Comparing accelerometer, pedometer and a questionnaire for measuring physical activity in bronchiectasis: a validity and feasibility study?
O'Neill et al. Respiratory Research
Comparing accelerometer, pedometer and a questionnaire for measuring physical activity in bronchiectasis: a validity and feasibility study?
B. O'Neill 3
S. M. McDonough 2 3
J. J. Wilson 1 2
I. Bradbury 3
K. Hayes 3
A. Kirk 6
L. Kent 5
D. Cosgrove 5
J. M. Bradley 0 4
M. A. Tully 1 2
0 Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast , Belfast , UK
1 Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast , Belfast , UK
2 UKCRC Centre of Excellence for Public Health (Northern Ireland) , Belfast , UK
3 Centre for Health and Rehabilitation Technologies, Institute for Nursing and Health Research, Ulster University , Newtownabbey , UK
4 Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast , Belfast , UK
5 Northern Ireland Clinical Research Network, Respiratory Health, Belfast Health and Social Care Trust , Belfast , UK
6 School of Psychological Sciences and Health, University of Strathclyde , Glasgow , UK
Background: There are challenges for researchers and clinicians to select the most appropriate physical activity tool, and a balance between precision and feasibility is needed. Currently it is unclear which physical activity tool should be used to assess physical activity in Bronchiectasis. The aim of this research is to compare assessment methods (pedometer and IPAQ) to our criterion method (ActiGraph) for the measurement of physical activity dimensions in Bronchiectasis (BE), and to assess their feasibility and acceptability. Methods: Patients in this analysis were enrolled in a cross-sectional study. The ActiGraph and pedometer were worn for seven consecutive days and the IPAQ was completed for the same period. Statistical analyses were performed using SPSS 20 (IBM). Descriptive statistics were used; the percentage agreement between ActiGraph and the other measures were calculated using limits of agreement. Feedback about the feasibility of the activity monitors and the IPAQ was obtained. Results: There were 55 (22 male) data sets available. For step count there was no significant difference between the ActiGraph and Pedometer, however, total physical activity time (mins) as recorded by the ActiGraph was significantly higher than the pedometer (mean ± SD, 232 (75) vs. 63 (32)). Levels of agreement between the two devices was very good for step count (97% agreement); and variation in the levels of agreement were within accepted limits of ±2 standard deviations from the mean value. IPAQ reported more bouted- moderate - vigorous physical activity (MVPA) [mean, SD; 167(170) vs 6(9) mins/day], and significantly less sedentary time than ActiGraph [mean, SD; 362(115) vs 634(76) vmins/day]. There were low levels of agreement between the two tools (57% sedentary behaviour; 0% MVPA10+), with IPAQ under-reporting sedentary behaviour and over-reporting MVPA10+ compared to ActiGraph. The monitors were found to be feasible and acceptable by participants and researchers; while the IPAQ was accepta ble to use, most patients required assistance to complete it. Conclusions: Accurate measurement of physical activity is feasible in BE and will be valuable for future trials of therapeutic interventions. ActiGraph or pedometer could be used to measure simple daily step counts, but ActiGraph was superior as it measured intensity of physical activity and was a more precise measure of time spent walking. The IPAQ does not appear to represent an accurate measure of physical activity in this population. (Continued on next page) © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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Trial registration: Clinical Trials Registration Number NCT01569009: Physical Activity in Bronchiectasis.
Global recommendations on physical activity for health have
been developed to support the promotion of physical activity
. Similarly, the promotion of physical activity for patients
with respiratory conditions is gaining momentum, and the
measurement of physical activity is becoming more
common in clinical practice [2–6]. Currently, it is unclear which
physical activity tool should be used to assess physical
activity in Bronchiectasis (BE). Research in other respiratory
populations (COPD and CF) supports the use of triaxial
accelerometers such as the ActiGraph; however, currently
there is no published research on the best tool for the
measurement of physical activity in BE [4, 7–9]. Questionnaires
e.g. the International Physical Activity Questionnaire are also
used for assessment of physical activity in respiratory
populations . A recent review on the validity of a range of
additional questionnaires to measure physical activity in
COPD has reported the lack of conceptual framework
underpinning their development . The value of
monitors, such as ActiGraph, over subjective questionnaires is
the provision of precise objective information on physical
activity dimensions (frequency, duration, intensity and type),
that is not limited by recall and response bias . It is not
clear if all these dimensions are useful or necessary, of if the
high levels of precision are needed to detect differences in
physical activity between groups or changes over time .
