Effectiveness of a Remote 3-week Booster Intervention to Reduce Sedentary Time in Patients With Coronary Artey Disease: a Randomized Clinical Trial.
Phase: NA
Conditions: Coronary Artery Disease
Sponsor: Radboud University Medical Center

BOOSTSITLESS, study protocol  
Date: 28-02-2023 
 
 
 
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Study protocol 
BOOSTSITLESS 
 
Remote 3-week Booster Intervention to Reduce Sedentary Time in 
Patients With Coronary Artery Disease: A randomized controlled trial 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Radboudumc, Nijmegen, the Netherlands 
Trial registration number: NCT06038188 
Version: 1.0. Date: 28-02-2023 

BOOSTSITLESS, study protocol  
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Table of Contents 
 
1. 
Research Team ................................................................................................................. 3 
2. 
Trial Summary .................................................................................................................. 4 
3. 
Scientific background – Trial rationale ................................................................................. 4 
4. 
Objectives ........................................................................................................................ 6 
5. 
Trial design ...................................................................................................................... 6 
6. 
Disease condition and selection of patients ......................................................................... 8 
7. 
Screening and recruitment ................................................................................................. 8 
8. 
Outcome Measures ........................................................................................................... 8 
9. 
Sample calculations and statistical analysis .......................................................................... 9 
10. 
Treatments/Interventions .............................................................................................10 
11. 
Adherence, attendance and compliance .........................................................................10 
12. 
Safety and adverse events .............................................................................................11 
13. 
Ethics and legal issues ...................................................................................................11 
14. 
References ..................................................................................................................11 

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1. Research Team 
 
Principal Investigator 
Thijs M.H. Eijsvogels, PhD 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
Contact details: 
- 
Radboud university medical centre, Dept. of Medical BioSciences (route 928), P.O. Box 9101, 
6500 HB, Nijmegen, The Netherlands.  
- 
E-mail: Thijs.Eijsvogels@radboudumc.nl,   
- 
Telephone: (+31) (0)24 36 14273 
 
Trial coördinator: 
Sophie H. Kroesen, MSc 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
 
Research Team:  
Esmée A. Bakker, PhD 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
- 
Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health 
University Research Institute (iMUDS), University of Granada, Granada, Spain 
- 
Department of Primary and Community Care, Radboud university medical centre, Nijmegen, 
The Netherlands 
 
Bram M.A. van Bakel, MD, PhD 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
 
Marijn de Bruin, full professor 
- 
Department of IQ healthcare, Radboud university medical centre, Nijmegen, The Netherlands 
 
Martijn F. Pisters, PhD 
- 
Department of Rehabilitation, Physical Therapy Science and Sport, University Medical Centre 
Utrecht Brain Centre, Utrecht University, Utrecht, The Netherlands  
- 
Research Group Empowering Healthy Behaviour, Department of Health Innovations and 
Technology, Fontys University of Applied Sciences, Eindhoven, The Netherlands  
- 
Centre for Physical Therapy Research and Innovation in Primary Care, Julius Health Care 
Centres, Utrecht, the Netherlands 
 
Francisco B. Ortega, full professor 
- 
Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health 
University Research Institute (iMUDS), University of Granada, Granada, Spain 
- 
CIBEROBN Physiopathology of Obesity and Nutrition, Granada, Spain 
- 
Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland. 

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Maria T.E. Hopman, MD, full professor 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
Dick H.J. Thijssen, PhD, full professor 
- 
Department of Medical BioSciences, Radboud university medical centre, Nijmegen, The 
Netherlands 
- 
Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, 
Liverpool, United Kingdom 
 
2. Trial Summary 
Official Title: Remote 3-week Booster Intervention to Reduce Sedentary Time in Patients With 
Coronary Artery Disease: A randomized controlled trial 
 
Brief title: BOOSTSITLESS  
 
ClinicalTrials.gov ID: NCT06038188 
 
Study ID: NL72604.091.20 
 
Brief Summary: The BOOSTSITLESS is a randomized controlled trial designed to examine the effects of 
a 3-week remote Booster intervention on changes in sedentary time among cardiac rehabilitation 
graduates. 
 
