Long COVIDREVEALNCT06933017
Feasibility of an Augmented Two-Day Step Test and Causal Modeling for Post-Exertional Symptom Exacerbation in Post Covid-19 Syndrome
A study testing Portable mask for respiratory gas analysis and Cardio-pulmonary exercise test in people with Long COVID, run by Universitair Ziekenhuis Brussel at 2 sites in Belgium.
Trial summary
This study aims to evaluate exercise capacity and identify causes of Post-Exertional Symptom Exacerbation (PESE) in individuals with Long COVID. The investigators will compare the effectiveness of the Two-Day 6-Minute Incremental Step Test (6MIST) and the Cardiopulmonary Exercise Test (CPET) in detecting PESE. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Long COVID
- What is being tested?
- Portable mask for respiratory gas analysis and Cardio-pulmonary exercise test
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 25 participants
- Where
- 2 sitesBelgium
- Study dates
- 20 Mar 2025to 3 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- ≥18 years old
- Long COVID patients following the World Health Organization (WHO) criteria: "the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation"
- Previously active as described in the WHO recommendations for physical activity (minimal 150 minutes/week of moderate intensity aerobic physical activity OR minimal 75 minutes of vigorous intensity activity/week OR an equivalent combination of moderate- and vigorous-intensity activity throughout the week)
- Patient suffers from PESE as defined by the DePaul Symptom Questionnaire PEM (Post-Exertional Malaise) subscale
- Able to understand and sign written informed consent in Dutch, French or English
Who cannot join
- Any pre-existing conditions or new medical diagnosis that can alternatively explain the current symptoms
- Being unable to perform a cycle ergometer test as decided upon by the medical study team members
- Suffering from Chronic Obstructive Pulmonary Disease (COPD) GOLD classification category 2,3 or 4 (by the Global Initiative for Chronic Obstructive Lung Disease)
- Allergies to medical adhesive bandages
- Skin conditions aggravated by sunlight including Porphyria
- Participation in other interventional trials
Show all 9Show fewer
- Mitochondrial diseases
- Pregnancy
- Lactation
Trial locations and contacts
2 sites in 1 country.
Belgium2 sites
Universitair Ziekenhuis Brussel
Brussels, Jette, 1090
Universitair Ziekenhuis Brussel
Jette, Brussels Capital, 1090
About this study
Official title: Feasibility Study of the Augmented Two-Day 6-Minute Incremental Step Test and Causal Exploration Through a Directed Acyclic Graph and Structural Equation Model for Post-Exertional Symptom Exacerbations in Long COVID Patients
This study aims to evaluate exercise capacity and identify causes of Post-Exertional Symptom Exacerbation (PESE) in individuals with Long COVID. The investigators will compare the effectiveness of the Two-Day 6-Minute Incremental Step Test (6MIST) and the Cardiopulmonary Exercise Test (CPET) in detecting PESE. Additionally, the investigators will assess metabolism, mitochondrial function, autonomic symptoms, psychological factors, and physical activity. Participants will complete both the Two-Day 6MIST and the Two-Day CPET, with a one-month gap between them. Each test is performed on two consecutive days to assess the delayed symptom response. The subjective symptoms of PESE will also be measured through questionnaires. To explore potential causes of PESE, the investigators will measure metabolism using indirect calorimetry, bioelectrical impedance analysis and food diaries, mitochondrial dysfunction with NIRS technology, autonomic symptoms using the COMPASS-31 questionnaire, psychological factors with questionnaires and physical activity levels using an activity tracker. This study will determine if the Two-Day Step Test (6MIST) is a feasible alternative to the two-day CPET for measuring PESE and will help uncover underlying mechanisms contributing to symptom exacerbation.
- Conditions
- Long COVID
- Being tested
- Portable mask for respiratory gas analysis, Cardio-pulmonary exercise test
- Keywords
- long covid, PEM, Post-Exertional Malaise, CPET, 6MIST, Fatigue
- Medical subject headings
- Post-Acute COVID-19 Syndrome, Fatigue
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Portable mask for respiratory gas analysisDevice
Also called SplendoHealth app
This is a portable mask, which is connected to the SplendoHealth app. The Polar sens 10 heartrate monitor and TrainRed NIRS device are also connected to this app. The three devices (mask, heartrate monitor and NIRS) are measuring respiratory gases, heart rate and muscle tissue oxygenation simultanuously and at the end of the 6 min step test, you get an individual cardiorespiratory fitness report.