Other simple objective tools are available e.g. pedometers
but the validity, feasibility and acceptability of these have not
been compared to the ActiGraph in this population.
There are challenges for researchers and clinicians to
select the most appropriate physical activity tool, and a
balance between precision and feasibility is needed. Feasibility
can be measured by examining the extent to which an
instrument provides extra information not already available
to the health care provider, the practicality of use within
clinical practice with respect to the degree of training
required, method of administration, ease of administration,
analysis and interpretation and time taken to administer
and score as well as acceptability of the device to patients
and clinicians . There is currently limited information
about the feasibility and precision of monitors in BE. This
information would be particularly useful for clinicians and
researchers when deciding which instrument to choose.
people with BE. Specifically we will (i) compare assessment
tools (pedometer and IPAQ) to our criterion method
(ActiGraph) for the measurement of physical activity
dimensions, and (ii) assess the feasibility and acceptability of
objective assessment tools (ActiGraph, pedometer) and
subjective assessment tools (IPAQ) to assess physical activity
dimensions in BE from two perspectives: those of the
participants’ and those of the researchers’ conducting the
Patients in this analysis were enrolled in a
crosssectional study using quantitative methodology.
Additional methods and results from the primary study
which relates to patterns correlates of sedentary
behaviour and physical activity have been published previously
. Participants who agreed to take part in the study
attended a clinical visit (Visit 1) where they provided
baseline demographics; disease severity was estimated
using the Bronchiectasis Severity Index . During this
visit, an ActiGraph GT3X+ accelerometer and DigiWalker
CW700 pedometer were attached and participants were
asked to wear the devices for 7 consecutive days following
this visit. Eight days later, participants attended for a
second clinical visit (Visit 2) where they returned the
activity monitors (ActiGraph and Pedometer) and
completed the IPAQ and questionnaires relating to the
feasibility and acceptability of the monitors/IPAQ.
Setting and participants
Patients (n = 63) with bronchiectasis were recruited from
the Northern Ireland Regional Respiratory Centre
(Belfast City Hospital) (n = 23), Craigavon Area Hospital
(n = 15) and Altnagelvin Area Hospital (n = 25) in one
UK region (N Ireland). Inclusion criteria were patients
aged ≥18 years, diagnosis of bronchiectasis confirmed by
High Resolution Computerised Tomography or CT,
clinically stable (no exacerbation and no significant change
in symptoms or medication in the last four weeks) and
sputum bacteriology completed over the past three
months. Exclusion criteria were clinically unstable
patients (pulmonary exacerbation or any change in
symptoms or medication in the last four weeks), current
severe haemoptysis, pregnancy or any other concomitant
condition that would prevent participation. The study
was approved by the NI Research Ethics Committees
(Ethics Approval REC Reference: 12/NI/0044) and
research departments of all the participating hospitals.
Written informed consent was obtained from all of
study participants. The study was supported by the
Northern Ireland Clinical Research Network (NICRN)
intensity, as well as measure number of steps. The
ActiGraph has been validated for measurement of physical
activity dimensions in different populations, and as an
accurate measure of sedentary behaviour [17, 18].
Table 1 Descriptors, categorisation and comparable dimensions of physical activity (PA) per instrument
Study activity monitors
The physical activity dimensions for each of the
instruments used are summarised in Table 1. At Visit 1,
participants were offered a reminder system to receive daily,
alternate-day or once-weekly reminders to wear their
monitors. All devices were worn during all waking hours
for seven consecutive full days following Visit 1; and any
periods of non-wear-time were to be recorded in a daily
‘log’ provided at visit 1. The ActiGraph device and a
sealed pedometer were placed beside one another on a
belt, worn on the dominant side of the body in line with
the anterior axillary line of the hip. As devices were not
waterproof they were removed during water sports,
washing or showering.
