Improving physical activity in patients with COPD with urban walking circuits

Open ArchivePublished:July 25, 2013DOI:https://doi.org/10.1016/j.rmed.2013.07.008

      Summary

      Background

      Even after a rehabilitation program, levels of physical activity in COPD progressively decrease unless strategies to encourage activity are implemented. We analyzed the effects of the implementation of urban walking circuits on levels of physical activity and exercise capacity of patients with severe and very severe COPD after a rehabilitation program.

      Method

      A total of 83 patients were randomized to either urban circuits group (UCG) or usual care in the non-circuit group (NCG), after completing a 2-week rehabilitation program. Results were evaluated 9 months after completion of the rehabilitation program and were compared with a control group of 54 patients not enrolled in the rehabilitation program.

      Results

      At the end of follow-up, UCG patients increased their physical activity by a mean of 32.4 (SE = 5.9) min per day and 1.09 (SE = 0.22) days walked per week; 33.9 (SE = 5.6) min per day and 1.12 (SE = 0.24) days per week more compared to the NCG (p < 0.001). There was a significant positive correlation between the results of the 6-min walking test and minutes walked per day in the UCG (r2 = 0.52, p < 0.05) but not in the NCG (r2 = 0.094, p > 0.05). Controls showed a significant decrease in exercise capacity and physical activity over the follow-up.

      Conclusions

      Urban circuits are an easy, inexpensive strategy, which demonstrated to be useful to stimulate physical activity in our population of severe and very severe COPD patients and resulted in increased exercise capacity even 9 months after completion of a rehabilitation program.

      Keywords

      Introduction

      Chronic obstructive pulmonary disease (COPD) is characterized by the presence of chronic and poor reversible airflow obstruction [
      • Decramer M.
      • Janssens W.
      • Miravitlles M.
      Chronic obstructive pulmonary disease.
      ] and is associated with systemic effects, including skeletal muscle weakness and wasting, which produce worsening exercise tolerance and impairment of health status [
      • Donaldson A.V.
      • Maddocks M.
      • Martolini D.
      • Polkey M.I.
      • Man W.D.-C.
      Muscle function in COPD: a complex interplay.
      ,
      • Watz H.
      • Waschki B.
      • Boehme C.
      • Claussen M.
      • Meyer T.
      • Magnussen H.
      Extrapulmonary effects of chronic obstructive pulmonary disease on physical activity: a cross-sectional study.
      ,
      • Baarends E.M.
      • Schols A.M.
      • Mostert R.
      • Wouters E.F.
      Peak exercise response in relation to tissue depletion in patients with chronic obstructive pulmonary disease.
      ].
      Airflow obstruction causes static and dynamic hyperinflation, altering pulmonary and cardiac mechanics [
      • García-Río F.
      • Lores V.
      • Mediano O.
      • Rojo B.
      • Hernanz A.
      • López-Collazo E.
      • et al.
      Daily physical activity in patients with chronic obstructive pulmonary disease is mainly associated with dynamic hyperinflation.
      ] and is expressed clinically by progressive worsening dyspnea on exertion. Dyspnea leads patients to become housebound as any physical activity becomes difficult to achieve. This reclusion occurs even in patients who have followed a pulmonary rehabilitation program, as many usually do not continue a program of physical activity after rehabilitation [
      • Troosters T.
      • Gosselink R.
      • Janssens W.
      • Decramer M.
      Exercise training and pulmonary rehabilitation: new insights and remaining challenges.
      ].
      Pulmonary rehabilitation increases exercise capacity, reduces dyspnea and fatigue, improves quality of life, reduces health-care resource utilization, increases peripheral muscle strength and reduces anxiety and depression. However, maintaining these benefits after a pulmonary rehabilitation program is still a challenge [
      • Goldstein R.S.
      • Hill K.
      • Brooks E.D.
      • Dolmage T.E.
      Recent advances in chest medicine. Pulmonary Rehabilitation. A review of the recent literature.
      ].
      It is important to increase the levels of physical activity of patients with COPD, because high activity levels are associated with a lower risk of mortality and hospital admission [
      • García-Aymerich J.
      • Lange P.
      • Benet M.
      • Schnohr P.
      • Antó J.M.
      Regular physical activity reduces hospital admission and mortality in chronic obstructive pulmonary disease: a population-based cohort study.
      ,
      • Benzo R.P.
      • Chang C.C.
      • Farrell M.H.
      • Kaplan R.
      • Ries A.
      • Martínez F.J.
      • et al.
      Physical activity, health status and risk of hospitalization in patients with severe chronic obstructive pulmonary disease.
      ]. Different strategies have been designed to increase the levels of physical activity after a rehabilitation program, but the results have been disappointing. Moreover, the improvement obtained with programs of physical activity tends to disappear 6 months to 2 years after rehabilitation [
      • Foglio K.
      • Bianchi L.
      • Bruletti G.
      • Battista L.
      • Pagani M.
      • Ambrosino N.
      Long-term effectiveness of pulmonary rehabilitation in patients with chronic airway obstruction.
      ,
      • Beauchamp M.K.
      • Evans R.
      • Janaudis-Ferreira T.
      • Goldstein R.S.
      • Brooks D.
      Systematic review of supervised exercise programs after pulmonary rehabilitation in individuals with COPD.
      ]. In a systematic review about the efficacy of maintenance programs of physical activity based on exercise training after rehabilitation, the authors concluded that there was a significant increase in physical activity at 6 months, but the improvement was not sustained at 12 months, and no significant differences were observed between the different interventions [
      • Beauchamp M.K.
      • Evans R.
      • Janaudis-Ferreira T.
      • Goldstein R.S.
      • Brooks D.
      Systematic review of supervised exercise programs after pulmonary rehabilitation in individuals with COPD.
      ]. In a systematic review of randomized trails and single-group interventional studies Cindy NG et al. [
      • Cindy N.G.
      • Mackney J.
      • Jenkins S.
      • Hill K.
      Does exercise training change physical activity in people with COPD? A systematic review and meta-analysis.
      ] observed that exercise training may confer a small, albeit significant, increase in physical activity.
      In order to be successful, a strategy to increase physical activity must be attractive to most patients with COPD and must be easily incorporated into their daily routine. One example is the Nordic walking program that resulted in improvement in walking distance and quality of life in COPD patients [
      • Breyer M.K.
      • Breyer-Kohansal R.
      • Funk G.C.
      • Dornhofer N.
      • Spruit M.A.
      • Wouters E.
      • et al.
      Nordic walking improves daily physical activities in COPD: a randomized controlled trial.
      ]. A Tai chi program was also able to improve activity tolerance in a group of COPD patients [
      • Leung R.W.M.
      • McKeough Z.J.
      • Peters M.J.
      • Alison J.A.
      Short-form sun-style Tai Chi as an exercise training modality in people with COPD.
      ]. However, regular walking is the most common activity in COPD patients and can be performed all year long in Mediterranean areas such as ours. To encourage daily walking, we designed and implemented a series of urban walking circuits adapted to the patient's characteristics.
      The aim of this study was to assess the effectiveness of the implementation of urban walking circuits in increasing the level of physical activity and exercise capacity in severe and very severe COPD patients after completing a pulmonary rehabilitation program compared with a control group receiving usual care. Secondary variables were respiratory muscular strength assessed with maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) and the BODE index.

