a higher DLCO, expiratory muscle strength, exercise capacity (6MWD and VO2 peak) as well as to lower levels of systemic inflammation, after adjusting for confounders (Garcia-Aymerich 2009) [evidence level III-2].  In a population-based sample of 2,386 individuals with COPD who were followed for a mean of 12 years, those who performed some level of regular PA had a significantly lower risk of COPD admissions or mortality than sedentary individuals (Garcia-Aymerich 2006) [evidence level III-2].

Regular PA is recommended for all individuals with COPD (Garcia-Aymerich 2009). In the absence of instruction from a health professional (i.e. physiotherapist, exercise physiologist), individuals with COPD should be encouraged to be physically activity (i.e. engage in at least moderate PA for 30 minutes on 5 days each week, e.g. walking) and participate in activities of daily living that require the use of muscle strength (e.g. lifting, squatting to complete tasks such as gardening) as well as doing activities such as bowls, golf, swimming and Tai Chi that they enjoy.

There is some evidence that interventions comprising PA counselling, especially when combined with coaching, can produce modest increases in physical activity in people with COPD however the quality of the evidence was rated as very low (Mantoani 2016) [evidence level I].  Further, supervised exercise training alone or within the context of a pulmonary rehabilitation program has been shown to produce significant but small increases in PA, however the benefits are inconsistent and overall the quality of the evidence was rated very low (Mantoani 2016) [evidence level I]. This highlights that little is known about how to transfer the benefits in exercise capacity that are achieved with pulmonary rehabilitation into greater PA in daily life.  It is also unknown what magnitude of improvement in PA is clinically meaningful.

In addition to low levels of PA, there is growing recognition that people with COPD spend a large proportion of their waking hours in sedentary behaviours, (Hunt 2014) defined as those behaviours which are undertaken in a sitting or reclined posture and have low energy requirements (e.g. watching television, reading, playing cards, sitting at a computer) (Sedentary Behaviour Research 2012). People with COPD who accumulate the greatest sedentary time during daily life are more likely to live with someone else and be characterised by more frequent exacerbations, lower exercise capacity, long-term oxygen use, lower motivation for exercise, and the presence of physical comorbidities such as obesity, musculoskeletal or neurological conditions (Hartman 2013, McNamara 2014).

In the general population, data from several large longitudinal studies have reported the deleterious health consequences (e.g. both all-cause and cardiovascular mortality) of increased sedentary time (Dunstan 2010, Thorp 2011) [evidence level I]. Notwithstanding these findings, studies showing the specific health consequences of increased sedentary time in people with COPD are sparse. For example, data collected in 76,688 people from Japan, who were followed for 19.4 years show that, when compared with men who watched television for <2 hours/day, men who watched television for ≥4 hours/day had an increased risk of COPD-related mortality (HR 1.63; 95% CI 1.04 to 2.55). However, this relationship was not observed in females (HR 0.84; 95% CI 0.29 to 2.48) (Ukawa 2015). Data collected in 223 people with COPD as part of the National Health and Nutrition Examination Survey (NHANES), showed modest positive associations between sedentary time and markers of cardiometabolic risk such as waist circumference and fasting glucose levels (Park 2014).

Given that people with COPD accumulate large amounts of sedentary time and this may have deleterious health consequences, reducing sedentary time would seem to be an appropriate lifestyle goal in this population. Compared with the goal of increasing PA, particularly moderate or vigorous intensity PA, the goal of reducing sedentary time by increasing light intensity PA is likely to be more feasible in those with marked reductions in exercise capacity who are limited by dyspnoea during activities of daily living (Cavalheri 2016, Hill 2015). Of note, in people with COPD, greater participation in light intensity PA, such as slow walking, has been reported to reduce the risk of respiratory-related hospitalisations (Donaire-Gonzalez 2015).  There is a need to identify approaches that are effective at reducing sedentary time in people with COPD, and most importantly, whether any reduction in sedentary time impacts health outcomes in this population.

The table in Appendix 4 provides some strategies aimed at avoiding prolonged sedentary time