DOI 10.1378/chest.07-2655 2008;134;273-280; Prepublished online April 10, 2008;Chest

 Decramer and Rik GosselinkFábio Pitta, Thierry Troosters, Vanessa S. Probst, Daniel Langer, Marc 

*Pulmonary Rehabilitation?Are Patients With COPD More Active After

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Are Patients With COPD More ActiveAfter Pulmonary Rehabilitation?*

Fabio Pitta, PhD; Thierry Troosters, PhD; Vanessa S. Probst, PhD;Daniel Langer, MSc; Marc Decramer, PhD; and Rik Gosselink, PhD

Background: Despite a variety of benefits brought by pulmonary rehabilitation to patients withCOPD, it is unclear whether these patients are more active during daily life after the program.Methods: Physical activities in daily life (activity monitoring), pulmonary function (spirometry),exercise capacity (incremental cycle-ergometer testing and 6-min walk distance testing), muscle force(quadriceps and handgrip force, and inspiratory and expiratory maximal pressures), quality of life(chronic respiratory disease questionnaire), and functional status (pulmonary functional status anddyspnea questionnaire-modified version) were assessed at baseline, after 3 months of a multidisci-plinary rehabilitation program, and at the end of a 6-month multidisciplinary rehabilitation programin 29 patients (mean [� SD] age, 67 � 8 years; FEV1, 46 � 16% predicted).Results: Exercise capacity, muscle force, quality of life, and functional status improved significantlyafter 3 months of pulmonary rehabilitation (all p < 0.05), with further improvements in muscle force,functional status, and quality of life at 6 months. Movement intensity during walking improvedsignificantly after 3 months (p � 0.046) with further improvements after 6 months (p � 0.0002).Walking time in daily life did not improve significantly at 3 months (mean improvement, 7 � 35%;p � 0.21), but only after 6 months (mean improvement, 20 � 36%; p � 0.008). No significant changesoccurred in other activities or in the pattern of the time spent walking in daily life. Changes indyspnea after the program were significantly related to changes in walking time in daily life (r � 0.43;p � 0.02).Conclusion: If one aims at changing physical activity habits in the daily life of COPD patients, thecontribution of long-lasting programs might be important. (CHEST 2008; 134:273–280)

Key words: COPD; exercise; physical activity; pulmonary rehabilitation

Abbreviations: ANOVA � analysis of variance; CI � confidence interval; CRDQ � chronic respiratory disease question-naire; DAM � DynaPort activity monitor; PFSDQ-M � pulmonary functional status and dyspnea questionnaire-modifiedversion; 6MWT � 6-min walk time

T here is a large body of evidence1,2 showing thatpulmonary rehabilitation programs are beneficial

to patients with COPD in order to improve exercisecapacity, muscle force, symptoms, and health-relatedquality of life. However, evidence is scarce concerningthe translation of these improvements into a moreactive lifestyle after the program. It is known thatpatients with COPD are significantly less active in dailylife than healthy elderly persons,3 and their activitylevel is further reduced by acute exacerbations.4 There-fore, an active lifestyle should be considered as atherapeutic priority in this population since it has beenshown that patients with COPD who perform somelevel of regular physical activity have a lower risk ofboth COPD admissions and mortality.5

Technological advances have resulted in the useof motion sensors to investigate the effects ofpulmonary rehabilitation programs on daily phys-ical activity during long-term assessments in thepatients’ own environment. However, previousstudies6 –9 that have sought to investigate theeffects of pulmonary rehabilitation on daily phys-ical activity using motion sensors in COPD pa-tients have produced conflicting results. Further-more, a limitation of the available studies is thatnone of them involved rehabilitation programslonger than 8 weeks. Longer interventions mightbe necessary to result in larger improvements, ashas been suggested for patients with chronic heartfailure.10

Original ResearchCOPD

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The primary aims of the present study were asfollows: to investigate the effects of 3 and 6 monthsof pulmonary rehabilitation on the time spent byCOPD patients in different activities and body pos-tures in daily life, as well as on the intensity at whichthe physical activity was performed; and to examinewhether pulmonary rehabilitation leads to a changein the duration of bouts of continuous walking.Secondary aims were to determine the predictors ofchanges in physical activities in daily life after theprogram and to analyze whether the occurrence ofan acute exacerbation during the program had anyinfluence on the changes in the time spent walking indaily life. Preliminary results of this study have beenpreviously reported in the form of abstracts.11,12

Materials and Methods

Study Design

In this longitudinal study, physical activities in daily life,pulmonary function, submaximal exercise capacity (6-min walktest [6MWT]), maximal exercise capacity (cycling), respiratoryand peripheral muscle force, functional status, and health-relatedquality of life were assessed before, 3 months after, and 6 monthsafter attending a multidisciplinary pulmonary rehabilitation pro-gram. An analysis of the duration of continuously active periodswas performed at baseline and at the end of the program.

Subjects

Forty-one consecutive patients (31 men; mean [� SD] age,66 � 8 years; mean FEV1, 45 � 16% predicted; mean body massindex, 25 � 6 kg/m2) were initially included in the study. Theadmission of patients to the study was done throughout the wholeyear to avoid seasonal bias in the assessments. None of theindividuals had been engaged in any exercise-training programbefore participating in the study. Details regarding the inclusioncriteria and sample size calculation are described in the onlinedata supplement. All patients had received a diagnosis of COPDranging from mild to very severe according to the Global

Initiative for Chronic Obstructive Lung Disease (or GOLD)[stages I to IV].13 Patients were all retired or on sick leave andwere no longer employed. Of the 41 patients included in thestudy, 8 had been hospitalized for an acute exacerbation ofCOPD in the previous 3 months before inclusion in the program,8 were still current smokers, and 7 used long-term oxygentherapy at home. All individuals gave informed consent, and allprocedures were performed according to the research ethicsguidelines of the Declaration of Helsinki.14 Baseline data from 19patients included in the present sample had been used in aprevious publication from our group.3

Pulmonary Rehabilitation Program

Patients participated in a 6-month outpatient multidisciplinarypulmonary rehabilitation program that consisted of the followingtwo periods: in the first 3 months, patients exercised three times perweek; and in the last 3 months, they exercised two times per week.Although the program did not include home exercise training,patients received education sessions and occupational therapy coun-seling regarding the importance of exercising regularly, and weretaught how to incorporate a more active routine in their daily lives.Detailed information on the content and characteristics of theprogram are provided in the online data supplement, as well asinformation on how the management of acute exacerbations ofCOPD that occurred during the program was handled.