      Method

       Population

      Patients were recruited from the Physical Medicine and Rehabilitation Department of the Hospital of Mataró (Barcelona, Spain) from February 2008 to December 2011 and were included if they fulfilled the following inclusion criteria: severe or very severe COPD (post-bronchodilator FEV1/FVC <0.7 and FEV1 <50%, respectively??) and stable disease defined as no exacerbation, hospital admission or change in treatment in the previous three months. The exclusion criteria were: other significant respiratory disease (bronchiectasis, lung fibrosis, asthma, etc.), active smoking, severe cardiovascular, neurological, musculoskeletal and/or metabolic pathology that could interfere with the results, alcoholism (>80 g/day) or severe malnutrition (BMI <19 kg/m2).
      The study was approved by the Research and Ethics Committee of the Hospital of Mataró and all patients provided written informed consent. The trial is registered at ClinicalTrials.gov, Identifier NCT01854008.

       Study design

      This was a randomized clinical trial designed to assess the impact of the implementation of urban walking circuits on the level of physical activity and in the improvement in functional capacity in severe and very severe COPD patients after a pulmonary rehabilitation program.
      Patients that fulfilled the inclusion criteria were informed about the characteristics of the study and written informed consent was obtained. They were first included in a standard rehabilitation program as described below. At the end of the program, participants were randomly assigned following simple randomization procedures (computerized random numbers) to 1 of 2 treatment groups. One group, the urban circuit group (UCG), received a leaflet that included urban walking circuits and the remaining patients formed the non-circuit group (NCG). All the patients received general recommendations on physical activity and lifestyle and were visited every two months to encourage them to continue physical activity. The total duration of the study was one year: 3 months of rehabilitation program and 9 months of follow-up (Fig. 1).
      Figure thumbnail gr1
      Figure 1The study design consisted of two phases. In the first phase the patients were divided into the rehabilitation group (RG) and the control group (CG). The RG performed a pulmonary rehabilitation program for 12 weeks, 3 times per week. In the second phase the patients in the RG were randomized into two groups, the urban circuits group (UCG) and non-circuits group (NCG).
      Patients who were referred to our institution for evaluation and fulfilled all the inclusion criteria but could not be included in the study because they lived in other cities were also invited to participate and formed the control group (CG). This group received the same general recommendations on physical activity and lifestyle and was requested to attend medical visits for clinical control and encouragement of physical activity every two months for the one year duration of the study, similar to the intervention group (Fig. 1).
      All the patients followed their regular pharmacological treatment. Those presenting an exacerbation during the course of the study, which could interfere with the results, defined as worsening of symptoms requiring treatment with systemic corticosteroids and/or antibiotics, were excluded from the analysis.

