COPDCaRe-BFRNCT05163600
The Acute Cardiorespiratory Response to Blood-flow Restricted Versus Traditional Exercise Training Regimens (CaRe BFR)
A study testing BFR-CYC 50% peak / 50% AOP (exhaustive), BFR-CYC 3x2min and BFR Resistance 80% LOP in people with COPD, run by University of Zurich at 1 site in Switzerland.
Trial summary
The investigators hypothesize that BFR exercise regimens result in a different acute cardiorespiratory response pattern compared to traditional exercise regimens. Furthermore, the investigators hypothesize that these patterns differ between healthy participants and participants with COPD. Read more about this study
- Who is it for?
- Ages 18 to 90 yearsHealthy volunteers can take part
- Conditions the study is for
- COPD
- What is being tested?
- BFR-CYC 50% peak / 50% AOP (exhaustive), BFR-CYC 3x2min and BFR Resistance 80% LOP
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteSwitzerland
- Study dates
- 20 May 2022to 31 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 to 90 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Age ≥ 18 years
- Clinically healthy
- Age ≥ 18 years
- Diagnosed COPD according to GOLD-guidelines12
Who cannot join
- Physical or intellectual impairment precluding informed consent or protocol adherence
- Non-German speaking (precluding informed consent)
- Pain during exercise of any origin
- Pregnancy
- History of thromboembolic event in the lower extremity
- Resting systolic blood pressure <100 mmHg
Show all 14Show fewer
- Inclusion and exclusion for the COPD participants are defined by the following criteria.
- Physical or intellectual impairment precluding informed consent or protocol adherence
- Non-German speaking (precluding informed consent)
- Acute or recent (within the last 6 weeks) exacerbation of COPD
- Pain during exercise of any origin
- Pregnancy
- History of thromboembolic event in the lower extremity
- Resting systolic blood pressure <100 mmHg
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site, 1 recruiting
- Recruiting
University Hospital Zürich
Zurich, Canton of Zurich, 8091
Manuel Kuhn, MSc, 0432532681, manuel.kuhn@usz.ch
Alexandra Arvaji, 0432530131, alexandra.arvaji@usz.ch
About this study
Official title: The Acute Cardiorespiratory Response to Blood-flow Restricted Versus Traditional Exercise Training Regimens (CaRe BFR):4 Randomized Crossover Studies
The investigators hypothesize that BFR exercise regimens result in a different acute cardiorespiratory response pattern compared to traditional exercise regimens. Furthermore, the investigators hypothesize that these patterns differ between healthy participants and participants with COPD.
Regarding secondary objective, the investigators hypothesize that BFR results in lower blood pressure responses compared to traditional exercise training in both healthy and COPD participants.
Read the detailed description
Detailed Description
This study investigates the acute physiological and perceptual responses to blood flow restriction (BFR) exercise compared with conventional endurance and resistance exercise in both patients with chronic obstructive pulmonary disease (COPD) and healthy individuals. The study consists of multiple experimental arms using randomized crossover designs to enable within-subject comparisons across exercise modalities and conditions.
Endurance Exercise - COPD Participants (Exhaustive Protocol)
Patients with COPD will complete three cycling exercise conditions in a randomized, crossover design:
Blood Flow Restriction Cycling (BFR-CYC)
Continuous Cycling (CONT-CYC)
Interval Cycling (INT-CYC)
All sessions will be performed on a cycle ergometer under standardized laboratory conditions, including a warm-up followed by the respective protocol. Exercise will be performed to symptom limitation (volitional exhaustion) unless predefined safety criteria are reached.
BFR-CYC: Continuous cycling at 50% peak work rate (PWR) with bilateral thigh cuffs inflated to 50% limb occlusion pressure (LOP). A maximum duration of 30 minutes is applied as a safety limit.
CONT-CYC: Continuous cycling at 65% PWR until symptom limitation.
INT-CYC: Interval cycling with repeated bouts at 80% PWR, interspersed with recovery periods at 50% PWR, until symptom limitation.
During all sessions, cardiorespiratory parameters (ventilation, oxygen uptake, carbon dioxide production), muscle oxygenation (NIRS), blood lactate, hemodynamic responses, and perceptual responses (dyspnea, perceived exertion) will be continuously measured.
Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol)
Both COPD patients and healthy participants will complete two endurance exercise conditions in a randomized, crossover design:
Blood Flow Restriction Cycling (BFR-CYC)
Non-BFR Control Cycling
All sessions will be conducted under standardized laboratory conditions on a cycle ergometer. Exercise will follow a fixed-duration protocol and will not be performed to volitional exhaustion, unless predefined safety criteria require early termination.
BFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals.