Methods

Spirometry was performed using the pneumotachograph of aconstant-volume plethysmograph (Vmax Autobox; SensorMedics;Bilthoven, the Netherlands), according to international stan-dards.15 In addition, the diffusing capacity of the lung for carbonmonoxide was measured by the single-breath method (V6200Autobox; SensorMedics). The results were referred to the pre-dicted values reported by Quanjer et al.16

Isometric quadriceps force was measured using a dynamometer(Cybex Norm Dynamometer; Enraf Nonius; Delft, the Nether-lands). Peak extension torque was measured at the dominant sideand was evaluated at 60° of knee flexion. Reference values forquadriceps force were developed in our laboratory.17 Isometrichandgrip force was measured with a hydraulic hand dynamometer(Jamar dynamometer; JA Preston Corporation; Jackson, MI). Peakhandgrip force was assessed at the dominant side with the elbow at90° of flexion, and the forearm and wrist in a neutral position. Thereference values used were those from the study by Mathiowetz etal.18 Inspiratory and expiratory maximal respiratory pressures weremeasured according to the method of Black and Hyatt.19 Thereference values were described by Rochester and Arora.20

Maximal exercise capacity was assessed by an incremental cycleergometer test (Ergoline 900; Ergoline; Bitz, Germany) accord-ing to the standard of the American Thoracic Society/AmericanCollege of Chest Physicians statement on cardiopulmonary exer-cise testing.21 Peak oxygen consumption, ventilation, and carbondioxide output were measured breath by breath (model 6200;SensorMedics), and heart rate was monitored continuously by a12-lead ECG. The values of peak oxygen consumption wererelated to the normal values by Jones et al.22 Functional exercisecapacity was assessed by the 6MWT according to the AmericanThoracic Society recommendations.23 The largest distance of twotests was used in the analysis, and normal values were thosedescribed by Troosters et al.24

The individualized chronic respiratory disease questionnaire(CRDQ)25 and the pulmonary functional status and dyspneaquestionnaire-modified version (PFSDQ-M)26 were used to as-sess health-related quality of life and functional status, respec-

*From the Respiratory Rehabilitation and Respiratory Division,University Hospitals, Katholieke Universiteit Leuven, Leuven,Belgium.The study was performed at the University Hospital Gasthuis-berg, Katholieke Universiteit Leuven, Leuven, Belgium.Dr. Pitta is supported by Coordençao de Aperfeiçoamento deNível Superior (CAPES)/Brasil. Dr. Troosters is supported by apostdoctoral fellowship of the Fonds Wetenschappelijk Onder-zoek (FWO), Vlaanderen, Belgium.The authors have reported to the ACCP that no significantconflicts of interest exist with any companies/organizations whoseproducts or services may be discussed in this article.Manuscript received December 14, 2007; revision acceptedMarch 6, 2008.Reproduction of this article is prohibited without written permissionfrom the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).Correspondence to: Rik Gosselink, PhD, PT, Respiratory Rehabili-tation and Respiratory Division, University Hospital Gasthuisberg,Herestraat 49, B-3000 Leuven, Belgium; e-mail: Rik.Gosselink@faber.kuleuven.beDOI: 10.1378/chest.07-2655

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tively. A more detailed description of all of the above-mentionedmethods can be found in the online data supplement.

Assessment of Physical Activities in Daily Life (Activity Monitoring)

The assessment was performed with an accelerometer-basedactivity monitor (DynaPort activity monitor [DAM]; McRoberts BV;The Hague, the Netherlands). It consists of a small, lightweight boxenclosed in a belt worn around the waist and a leg sensor (totalweight, 375 g). The DAM has been validated in patients withCOPD.27 It measures the time spent in walking, cycling, standing,sitting, or lying, as well as movement intensity during walking, and isas accurate as video recordings. The technical specifications for theDAM can be found elsewhere.27 Assessments were performed on 5consecutive weekdays (Monday to Friday) for 12 h per day (fromwake-up time to 12 h after awaking). However, due to logisticlimitations (eg, the unavailability of activity monitors, scheduleconstraints, personal request from the patients, misplacement of thedevice by the patient, or technical problems with the measure-ments), not all patients had 5 valid days of assessment. Of the 41patients included in the study, 28 (68%) had 5 assessment days, andnone of the remaining patients had � 2 days of assessment. A similarpercentage of valid assessment days was obtained when patientswere assessed after 3 months and after 6 months of pulmonaryrehabilitation. We have previously shown3 that a minimum of 2 daysof assessment provide an acceptable intraclass reliability coefficientin order to monitor physical activities in daily life in patients withCOPD. Regardless of the number of valid assessment days in eachassessment moment (ie, at baseline, and after 3 and 6 months ofrehabilitation) for a given patient, the results were averaged foranalysis.

Pattern of Time Spent Walking in Daily Life

Using the DAM software, the periods of time spent continuouslywalking were counted in each valid assessment day at baseline andafter 6 months of pulmonary rehabilitation. Any period of walkingtime was incorporated into the analysis. Periods of continuouswalking were categorized from 1 s to 1 min (� 1 min), from 1 to 2min, from 2 to 3 min, and so on up to 10 min; longer periods werecategorized as � 10 min. Periods in each category were calculated asthe average number of periods per day.

Statistical Analysis

Statistical analysis was performed using a statistical softwarepackage (SAS, version 8; SAS Institute; Cary, NC; and GraphPadPrism 3; GraphPad Software; San Diego, CA). Normal distribu-tion was checked with the Kolmogorov-Smirnov test. The resultswere described as the mean � SD, except for cycling time indaily life, which was shown as the median (interquartile range)due to the nonnormal distribution of the data.

Comparison of the outcomes in the three assessment moments(ie, at baseline, and after 3 and 6 months of rehabilitation) wasperformed with repeated-measures analysis of variance (ANOVA)except for the cycling time in daily life, which was analyzed withthe equivalent nonparametric test (Friedman test). The Pearsoncorrelation coefficient was used for the single correlation be-tween improvements in walking time in daily life and the othervariables. The level of significance was set at p � 0.05 for all ofthe analyses.

Results

Dropouts

Twelve patients (29%) dropped out of the reha-bilitation program due to a lack of motivation or

personal reasons (n � 7), unrelated problems (ie,orthopedic or GI; n � 4), or a sequence of threeconsecutive severe acute exacerbations requiringlong-term hospitalization (n � 1). There were nostatistically significant differences at baseline be-tween the group of patients who dropped out(n � 12) and the group of patients who completedthe program (n � 29), including measurements ofphysical activities in daily life. More details aredescribed in the online data supplement.