The ActiGraph GT3X+ (ActiGraph, Pensacola, Florida)
is a tri-axial accelerometer that measures body
acceleration as counts per unit time; using defined cut points
for accelerometer counts it is possible to measure
activity at different intensities e.g. light, moderate, vigorous
Total steps taken per day
Average daily time spent at rest
or inactive e.g. sitting/lying
Total MVPA time (mins)
Average daily time spent in physical
activity at a low intensity such as
standing and slow walking around
Average daily time spent in physical
activity at a higher intensity such as
MVPA in ≥10-min bouts
n/a parameter not available
apedometer dimensions comparable to ActiGraph
bIPAQ dimensions comparable to ActiGraph
Yamax DigiWalker pedometer
The DigiWalker CW-700 is a pedometer which has been
used in recent studies to measure step counts in the
general population [19, 20], and also in respiratory
populations such as COPD [21–23]. This has been shown to
be the most reliable, commercially obtainable pedometer
available . This device does not measure intensity of
International Physical Activity Questionnaire (IPAQ)
The long-form IPAQ is a validated 27-item,
selfcompleted physical activity questionnaire which was
developed to measure health related physical activity (i.e.
activity in bouts of at least 10 min) in most daily
situations. It was chosen as it allows participants to include
leisure/exercise, walking, occupation, and transportation
physical activity in their responses, and the scoring
protocol allows greater flexibility in how physical activity
is accumulated than other questionnaires [10, 25]. The
IPAQ identifies the frequency and duration of moderate
ActiGraph – moderate-vigorous physical activity
≥1952 cpm accumulated in ≥10-min bouts
Pedometer – n/a
bIPAQ – Scores are usually reported as MET-mins,
and we converted this to mins/day
and vigorous physical activity, walking physical activity,
and time spent sitting during the past week in (i) work
related physical activity (ii) transportation physical
activity (iii) housework/house maintenance/caring for the
family time physical activity and (iv) recreation/sport/
leisure time physical activity. The IPAQ has been utilised
in patients with COPD .
Feasibility questionnaires for the study were developed
to facilitate feedback from both participants and
researchers about the activity monitors and the IPAQ.
These were informed by questionnaires that were used
in previous research exploring feasibility of
accelerometers . A 10-point visual analogue scale (VAS) (0 ‘very
difficult/uncomfortable’ through to 10 ‘very
easy/comfortable’) was used to assess participants’ perspectives on
the ease of fitting, and comfort of wearing the
ActiGraph/pedometer. Participants were also asked to report
any difficulties relating to wearing the monitors, or any
strategies they adopted to make it easier to wear the
Researchers’ perspectives on how easy it was to teach
participants to apply and wear the monitors was assessed
on a 10-point VAS (0 ‘very difficult’ through to 10 ‘very
easy’), and they also recorded how long it took to
download data. Both participants and researchers’ perspectives
on ease of completing/administering and usefulness of the
IPAQ was also assessed using a 10-point VAS (0 ‘very
difficult/not useful’ through to 10 ‘very easy/very useful’).
Data handling and analysis
For the ActiGraph and pedometer, participant wear time logs
were cross-checked to explore periods of non-wear time of
the monitors; for example, if the participant had removed
the monitor for bathing or swimming during waking hours.
Step count was classified into the following categories:
sedentary <5000 steps per day, low active 5000–7499 steps
per day, somewhat active/active ≥7500 steps per day .
Table 1 indicates the physical activity dimension
variables that were compared between the ActiGraph and
the pedometer or the IPAQ. Due to the limited number
of participants performing vigorous physical activity,
moderate and vigorous categories were combined. Thus,
ActiGraph moderate - vigorous physical activity (MVPA)
reflected time spent in moderate/vigorous activity and
this included walking time . The IPAQ records
walking and moderate/vigorous activity domains separately
so to aid comparison these were combined into a ‘single’
moderate/vigorous activity domain for analysis.