Keywords: Cardiac rehabilitation; e-Health; prevention; sitting; physical activity; cardiovascular 
disease. 
 
Detailed summary:  
Introduction: Previous studies revealed that sedentary time (ST) can effectively be targeted in patients 
with coronary artery disease (CAD) participating in cardiac rehabilitation (CR). However, only transient 
effects were observed, as patients relapsed to a sedentary lifestyle in subsequent months. We 
examined the effectiveness of a 3-week remote Booster intervention on changes in ST among CR 
graduates. 
Methods: CAD patients previously completing CR with a ST reduction program (1.5-2.5 years ago) were 
included in this randomized controlled trial (1:1, stratified for gender). All participants received usual 
care, whereas Booster participants additionally received a 3-week remote behavioral change 
intervention consisting of education, goal-setting, motivational interviewing, and telemonitoring. The 
primary outcome was the change in accelerometer-derived ST from baseline to post-intervention and 
secondary outcomes included changes in ST and physical activity characteristics. A baseline 
constrained linear mixed-model was performed. 
Expected conclusions: We hypothesized that the Booster intervention would result in a greater 
replacement of ST for physical activity compared to control. The results of the study will have 
important clinical implications as it can show the potential of eHealth to improve activity behavior of 
patients beyond completion of traditional CR programs. 
 
3. Scientific background – Trial rationale 
Cardiovascular disease is the leading global cause of death and the prevalence of coronary artery 
disease (CAD) increased by 74.7% from 1990 to 2016.1 In developed countries survival rates following 
myocardial infarction (MI) improved over the past decades2, which has largely been due to the 

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development of reperfusion techniques and modern drug therapies3. Despite this progress, rates of 
recurrent MI or fatal CAD within 5 years after MI are high in both males (17%) and females (21%).1 
Therefore, the current focus has to be on further improvements of secondary prevention.  
 
The beneficial effects of physical activity (PA) in secondary prevention after MI are well known. A 
physically active lifestyle is related to a reduction of cardiovascular mortality and morbidity in patients 
with CAD4,5 and because of survival benefits and lower recurrence risk, referral to an exercise 
rehabilitation program is strongly recommended for cardiac patients.6 Importantly, emerging evidence 
from epidemiological studies reveal that, independent of engagement in PA, high levels of sedentary 
behaviour (SB; defined as any waking behaviour characterized by an energy expenditure ≤1.5 
metabolic equivalents (MET) while in a seated, reclined or lying posture7,8) are associated with 
increased risks for cardiovascular mortality and morbidity in the general population.9-11 Patients with 
cardiovascular disease show higher levels of SB compared to the general population12, and in these 
patients SB is associated with lower cardiorespiratory fitness.13 This suggests that SB may play an 
important role in the prognosis of patients with CAD. 
 
Cardiac rehabilitation (CR) is a comprehensive program in which supervised exercise training is the 
cornerstone, complemented with risk factor management and psychosocial support.14 The efficacy of 
CR in secondary prevention of CAD is well established.15 CR participation is therefore a class I 
recommendation in guidelines of European and American cardiovascular societies.16,17 Although 
current CR programs go beyond exercise training with a multidisciplinary approach, including 
psychosocial management, smoking cessation, nutrition counselling and management of blood 
pressure, lipid spectrum and weight, most programs do not specifically target SB.14 Yet, increasingly 
evidence is available that SB in patients with CAD remains high after following CR programs.13,18-20 
Reducing SB might have cumulative and clinically relevant effects on the secondary prevention of 
CAD21,22. Additionally, breaking up SB by taking active breaks may counteract the detrimental effects 
of prolonged SB regardless of reducing total SB or increasing time spent in moderate- to vigorous 
intensity physical activity (MVPA).23 Given these highly relevant benefits, reducing SB in patients with 
CAD is a very promising new area of focus among CR programs and probably more feasible and 
sustainable in this predominantly inactive population.24  
 