Cardio-pulmonary exercise testDevice
Also called CPET
Golden standard for measuring PEM: the double cardio-pulmonary exercise test on a bike.
| Study group | Role | What they receive |
|---|---|---|
| Two day 6-Minute Incremental Step Test (6 MIST) | Experimental | The 6-Minute Incremental Step Test (6MIST) is an incremental pace stationary stepping test wherein the pace increases by 5 steps every 30 seconds using a metronome, lasting a maximum of 6 minutes. Clinical cardio-respiratory variables are simultaneously recorded. A portable metabolic analyzer, the Calibre Biometric Tracker, will be utilized to evaluate VO2 and VE (TV and RR). The Polar Sense of the Polar 10 heart rate monitor will measure HR on a continuous basis. The Train-Red Fyer NIRS Muscle Oxygen Sensor will be utilized to gather oxygenation data from muscle tissue. Receives: Device: Portable mask for respiratory gas analysis |
| Two day Cardio-Pulmonary Exercise Test (CPET) | Active comparator | Prior to the CPET, spirometry is executed to predict the Maximum Voluntary Ventilation (MVV) from the Forced Expiratory Volume in one second (FEV1).The test is performed on a bicycle. The protocol is customized for each patient to achieve a fatigue-limited exercise duration of 8 to12 minutes. The predicted peak wattage is calculated according to a formula and by taking into account the patient's clinical profile. Patients start at 0 watts per minute. The intensity is increased until exhaustion (incremental step protocol) or if the test needs to be stopped for safety reasons. Patients are connected to an electrocardiogram (ECG), oximeter and blood pressure cuff. A mouthpiece is used to collect information about gas exchange. Receives: Device: Cardio-pulmonary exercise test |
What is being measured
The primary outcome is the main question the study is designed to answer.
Difference in oxygen uptake at peak (VO2 peak) between day 1 and day 2 measured with the CPET compared to measured with the Calibre device
The goal is to show that the Calibre device is a feasible alternative to the CPET.
Measured: From day 1 and day 2 of experimental session 1 to day 1 and day 2 of experimental session 2, one month apart (±10 days)
Difference in Rate of Perceived Exertion (RPE) measured with the CPET compared to measured with the Calibre device
Rate of Perceived Exertion is measured with the Borg RPE Scale which is a subjective measurement instrument. The scores range from 6 to 20, in which 6 is equal to no exertion at all and 20 is maximal exertion.
Measured: RPE will be measured during two experimental sessions, each with two days, one month apart. On day 1, RPE is recorded 15 minutes (±15 min) before and after the test. On day 2, RPE is measured 24 hours (±120 min) after test 1 and before test 2.]
Resting Energy Expenditure (kcal/kg/day), measured through Indirect Calorimetry (IC)
Measuring Resting Energy Expenditure as part of the Directed Acyclic Graph (DAG).
Measured: Baseline (measured once, during the first study visit)
Total Energy Expenditure (TEE) in kcal/kg/day, measured through Indirect Calorimetry (IC)
Measuring Total Energy Expenditure as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Phase angle (degrees), measured through Bioelectrical Impedance Analysis (BIA)
Measuring Phase Angle as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Muscle mass (kg/m2), measured through Bioelectrical Impedance Analysis (BIA)
Measuring muscle mass as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Fat mass index (kg/m2), measured through Bioelectrical Impedance Analysis (BIA)
Measuring fat mass index as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Fat-free mass index (kg/m²), measured through Bioelectrical Impedance Analysis (BIA)
Measuring fat free mass index as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Fat to fat-free mass ratio, measured through bioelectrical impedance analysis (BIA)
Measuring fat-free mass ratio as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Hydration (%), measured through Bioelectrical Impedance Analysis (BIA)
Measuring hydration as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Ratio of calorie and protein intake to individual need, measured through food diaries
Adequacy of feeding: the ratio between intake of calories and proteins and the individual need.
Record of all food and drinks consumed over a 3-day period as part of the DAG.
Measured: Between day 1 of study visit and day 1 of experimental session
Mean daily intake of calories, fats, proteins, and carbohydrates, measured through food diaries
Mean daily intake: calories, fats, proteins, carbohydrates Record of all food and drinks consumed over a 3-day period.