       Interventions

      The pulmonary rehabilitation program in our hospital has been previously described [
      American Thoracic Society (ATS) statement: guidelines for the six-minute walk test.
      ] and consisted in a moderate intensity program, with a frequency of 3 sessions per week for 12 weeks. The exercise intensity was controlled by the patient using the modified Borg scale (from 0 to 10) [
      • Pleguezuelos E.
      • Pérez M.E.
      • Guirao Ll
      • Samitier B.
      • Costea M.
      • Ortega P.
      • et al.
      Effects of whole body vibration training in severe COPD patients.
      ]. Patients were informed as to the correct use of the scale to ensure that the mean value was not exceeded during exercise training. Basal oxygen flow was increased by one liter in oxygen carrier patients.
      Each training session consisted of warm-up exercises of the upper and lower limbs and spine for 10 min, followed by continuous aerobic exercise by cycling for 25 min. The initial intensity of training was 50 W, increasing progressively with tolerance to the exercise. This was followed by strengthening exercises of the upper limb muscles during 15 min, initially without resistance, and increasing progressively with the increase in tolerance, 10 min of stretching exercises and 10 min of relaxation exercises.
      A total of 32 urban walking circuits were developed jointly with the town hall of Mataró (124,000 inhabitants) and were included in a leaflet called “A PEU, FEM SALUT! Itineraris Urbans per Mataró” (On foot, keep healthy! Urban itineraries around Mataró). Each circuit includes a map marked with the route and a description of the beginning and end, cultural attractions on the itinerary such as buildings, museums, churches, and other places of interest, comments such as the amplitude of the crossings, lighting or the presence of commercial areas in the surroundings. They include information about the approximate duration, the distance in kilometers, the percent of slope, and the difficulty of the circuits (low, mild, moderate, and high), also shown with a colored circle (green = low, blue = light, orange = moderate and red = high). In addition, bus connections at the beginning and end of the tour are included. These circuits can be obtained on the website http://www.mataro.cat/web/portal/ca/salut/salut_publica/itineraris/index. All patients received individualized information about the content of the leaflet, the meaning of the symbols and interpretation of the maps. This information was reviewed at each bimonthly visit. Patients in the NCG and controls were also visited bimonthly to check proper data collection and encourage physical activity.

       End points

      The co-primary end points were the physical activity and the exercise capacity at the end of the study (one year after inclusion or 9 months after completion of the rehabilitation program). Physical activity was measured by the mean of minutes per day walked and the mean of days per week walked. Patients were instructed to write the minutes walked every day in a diary card during the one year of the study and this information was collected at every two-month follow-up visit. The functional capacity was measured with the distance walked in meters in the 6-min walking test (6MWT). The 6MWT was standardized following international recommendations [
      American Thoracic Society (ATS) statement: guidelines for the six-minute walk test.
      ]. Oxygen saturation and heart rate were recorded throughout the test using a pulsioximeter (Digit® Finger Oximeter, Smiths Medical PM, USA). Dyspnea was evaluated using the modified Borg scale at the beginning and end of the test [
      • Börg G.
      Perceived exertion as an indicator of somatic stress.
      ].

       Secondary end points

      The same measurements of physical activity and exercise capacity were measured at 3 months to evaluate the effect of the rehabilitation program compared to the control group before the implementation of the urban circuits. Other secondary variables were respiratory muscular strength assessed with maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) and the BODE index.
      MIP and MEP were evaluated using a Jaeger MasterScreen (Quebec, Canada) with a pressure transducer connected to the mouth in accordance with guidelines and using recommended reference values [
      • Morales P.
      • Sanchis J.
      • Cordero P.J.
      • Díez J.L.
      Maximum static respiratory pressures in adults. The reference values for a Mediterranean Caucasian population.
      ].
      The BODE index (Body mass index, Obstruction, Dyspnea and Exercise) was calculated for all the participants as previously described by the authors [
      • Celli B.R.
      • Cote C.G.
      • Marín J.M.
      • Casanova C.
      • Montes de Oca M.
      • Méndez R.A.
      • et al.
      The body-mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease.
      ]. This index scores the risk of patient mortality from 0 to 10, with a higher BODE score reflecting an increase in the risk of mortality.

       Statistical analysis

      Quantitative variables were expressed as means and standard error (Mean ± SE). The Wilcoxon–Mann–Whitney test was used to compare baseline and post-intervention measurements between CG and Rehabilitation group. To statistically compare the change in each group of patients between pre- and post-intervention treatment responses the Wilcoxon signed rank sum test was performed. To determine the effectiveness of the urban walking circuits, linear regression models were applied to one year measurements as dependent variables, and group (CG, UCG and NCG) and post-rehabilitation measurements as independent variables in an ANCOVA model. The coefficients, 95% confidence intervals and p-values associated with the patient group are reported. Poisson regression was used for Borg and BODE indices analysis. We reported the estimated mean ratio (by exponentiating the Poisson regression coefficients) comparing the UCG and CG with the NCG. The relationship between meters and minutes walked post-intervention by rehabilitation groups was estimated by Pearson correlation, and regression models were used to quantify the correlation. All analyses were performed with the SPSS (version 11.5) for Windows®. Statistical tests of hypotheses were two-tailed with significance set at p < 0.05.