Many (e-Health) initiatives arose focussing on physical activity in CVD patients, but in general it sorted 
only into small-to-medium effects that are not sustained over time and the more effective 
interventions are complex and therefore difficult to implement in routine care.25-27 Intervention studies 
targeting SB in CVD patients are scarce. To address this gap, we developed an in-person delivered 
intervention integrated in routine care with an add-on e-health component to prompt and monitor 
behaviour change. This intervention was co-created together with both patients and health care 
professionals (HCPs) and adapted to fit with restrictions and opportunities in routine care. In this study 
we investigated the effect of the ‘Sitting Interruption Treatment as a personaLizEd Secondary 
prevention Strategy’ (SIT LESS) intervention on SB in patients with coronary artery disease directly after 
CR and after 6 months of follow-up. This study showed that enrichment of CR with a tailored sedentary 
behavior intervention induces greater reductions in ST compared to usual care28. However, these 
beneficial lifestyle adaptations were only temporary28 as sustainable PA habits after CR remain 
challenging29,30.  
 
E-Health programs could support patients to maintain beneficial PA levels following CR29. Moreover, 
short, remote Booster programs may already nudge CR graduates towards a more physically active 
lifestyle31. Such Booster programs should include continued support to allow self-monitoring of 
behavior, goal-setting and associated feedback29. However, the effect of a remote eHealth-based 
Booster program aiming to reducing ST in patients with CAD is currently unknown. Therefore, the 

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effects of SIT LESS Booster sessions on SB will be examined among patients who participated in the SIT 
LESS group ~2 years ago.  
 
4. Objectives 
The primary objective is to examine the effectiveness of a remote 3-week Booster behavior 
intervention compared to usual care on reducing ST.  
 
Secondary objectives are:  
a) To examine the effectiveness of a remote 3-week Booster behavior intervention compared to 
usual care on improving sedentary behavior defined as number of prolonged sedentary bouts 
and prevalence of a ST ≥9.5 h/day. 
b) To examine the effectiveness of a remote 3-week Booster behavior intervention compared to 
usual care on improving physical activity characteristics. 
 
5. Trial design 
A parallel-group randomized controlled trial will be conducted to determine the effectiveness of a 3-
week, fully-remote and personalized behavior change intervention (Booster intervention) with a 
primary focus on reducing and interrupting ST in patients with CAD. The Booster is a compressed 
version of the SIT LESS intervention, which has previously been described in detail32. Participants who 
received the original SIT LESS intervention during their CR program (1.5 to 2.5 years ago) and of which 
accelerometry-based ST and PA characteristics were derived will be approached for this study at the 
end of August 2023. After inclusion, baseline characteristics are gathered including the same 
assessment of ST and PA characteristics by an accelerometer send by mail (Figure 1). Following 
baseline measurements, participants are randomly assigned into the control or Booster group. The 
control groups received usual care, where the Booster group additionally receives the Booster 
intervention. Finally, the accelerometry measurement are repeated in both groups at the end of the 
Booster intervention (post-intervention). Our trial is approved by the Medical Ethics Committee of the 
Radboud university medical center (NL72604.091.20), is in accordance with the principles of the 
Declaration of Helsinki and all participants will give written informed consent.  
 
Randomization will occur after the completion of all baseline assessments using a computerized 
algorithm (Castor Electronic Data Capture 2021, Ciwit B.V., Amsterdam, The Netherlands).   