ActiGraph data was considered valid if there were more
than 600 min of monitoring per day and at least 5 days,
one being a Saturday or Sunday, giving a sample with valid
data of n = 55 [30, 31]. Using ActiLife software version
6.8.0, wear-time validation was applied using parameters
set by Choi (2011) which allowed for a 2 min interval of
non-zero counts with an up/downstream 30 min of
consecutive zero counts window . Step counts were
calculated using cut-off points based on manufacturer
guidelines . Categorisation of physical activity
dimensions from the ActiGraph is summarised in Table 1.
After the 7 day monitoring period, data collected from the
pedometer on daily step counts and time spent in walking
was recorded. A valid day of pedometer data required
steps to lie between 100 and 50,000 steps (Table 1).
Datasets which aligned with ActiGraph data (n = 50), with
respect to wear time, were included in the analyses.
Scores are reported as METs (n = 55), one MET-minute
is defined as the MET-intensity multiplied by the
minutes per week of activity. MET-intensity levels used to
score the IPAQ questions were vigorous (8.0 METs),
vigorous chores (5.5 METs), moderate (4.0 METs), outside/
yard chores (4.0 METs) inside chores (3.0 METs), cycling
(6.0 METs) and walking (3.3 METs). Time spent sitting,
walking, and in moderate, and vigorous activity was
calculated along with walking, moderate and vigorous
MET/mins. Physical activity categorical scores (low,
moderate or high) were calculated [International
Physical Activity Questionnaire 2005].
Descriptive statistics were used to summarise study
populations demographic and clinical characteristics. All
data was transferred to SPSS for statistical analysis and
all statistical analyses were performed using SPSS 20
(IBM), unless otherwise stated. Summary data is
reported as Mean (SD) and statistical significance was
assumed at p < 0.05.
To investigate validity of the IPAQ questionnaire and
pedometer, the percentage agreement between ActiGraph
and these other measures was calculated using limits of
agreement . ActiGraph was considered the criterion
measure and a value close to or equal to 100%, with
narrow limits of agreement (LOA) indicated higher levels of
agreement between the two measures under investigation.
Patterns in the plots were also explored to identify any
systematic bias between the measurements .
Demographics and physical activity data
There were 55 (22 male) data sets available for analysis
(Table 2). The mean[SD] age of the participants was
Table 2 Demographic and clinical characteristics of patients with bronchiectasis (n = 55)
FEV1 (% predicted)
Disease Severity (%)a
Number of oral antibiotic courses within last year
Number of IV antibiotic courses within last year
Results are Mean (SD) or Frequency [%]
Abbreviations: BMI body mass index, FEV1 forced expiratory volume in 1 s (% predicted), FVC forced vital capacity (% predicted)
aDisease severity based on Bronchiectasis Severity Index 
63years and disease severity was categorised as Stage 1
Mild 27% and Stage 2 Moderate/severe 28%
(Bradley et al 2015). There were n = 55/55 datasets
available for ActiGraph and IPAQ, n = 50/55 for pedometer
(five datasets had less than 5 valid days of pedometer
ActiGraph (n = 50) versus Pedometer (n = 50).
Steps per day and total physical activity time (mins)
and were compared between the ActiGraph and the
Yamax pedometer (Table 3). In terms of steps per day,
there was no significant difference between the two
devices; however total physical activity time (mins) as
recorded by the ActiGraph was significantly higher than
the pedometer (mean ± SD, 232 (75) vs. 63 (32)).
The Bland and Altman plots (Fig. 1) showed that the
mean levels of agreement between the two devices was
very good for step count (97% agreement); and although
the individual differences between the devices were
within acceptable limits for all but 3 participants (Fig. 1),
the 95% LOA were wide and for some individuals this
could vary by as much as 5823 steps. With respect to
total physical activity time (mins) there was a lower level
of agreement (28%, Fig. 2), with the pedometer under
reporting total physical activity (or steps) time by 165
mins (or 2.75 h); and this was proportionally greater in
people who were more active, so that the under
reporting could be a great as 234 min (nearly 4 h).
ActiGraph (n = 55) versus IPAQ (n = 55).