      Results

       Patients' characteristics

      A total of 160 patients were recruited, 73 of whom lived outside the city of Mataró and were included in the control group (CG). A total of 35 patients did not complete the study; 18 did not attend appointments, 12 required hospital admissions for exacerbation, and 5 died, leaving 125 patients valid for analysis (Fig. 1). The mean age was 71 years (standard deviation [SD]: 2.2). All patients were male and the mean FEV1 (%) was 31.7% (SD 0.9%). At baseline, the patients reported an average of 2.9 (SD 0.19) days/week walked and an average of 42.9 (SD 3.5) min/day walked. The general characteristics, BODE index, functional tests, physical activity, 6MWT, and respiratory muscle strength are shown by patient group in Table 1.
      Table 1Descriptive analysis of the baseline measurements obtained in the control group (CG), the urban circuits group (UCG) and the non-circuits group (NCG) (mean (SD)).
      CG (N = 54)UCG (N = 34)NCG (N = 37)p
      Characteristics
      Age (years)72.4 (1.7)70.2 (2.5)70.5 (2.5)0.095
      Previous years COPD10.4 (0.8)10.7 (0.7)11.0 (0.8)0.087
      Admissions number3.3 (0.3)3.6 (0.4)3.6 (0.3)0.098
      BMI26.1 (0.2)27.2 (0.6)27.6 (0.6)0.140
      BODE index5.9 (0.1)5.7 (0.2)5.8 (0.2)0.068
      Spirometry results
      FEV1 (L)1.04 (0.03)1.0 (0.04)1.02 (0.04)0.837
      FEV1 (%)31.6 (0.8)32.0 (1.2)31.8 (1.0)0.970
      FVC (L)2.5 (0.06)2.5 (0.06)2.4 (0.06)0.410
      FVC (%)57.0 (0.5)55.3 (2.5)51.7 (2.3)0.100
      FEV1/FVC (%)37.7 (1.0)41.6 (1.8)40.5 (1.6)0.270
      Physical activity
      Minutes/day walked47.1 (3.3)43.6 (3.4)38.2 (3.7)0.251
      Days/week walked3.1 (0.1)3.03 (0.1)2.5 (0.2)0.078
      6MWT
      Meters387.0 (14.4)358.8 (16.4)347.5 (16.7)0.167
      Maximum O2 desaturation86.3 (0.9)88.7 (0.8)88.5 (0.8)0.097
      Borg scale7.9 (0.1)8.1 (0.1)8.2 (0.1)0.444
      Respiratory muscular function
      MIP (cm2 H2O)70.7 (1.3)69.4 (2.8)65.3 (2.7)0.193
      MEP (cm2 H2O)105.7 (3.2)97.3 (3.9)98.1 (4.2)0.192
      BMI: Body Mass Index, FEV1: Forced expiratory volume in 1 s, FVC: Forced vital capacity, 6MWT: 6-min walking test, MIP: Maximum inspiratory pressure, MEP: Maximum expiratory pressure.

       Results of the rehabilitation program

      After the 12-week rehabilitation program, there was a significant increase in minutes walked per day, days walked per week, and the distance walked in the 6MWT. In contrast, patients in the CG showed a significant decrease in minutes walked per day and distance in the 6MWT, resulting in a mean difference of almost 7 min per day less and 119 m less in the 6MWT compared to rehabilitation group (p < 0.001) (Table 2).
      Table 2Descriptive analysis (mean (SE)) of the evolution of the measurements in the control group (CG) and in patients included in the rehabilitation program.
      WalkingControl group (n = 54)Rehabilitation (n = 71)CG vs. rehabilitation.
      Mean (SE)p-value
      p-value of Wilcoxon signed rank sum test.
      Mean (SE)p-value
      p-value of Wilcoxon signed rank sum test.
      Mean (SE)p-value
      p-value of Wilcoxon–Mann–Whitney test.
      3 months-baseline
       Days−0.08 (0.05)0.1570.29 (0.06)<0.001−0.37 (0.08)<0.001
       Minutes−2.27 (0.97)0.0244.77 (0.91)<0.001−7.04 (1.34)<0.001
       Meters (6MWT)−42.87 (11.64)<0.00176.44 (6.94)<0.001−119.31 (12.90)<0.001
      a p-value of Wilcoxon signed rank sum test.
      b p-value of Wilcoxon–Mann–Whitney test.

