Background: Chronic obstructive pulmonary disease (COPD) is an
important common chronic lung condition that is a leading cause of morbidity
and mortality worldwide, resulting in a substantial and increasing economic
and social burden to health care systems. Physical activity (PA) is the
strongest predictor of mortality in this population, playing an important role
determining the quality of life in COPD, with better outcomes being reported
by those who have higher levels of PA. Therefore, improving PA levels has
been considered a key component in the management of patients with
COPD. Likewise, it is important to understand the mechanisms that lead to
inactivity, as it is to develop accurate methods of measuring PA in this
population. Aims of the thesis: 1) To identify and to summarize the
interventions able to increase PA levels in patients with COPD; 2) To
understand the longitudinal interaction between muscle mass and function
and PA levels in COPD; 3) To study the acceptability and the suitability of a
new activity monitor (TracMor D – Philips, the Netherlands) for home
coaching in daily routine of patients with COPD; and 4) To investigate
whether a PA enhancing programme with set targets and feedback would
constitute a successful intervention to increase PA levels in patients with
COPD attending pulmonary rehabilitation (PR). Methods: To achieve the first
aim of the thesis I performed a systematic review summarizing interventional
studies that assessed PA as an outcome in patients with COPD. For the
second aim, I analysed some multicentric longitudinal data (one year follow-up)
on PA and muscle mass/function in COPD. The third aim was achieved
with a pilot study I conducted in Edinburgh, where patients with COPD wore
three TracMor D in different body places simultaneously with the criterion
method (Actigraph GT3x activity monitor) for a week. To accomplish the
fourth and main aim of my PhD, I conducted a randomised controlled trial
(RCT) where patients with COPD undergoing PR were randomised to either
receive PR only or PR plus a PA coaching programme using the TracMor D
activity monitor for 12 weeks. Main Results: Study 1: Sixty studies were
considered for data extraction in the systematic review. Seven types of
intervention with the potential to increase PA levels in patients with COPD
were identified. PR programmes with more than 12 weeks of duration and PA
coaching programmes with feedback of an activity monitor are promising
interventions to increase activity levels in patients with COPD. Overall, the
quality of evidence across interventional studies was graded as very low.
Study 2: The longitudinal study showed that there were weak correlations
between PA levels and muscle strength at baseline (0.19 ≤ r ≤ 0.33 p<0.001
for all). No correlations were found between changes in PA and muscle
strength (-509 [-1295-362] vs -0.4 [-3.5-2.6] - 12 months minus baseline -
respectively) and future muscle mass (p>0.05). Baseline PA levels are
related to future muscle strength (0.30 ≤ r ≤ 0.41, p<.0001) but not with
muscle mass. Study 3: This study showed that TracMor D had strong
correlations with Actigraph GT3x in terms of Kcal consumption in all three
positions (necklace, pocket and hip) (0.84≥r<0.86, p<0.001 for all). TracMor
D was considered comfortable and easy to use at home, receiving a mean
usability score of 98 out of 100 maximum points. Study 4: My RCT showed
that the proposed PA intervention was effective in changing steps/day (1251
± 2408 vs control -410 ± 1118, p=0.01), time spent in light activities (21 ± 60
vs -37 ± 55, p=0.004), exercise capacity (99 ± 139 vs 3 ± 83 meters; 85 ±
114 vs 2 ± 62 seconds, p<0.03 for both) and muscle strength (15 ± 20 vs -5 ±
18, p=0.01) among others when compared to the control group.
Conclusions: Strategies focussing specifically on increasing PA and longer
PR programmes may have greater impacts on PA levels in COPD. Well-designed
clinical trials with objective assessment of PA in patients with
COPD are needed. PA levels are not related to one-year changes in muscle
mass and muscle strength in patients with COPD. However, higher PA levels
at baseline are related to having higher muscle strength at one-year. TracMor
D strongly correlated with the criterion method and was highly accepted by
patients with COPD in their daily routine, being considered comfortable and
easy to use at home. The combination of PR with a physical activity
enhancing programme using a PA monitor to set targets and give feedback
on activity levels significantly improves PA, exercise capacity, muscle
strength, quality of life, and anxiety and depression levels in patients with
COPD