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Figure 1. SIT LESS (transparent) and BOOSTSITLESS randomized controlled trial flowchart.  
CR: Cardiac Rehabilitation; SIT LESS, Sedentary Behavior Intervention as a Personalized Secondary 
Prevention Strategy 

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6. Disease condition and selection of patients 
Eligible patients are defined on the inclusion and exclusion criteria. In general, patients with coronary 
artery disease who followed cardiac rehabilitation with a special sedentary reduction program (SIT 
LESS). Specific inclusion and exclusion criteria are:  
 
Inclusion Criteria: 
1. Participation in the SIT LESS intervention group of the original SIT LESS study. Inclusion criteria 
of the SIT LESS study were: 
a. Patients aged ≥ 18 years old  
b. Referred to CR because of stable CAD, an acute coronary syndrome, and/or after 
coronary revascularization. 
  
Exclusion Criteria: 
1. Unable to give informed consent 
2. Wheelchair-bounded / not physically able to stand or walk. 
3. Dutch Language barrier 
4. Coronary arterial bypass graft surgery expected within 8 weeks after inclusion 
5. New York Heart Association class III or IV heart failure 
6. Participation in another interventional study targeting sedentary behavior or physical activity 
 
 
7. Screening and recruitment 
No screening was needed as participants randomized to the intervention group during the original SIT 
LESS study were eligible for inclusion.  
 
Participants meeting the eligibility criteria will be recruited by email and telephone call. Recruitment 
starts at the end of August 2023 and may extend until November 2023 (~2 years after the pre-CR 
measurement of the SIT LESS study). Information necessary for the CONSORT flow diagram will be 
collected. For the enrollment phase, we will note the number of patients that were assessed for 
eligibility by the research team, the number of excluded patients (plus reason for exclusion), and the 
number of randomized participants. For the allocation, the number of participants allocated to the 
BOOSTSITLESS intervention, and the number of participants who received or did not receive the 
intervention (plus reasons) will be noted. For follow-up, the number of participants who were lost to 
follow-up and the number who discontinued the intervention (plus reasons) were counted. Finally, the 
number of participants that were included in the analyses using the intention-to-treat will be described 
together with the reasons for exclusion. 
 
8. Outcome Measures 
Primary outcome 
Change in daily ST (h/day; baseline and post-intervention).  
 
ST is objectively assessed using a validated accelerometer (ActivPAL3TMmicro, PAL Technologies Ltd., 
Glasgow, United Kingdom)3. The ActivPAL is a small device (25x45x5 mm), waterproof attached to the 
participant’s thigh using hypoallergenic tape. The ActivPAL combines a tri-axial accelerometer with an 
inclinometer which accurately distinguishes between sitting, standing and walking3. Participants are 
instructed to wear the ActivPAL 24 h/day for 8 consecutive days and to fill in a diary with sleep times 
and moment of attachment and detachment. Raw data is analyzed by a modified version of the script 
of Winkler et al.4. Total ST (Metabolic Equivalent of Task score (METs) ≤1.5 while awake in a sitting, 
lying or reclining posture)5  is expressed in h/day.  
 

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Secondary outcomes 
• 
Change in number of prolonged sedentary (bouts/day; baseline and post-intervention). 
Prolonged sedentary bouts are defined as an accumulation of ST (≥30 min) and based on 
ActivPAL data. 
• 
Prevalence of an average ST >9.5 h/day (number, (%); baseline and post-intervention). Daily 
ST will be dichotomized using 9.5 h/day as cut-off as it was previously shown that exceeding 
this upper limit of normal was associated with an increased risk of morbidity and mortality6. 
ActivPAL data will be used for this outcome. 
• 
Change in the prevalence of a sitting time ≥9.5 h/day. 
• 
Change in daily time spent in light-intensity physical activity (LIPA in h/day; baseline and post-
intervention). The ActivPAL data will be used and LIPA is categorized as physical activity with 
MET levels < 3.  
• 
Change in daily time spent in moderate-to-vigorous intensity physical activity (MVPA in h/day; 
baseline and post-intervention). The ActivPAL data will be used and MVPA is categorized as 
physical activity with MET levels ≥ 3.  
• 
Change in step count (steps/day; baseline and post-intervention). The ActivPAL data will be 
used for this outcome. 
 