       Results of the urban walking circuits

      The 83 patients who completed the rehabilitation program were randomized into the UCG and NCG. A total of 12 patients did not complete the study, 9 did not attend appointments, 2 required hospital admission, and 1 died, leaving 34 patients in UCG and 37 in NCG valid for analysis.
      At the end of follow-up, those included in the UCG increased the time walked 32.44 (standard error [SE]: 5.91) min/day and the days walked by 1.09 (SE: 0.22) days/week compared to baseline; whereas the changes observed in the NCG were an increase of 2.39 (SE: 3.65) min/day and 0.15 (SE: 0.28) days/week respectively (Table 3, Fig. 2).
      Table 3Descriptive analysis (mean (SE)) of values obtained at the end of follow-up (one year) and the change (one year compared to 3 months at completion of the respiratory rehabilitation program) in the control group (CG), non-circuit group (NCG) and the urban circuit group (UCG).
      CG (n = 54)NCG (n = 37)UCG (n = 34)p-value
      p-value Kruskal–Wallis test for differences between groups.
      One year after
      Physical activity
      Minutes/day40.30 (3.12)49.05 (2.31)81.62 (5.35)<0.001
      Days/week2.74 (0.14)3.43 (0.20)4.44 (0.16)<0.001
      6MWT
      Meters327.00 (13.78)406.59 (11.21)445.41 (10.45)0.006
      Maximum O2 desaturation87.37 (0.83)87.59 (0.97)87.26 (1.09)0.798
      Borg scale8.56 (0.16)8.41 (0.16)7.85 (0.20)0.012
      Respiratory muscular function
      MIP (cm2 H2O)61.32 (1.74)65.60 (2.00)76.98 (2.49)0.001
      MEP (cm2 H2O)99.15 (3.85)110.25 (2.52)122.95 (2.27)<0.001
      BODE index6.02 (0.20)5.00 (0.15)4.65 (0.14)0.067
      Change (one year 3 months)
      Physical activity
      Minutes/day−5.43 (3.94)2.39 (3.65)32.44 (5.91)<0.001
      Days/week−0.39 (0.14)0.15 (0.28)1.09 (0.22)<0.001
      6MWT
      Meters−17.20 (4.09)−25.68 (5.88)19.09 (4.14)<0.001
      Maximum O2 desaturation−6.46 (0.71)−7.76 (0.92)−8.09 (1.03)0.509
      Borg scale0.57 (0.13)0.16 (0.12)−0.32 (0.08)<0.001
      Respiratory muscular function
      MIP (cm2 H2O)−3.73 (0.57)−0.95 (0.65)3.51 (0.93)<0.001
      MEP (cm2 H2O)−3.32 (1.10)−12.55 (2.02)0.00 (1.23)<0.001
      BODE index0.22 (0.07)0.16 (0.06)−0.12 (0.09)0.082
      a p-value Kruskal–Wallis test for differences between groups.
      Figure thumbnail gr2
      Figure 2Minutes walked per day at the beginning, at the end of the pulmonary rehabilitation program (3 months) and at one year after inclusion in the study.
      In a regression analysis with correction for baseline scores, the UCG significantly increased the min/day walked by a mean of 33.97 (95%CI: 22.71–45.23; p < 0.001) and the days walked by week by a mean of 1.12 (95%CI: 0.64–1.61; p < 0.001) compared to the NCG (Table 4), but the patients in the control group walked almost half a day/week less (−0.48 days, 95%CI: −0.92 to −0.05; p = 0.029) than NCG, without significant differences in minutes walked per day (Table 4).
      Table 4Estimated effect of urban circuits (results of regression analysis with correction for baseline scores).
      Control groupp-valueUrban circuits groupp-value
      Coef95% C.I.Coef95% C.I.
      Physical activity
       Minutes/day−7.42−17.53 to 2.680.14833.9722.71 to 45.23<0.001
       Days/week−0.48−0.92 to −0.050.0291.120.64 to 1.61<0.001
      6MWT
       Meters−3.64−16.40 to 9.130.57443.9530.81 to 57.08<0.001
       Maximum O2 desaturation3.150.66 to 5.640.014−0.33−2.84 to 2.170.793
       Borg scale
      Mean ratio was presented.
      1.040.90 to 1.210.5560.940.80 to 1.110.466
      Respiratory muscular function
       MIP (cm2 H2O)−2.99−4.70 to −1.270.0015.413.48 to 7.35<0.001
       MEP (cm2 H2O)5.231.68 to 8.770.00412.588.86 to 16.31<0.001
      BODE index
      Mean ratio was presented.
      1.020.84 to 1.240.8280.940.76 to 1.160.572
      Reference treatment group: NCG.
      a Mean ratio was presented.
      Regarding the 6MWT, the UCG showed a significant increase of 19.09 m (SE = 4.14) compared to baseline, while the NCG and control patients experienced a significant reduction in distance walked (Table 3). The results of the regression analysis showed a significant increase of 43.95 m (95%CI: 30.81–57.08) in 6MWT for the UCG compared to the distance walked by the NCG 9 months after rehabilitation. There were no significant differences in meters walked in the 6MWT at the end of follow-up between the NCG and the control group (3.64 m, 95%CI: −16.40–9.13) (Table 4).

       Secondary end points

      The MIP and MEP increased in the UCG and decreased in the NCG and CG from the end of the rehabilitation program to the end of the follow-up, with significant differences among groups at the end of the study (Table 3). In regression analysis, the MEP was 12.58 cm2 H2O higher (95%CI: 8.86–16.31) and MIP 5.41 cm2 H2O higher compared to the NCG. Differences in MIP and MEP between the NCG and the control group were smaller (Table 4). No significant differences were observed in the changes of the BODE index between groups (Tables 3 and 4).

       Correlation between exercise capacity and physical activity

      We found a strong positive correlation between the distance walked in the 6MWT and minutes/day walked in the UCG (r2 = 0.502, p < 0.05). However, this correlation was not observed in the NCG (r2 = 0.094, p > 0.05) (Fig. 3).
      Figure thumbnail gr3
      Figure 3Correlation between minutes walked per day and meters walked in the 6MWT at the end of follow-up (one year) for patients in the urban circuits group (UCG) and the non-circuits group (NCG).