IPAQ reported significantly less sedentary time than
ActiGraph [mean, SD; 362(115) vs 634(76) vmins/day],
and a much greater number of bouts of at least 10 min
of -MVPA10+ [mean, SD; 167(170) vs 6(9) mins/day]
Average times in different PA intensitiesd (mins/day) unbouted (cpm)
Total physical activity time(mins/day)
Sedentary behaviour time
Light physical activity time
Pedometer (n = 50)
IPAQ (n = 55)
Total physical activity time (mins/day)
Total PA level (MET-min/week)
Sedentary behaviour time (mins/day)
Abbreviations: cpm counts per minute, IPAQ International Physical Activity
Questionnaire, MVPA moderate-vigorous physical activity, MVPA10+ MVPA
accumulated in ≥10-min bouts
apedometer dimensions comparable to ActiGraph
bIPAQ dimensions comparable to ActiGraph
Results are Mean(SD) or Freq [%] or cresults given as median (IQR)
dActiGraph PA category Sedentary <5000, Low active 5000–7499, Somewhat
active and above >7500 steps per day
Average of ActiGraph and Pedometer step counts
Fig. 1 Bland-Altman Plot of ActiGraph vs Pedometer step counts. The mean (SD) difference in steps was -167 (1485), and the upper and lower
LOA (2745, -3078)
The Bland and Altman plots (Figs. 3 and 4) showed low
levels of agreement between the two tools (57% sedentary
behaviour; 0% MVPA10+), with IPAQ under-reporting
sedentary behaviour and over-reporting MVPA10+ compared to
ActiGraph. The latter finding showed bias, in that the
overreporting with IPAQ was greater in people who were more
active; people who were very inactive were less likely to
Categorising activity levels
It was possible to categorise patients into either ‘meeting’
or ‘not meeting’ the volume guidelines (≥150mins of at
least moderate physical activity per week) or step
guidelines (>10,000 steps per day) . For the volume
guidelines, 11% of patients met these guidelines according
to ActiGraph compared to 82% with IPAQ. For the step
guidelines, 7% (ActiGraph) compared to 14% (pedometer)
respectively met these step-based recommendations.
A more detailed categorisation was possible for all 3
measurement tools. Using daily step count categories (see Data
Handling and Analysis) and the ActiGraph data: 42% (n =
23/55) were categorised as sedentary, 29% (n = 16/55) low
active and 29% (n = 16) somewhat active and above. Using
daily step count categories and the pedometer step data
(48%) n = 24/50 were categorised as sedentary, 14% (n = 7/
50) low active and 38% (n = 19/50) somewhat active and
above. The IPAQ scoring classification differs and IPAQ
classified 18% (n = 10) of patients in low, 38% (n = 21) in
100 150 200 250 300
Average of ActiGraph and Pedometer walk-time
Fig. 2 Bland-Altman Plot of ActiGraph vs Pedometer walk time. The mean (SD) difference in walk time was 165 (53) minutes and the upper and
lower LOA (269, 62)
100 200 300
Average of ActiGraph and IPAQ time in moderate-vigorous physical
activity bouts (minutes/day)
Fig. 3 Bland-Altman Plot of ActiGraph vs IPAQ time in moderate-vigorous physical activity bouts (MVPA10+). The mean (SD) difference in bouts
was 272 (135), and the upper and lower LOA (536, 7)
Feasibility and acceptability
Feasibility and acceptability of monitors revealed that
participants found them easy to fit: VAS (out of 10)
mean ± SD score ActiGraph 9.8(0.76); pedometer 9.8
(0.76), and comfortable to wear VAS mean score
mean score ActiGraph 9.22(1.03); pedometer 9.11
(1.24). Difficulties common to both ActiGraph (25%;
n = 14) and pedometer (34%; n = 17) related to the
elastic belt, on which both devices were located,
becoming loose and slipping from its original location,
the belt twisting on strenuous movement or
difficulties opening and closing the belt clasp. One
additional difficulty specific to the pedometer included
discomfort and irritation from the metal clip against
the body (2% n = 1/50). Strategies adopted by
participants to make it easier to wear the ActiGraph and
pedometer on the belt included wearing it next to
their body as opposed to over clothing or vice versa
to ensure a secure fit, and wearing the belt through
trouser belt-loops to ensure a secure fit. To alleviate
300 400 500 600 700 800
Average of ActiGraph and IPAQ time in sedentary behaviour (minutes/day)
Fig. 4 Bland-Altman Plot of ActiGraph vs IPAQ time in sedentary behaviour. The mean (SD) difference in sedentary behaviour was -160 (171)
minutes, and upper and lower LOA (175, -495)
any skin irritation from the pedometer clip strategies
included placing cotton between the pedometer clip
Feasibility and acceptability of IPAQ revealed that
participants reported that it was easy to understand
the questionnaire: VAS mean ± SD score 7.4 (2.03)
and found it useful in its measurement of everyday
activity levels: VAS mean score 7.64 (2.30). The
average time to complete IPAQ was 12(6) minutes.