Measured: Between day 1 of study visit and day 1 of experimental session
Oxygen availability as the partial pressure of oxygen (mitoPO2) (mmHg), measured through Near-infrared spectroscopy (NIRS)
Measuring oxygen availability as the partial pressure of oxygen as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Kinesiophobia with the Tampa Scale for Kinesiophobia (TSK)
The Tampa Scale for Kinesiophobia (TSK) consists of 17 statements, each scored from 1 to 4, with 1 being 'strongly disagree' and 4 being 'strongly agree.' Higher scores indicate greater kinesiophobia. Measuring kinesiophobia as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Ability to bounce back after stressful events with the Brief Resilience Scale (BRS) Questionnaire
The Brief Resilience Scale (BRS) consists of 6 statements, each scored from 1 to 4, with 1 being 'strongly disagree' and 4 being 'strongly agree.' Higher scores indicate greater resilience. Measuring resilience as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Coping style with the Ways of Coping (WAYS) Questionnaire
Sixty-six statements about a stressful situation that participants experienced in the past week, for which they need to give a score ranging from 0 to 3, with 0 being "does not apply" or "not used," and 3 being "used a great deal". Measuring coping style as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Autonomic symptoms, measured with the COMPASS-31 questionnaire
Measuring autonomic symptoms as part of the DAG.
Measured: Baseline (measured once during the first study visit)
Level of Physical Activity (PA) and sedentary behavior assessed by accelerometry (activity tracker)
Using an actigraph, with a frequenncy of 60 Hertz, that participants wear at their hip on their dominant side. Measuring physical activity as part of the DAG.
Measured: During 7 days before the first experimental session
Secondary outcomes (10)
Change from Day 1 to Day 2 in Oxygen Uptake at First Ventilatory Threshold (VO₂ in ml/min/kg) during experimental session 1 or 2 (CPET)
Measured: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Oxygen uptake at peak (VO2 in ml/min/kg) during experimental session 1 and 2 (CPET & 6MIST))
Measured: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST)
Change from Day 1 to Day 2 in Workload (Watts) at first ventilatory threshold during experimental session 1 or 2 (CPET)
Measured: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Workload (Watts) at peak during experimental session 1 or 2 (CPET)
Measured: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Heart Rate (bpm) peak during experimental sessions 1 and 2 (CPET & 6MIST))
Measured: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST)
Change from Day 1 to Day 2 in Ventilation (VE) (Tidal Volume (TV) and Respiration Rate (RR)) during experimental sessions 1 and 2 (CPET 1 6MIST)
Measured: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in VE/VO2 slope during experimental sessions 1 and 2 (CPET and 6 MIST)
Measured: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in VO2/HR slope (= O2 pulse) during experimental sessions 1 and 2 (CPET and 6 MIST)
Measured: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in Respiratory Exchange Ratio (RER) = VCO2/VO2 during experimental sessions 1 or 2 (CPET)
Measured: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Cardiorespiratory Optimal Point (COP) = VO2/VE during experimental session 1 or 2 (CPET)
Measured: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Apr 2025
- Study start20 Mar 2025
- Primary completion3 Jul 2025
- Study completion3 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Long COVIDStudies of the same condition, open and under way.
- More trials run by Universitair Ziekenhuis BrusselThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Device feasibility
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Feasibility study in a cross-over model. The investigators calculated 40% drop out because this protocol presents considerable challenges for participants to complete.
- Masking
- None (open label)
- Enrolment
- 25 participants (actual)
Sponsor and investigators
- Lead sponsor
- Universitair Ziekenhuis Brussel
- Sponsor type
- University, hospital or other
- Collaborators
- Vrije Universiteit Brussel
- Responsible party
- Sponsor
- Investigators
- Elisabeth De Waele, MD, PhD, Principal investigator, Universitair Ziekenhuis Brussel
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06933017
- Sponsor's protocol ID
- 2024-EDW-REVEAL
- Other IDs
- G075423N
- Acronym
- REVEAL
- Status last verified
- Feb 2025
- First submitted
- 3 Apr 2025
- Last updated
- 8 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Bomans S, Michotte N, El M'Rabet I, Jimenez Garcia B, Leemans L, Janssens P, Hanon S, De Waele E, Beckwee D. Agreement and reliability between the two-day 6-minute incremental step test and two-day cardiopulmonary exercise test in post COVID-19 condition for assessing post-exertional malaise: The REVEAL-study. PLoS One. 2026 Jul 14;21(7):e0353132. doi: 10.1371/journal.pone.0353132. eCollection 2026.