General Results

The mean attendance for the program in the 29patients (23 men) who completed the study was55 � 5 sessions (92 � 8% of expected). The generalcharacteristics of these patients are summarized inTable 1. The 6-min walk distance, the maximalworkload, the peak oxygen consumption, and quad-riceps force improved significantly after 3 months oftraining (p � 0.05), as well as the FEV1 (p � 0.05)[see the discussion in the online data supplement]and all the domains of the PFSDQ-M and CRDQquestionnaires (all p � 0.0001). Further improve-ments after 6 months of training were observed infunctional status, with similar trends for quadricepsforce and health-related quality of life (Table 1).

Physical Activities in Daily Life

The mean walking times assessed in daily life were55 � 26 min/d at baseline, 59 � 27 min/d after 3months of rehabilitation (p � 0.21 vs baseline), and65 � 29 min/d after 6 months of rehabilitation(p � 0.008 vs baseline and p � 0.10 vs 3 months;p � 0.02 [ANOVA]). Figure 1 shows that the meanimprovement in walking time after 3 months ofpulmonary rehabilitation was 7%, whereas it was20% after 6 months.

Assessment at baseline showed that patients spent amean duration of 227 � 92 min/d standing, 355 � 121min/d sitting, and 77 � 87 min/d lying down. Therewere no significant changes in these outcomes bothafter 3 months and after 6 months of training (p � 0.14for all [ANOVA]; Fig 2). The mean movement intensityduring walking increased significantly after 3 months(from 1.81 � 0.24 to 1.88 � 0.30 m/s2; p � 0.046).After 6 months of training, the mean movement inten-sity during walking (1.94 � 0.30 m/s2) was significantlyhigher in comparison to baseline (p � 0.0002), with astrong trend of improvement in comparison to 3months of training (p � 0.07). The number of blocks ofcontinuous walking done per day did not change after6 months of pulmonary rehabilitation (Fig 3 and onlinedata supplement).

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Correlates of Improvement in Walking Time inDaily Life

Changes in walking time in daily life after 6 monthsof pulmonary rehabilitation were not correlated to anyof the baseline characteristics. Changes in walking timein daily life were significantly related to changes in thedyspnea domain of the CRDQ (r � 0.43; p � 0.02) andthe number of sessions completed by the patient(r � 0.38; p � 0.04). The gray area in Figure 4 showsthat the vast majority of patients who improved their

walking time in daily life decreased their lying time (19of 23 patients; 83%), which was not observed for sittingtime or standing time.

Acute Exacerbations and the Rehabilitation Program

Twelve of the 29 patients who completed thepulmonary rehabilitation program (41%) were hos-pitalized due to severe acute exacerbation during theperiod of the program. Despite the hospitalization,the mean improvement in walking time after 6

Table 1—General Characteristics of COPD Patients at Baseline, and After 3 and 6 Months of PulmonaryRehabilitation*

Characteristics Baseline 3 Mo 6 Mo

Age, yr 67 � 8BMI, kg/m2 25 � 5 25 � 5 25 � 5Fat free mass, kg (n � 26) 48 � 8 48 � 7 47 � 8Pulmonary function, % predicted

FEV1 46 � 16 50 � 21† 48 � 19FVC 92 � 21 92 � 24 92 � 19FRC 176 � 42 181 � 34 186 � 38TLC 114 � 15 117 � 12 116 � 12Dlco (n � 28) 51 � 22

Muscle forceQF

% predicted (n � 27) 70 � 19 75 � 16† 78 � 14†‡Nm (n � 27) 117 � 31 125 � 26§ 132 � 26†‡

HF, % predicted (n � 27) 100 � 19 107 � 25§ 107 � 20Pimax, % predicted 80 � 29 85 � 23 84 � 29Pemax, % predicted 105 � 31 109 � 27 110 � 29

Exercise capacity6MWD

% predicted 68 � 19 75 � 18† 76 � 20†m 436 � 121 484 � 120† 483 � 125†

Wmax% predicted (n � 28) 55 � 25 65 � 24† 64 � 29†W (n � 28) 78 � 33 92 � 32† 89 � 32†

Peak Vo2

% predicted (n � 28) 63 � 30 70 � 31§ 66 � 30L/min (n � 28) 1.06 � 0.35 1.18 � 0.42† 1.10 � 0.39

Functional status (n � 26)PFSDQ-M�

Change in activities 44 � 12 35 � 12† 31 � 13†¶Dyspnea 44 � 13 36 � 12† 33 � 14†Fatigue 39 � 13 31 � 12† 28 � 14†‡

Quality of life (n � 26)CRDQ#

Dyspnea (5–35) 14 � 3 22 � 7† 23 � 7†Fatigue (4–28) 15 � 5 19 � 4† 21 � 4†Emotional aspect (7–49) 28 � 8 33 � 6† 35 � 6†Mastery (4–28) 18 � 6 22 � 4† 23 � 4†

CRDQ total score (20–140) 74 � 20 97 � 16† 103 � 17†‡

*Values are given as the mean � SD. FRC � functional residual capacity; TLC � total lung capacity; Dlco � diffusing capacity of the lung forcarbon monoxide; QF � quadriceps force; Nm � Newtonmeters; HF � handgrip force; Pimax � maximal inspiratory pressure; Pemax � maximalexpiratory pressure; 6MWD � 6-min walk distance; Wmax � maximal workload; peak Vo2 � peak oxygen uptake.

†p � 0.05 vs baseline.‡p � 0.05 and � 0.10 vs 3 mo.§p � 0.05 and � 0.10 vs baseline�Values range from 0 to 100; lower values mean better functional status.¶p � 0.05 vs 3 mo.#Higher values mean better health-related quality of life.

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months in these patients (10 � 25 min) was notdifferent from the improvement observed in patientswho did not have an acute exacerbation during theprogram (11 � 16 min; p � 0.91). Furthermore,there was no difference concerning the changes inthe 6MWT at the end of the program betweenpatients who experienced an exacerbation and pa-tients who did not (� 7% vs � 9% predicted, respec-tively; p � 0.51). More details are described in theonline data supplement.

Discussion

The present study showed that exercise perfor-mance, muscle force, health-related quality of life, andfunctional status improved after 3 months of multidis-

ciplinary pulmonary rehabilitation in COPD patients.However, the changes in physical activities in daily lifein this period were limited to an improvement inmovement intensity during walking in daily life. Im-provement in the time spent walking in daily life wasonly obtained after 6 months of rehabilitation, togetherwith a trend for further improvement in movementintensity. Improvement in the time spent walking wasnot due to the exchange of shorter periods of walkingfor longer periods, but likely was due to the slightincrease in bouts of walking of � 1 min. The majority of

Figure 2. Time spent standing, sitting, and lying in daily life in29 COPD patients at baseline, and after 3 and 6 months ofpulmonary rehabilitation (in minutes per day). The results areshown as the mean and SD. No significant changes were foundfor the three variables at any time point (p � 0.14 for standing,p � 0.18 for sitting, p � 0.53 for lying [ANOVA]).