Researchers reported that it was easy to teach
participants how to apply and wear the monitors: VAS (out of
10) mean ± SD score ActiGraph 9.42(1.07); pedometer
9.29 (1.21). 13 participants requested one or more
reminders as a prompt to wear the activity monitor belt.
Downloading of the data by researchers took less time
for the pedometer compared to the ActiGraph (1.5 min
compared to just under 5 mins).
Researchers reported that while it was easy to
administer the questionnaire, VAS mean score 7.87 (1.72), they
noted that 48/55 (87.3%) participants required assistance
to complete the questionnaire. Reasons for assistance
included additional explanation or clarification of question
terminology (24%); some participants required
clarification of physical activity categories (69%) e.g. were unsure
which physical activities should be included in different
categories; some required clarification of the scoring of
their answers (20%) or prompting to complete missing
answers (44%); ‘other’ aspects (11%) included patients
having difficulty recalling the week’s physical activity and
they suggested future inclusion of a diary in the
preceding week to act as an aide memoire.
This study aimed to compare two assessment tools
(pedometer and IPAQ), with our criterion measure (the
ActiGraph) to measure physical activity dimensions. In
general, we showed that when measuring mean step
count for a group of people either ActiGraph or
pedometer could be used. However, when comparing individual
step counts or when classifying physical activity
according to step categories the devices were not
interchangeable, as different step values were obtained from the
ActiGraph and the pedometer within the same
individual when worn for the same period of time. In addition,
time spent in physical activity did not compare well
between these two objective tools. The IPAQ does not
appear to represent an accurate measure of physical
activity in this population. All three tools appeared to be
generally feasible and acceptable to patients and
The information from this study will help clinicians
and researchers to make an informed decision about
which tool to use. ActiGraph provides an advantage
compared to the pedometer when a precise profile for
patterns and intensity of physical activity dimensions is
required e.g. total time spent in light physical activity,
number of daily bouts of MVPA or sedentary periods
. However, the ActiGraph devices are significantly
more expensive than pedometers (approximately $225
versus $20) and have a higher resource burden as
qualified personnel are needed to manage and analyse this
more complex data. If the primary outcome of interest is
to change step counts in a group of people, as opposed
to change intensity of physical activity, then a pedometer
is a valid choice given the very high levels of agreement
between group means for ActiGraph and pedometer step
counts; this has been shown in other populations also
. Pedometers could be a cost effective option in large
studies , as they are significantly less expensive than
accelerometers; and resources such as specialised
personnel or data management expertise are not
required for the analysis of their simple step count
The low levels of agreement between the two devices
for an individual is notable, and is in agreement with
previous studies [38–40]. For example, in the study by
Harris et al, 2009 in 121 older adults the LOA for an
individual was approximately 8000 step while Kinnunen et
al, 2011 reported a LOA of approximately 5000 steps
[38, 40]. The reason for the wide variation in step counts
between the two devices, demonstrated in our data, is
not clear but suggests that the two assessment tools are
not interchangeable; this is also suggested by Barriera et
al. . The devices measure movement in different
ways; e.g. ActiGraph contains a triaxial electronic
accelerometer and the pedometer is a uniaxial mechanical
device, and such differences in technical specifications may
impact on the validity of monitors [41, 42]. The lack of
agreement in total physical activity time between the
objective devices in our study remains unclear.