PubMed 42447127
Study at a glance
From the registry record, last updated by the sponsor on 8 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Feasibility Study of the Augmented Two-Day 6-Minute Incremental Step Test and Causal Exploration Through a Directed Acyclic Graph and Structural Equation Model for Post-Exertional Symptom Exacerbations in Long COVID Patients
- ClinicalTrials.gov ID
- NCT06933017
- Acronym / sponsor ID
- REVEAL / 2024-EDW-REVEAL
- Conditions
- Long COVID
- Keywords
- long covid, PEM, Post-Exertional Malaise, CPET, 6MIST, Fatigue
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 25 participants (actual)
- Lead sponsor
- Universitair Ziekenhuis BrusselUniversity, hospital or other
- Collaborators
- Vrije Universiteit Brussel
- Study start
- 20 Mar 2025 (actual)
- Primary completion
- 3 Jul 2025 (actual)
- Study completion
- 3 Jul 2025 (actual)
- First posted
- 17 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study aims to evaluate exercise capacity and identify causes of Post-Exertional Symptom Exacerbation (PESE) in individuals with Long COVID. The investigators will compare the effectiveness of the Two-Day 6-Minute Incremental Step Test (6MIST) and the Cardiopulmonary Exercise Test (CPET) in detecting PESE. Additionally, the investigators will assess metabolism, mitochondrial function, autonomic symptoms, psychological factors, and physical activity. Participants will complete both the Two-Day 6MIST and the Two-Day CPET, with a one-month gap between them. Each test is performed on two consecutive days to assess the delayed symptom response. The subjective symptoms of PESE will also be measured through questionnaires. To explore potential causes of PESE, the investigators will measure metabolism using indirect calorimetry, bioelectrical impedance analysis and food diaries, mitochondrial dysfunction with NIRS technology, autonomic symptoms using the COMPASS-31 questionnaire, psychological factors with questionnaires and physical activity levels using an activity tracker. This study will determine if the Two-Day Step Test (6MIST) is a feasible alternative to the two-day CPET for measuring PESE and will help uncover underlying mechanisms contributing to symptom exacerbation.
Study design
- Primary purpose
- Device feasibility
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Feasibility study in a cross-over model. The investigators calculated 40% drop out because this protocol presents considerable challenges for participants to complete.
| Arm | Type | Receives |
|---|---|---|
| Two day 6-Minute Incremental Step Test (6 MIST) | Experimental | Device: Portable mask for respiratory gas analysisThe 6-Minute Incremental Step Test (6MIST) is an incremental pace stationary stepping test wherein the pace increases by 5 steps every 30 seconds using a metronome, lasting a maximum of 6 minutes. Clinical cardio-respiratory variables are simultaneously recorded. A portable metabolic analyzer, the Calibre Biometric Tracker, will be utilized to evaluate VO2 and VE (TV and RR). The Polar Sense of the Polar 10 heart rate monitor will measure HR on a continuous basis. The Train-Red Fyer NIRS Muscle Oxygen Sensor will be utilized to gather oxygenation data from muscle tissue. |
| Two day Cardio-Pulmonary Exercise Test (CPET) | Active comparator | Device: Cardio-pulmonary exercise testPrior to the CPET, spirometry is executed to predict the Maximum Voluntary Ventilation (MVV) from the Forced Expiratory Volume in one second (FEV1).The test is performed on a bicycle. The protocol is customized for each patient to achieve a fatigue-limited exercise duration of 8 to12 minutes. The predicted peak wattage is calculated according to a formula and by taking into account the patient's clinical profile. Patients start at 0 watts per minute. The intensity is increased until exhaustion (incremental step protocol) or if the test needs to be stopped for safety reasons. Patients are connected to an electrocardiogram (ECG), oximeter and blood pressure cuff. A mouthpiece is used to collect information about gas exchange. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- ≥18 years old
- Long COVID patients following the World Health Organization (WHO) criteria: "the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation"
- Previously active as described in the WHO recommendations for physical activity (minimal 150 minutes/week of moderate intensity aerobic physical activity OR minimal 75 minutes of vigorous intensity activity/week OR an equivalent combination of moderate- and vigorous-intensity activity throughout the week)
- Patient suffers from PESE as defined by the DePaul Symptom Questionnaire PEM (Post-Exertional Malaise) subscale
- Able to understand and sign written informed consent in Dutch, French or English
Key exclusion criteria (9 listed)