Figure 4. Plot of changes (�) in walking time and lying time indaily life in 29 COPD patients after 6 months of pulmonaryrehabilitation (r � 0.36; p � 0.06). The points included in thegray area correspond to patients who improved their walking timeand decreased their lying time at the end of the rehabilitationprogram (19 of 23 patients; 83%).

Figure 1. Average improvement in walking time in daily life in29 COPD patients after 3 months (7%) and after 6 months (20%)of pulmonary rehabilitation (in % change compared to baselinevalues). The results are shown as the mean and SD. # � p � 0.10vs changes after 3 months. In comparison to baseline values,walking time in daily life did not improve significantly after 3months (p � 0.21), but only after 6 months (p � 0.008).

Figure 3. Pattern of walking in daily life in 22 COPD patients atbaseline and after 6 months of pulmonary rehabilitation. The dataare shown as the mean (SE) number of periods of any duration ofcontinuous walking per day. No significant pattern changes werefound between baseline and after 6 months of rehabilitation. Dueto technical problems with backup sources, the results concern-ing this analysis in seven patients who completed the study couldnot be retrieved. Their baseline values were not statisticallydifferent from those patients in whom the analysis was possible.

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patients who improved their walking time had a de-crease in lying time, and patients who were moreadherent to the training sessions showed a largerimprovement in walking time in daily life. Improve-ments in walking time in daily life could not besignificantly predicted by any variable at baseline, butonly by changes in dyspnea after the program, asassessed by the CRDQ. Finally, the present study hasalso shown that the occurrence of a severe acuteexacerbation of COPD requiring hospitalization did notjeopardize the improvements obtained with the6-month rehabilitation program in terms of walkingtime in daily life and 6MWT. For a detailed discussionon topics such as the capacity to predict improvementin walking time in daily life, the relationship betweenphysical activity in daily life and the activities of dailyliving, and the impact of acute exacerbations during therehabilitation program, please see the online data sup-plement.

Previous studies6–9 have shown conflicting resultsconcerning improvements in physical activities in dailylife after short-term pulmonary rehabilitation programs(ie, � 2 months). These studies used devices withoutputs that are largely dependent on the intensity atwhich movements are performed rather than the timespent in different activities in daily life (eg, vectormagnitude units, counts above a determined intensitythreshold, and the percentage of activity energy expen-diture to the resting energy expenditure). Results var-ied from very modest and nonsignificant improvements(approximately 1 to 6%)6,7 to significant improvements(approximately 19 to 40%).8,9 Our results showed thatafter 3 months of pulmonary rehabilitation, the im-provement in movement intensity during walking wasconsistent but modest, and just reached statisticalsignificance (p � 0.046). This borderline result mayillustrate the fact that some studies have found statisti-cally significant improvement in this outcome andothers have not. In other words, an improvement inactivity-monitoring outcomes related to movement in-tensity after short duration rehabilitation programs hasnot been a consistent finding in studies that haveexamined this issue, most likely reflecting methodolog-ical issues such as the sensitivity of the activity monitor,the characteristics of the training program, studypower, and the characteristics of the study sample.Attention must also be given to the fact that differencesin output from device to device require caution wheninterpreting the results from different studies.

Changes in Walking Time in Daily Life After 3 and 6Months of Rehabilitation: Possible Explanations

Although patients achieved improvements inmovement intensity after 3 months of pulmonaryrehabilitation (ie, walking faster), more time was

needed to induce the important lifestyle change ofspending more time actively. Therefore, the transferof the well-documented improvements in exerciseperformance, functional status, and quality of life toan increased amount of daily life physical activity islimited and takes longer than these traditional out-comes of pulmonary rehabilitation to be obtained.The lack of improvement in walking time in daily lifeafter 3 months cannot be explained by the lack ofimprovement in functional exercise capacity andfunctional status since the 6MWT (the best predictorof walking time in daily life3) and the PFSDQ-Mscore improved significantly over this period of time.Therefore, on one hand, the rehabilitation programused in the current trial was adequate to improve thecapacity to walk and reduce the symptoms andperceived difficulties to perform activities of dailyliving after 3 months. However, on the other hand,these gains obtained in the short term were nottranslated immediately into a significant increase inwalking time in daily life, showing that augmentingthe functional exercise capacity and functional statusdoes not suffice to induce a more active lifestyle.From the present data, it could be hypothesized thatpatients with COPD require rehabilitation programsthat last � 3 months in order to increase their timespent actively, as has been suggested for patientswith chronic heart failure.10 The absence of strongrelationships between the change in walking time indaily life and the changes in exercise capacity, func-tional status, and symptoms suggest that the long-lasting rehabilitation program was the major contrib-uting factor to the changes in physical activity habitsin everyday life that were observed in the presentstudy. Furthermore, some psychological and envi-ronmental factors not investigated in detail in thepresent study (eg, depression, anxiety, motivation,feelings of self-efficacy, assumed obstacles, lack ofinterest, assumed benefits, support by others, andthe possibility of walking in the neighborhood) mayhave played a role in the results. In addition, it alsohas to be underlined that the sample size calculationfor the present study took into account the detectionof the change in walking time after 6 months ofrehabilitation. Therefore, it may not be ruled outthat the lack of statistically significant improvementin walking time after 3 months of rehabilitation maybe, at least in part, linked to a type II error. Theeffect size for walking time after 3 months was 0.24(95% confidence interval [CI], � 0.32 to 0.79), after6 months was 0.53 (95% CI, 0.00 to 1.05), and from3 months to 6 months was 0.32 (95% CI, � 0.24 to0.87).

Standing time and sitting time remained practi-cally unchanged after 6 months of pulmonary reha-bilitation, in contrast to the gradual decline in lying

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time. This decline in lying time did not reachstatistical significance, possibly due to the large SD.Interestingly, improvement in walking time tendedto be correlated with a decrease in lying time in dailylife (Fig 4), but was not correlated to changes insitting or standing time. In fact, the gray area inFigure 4 shows that 83% of the patients who im-proved their walking time decreased their lying time.This is obviously a favorable transition as patients arenot only walking more, but are likely doing that atthe expense of a decrease in time spent in the leastactive position (lying).