Control: Time- and structure-matched protocol (3 × 2 minutes) without blood flow restriction at 65% PWR, with identical recovery periods.
During all sessions, cardiorespiratory, hemodynamic, and perceptual responses (dyspnea, perceived exertion) will be continuously measured.
Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol)
Both COPD patients and healthy participants will complete two resistance exercise conditions in a randomized, crossover design:
Blood Flow Restriction Resistance Exercise (BFR-RE)
Non-BFR Control Resistance Exercise
All sessions will be performed on a leg press device under standardized laboratory conditions. Exercise will follow a fixed set and repetition scheme and will not be performed to volitional exhaustion, unless predefined safety criteria require early termination.
BFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions).
Control: Bilateral leg press at 40% 1RM, 3 sets of 15 repetitions, without blood flow restriction.
During all sessions, cardiorespiratory, hemodynamic, and perceptual responses will be continuously measured.
Resistance Exercise - Healthy Participants (LOP Comparison Arm)
Healthy participants will complete two BFR resistance exercise conditions in a randomized, crossover design:
BFR at 40% LOP
BFR at 80% LOP
All sessions will be conducted on a leg press device under standardized laboratory conditions. Pneumatic cuffs will be applied to the proximal thigh of the right leg.
Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination.
Neuromuscular function will be assessed using maximal voluntary contraction (MVC) of the knee extensors measured before and immediately after exercise. Voluntary activation will be evaluated using the twitch interpolation technique with supramaximal electrical stimulation.
- Conditions
- COPD
- Being tested
- BFR-CYC 50% peak / 50% AOP (exhaustive), BFR-CYC 3x2min, BFR Resistance 80% LOP, BFR REsistance 48% vs. 80% LOP
- Medical subject headings
- Pulmonary Disease, Chronic Obstructive
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BFR-CYC 50% peak / 50% AOP (exhaustive)Other
BFR-CYC: Continuous cycling at 50% peak work rate (PWR) with bilateral thigh cuffs inflated to 50% limb occlusion pressure (LOP). A maximum duration of 30 minutes is applied as a safety limit.
BFR-CYC 3x2minOther
BFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals.
BFR Resistance 80% LOPOther
BFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions).
BFR REsistance 48% vs. 80% LOPOther
- BFR at 40% LOP
- BFR at 80% LOP All sessions will be conducted on a leg press device under standardized laboratory conditions. Pneumatic cuffs will be applied to the proximal thigh of the right leg.
Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination.
| Study group | Role | What they receive |
|---|---|---|
| Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol) | Experimental | Both COPD patients and healthy participants will complete two endurance exercise conditions in a randomized, crossover design:
* Blood Flow Restriction Cycling (BFR-CYC)
* Non-BFR Control Cycling
BFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals.
Control: Time- and structure-matched protocol (3 × 2 minutes) without blood flow restriction at 65% PWR, with identical recovery periods. Receives: Other: BFR-CYC 3x2min |
| Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol) | Experimental | Both COPD patients and healthy participants will complete two resistance exercise conditions in a randomized, crossover design:
* Blood Flow Restriction Resistance Exercise (BFR-RE)
* Non-BFR Control Resistance Exercise BFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions).
Control: Bilateral leg press at 40% 1RM, 3 sets of 15 repetitions, without blood flow restriction. Receives: Other: BFR Resistance 80% LOP |
| Endurance Exercise - COPD Participants (Exhaustive Protocol) | Experimental | Patients with COPD will complete three cycling exercise conditions in a randomized, crossover design:
* Blood Flow Restriction Cycling (BFR-CYC)
* Continuous Cycling (CONT-CYC)
* Interval Cycling (INT-CYC) Receives: Other: BFR-CYC 50% peak / 50% AOP (exhaustive) |
| Resistance Exercise - Healthy Participants (LOP Comparison Arm) | Experimental | Healthy participants will complete two BFR resistance exercise conditions in a randomized, crossover design:
* BFR at 40% LOP
* BFR at 80% LOP Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination. Receives: Other: BFR REsistance 48% vs. 80% LOP |
What is being measured
The primary outcome is the main question the study is designed to answer.
Endurance Exercise:(Fixed-Duration Protocol):
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Within-subject difference change in Maximal Voluntary Contraction (MVC)
Maximal voluntary contraction (MVC) of the knee extensors will be assessed before and immediately after unilateral leg press exercise performed with blood flow restriction at 40% and 80% limb occlusion pressure (LOP). MVC will be measured using an isometric setup, and voluntary activation will be evaluated using the twitch interpolation technique with supramaximal electrical stimulation. The primary outcome is the change in MVC from pre- to post-exercise, reflecting exercise-induced neuromuscular fatigue.