- Any pre-existing conditions or new medical diagnosis that can alternatively explain the current symptoms
- Being unable to perform a cycle ergometer test as decided upon by the medical study team members
- Suffering from Chronic Obstructive Pulmonary Disease (COPD) GOLD classification category 2,3 or 4 (by the Global Initiative for Chronic Obstructive Lung Disease)
- Allergies to medical adhesive bandages
- Skin conditions aggravated by sunlight including Porphyria
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Portable mask for respiratory gas analysisAlso: SplendoHealth appThis is a portable mask, which is connected to the SplendoHealth app. The Polar sens 10 heartrate monitor and TrainRed NIRS device are also connected to this app. The three devices (mask, heartrate monitor and NIRS) are measuring respiratory gases, heart rate and muscle tissue oxygenation simultanuously and at the end of the 6 min step test, you get an individual cardiorespiratory fitness report. | Device | Two day 6-Minute Incremental Step Test (6 MIST) |
| Cardio-pulmonary exercise testAlso: CPETGolden standard for measuring PEM: the double cardio-pulmonary exercise test on a bike. | Device | Two day Cardio-Pulmonary Exercise Test (CPET) |
Primary outcome
Difference in oxygen uptake at peak (VO2 peak) between day 1 and day 2 measured with the CPET compared to measured with the Calibre device
Time frame: From day 1 and day 2 of experimental session 1 to day 1 and day 2 of experimental session 2, one month apart (±10 days)
The goal is to show that the Calibre device is a feasible alternative to the CPET.
Difference in Rate of Perceived Exertion (RPE) measured with the CPET compared to measured with the Calibre device
Time frame: RPE will be measured during two experimental sessions, each with two days, one month apart. On day 1, RPE is recorded 15 minutes (±15 min) before and after the test. On day 2, RPE is measured 24 hours (±120 min) after test 1 and before test 2.]
Rate of Perceived Exertion is measured with the Borg RPE Scale which is a subjective measurement instrument. The scores range from 6 to 20, in which 6 is equal to no exertion at all and 20 is maximal exertion.
Resting Energy Expenditure (kcal/kg/day), measured through Indirect Calorimetry (IC)
Time frame: Baseline (measured once, during the first study visit)
Measuring Resting Energy Expenditure as part of the Directed Acyclic Graph (DAG).
Total Energy Expenditure (TEE) in kcal/kg/day, measured through Indirect Calorimetry (IC)
Time frame: Baseline (measured once during the first study visit)
Measuring Total Energy Expenditure as part of the DAG.
Phase angle (degrees), measured through Bioelectrical Impedance Analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring Phase Angle as part of the DAG.
Muscle mass (kg/m2), measured through Bioelectrical Impedance Analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring muscle mass as part of the DAG.
Fat mass index (kg/m2), measured through Bioelectrical Impedance Analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring fat mass index as part of the DAG.
Fat-free mass index (kg/m²), measured through Bioelectrical Impedance Analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring fat free mass index as part of the DAG.
Fat to fat-free mass ratio, measured through bioelectrical impedance analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring fat-free mass ratio as part of the DAG.
Hydration (%), measured through Bioelectrical Impedance Analysis (BIA)
Time frame: Baseline (measured once during the first study visit)
Measuring hydration as part of the DAG.
Ratio of calorie and protein intake to individual need, measured through food diaries
Time frame: Between day 1 of study visit and day 1 of experimental session
Adequacy of feeding: the ratio between intake of calories and proteins and the individual need. Record of all food and drinks consumed over a 3-day period as part of the DAG.
Mean daily intake of calories, fats, proteins, and carbohydrates, measured through food diaries
Time frame: Between day 1 of study visit and day 1 of experimental session
Mean daily intake: calories, fats, proteins, carbohydrates Record of all food and drinks consumed over a 3-day period.
Oxygen availability as the partial pressure of oxygen (mitoPO2) (mmHg), measured through Near-infrared spectroscopy (NIRS)
Time frame: Baseline (measured once during the first study visit)
Measuring oxygen availability as the partial pressure of oxygen as part of the DAG.
Kinesiophobia with the Tampa Scale for Kinesiophobia (TSK)
Time frame: Baseline (measured once during the first study visit)
The Tampa Scale for Kinesiophobia (TSK) consists of 17 statements, each scored from 1 to 4, with 1 being 'strongly disagree' and 4 being 'strongly agree.' Higher scores indicate greater kinesiophobia. Measuring kinesiophobia as part of the DAG.