      Discussion

      The results of our study show an increase in the physical activity of patients with severe and very severe COPD measured by the mean of minutes walked per day and days walked per week, when the urban walking circuits were offered after a pulmonary rehabilitation program. This increased physical activity was correlated with the maintenance of functional capacity assessed with the 6MWT, even nine months after completion of the rehabilitation program.
      There is unanimity about the benefits of pulmonary rehabilitation of COPD. Systematic reviews have shown significant clinical effects in COPD patients, both in a stable state and after an exacerbation [
      • Lacasse Y.
      • Goldstein R.
      • Lasserson T.J.
      • Martin S.
      Pulmonary rehabilitation for chronic obstructive pulmonary disease.
      ,
      • Puhan M.A.
      • Gimeno-Santos E.
      • Scharplatz M.
      • Troosters T.
      • Walters E.H.
      • Steurer J.
      Pulmonary rehabilitation following exacerbations of chronic obstructive pulmonary disease.
      ]. Rehabilitation modifies prognostic indicators such as exercise tolerance, activity levels, and dyspnea. The results obtained in our pulmonary rehabilitation program during the first 3 months of the study were consistent with those previously observed regarding improvement in functional capacity [
      • Lacasse Y.
      • Goldstein R.
      • Lasserson T.J.
      • Martin S.
      Pulmonary rehabilitation for chronic obstructive pulmonary disease.
      ].
      However, rehabilitation programs may not be effective in changing the behavior of patients towards a more active life, and therefore, the benefits of the program will decrease over time and eventually disappear. In a systematic review Cindy NG et al. [
      • Cindy N.G.
      • Mackney J.
      • Jenkins S.
      • Hill K.
      Does exercise training change physical activity in people with COPD? A systematic review and meta-analysis.
      ] concluded that exercise training can lead to a significant, but small, increase in physical activity in COPD patients. The authors ratify the need for randomized trials to determine the effect of exercise training in physical activity and in exercise capacity. Beauchamp et al. [
      • Beauchamp M.K.
      • Evans R.
      • Janaudis-Ferreira T.
      • Goldstein R.S.
      • Brooks D.
      Systematic review of supervised exercise programs after pulmonary rehabilitation in individuals with COPD.
      ] investigated the efficacy of maintenance programs of physical activity after rehabilitation in a systematic review. Most of the programs were administered in a hospital-based outpatient setting, except for one in which patients were integrated into a local community exercise group. The duration of the programs ranged from 9 to 15 months, and they were based on exercise training including aerobic exercise, and most added lower and/or upper extremity strength training [
      • Elliott M.
      • Watson C.
      • Wilkinson E.
      • Musk A.W.
      • Lake F.R.
      Short-and long-term hospital and community exercise programmes for patients with chronic obstructive pulmonary disease.
      ,
      • Berry M.J.
      • Rejeski W.J.
      • Adair N.E.
      • Ettinger Jr., W.H.
      • Zaccaro D.J.
      • Sevick M.A.
      A randomized, controlled trial comparing long-term and short-term exercise in patients with chronic obstructive pulmonary disease.
      ,
      • Ries A.L.
      • Kaplan R.M.
      • Myers R.
      • Prewitt L.M.
      Maintenance after pulmonary rehabilitation in chronic lung disease: a randomized trial.
      ,
      • Ringbaek T.
      • Brondum E.
      • Martinez G.
      • Thogersen J.
      • Lange P.
      Long-term effects of 1-year maintenance training on physical functioning and health status in patients with COPD: a randomized controlled study.
      ]. Exercise training was usually supervised by a physiotherapist with frequencies ranging from one session per month [
      • Ries A.L.
      • Kaplan R.M.
      • Myers R.
      • Prewitt L.M.
      Maintenance after pulmonary rehabilitation in chronic lung disease: a randomized trial.
      ,
      • Brooks D.
      • Krip B.
      • Mangovski-Alzamora S.
      • Goldstein R.
      The effect of postrehabilitation programs among individuals with COPD.
      ] to three per week [
      • Berry M.J.
      • Rejeski W.J.
      • Adair N.E.
      • Ettinger Jr., W.H.
      • Zaccaro D.J.
      • Sevick M.A.
      A randomized, controlled trial comparing long-term and short-term exercise in patients with chronic obstructive pulmonary disease.
      ]. Only in one study was exercise training performed with weekly supervised sessions for 6 months followed by twice monthly sessions for the next 6 months [
      • Brooks D.
      • Krip B.
      • Mangovski-Alzamora S.
      • Goldstein R.
      The effect of postrehabilitation programs among individuals with COPD.
      ]. Patients were encouraged to perform exercise training at home by oral, written and/or telephone support [
      • Ries A.L.
      • Kaplan R.M.
      • Myers R.
      • Prewitt L.M.
      Maintenance after pulmonary rehabilitation in chronic lung disease: a randomized trial.
      ,
      • Ringbaek T.
      • Brondum E.
      • Martinez G.
      • Thogersen J.
      • Lange P.
      Long-term effects of 1-year maintenance training on physical functioning and health status in patients with COPD: a randomized controlled study.
      ,
      • Brooks D.
      • Krip B.
      • Mangovski-Alzamora S.
      • Goldstein R.
      The effect of postrehabilitation programs among individuals with COPD.
      ,
      • Spencer L.M.
      • Alison J.A.
      • McKeough Z.J.
      Maintaining benefits following pulmonary rehabilitation: a randomised controlled trial.
      ]. The authors suggested that supervised post-rehabilitation exercise programs were superior to usual care for sustaining benefits in exercise capacity in the medium-term for patients with moderate to severe COPD. However, this effect was not sustained at 12 months and no between-group differences were observed [
      • Beauchamp M.K.
      • Evans R.
      • Janaudis-Ferreira T.
      • Goldstein R.S.
      • Brooks D.
      Systematic review of supervised exercise programs after pulmonary rehabilitation in individuals with COPD.
      ]. It is essential to develop strategies to maintain or increase the benefits obtained after respiratory rehabilitation. The prescription of physical activity and the development of strategies for adherence should be considered as a second phase after a pulmonary rehabilitation program.