There is increasing interest in the measurement of
sedentary behaviour resulting from evidence that it may
be a distinct risk factor, independent of physical activity,
for multiple adverse health outcomes in adults . In
our study, the ActiGraph and IPAQ assessment tools
were not comparable in their measurement of either of
these behaviours; the IPAQ underreported sedentary
behaviour as well as over-reporting 10 min bouts of
MVPA. These findings concur with a large population
study of 1751 adults aged between 19–84 years which
showed the same findings when comparing these two
tools ; and can be explained by an increasing body of
evidence that questionnaires do not relate accurately to
objective physical activity assessment as their use is
limited by recall and response bias and lack of
precision/accuracy of the dimension data [4, 12, 45]. Conceptual
frameworks for physical activity measurement propose a
combined approach of direct and self-report
(questionnaire) to enable a comprehensive exploration of physical
activity patterns and behaviour [7, 46, 47].
The additional assessment of the feasibility of using
different physical activity instruments in this study is important
. Both the ActiGraph and pedometer were feasible and
acceptable to researchers in terms of their use and
downloading data, with shorter data download time required for
the pedometer as it provided less physical activity outputs;
both monitors were acceptable to patients. While patients in
this study indicated that the IPAQ was acceptable, most
patients required assistance to complete it and therefore even
though it is reportedly self-completed there needs to be a
clinician/researcher present during completion to minimise
misinterpreted or missing responses.
Research into the measurement of physical activity is
expanding in other populations and suggestions for key
factors to consider when selecting physical activity
assessment tools include (a) the specific component of
physical activity of interest; (b) the population; (c) cost
and ease measurement; and (d) precision of
measurement that is required . A limitation of our study may
be the positioning of the pedometer on the ActiGraph
belt, which proved slightly problematic on some
occasions and may have resulted in less step
counts/walktime being recorded in some people. Also we based our
feasibility questionnaire around similar themes and
response format to Hale et al. 2008, but such questions
have not been validated for this specific use. However,
to date research on the measurement on physical
activity in bronchiectasis is limited, and this is the first study
to assess multiple activity monitors in bronchiectasis.
This study will help future research and clinical
practice in bronchiectasis by providing data on the use and
feasibility of physical activity measurement with
ActiGraph, pedometer and IPAQ.
Accurate measurement of physical activity is feasible
in BE and will be valuable for future trials of
therapeutic interventions. ActiGraph or pedometer could
be used to measure simple daily step counts in BE,
but ActiGraph was superior as it measured intensity
of physical activity and was a more precise measure
of time spent walking. The IPAQ does not appear to
represent an accurate measure of physical activity in
this population. The information reported in this
study will be valuable for future trials of physical
activity and sedentary behaviour patterns, and
interventions. Future research could explore the
application of a monitor like the ActiGraph, combined with
a new validated and relevant self-report physical
activity questionnaire in BE.
cpm: Counts per minute; IPAQ: International Physical Activity
Questionnaire; IQR: Interquartile range; MVPA: Moderate-vigorous physical
activity; MVPA10+: MVPA accumulated in ≥10-minute bouts; n/a: Not
available; PA: Physical activity; SD: Standard deviation
This study was funded by The Physiotherapy Research Foundation (PRF); the
Charitable Trust of the Chartered Society of Physiotherapy (PRF Award (11)
A02). Jason J Wilson was funded by the Department for Employment and
Learning as part of a PhD scholarship.
Availability of data and materials
Data relating to this study is from available from the Author on request.
All authors contributed to study conception and design. The draft
manuscript was prepared by BO’N, SMcD, JW, IB, AK, JB, MT and these
authors along with KH, DC edited and revised the manuscript. All authors are
accountable for all aspects of the work and for the integrity of the data and
the accuracy of the data analysis. JB had full access to all of the data in the
study. All authors read and approved the final manuscript.
Consent for publication
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Ethics approval and consent to participate
The study was approved by the NI Research Ethics Committees (Ethics
Approval REC Reference: 12/NI/0044) and research departments of all the
participating hospitals. Written informed consent was obtained from all of
study participants. The study was supported by the Northern Ireland Clinical
Research Network (NICRN) Respiratory Health.
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