Ability to bounce back after stressful events with the Brief Resilience Scale (BRS) Questionnaire
Time frame: Baseline (measured once during the first study visit)
The Brief Resilience Scale (BRS) consists of 6 statements, each scored from 1 to 4, with 1 being 'strongly disagree' and 4 being 'strongly agree.' Higher scores indicate greater resilience. Measuring resilience as part of the DAG.
Coping style with the Ways of Coping (WAYS) Questionnaire
Time frame: Baseline (measured once during the first study visit)
Sixty-six statements about a stressful situation that participants experienced in the past week, for which they need to give a score ranging from 0 to 3, with 0 being "does not apply" or "not used," and 3 being "used a great deal". Measuring coping style as part of the DAG.
Autonomic symptoms, measured with the COMPASS-31 questionnaire
Time frame: Baseline (measured once during the first study visit)
Measuring autonomic symptoms as part of the DAG.
Level of Physical Activity (PA) and sedentary behavior assessed by accelerometry (activity tracker)
Time frame: During 7 days before the first experimental session
Using an actigraph, with a frequenncy of 60 Hertz, that participants wear at their hip on their dominant side. Measuring physical activity as part of the DAG.
10 secondary outcomes
Change from Day 1 to Day 2 in Oxygen Uptake at First Ventilatory Threshold (VO₂ in ml/min/kg) during experimental session 1 or 2 (CPET)
Time frame: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Oxygen uptake at peak (VO2 in ml/min/kg) during experimental session 1 and 2 (CPET & 6MIST))
Time frame: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST)
Change from Day 1 to Day 2 in Workload (Watts) at first ventilatory threshold during experimental session 1 or 2 (CPET)
Time frame: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Workload (Watts) at peak during experimental session 1 or 2 (CPET)
Time frame: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Heart Rate (bpm) peak during experimental sessions 1 and 2 (CPET & 6MIST))
Time frame: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST)
Change from Day 1 to Day 2 in Ventilation (VE) (Tidal Volume (TV) and Respiration Rate (RR)) during experimental sessions 1 and 2 (CPET 1 6MIST)
Time frame: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in VE/VO2 slope during experimental sessions 1 and 2 (CPET and 6 MIST)
Time frame: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in VO2/HR slope (= O2 pulse) during experimental sessions 1 and 2 (CPET and 6 MIST)
Time frame: From Day 1 to Day 2 during experimental sessions 1 and 2 (CPET & 6MIST
Change from Day 1 to Day 2 in Respiratory Exchange Ratio (RER) = VCO2/VO2 during experimental sessions 1 or 2 (CPET)
Time frame: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Change from Day 1 to Day 2 in Cardiorespiratory Optimal Point (COP) = VO2/VE during experimental session 1 or 2 (CPET)
Time frame: From Day 1 to Day 2 during experimental session 1 or 2 (CPET)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Jul 2025.
- Derived from this study: PubMed 42447127Bomans S, Michotte N, El M'Rabet I, Jimenez Garcia B, Leemans L, Janssens P, Hanon S, De Waele E, Beckwee D. Agreement and reliability between the two-day 6-minute incremental step test and two-day cardiopulmonary exercise test in post COVID-19 condition for assessing post-exertional malaise: The REVEAL-study. PLoS One. 2026 Jul 14;21(7):e0353132. doi: 10.1371/journal.pone.0353132. eCollection 2026.
- Individual participant dataSharing planned: No
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Post-acute COVID-19 Syndrome
Enrolling by invitationPhase 2
Immunotherapy for Neurological Post-Acute Sequelae of SARS-CoV-2
Systemic Inflammation, Neuroinflammation
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Elisabeth De Waele, MD, PhD principal investigator
Universitair Ziekenhuis Brussel
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Portable mask for respiratory gas analysis and Cardio-pulmonary exercise test in people with Long COVID, run by Universitair Ziekenhuis Brussel at 2 sites in Belgium.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 8 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Belgium. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Difference in oxygen uptake at peak (VO2 peak) between day 1 and day 2 measured with the CPET compared to measured with the Calibre device (time frame: From day 1 and day 2 of experimental session 1 to day 1 and day 2 of experimental session 2, one month apart (±10 days)). The study lists 18 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06933017, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Jul 2025.