      In this context, we included patients with severe or very severe COPD in an urban circuits program after completing pulmonary rehabilitation. At baseline, our patients walked a mean of 43 min per day and a mean of 3 days per week. Our findings are similar to those obtained by Pitta et al. [
      • Pitta F.
      • Troosters T.
      • Spruit M.A.
      • Probst V.S.
      • Decramer M.
      • Gosselink R.
      Characteristics of physical activities in daily life in chronic obstructive pulmonary disease.
      ] and Hernandes et al. [
      • Hernandes N.A.
      • Teixeira Dde C.
      • Probst V.S.
      • Brunetto A.F.
      • Ramos E.M.
      • Pitta F.
      Profile of the level of physical activity in the daily lives of patients with COPD in Brazil.
      ] who reported an average of 44 and 55 min per day walked, respectively. A correlation has been demonstrated between increased regular physical activity in COPD and a lower risk of hospital readmission and mortality [
      • García-Aymerich J.
      • Lange P.
      • Benet M.
      • Schnohr P.
      • Antó J.M.
      Regular physical activity reduces hospital admission and mortality in chronic obstructive pulmonary disease: a population-based cohort study.
      ], and more recently Waschki et al. [
      • Waschki B.
      • Kirsten A.
      • Holz O.
      • Müller K.C.
      • Meyer T.
      • Watz H.
      • et al.
      Physical activity is the strongest predictor of all-cause mortality in patients with COPD: a prospective cohort study.
      ] showed that a low level of physical activity was the strongest predictor of all-cause mortality in COPD. It is therefore essential to develop strategies to increase physical activity in COPD patients.
      Data correlating pulmonary rehabilitation programs with increased physical activity are controversial [
      • Dallas M.I.
      • McCusker C.
      • Haggerty M.C.
      • Rochester C.L.
      • Zuwallack R.
      Northeast Pulmonary Rehabilitation Consortium
      Using pedometers to monitor walking activity in outcome assessment for pulmonary rehabilitation.
      ,
      • Walker P.P.
      • Burnett A.
      • Flavahan P.W.
      • Calverley P.M.
      Lower limb activity and its determinants in COPD.
      ,
      • Steele B.G.
      • Belza B.
      • Hunziker J.
      • Holt L.
      • Legro M.
      • Coppersmith J.
      • et al.
      Monitoring daily activity during pulmonary rehabilitation using a triaxial accelerometer.
      ], and it has become evident that strategies to maintain and even increase the long-term benefits obtained after rehabilitation are necessary. In our study, we demonstrated that a simple and inexpensive intervention with urban walking circuits was able to increase physical activity and exercise capacity after a rehabilitation program. In contrast patients in the control group experienced a decrease in their physical activity and exercise capacity. Similarly, the patients included in the rehabilitation program, but not in the urban circuits group, showed a decrease in exercise capacity, and their physical activity did not increase at the end of the study after the initial improvement observed with rehabilitation. Therefore, our results confirm that the beneficial effects of pulmonary rehabilitation are not long lasting, and that a substantial number of subjects return to a sedentary life, even after the improvement experienced with rehabilitation [
      • Foglio K.
      • Bianchi L.
      • Bruletti G.
      • Battista L.
      • Pagani M.
      • Ambrosino N.
      Long-term effectiveness of pulmonary rehabilitation in patients with chronic airway obstruction.
      ,
      • Beauchamp M.K.
      • Evans R.
      • Janaudis-Ferreira T.
      • Goldstein R.S.
      • Brooks D.
      Systematic review of supervised exercise programs after pulmonary rehabilitation in individuals with COPD.
      ].
      A previous study in primary care demonstrated that informative talks about the benefits of physical activity and individual 15-min interviews resulted in a significant improvement in the level of physical activity in patients with chronic diseases, with an adjusted difference of 18 min per week after 6 months compared to a control group [
      • Grandes G.
      • Sanchez A.
      • Sanchez-Pinilla R.O.
      • Torcal J.
      • Montoya I.
      • Lizarraga K.
      • et al.
      Effectiveness of physical activity advice and prescription by physicians in routine primary care: a cluster randomized trial.
      ]. In contrast, in our control group there was a small reduction of 5.4 min per day, despite the repeated encouragement during follow-up visits every 2 months. This is consistent with the deterioration in exercise capacity observed in severe COPD patients not submitted to any training program [
      • Oga T.
      • Nishimura K.
      • Tsukino M.
      • sato S.
      • Hajiro T.
      • Mishima M.
      Exercise capacity deterioration in patients with COPD. Longitudinal evaluation over 5 years.
      ]. In any case, the improvement demonstrated in the previous study with advice and prescription was clearly lower than that obtained with our urban circuits of a mean of 38 min per day.
      Other strategies to improve physical activity in COPD patients have been tested with good results, such as Nordic Walking [
      • Breyer M.K.
      • Breyer-Kohansal R.
      • Funk G.C.
      • Dornhofer N.
      • Spruit M.A.
      • Wouters E.
      • et al.
      Nordic walking improves daily physical activities in COPD: a randomized controlled trial.
      ]. Urban walking circuits have the advantage of not requiring any trained support personnel and no specific equipment, but it can be influenced by climatic circumstances in different areas.
      An important result of the current study is the demonstration of a good correlation at the end of follow-up between the meters walked in the 6MWT and the mean number of minutes walked per day in the urban circuits group, but with no correlation in the non circuit group. These results suggests that it is not the functional capacity that limits the physical activity [
      • Troosters T.
      • Gosselink R.
      • Janssens W.
      • Decramer M.
      Exercise training and pulmonary rehabilitation: new insights and remaining challenges.
      ,
      • Eliason G.
      • Zakrisson A.-B.
      • Piehl-Aulin K.
      • Hurtig-Wennlöf A.
      Physical activity patterns in patients in different stages of chronic obstructive pulmonary disease.