9. Sample calculations and statistical analysis 
Sample size.  
As our study has an explorative character, no formal sample size calculation was performed prior to 
trial initialization. Before the original SIT LESS study, a sample size calculation was performed and 
described32. Based on that calculation, 106 patients were needed in the SIT LESS arm of the trial. 
Participants in this study arm will be eligible for participation in the BOOSTSITLESS. 
 
In the original SIT LESS study, we found an effect size Cohen D of 0.328 with an alpha of 0.05 and beta 
of 0.2 (power 0.8). The estimated sample size, based on previously mentioned parameters and 
repeated-measures ANOVA, needed for this study was 24 participants (12 in each study arm)(Figure 
2). 
 
Figure 2. Sample size calculation using G*power (version 3.1) 
 

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Statistical analyses.  
The treatment effects will be tested using baseline constrained mixed models (i.e. adjusting for 
baseline of the outcome studied) for the study outcomes using an intention-to-treat approach as 
primary analysis. A detailed Statistical Analysis Plan has been developed in a separate document that 
will be available.  
 
10. Treatments/Interventions 
Control group: The control group (as well as the Booster group) will be treated with usual care, which 
includes periodic medical revisions and medication control of the cardiologist. 
 
Booster group: 3-week duration. Participants will use a pocket-worn, commercially available, small 
(30x32x10 mm) and lightweight (20 g), activity tracker (Activ8sit, 2M Engineering, Valkenswaard, The 
Netherlands, Figure 3). The activity tracker consists of an inclinometer and a tri-axial accelerometer, 
which allows for recognizing prolonged periods of sedentary behavior and physical activity patterns. 
Upon recording prolonged, uninterrupted sitting (i.e. 30 minutes), vibrotactile feedback will be 
provided by the activity tracker to remind patients to replace sedentary behavior by low-intensity 
physical activity (e.g. standing or walking). Patients can review their sedentary behaviour and physical 
activity patterns in a web-based environment. 
 
A  
 
 
 
     B 
 
Figure 3: Activity tracker. For the SIT LESS intervention the Activ8sit (A) will be used. The activity tracker 
can easily be worn in the trouser pocket (B). 
 
During the first online Booster consult, the researcher and participant will reactivate knowledge on the 
detrimental health effects of SB, discuss patients’ personal goals and motivation, and collaboratively 
set action plans for reducing SB in the upcoming week (±30 minutes). Thereafter, the Booster group 
will be contacted on a weekly basis by phone to evaluate SB of the preceding week. The Booster 
sessions will be delivered completely remote, so all devices will be sent home to the participants by 
mail, and participants do not have to visit the hospital for this study. (Figure 1)   
 
11. Adherence, attendance and compliance 
For participants randomized to the Booster-arm, the adherence will be assessed by counting the 
number of valid wear days of the activity tracker (≥ 10 h/day), and by dividing the number of valid days 
by the total number of days of the intervention period x 100%. 
 
The adherence to the daily use of the activity tracker will be reported as the mean ± standard deviation 
(when normally distributed) or as median [interquartile range] (when not-normally distributed).  
 
All protocol deviations made to the protocol (e.g. change in pre-defined inclusion/exclusion criteria, 
baseline and post-intervention, data cleaning/processing) will be reported and described. 
 

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12. Safety and adverse events 
We assess the risks regarding this study as negligible. Nevertheless, the number and reasons of adverse 
events (e.g. falls, injuries, musculoskeletal problems, major cardiovascular disease events, and any 
other events potentially related to the implementation of the trial protocol) at each time point will be 
collected, reported, and described separately for each study arm. No formal statistical testing will be 
undertaken. 
 
13. Ethics and legal issues 
Our trial is approved by the Medical Ethics Committee of the Radboud university medical center 
(NL72604.091.20), is in accordance with the principles of the Declaration of Helsinki and all participants 
will give written informed consent.  
 
14. References 
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Version: 1 
 
Version number: 3.0, date 28-02-2023 
 
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