Measured: Pre-exercise and immediately post-exercise (within minutes after completion of the exercise protocol)
Endurance Exercise - COPD Participants (Exhaustive Protocol): Within-subject difference in maximal minute ventilation (VE) between BFR and traditional exercise regimens
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand and response.
Measured: Continuously during exercise, at end of exercise (peak value), and within 4 minutes post-exercise
Resistance Exercise:(Healthy and COPD): Ventilatory Response (Ventilation, VE)
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Secondary outcomes (11)
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Muscle Oxygenation (NIRS)
Muscle oxygenation of the knee extensors will be continuously assessed using near-infrared spectroscopy (NIRS) during unilateral leg press exercise performed with blood flow restriction at 40% and 80% limb occlusion pressure (LOP). Parameters such as tissue oxygen saturation will be analyzed to evaluate local muscular oxygenation responses.
Measured: Continuously during exercise and immediately post-exercise
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Perceived Exertion / Dyspnea (Borg Scale)
Perceived exertion will be assessed using the Borg rating of perceived exertion (RPE) scale during cycling exercise.
Perceived breathlessness will be assessed using the Borg dyspnea scale during exercise.
Measured: At baseline (pre-exercise), after each set, immediately post-exercise, and at 2 and 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Cardiorespiratory Response (Vo2 , VCO2)
Oxygen uptake (VO₂) will be continuously measured during cycling exercise performed under three conditions (BFR-CYC, CONT-CYC, INT-CYC) to symptom limitation. The primary outcome will be the peak VO₂ achieved at end of exercise, reflecting maximal cardiorespiratory response.
Carbon dioxide production (VCO₂) will be continuously measured during exercise to assess metabolic and ventilatory responses.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol):NIRS
Muscle oxygenation will be assessed using near-infrared spectroscopy (NIRS) during cycling exercise to evaluate local muscular oxygenation under BFR and non-BFR conditions.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Blood Lactate Concentration
Capillary blood lactate concentration will be measured to assess metabolic stress induced by the different exercise conditions.
Measured: At baseline (pre-exercise) at peak and 3 min wpost-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Perceived Exertion and Dyspnea (Borg Scale)
Perceived exertion will be assessed using the Borg rating of perceived exertion (RPE) scale during cycling exercise.
Perceived breathlessness will be assessed using the Borg dyspnea scale during exercise.
Measured: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Exercise Tolerance (Time to Exhaustion)
Exercise tolerance will be defined as the time from the start of exercise to symptom limitation (volitional exhaustion).
Measured: During exercise (recorded at end of exercise)
Endurance Exercise:(Fixed-Duration Protocol): Cardiorespiratory Response (Vo2 , VCO2)
Carbon dioxide production (VCO₂) will be continuously measured during exercise to assess metabolic and ventilatory responses Oxygen uptake (VO₂) will be continuously measured during cycling exercise performed under two conditions. The primary outcome will be the peak VO₂ achieved at end of exercise, reflecting maximal cardiorespiratory response.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise:(Fixed-Duration Protocol): Borg Scale (Dyspnea/Perceived Exertion)
Perceived exertion will be assessed using the Borg rating of perceived exertion (RPE) scale during cycling exercise.
Perceived breathlessness will be assessed using the Borg dyspnea scale during exercise.
Measured: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Resistance Exercise:(Healthy and COPD): Cardiorespiratory Response
Oxygen uptake (VO₂) will be continuously measured during cycling exercise performed under two conditions.
Carbon dioxide production (VCO₂) will be continuously measured during exercise to assess metabolic and ventilatory responses.
Measured: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Resistance Exercise:(Healthy and COPD): Dyspnea (Borg Scale/ Perceived Exertion )
Perceived exertion will be assessed using the Borg rating of perceived exertion (RPE) scale during cycling exercise.
Perceived breathlessness will be assessed using the Borg dyspnea scale during exercise.
Measured: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Dec 2021
- Study start20 May 2022
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for COPDStudies of the same condition, open and under way.
- More trials run by University of ZurichThe 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- monocenter / multicenter with a new study arm
- Masking
- None (open label)
- Enrolment
- 24 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Zurich
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Christian Clarenbach, University of Zurich
- Investigators
- Christian Clarenbach, Dr. med, Principal investigator, University of Zurich
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05163600
- Sponsor's protocol ID
- 2021-02038
- Acronym
- CaRe-BFR
- Status last verified
- Jul 2026
- First submitted
- 3 Dec 2021
- Last updated
- 7 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Kuhn M, Clarenbach CF, Klay A, Kohler M, Baur DM, Senn O, Radtke T, Haile SR, Mayer LC, Sievi NA, Kohlbrenner D. Acute cardiorespiratory responses to low-load blood-flow restriction vs high-load resistance exercise in COPD: a randomised crossover trial. Thorax. 2026 Aug 26:thorax-2026-225047. doi: 10.1136/thorax-2026-225047. Online ahead of print.