      ] and highlight the importance of encouraging patients to be physically active after pulmonary rehabilitation programs using effective strategies. Similar results have been reported in a recent study that showed a correlation between change in steps/day and in exercise capacity in patients with COPD submitted to an exercise training program, but with no correlation in the control group [
      • Zwerink M.
      • van der Palen J.
      • van der Valk P.
      • Brusse-Keizer M.
      • Effing T.
      Relationship between daily physical activity and exercise capacity in patients with COPD.
      ].
      Patients in the urban circuits group also obtained better results in secondary outcomes at the end of the study. However, the magnitude of the changes in MIP and MEP was small and probably not clinically meaningful [
      • Morales P.
      • Sanchis J.
      • Cordero P.J.
      • Díez J.L.
      Maximum static respiratory pressures in adults. The reference values for a Mediterranean Caucasian population.
      ]. These results can be explained by the multifactorial causes of muscular dysfunction in COPD patients, which include those derived from lung disease and peripheral involvement: increased activity and unfavorable geometry of the respiratory muscles, inflammation and oxidative stress, nutritional and gas exchange disturbances, comorbidity and the use of myotoxic drugs among others [
      • Donaldson A.V.
      • Maddocks M.
      • Martolini D.
      • Polkey M.I.
      • Man W.D.-C.
      Muscle function in COPD: a complex interplay.
      ,
      • Eliason G.
      • Zakrisson A.-B.
      • Piehl-Aulin K.
      • Hurtig-Wennlöf A.
      Physical activity patterns in patients in different stages of chronic obstructive pulmonary disease.
      ].
      One of the limitations of our study is the use of a diary card for the measurement of physical activity. Other groups have used pedometers to assess the impact of a lifestyle physical activity counselling program after rehabilitation [
      • Gea J.
      • Casadevall C.
      • Pascual S.
      • Orozco-Levi M.
      • Barreiro E.
      Respiratory diseases and muscle dysfunction.
      ]. However, a pedometer may, in itself, introduce a possible bias by conditioning an increase in physical activity during its use. The compliance with diaries in our patient population was excellent, with all the patients reporting more than 80% of filled diaries at control visits. The consistency of the results of physical activity and the 6MWT, particularly in the patients in the circuits groups, provides consistency to our findings. Furthermore, the self-declared time walked per day has demonstrated to be significantly correlated with quality of life and mortality [
      • De Blok B.M.
      • de Greef M.H.
      • tenHacken N.H.
      • Sprenger S.R.
      • Postema K.
      • Wempe J.B.
      The effects of a lifestyle physical activity counseling program with feedback of a pedometer during pulmonary rehabilitation in patients with COPD: a pilot study.
      ,
      • Esteban C.
      • Arostegui I.
      • Moraza J.
      • Aburto M.
      • Quintana J.M.
      • Pérez-Izquierdo J.
      • et al.
      Development of a decision tree to assess the severity and prognosis of stable COPD.
      ] and has been included as a parameter of severity in guidelines on the management of COPD [
      • Esteban C.
      • Quintana J.M.
      • Aburto M.
      • Moraza J.
      • Egurrola M.
      • Pérez-Izquierdo J.
      • et al.
      Impact of changes in physical activity on health-related quality of life among patients with COPD.
      ,
      • Miravitlles M.
      • Soler-Cataluña J.J.
      • Calle M.
      • Molina J.
      • Almagro P.
      • Quintano J.A.
      • et al.
      Spanish COPD guidelines (GesEPOC). Pharmacological treatment of stable COPD.
      ].
      Drop outs have to be considered when interpreting our results. A total of 18 patients were lost to follow-up (11.2%), which may affect the internal validity of the results. The control group was non-randomized. However, the selection criteria did not depend on the patient or the research team and this group was made up of patients fulfilling the same inclusion and exclusion criteria but living outside of the town of Mataró and were therefore not eligible for urban circuits in town. In fact, the demographic and clinical characteristics of the control group and the rehabilitation group were similar. The exclusion of patients experiencing an exacerbation during the study may be debatable; however, we believe that exacerbated patients could have influenced the results because these episodes are associated with a significant decrease in physical activity [
      • Pitta F.
      • Troosters T.
      • Probst V.S.
      • Spruit M.A.
      • Decramer M.
      • Gosselink R.
      Physical activity and hospitalization for exacerbation of COPD.
      ] and with generalised muscle dysfunction that may persist even during recovery [
      • Gayan-Ramirez G.
      • Decramer M.
      Mechanisms of striated muscle dysfunction during acute exacerbations of COPD.
      ].
      Finally the lack of female patients is another limitation of our study. The gender distribution in our study corresponds to the gender distribution of COPD in Spain where most patients, particularly with severe or very severe COPD, are males [
      • Miravitlles M.
      • Soriano J.B.
      • García-Río F.
      • Muñoz L.
      • Duran-Taulería E.
      • Sánchez G.
      • et al.
      Prevalence of COPD in Spain: impact of undiagnosed COPD on quality of life and daily life activities.
      ]. Therefore, extrapolation to women must be made with caution.
      In conclusion, patients that were offered the option of urban walking circuits after a rehabilitation program increased their level of physical activity and exercise capacity compared with those not offered this option after rehabilitation. Strategies to encourage physical activity should be established after rehabilitation programs to maintain or even increase the beneficial effects of exercise in COPD.

      Conflicts of interest

      Marc Miravitlles has received speaker fees from Boehringer Ingelheim, Pfizer, AstraZeneca, Bayer Schering, Novartis, Talecris-Grifols, Takeda-Nycomed, Merck, Sharp & Dohme and Novartis, and consulting fees from Boehringer Ingelheim, Pfizer, GSK, AstraZeneca, Bayer Schering, Novartis, Almirall, Merck, Sharp &Dohme, Talecris-Grifols and Takeda-Nycomed. The remaining authors have no conflicts of interest to disclose.

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