Changes in the Pattern of Time Spent Walking inDaily Life

The present study showed that the patients’ pat-tern of walking did not change after 6 months. As aresult, the increase in daily walking time was due toa slight increase of the number of very short bouts ofwalking (ie, bouts up to 1 min in length). Theseresults do not confirm the expectation that patientswould exchange shorter periods of walking for longerperiods. As extended activities of moderate intensityare important to maintain the effects of rehabilita-tion,28 it is essential to make patients aware of theimportance of walking for longer periods of time.Further studies looking at strategies to enhanceperiods of continuous physical activity are impera-tive.

Practical Implications

First, this study underscores the importance oflonger programs to effectively increase the timespent walking in daily life in COPD patients, despitethe improvement in movement intensity at 3 months.This is relevant information since walking is consid-ered to be the most common and important type ofphysical activity among older adults,29,30 and itsregular performance is related to reduced morbidityand mortality.31,32 However, the present study wasnot aimed at defining how the long-term programshould be set up. Furthermore, short-term pulmo-nary rehabilitation programs that are not currentlyfocusing on improving the time spent walking indaily life may fail to achieve this important objective.Making the patient more active in daily life should bea goal of pulmonary rehabilitation programs, andstrategies specifically aimed at improving active time(eg, behavioral strategies) should be considered ascomponents to be added to the program. Second, bydemonstrating further improvements in functionalstatus and similar statistical trends of improvementin muscle force and quality of life after 6 months, thepresent study reinforced previous reports33–36 show-ing that long-term pulmonary rehabilitation pro-

grams result in additional effects to those obtainedwith short-term programs. Third, health profession-als should encourage COPD patients as much aspossible to adhere to the rehabilitation program andto resume training after an acute exacerbation, sincethe improvement in walking time and 6MWT werenot hindered by the occurrence of hospitalization forsevere exacerbations of COPD.

Limitations

Since there was no long-term follow-up, it isunknown how long the patients will continue to bemore active. Further research into this issue isrequired. Furthermore, it can be argued that thepresent study does not have a control group. How-ever, it has been previously shown that COPDpatients who are not following a pulmonary rehabil-itation program decrease their daily physical activityover time.37 In addition, since it has been convinc-ingly shown that pulmonary rehabilitation is benefi-cial to COPD patients,1,2 it might be consideredunethical to perform randomized controlled trialsinvolving pulmonary rehabilitation programs.

Summary

In summary, although 3 months of multidisciplinarypulmonary rehabilitation improved a variety of out-comes in patients with COPD, patients were not yetspending more time walking in daily life. Significantimprovements in walking time in daily life withoutchanging the pattern of time spent walking were ob-served only after 6 months of pulmonary rehabilitation.If one aims at changing physical activity habits in thedaily life of COPD patients, the contribution of long-lasting programs might be important.

ACKNOWLEDGMENT: The authors thank the following pro-fessionals for their contribution to the present study: Iris Coose-mans, Veronica Barbier, Ilse Muylaert, Chris Burtin, AnneCattaert, Paul Baten, Rina Droogmans, Linda Stans, Dirk Delva,Stefaan Ledeganck, and Maarten Govaert.

References1 Lacasse Y, Goldstein R, Lasserson TJ, et al. Pulmonary

rehabilitation for chronic obstructive pulmonary disease. Co-chrane Database Syst Rev (database online). Issue 4, 2006

2 Troosters T, Casaburi R, Gosselink R, et al. Pulmonaryrehabilitation in chronic obstructive pulmonary disease. Am JRespir Crit Care Med 2005; 172:19–38

3 Pitta F, Troosters T, Spruit MA, et al. Characteristics ofphysical activities in daily life in chronic obstructive pulmo-nary disease. Am J Respir Crit Care Med 2005; 171:972–977

4 Pitta F, Troosters T, Probst VS, et al. Physical activity andhospitalization for exacerbation of COPD. Chest 2006; 129:536–544

5 Garcia-Aymerich J, Lange P, Benet M, et al. Regular physicalactivity reduces hospital admission and mortality in chronic

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8 Sewell L, Singh SJ, Williams JE, et al. Can individualizedrehabilitation improve functional independence in elderlypatients with COPD? Chest 2005; 128:1194–1200

9 Mercken EM, Hageman GJ, Schols AM, et al. Rehabilitationdecreases exercise-induced oxidative stress in chronic ob-structive pulmonary disease. Am J Respir Crit Care Med2005; 172:994–1001

10 Berg-Emons R, Balk A, Bussmann H, et al. Does aerobictraining lead to a more active lifestyle and improved quality oflife in patients with chronic heart failure? Eur J Heart Fail2004; 6:95–100

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17 Decramer M, Lacquet LM, Fagard R, et al. Corticosteroidscontribute to muscle weakness in chronic airflow obstruction.Am J Respir Crit Care Med 1994; 150:11–16

18 Mathiowetz V, Kashman N, Volland G, et al. Grip and pinchstrength: normative data for adults. Arch Phys Med Rehabil1985; 66:69–74

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27 Pitta F, Troosters T, Spruit MA, et al. Activity monitoring forassessment of physical activities in daily life in patients withchronic obstructive pulmonary disease. Arch Phys Med Re-habil 2005; 86:1979–1985

28 Heppner PS, Morgan C, Kaplan RM, et al. Regular walkingand long-term maintenance of outcomes after pulmonaryrehabilitation. J Cardiopulm Rehabil 2006; 26:44–53

29 Yusuf HR, Croft JB, Giles WH, et al. Leisure-time physicalactivity among older adults: United States, 1990. Arch InternMed 1996; 156:1321–1326

30 Schutz Y, Weinsier RL, Hunter GR. Assessment of free-livingphysical activity in humans: an overview of currently availableand proposed new measures. Obes Res 2001; 9:368–379

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32 LaCroix AZ, Leveille SG, Hecht JA, et al. Does walkingdecrease the risk of cardiovascular disease hospitalizationsand death in older adults? J Am Geriatr Soc 1996; 44:113–120

33 Troosters T, Gosselink R, Decramer M. Short- and long-termeffects of outpatient rehabilitation in patients with chronicobstructive pulmonary disease: a randomized trial. Am J Med2000; 109:207–212

34 Verrill D, Barton C, Beasley W, et al. The effects ofshort-term and long-term pulmonary rehabilitation on func-tional capacity, perceived dyspnea, and quality of life. Chest2005; 128:673–683

35 Berry MJ, Rejeski WJ, Adair NE, et al. A randomized,controlled trial comparing long-term and short-term exercisein patients with chronic obstructive pulmonary disease. J Car-diopulm Rehabil 2003; 23:60–68

36 Rossi G, Florini F, Romagnoli M, et al. Length and clinicaleffectiveness of pulmonary rehabilitation in outpatients withchronic airway obstruction. Chest 2005; 127:105–109

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280 Original Research

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1

ARE PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

MORE ACTIVE AFTER PULMONARY REHABILITATION?

Fabio Pitta, PhD 1,2, Thierry Troosters PhD 1, Vanessa S. Probst, PhD 1,2,

Daniel Langer, MSc 1, Marc Decramer, PhD 1 and Rik Gosselink, PhD 1

1 Respiratory Rehabilitation and Respiratory Division, University Hospitals;

and Faculty of Kinesiology and Rehabilitation Sciences, Katholieke

Universiteit Leuven, Leuven, Belgium; 2 Laboratório de Pesquisa em

Fisioterapia Pulmonar (LFIP), Department of Physiotherapy, Universidade

Estadual de Londrina, Londrina, Brazil.

ONLINE DATA SUPPLEMENT

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Rationale to the study

The available studies aiming at investigating changes in the amount of

daily physical activity after pulmonary rehabilitation assessed by motion

sensors in COPD showed conflicting results1-4. Two studies showed very

modest or no improvements in the motion sensors’ output after programs

lasting 3 and 8 weeks1,2, in contrast to two other studies which found

significant improvements after programs of 7 and 8 weeks of duration3,4. The

motion sensors used in the aforementioned studies have limited outputs,

showing basically the total amount of movements performed and the

magnitude of measured acceleration, e.g., how briskly subjects walk. In other

words, these devices reflect the intensity at which movements are performed,

but are not able to distinguish time spent by the patients in different activities

and body postures such as walking, cycling, standing, sitting and lying. An

activity monitor with these additional characteristics (DynaPort activity

monitor, McRoberts BV, The Nethelands) has been recently validated in

COPD patients5. It is able to measure the intensity at which activities are

performed and also the time spent in these activities and body postures as

accurately as video recordings. Furthermore, another limitation to the

available studies is that none of them involved rehabilitation programs longer

than 8 weeks. Longer interventions might be necessary to result in larger

improvements, as suggested for patients with chronic heart failure6.

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Methods Inclusion criteria

Inclusion criteria were: 1) absence of severe cardiac disease as shown

by electrocardiogram at rest and during the maximal exercise test; 2) absence

of other pathologic conditions that could impair physical activities in daily life,

e.g., cerebrovascular diseases, malignancy, arthritis and rheumatism.

Admission of patients to the study was done throughout the whole year

to avoid seasonal bias in the assessments. Out of the 41 patients included, 10

were initially assessed during winter, 14 during spring, 11 during summer and

6 during autumn.

Sample size calculation

The primary outcome of the present study was the change in walking

time in daily life after 6 months of pulmonary rehabilitation. Since there is no

available minimal clinical important difference in walking time in daily life, an

hypothetical improvement of 33% based on a study by Regensteiner et al.7

was used. Those authors used a similar assessment tool to study physical

activity in patients with peripheral arterial disease after a rehabilitation

program of similar duration and composition as the present study. To

calculate the sample size of the present study, we used the same magnitude

of improvement, an α = 0.05, a power of 80% and the values of walking time

in stable COPD patients obtained in pilot data from our laboratory. Based on

these parameters, the estimated number of patients who should complete the

present study was 26. Taking into consideration a drop-out rate of 32% in the

6-month rehabilitation program as found in another study published by our

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group8, the minimum number of patients to be initially included was set at 34.

In order to avoid lack of statistical power, the sample size of the present study

surpassed the calculated number of patients to be included as well as the

calculated number of patients to complete the study.

Management of acute exacerbations occurring during the program

In case a severe acute exacerbation occurred, patients were

hospitalized for 9-10 days following a protocol used for management of COPD

patients during severe exacerbations in the University Hospital Gasthuisberg.

Description of this standardized protocol can be found elsewhere9. These

patients stayed away from the training sessions for a period of 2 weeks, and

each patient had his/her program prolonged to the same extent of the

respective leave. Hence, missing sessions were compensated. Patients

during recovery of an acute exacerbation followed the same program as the

non-exacerbating patients, except that their training workload was reduced, if

needed. In case of mild exacerbations, appropriate medication was introduced

or increased by the pulmonary physician or general practitioner and patients

continued to follow the program without interruption.

Pulmonary function

All subjects performed spirometry with determination of forced

expiratory volume in the first second (FEV1) and forced vital capacity (FVC).

Spirometry was done using the pneumotachograph of a constant volume

plethysmograph (Vmax Autobox, Sensor Medics, Bilthoven, The

Netherlands), according to European Respiratory Society recommendations,

using the tracing yielding the greatest sum of FVC and FEV1. Functional

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residual capacity (FRC) and total lung capacity (TLC) were measured with the

above-mentioned constant volume plethysmograph. In addition, the diffusing

capacity for carbon monoxide (TLCO) was measured by the single breath

method (V6200 Autobox, Bilthoven, The Netherlands). The results were

referred to the predicted values reported by Quanjer et al.10.

Peripheral and respiratory muscle force

Isometric quadriceps force was measured using a Cybex Norm

Dynamometer (Cybex® Norm, Enraf Nonius, Delft, The Netherlands). Peak

extention torque was measured at the dominant side, and evaluated at 60° of

knee flexion. Reference values for quadriceps force were developed in our

laboratory 11. Tests were performed at least 3 times and the best of 2

reproducible tests was used for further analyses.

Isometric handgrip force was measured with a hydraulic hand

dynamometer (Jamar Preston, Jackson, Michigan, United States of America).

Peak handgrip force (HF) was assessed at the dominant side with the elbow

at 90° of flexion, forearm and wrist in neutral position. At least 3 attempts were

performed, and the highest value was taken and related to the reference

values from Mathiowetz et al.12.

Inspiratory and expiratory maximal respiratory pressures were

measured according to a modification of the Black and Hyatt method13. The

modification consisted in the use of an electronic transducer instead of an

aneroid manometer. Maximal inspiratory pressure was measured from

residual volume, while maximal expiratory pressure was measured from TLC.

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Tests were repeated at least 5 times, until 3 attempts differed by <5%. The

highest values were related to the reference values of Rochester and Arora14.

Exercise capacity

Maximal exercise capacity was assessed by an incremental cycle

ergometer test (Ergoline 900, Bitz, Germany). The test was performed

according to the standard of the ATS/ACCP statement on Cardiopulmonary

Exercise Testing15. Patients started the test with a workload of 20 watts and

cycled at an incremental workload of 10 watts each minute. Peak oxygen

consumption, ventilation and carbon dioxide output were measured breath by

breath (Sensor Medics 6200, Bilthoven, The Netherlands). Heart rate was

monitored continuously by 12 leads electrocardiogram. The values of peak

oxygen consumption were related to the normal values by Jones et al.16.

Functional exercise performance was measured by six-minute walking

test (6MWT) in a 53-meter corridor. Encouragement was standardized17. The

test was performed twice, on non-consecutive days. The largest distance was

used in the analysis, and normal values were those described by Troosters et

al.18.

Health-related quality of life and functional status questionnaires

The individualized Chronic Respiratory Disease Questionnaire (CRDQ)

was used to assess health-related quality of life19. This twenty-item

questionnaire scores quality of life into 4 domains (dyspnea, fatigue,

emotional functioning, mastery) and has been validated for the Dutch

language20. A total score is obtained by summation of the 4 above-mentioned

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domains and can potentially range from 20 to 140 with higher scores

indicating better quality of life.

The modified version of the Pulmonary Functional Status and Dyspnea

Questionnaire (PFSDQ-M) was used to assess subjective aspects of activities

of daily living. It consists of 3 components: activity, dyspnea and fatigue. For

10 activities, the level of change in comparison to health status preceding the

respiratory problems is reported. Scores are rated on an eleven-point scale

(0-10). A high score means a great level of change. For dyspnea and fatigue,

5 general questions are asked. They assess the patient’s experience with

shortness of breath/fatigue, the frequency of occurrence over the past month

and 3 questions relating to overall intensity (i.e. on most days, today and with

usual activities). These last 3 questions are rated on an eleven-point scale (0-

10) with 10 indicating severe shortness of breath/fatigue. For each of the 3

components, lower values indicate better functional status.

Design of the pulmonary rehabilitation program

Patients participated in a six-month out-patient multidisciplinary

pulmonary rehabilitation program, composed of two periods: in the first 3

months, patients exercised 3 times per week, and in the last 3 months, 2

times per week. Hence, the anticipated total number of exercise training

sessions for each patient was 60. No home-based training was included in the

protocol. Besides the exercise training performed by the physiotherapists, the

pulmonary rehabilitation program also included 8 group education sessions

concerning important topics in COPD management (described below). In

addition, visits for support and/or counseling with a pulmonary physician, a

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nutritionist, a psychologist, an occupational therapist, a respiratory nurse and

a social assistant were also included in the program, providing its

multidisciplinary character.

Pulmonary rehabilitation program: education and occupational therapy

The 8 group education session included in the pulmonary rehabilitation

program were given by the professionals involved in the program

(physiotherapist, pulmonary physician, nutritionist, psychologist, occupational

therapist, respiratory nurse and social assistant). The topics of the sessions

were:

- What is COPD? Causes, symptoms, diagnostic and management

- What are the effects that can be expected from the rehabilitation program?

- Nutrition

- Moving and breathing. How can this be improved?

- Psychological aspects

- Activities of daily living

- Financial and social aspects

- How to use the inhaled medication

The occupational therapy sessions aimed at teaching the patients how

to re-organize their habits and houses in order to achieve maximal function

and independence to sustain specific activities of daily living21.

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Exercise training characteristics

The circuit exercise training included cycling, walking, strength training

for lower (quadriceps) and upper (pectoralis, triceps) extremities, arm

cranking and stair climbing. The training program is based on previous

experience22 and driven by symptoms’ perception by the patient. Each

exercise training session lasted about 1.5 hour. Initial training intensity was

set at 60% of the baseline maximal workload for ergometry cycling and at

75% of the average walking speed during the baseline 6MWT for treadmill

walking. Physiotherapists increased patients’ workload on a weekly basis,

guided by Borg-symptom scores23. A Borg score of 4-6 for dyspnea or fatigue

was set as a target24. For the cycling training, the aim was to achieve 85% of

the baseline maximal workload for 16 minutes at 3 months of training,

whereas for the treadmill the aim was to achieve 110% of the average walking

speed of the baseline 6MWT for 16 minutes at 3 months of training. During

cycling, patients in whom the progression of the workload was difficult

performed interval training (5 to 8 sets of 2-minute blocks interspersed by 1

minute of rest). This is a common approach used in our center in order to be

able to increase patients’ workload. In the strength training, patients

performed 3 times of 8 repetitions with the initial load determined as 70% of

the one repetition maximum (1RM) (the maximum load which can be moved

only once over the full range of motion without compensatory movements).

For this modality, the aim was to increase the load by 3% to 6% of the 1RM

per week in order to achieve 121% of the 1RM at 3 months of training25. Arm

cranking was performed in 2-minute blocks (1 to 3 sets) with load set in an

individual basis. Stair climbing was performed in a two-step stair in which

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patients stepped up and down during 1-3 minute blocks (1 to 3 sets). For all

modalities, progression of the load for the last 3 months of training was done

in an individual basis guided by Borg-symptom scores.

Results

Drop-outs, long term oxygen therapy at home (LTOT) and current

smoking status

There were no statistically significant differences at baseline between

the group of patients who dropped out (n=12) and the group of patients who

completed the program (n=29), including in terms of physical activities in daily

life. However, patients who dropped out tended to have lower maximal cycling

workload (58±19 versus 78±33 watts; p=0.06).

Prevalence of patients using LTOT was higher in the group who

dropped out in comparison to the group of patients who completed the study

(3 out of 12 [25%] versus 4 out of 29 [14%], respectively), although this

difference was not statistically significant (Chi square = 1.01 [p=0.32]; Fisher’s

test 0.37). The same was observed for the prevalence of current smokers (4

out of 12 [33%] versus 4 out of 29 [14%], respectively; Chi square = 1.67

[p=0.19]; Fisher’s test 0.22).

In the group who completed the study, neither the use of LTOT nor the

current smoking status of the patients was correlated to changes in walking

time in daily life.

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Correlates of improvement in walking time in daily life - trends

There were strong trends of correlation between changes in walking

time in daily life with: changes in the 6MWT (r=0.35, p=0.06); changes in lying

time in daily life (r=-0.36; p=0.06); and changes in the domain ‘change in

activities’ of the PFSDQ-M (r=-0.34, p=0.09). Figure 1 shows that, out of 15

patients who improved their 6MWT above the minimal clinically important

difference (MCID) (54 meters26), 11 (73%) also improved their walking time in

daily life (sensitivity 0.55 [95% confidence interval 0.32-0.76]). However, it is

worthwhile to underscore that the MCID for the 6MWT originally refers to

changes in a group of patients rather than individual patients.

Pattern of time spent walking in daily life

The number of blocks of continuous walking per day is shown in figure

3. At baseline, the 22 analyzed patients performed on average 8.4 ± 6.5 one-

minute blocks of continuous walking per day, 3.3 ± 3.5 blocks of two minutes

per day and 1.4 ± 2.2 blocks of three minutes per day. Blocks of walking

longer than three minutes were performed less than once per day on average.

There was no significant change in this pattern after six months of pulmonary

rehabilitation.

Acute exacerbations and the rehabilitation program

In those patients who suffered from exacerbations during the program

(n=12), there was no correlation between changes in walking time in daily life

after 6 months and changes in FEV1, whereas there was a trend for

correlation between changes in walking time in daily life and changes in the

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6MWT in this group (r=0.54; p=0.07). In addition, these patients tended to

decrease their FEV1 at the end of the program in comparison to patients

without exacerbations (-2.5% predicted versus +3% predicted, respectively;

p=0.06). There was no difference concerning changes in the 6MWT at the end

of the program between patients who exacerbated and patients who did not

exacerbate (+7% predicted versus +9 % predicted, respectively; p=0.51).

Discussion

Changes in FEV1

In the present study, FEV1 improved by 4% (p<0.05) after 3 months of

pulmonary rehabilitation. Significant reduction in airflow obstruction after

comprehensive multidisciplinary pulmonary rehabilitation has been previously

described in other studies27. Education sessions, which were part of the

program (see previous topic), have been shown to increase adherence to

medication28 and may have played a role in this finding. Adjustments in the

medication of patients in which pharmacological therapy was not optimal

previously to the program might have also contributed. However, the FEV1

returned to values close to baseline at the end of the program, showing that

the improvements were only temporary. In addition, improvements in FEV1

were not related to improvements in physical activities in daily life. This was

not surprising, since it is common sense that impairment in daily physical

activities is out of proportion to impairment in lung function29.

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Predicting improvement in walking time in daily life

None of the baseline variables was capable of predicting accurately

patients who would improve their walking time and walking intensity in daily

life after the program. It has been previously suggested that changes in daily

physical activity obtained after exercise training were not proportional to what

was predicted from exercise capacity tests30. There were a modest but

significant correlation between improvement in walking time in daily life and

improvement in dyspnea (0.43; p=0.02), besides a strong trend of correlation

with the 6MWT (0.35; p=0.06; figure 1). Concerning the 6MWT, figure 1

shows that 11 out of the 15 patients who improved their 6MWT above the 54-

meter MCID (73%) also improved their walking time in daily life. On the other

hand, figure 1 also shows that 9 out of the 20 patients who improved their

walking time in daily life (45%) did not reach this 54-meter improvement

threshold in the 6MWT. These limitations in predicting improvements in

walking time in daily life point to the fact that the level of physical activities in

daily life is difficult to predict and probably requires objective assessment, as

previously suggested31. This may very well indicate that aspects other than

exercise training did contribute to the changes observed after the

rehabilitation program in these patients. For instance, pacing strategies may

have contributed to improvements that exceed the effect predicted from

improved exercise capacity only. In contrast, some patients had clearly not yet

implemented their increased capacity into a more active lifestyle. Further

research could focus on the usefulness of performing activity monitoring

aiming to follow more closely the progression of changes in daily life after

interventions such as pulmonary rehabilitation.

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Correlates of improvement in movement intensity

Improvements in walking intensity after 6 months were correlated with

the improvement in maximal workload in the incremental cycling test (r=0.60;

p=0.0006) and in health related quality of life (CRDQ total score; r=0.42;

p=0.04).

Relationship between physical activity in daily life and activities of daily

living

A study by Bendstrup et al. showed improvement in activities of daily

living (ADL) measured by a questionnaire after a 3-month pulmonary

rehabilitation program32. ADL and physical activities in daily life are different

aspects of COPD patients’ disability. Physical activities in daily life refer to the

quantification of the amount and intensity of physical activity performed by the

subject, whereas ADL refer to the perceived difficulties and independence

during specific daily tasks such as dressing, cleaning the house and

gardening33. It may happen that COPD patients perform more easily their ADL

after pulmonary rehabilitation, but in the short-term they remain as inactive in

daily life as before. The present study showed a clear improvement in

functional status (the capacity to perform ADL) after 3 months of pulmonary

rehabilitation, with further improvements after 6 months. Therefore, results

from our study are in line with results from Bendstrup et al.32. since difficulties

to perform ADL decreased significantly already after 3 months of pulmonary

rehabilitation (table 1). In addition, further improvements in functional status

after 6 months clearly underline the additional effects of a longer program.

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Impact of acute exacerbations during the rehabilitation program

Although patients that had an acute exacerbation during the program

worsened their lung function, they were able to have similar improvement in

walking time in daily life and 6MWT than those patients who did not suffer

from exacerbations. This indicates the positive effects of continuing with the

training program immediately after the exacerbation, and even suggest a

possible “protective effect” against the typical functional losses linked to acute

exacerbations in patients those patients who were undergoing pulmonary

rehabilitation. In other words, the negative impact of severe acute

exacerbations in the walking time in daily life and the 6MWT3 was probably

counteracted by the participation in a rehabilitation program and/or by the fact

that they resumed training immediately after the hospitalization period. This

was also suggested in a recent study by Man and colleagues which indeed

showed large increases in walking distance when rehabilitation was initiated

immediately after an exacerbation34.

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(3) Sewell L, Singh SJ, Williams JE et al. Can Individualized Rehabilitation

Improve Functional Independence in Elderly Patients With COPD?

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Exercise-induced Oxidative Stress in Chronic Obstructive Pulmonary

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(5) Pitta F, Troosters T, Spruit MA et al. Activity Monitoring for Assessment

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Figure 1

Figure 1. Plot of changes (Δ) in walking time in daily life and 6-minute walking

distance test (6MWT) life in 29 COPD patients after 6 months of pulmonary

rehabilitation (r=0.35; p=0.06). The dashed horizontal line correspond to a 54

meters improvement in the 6MWT, the minimal clinically important difference

(MCID). Points included in the gray area above that line correspond to 15

patients who improved their 6MWT above the MCID. Eleven out of these 15

patients (73%) also improved their walking time in daily life (sensitivity 0.55

[95% confidence interval 0.32-0.76]).

-50 -25 0 25 50 75-200

-100

0

100

200

54

! walking time

6 months-pre (min)

! 6MWD

6 months-pre

(m)

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DOI 10.1378/chest.07-2655; Prepublished online April 10, 2008; 2008;134; 273-280Chest

Decramer and Rik GosselinkFábio Pitta, Thierry Troosters, Vanessa S. Probst, Daniel Langer, Marc

*Are Patients With COPD More Active After Pulmonary Rehabilitation?

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