PubMed 42648900Kuhn M, Clarenbach CF, Klay A, Kohler M, Mayer LC, Luchinger M, Andrist B, Radtke T, Haile SR, Sievi NA, Kohlbrenner D. Exploring immediate cardiorespiratory responses: low-intensity blood flow restricted cycling vs. moderate-intensity traditional exercise in a randomized crossover trial. BMC Sports Sci Med Rehabil. 2024 Aug 15;16(1):172. doi: 10.1186/s13102-024-00951-0.
PubMed 39148127
Study at a glance
From the registry record, last updated by the sponsor on 7 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Acute Cardiorespiratory Response to Blood-flow Restricted Versus Traditional Exercise Training Regimens (CaRe BFR):4 Randomized Crossover Studies
- ClinicalTrials.gov ID
- NCT05163600
- Acronym / sponsor ID
- CaRe-BFR / 2021-02038
- Conditions
- COPD
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 24 participants (estimated)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Study start
- 20 May 2022 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 20 Dec 2021 (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.
The investigators hypothesize that BFR exercise regimens result in a different acute cardiorespiratory response pattern compared to traditional exercise regimens. Furthermore, the investigators hypothesize that these patterns differ between healthy participants and participants with COPD.
Regarding secondary objective, the investigators hypothesize that BFR results in lower blood pressure responses compared to traditional exercise training in both healthy and COPD participants.
Detailed description
Detailed Description
This study investigates the acute physiological and perceptual responses to blood flow restriction (BFR) exercise compared with conventional endurance and resistance exercise in both patients with chronic obstructive pulmonary disease (COPD) and healthy individuals. The study consists of multiple experimental arms using randomized crossover designs to enable within-subject comparisons across exercise modalities and conditions.
Endurance Exercise - COPD Participants (Exhaustive Protocol)
Patients with COPD will complete three cycling exercise conditions in a randomized, crossover design:
Blood Flow Restriction Cycling (BFR-CYC)
Continuous Cycling (CONT-CYC)
Interval Cycling (INT-CYC)
All sessions will be performed on a cycle ergometer under standardized laboratory conditions, including a warm-up followed by the respective protocol. Exercise will be performed to symptom limitation (volitional exhaustion) unless predefined safety criteria are reached.
BFR-CYC: Continuous cycling at 50% peak work rate (PWR) with bilateral thigh cuffs inflated to 50% limb occlusion pressure (LOP). A maximum duration of 30 minutes is applied as a safety limit.
CONT-CYC: Continuous cycling at 65% PWR until symptom limitation.
INT-CYC: Interval cycling with repeated bouts at 80% PWR, interspersed with recovery periods at 50% PWR, until symptom limitation.
During all sessions, cardiorespiratory parameters (ventilation, oxygen uptake, carbon dioxide production), muscle oxygenation (NIRS), blood lactate, hemodynamic responses, and perceptual responses (dyspnea, perceived exertion) will be continuously measured.
Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol)
Both COPD patients and healthy participants will complete two endurance exercise conditions in a randomized, crossover design:
Blood Flow Restriction Cycling (BFR-CYC)
Non-BFR Control Cycling
All sessions will be conducted under standardized laboratory conditions on a cycle ergometer. Exercise will follow a fixed-duration protocol and will not be performed to volitional exhaustion, unless predefined safety criteria require early termination.
BFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals.
Control: Time- and structure-matched protocol (3 × 2 minutes) without blood flow restriction at 65% PWR, with identical recovery periods.
During all sessions, cardiorespiratory, hemodynamic, and perceptual responses (dyspnea, perceived exertion) will be continuously measured.
Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol)
Both COPD patients and healthy participants will complete two resistance exercise conditions in a randomized, crossover design:
Blood Flow Restriction Resistance Exercise (BFR-RE)
Non-BFR Control Resistance Exercise
All sessions will be performed on a leg press device under standardized laboratory conditions. Exercise will follow a fixed set and repetition scheme and will not be performed to volitional exhaustion, unless predefined safety criteria require early termination.
BFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions).
Control: Bilateral leg press at 40% 1RM, 3 sets of 15 repetitions, without blood flow restriction.
During all sessions, cardiorespiratory, hemodynamic, and perceptual responses will be continuously measured.
Resistance Exercise - Healthy Participants (LOP Comparison Arm)
Healthy participants will complete two BFR resistance exercise conditions in a randomized, crossover design:
BFR at 40% LOP
BFR at 80% LOP
All sessions will be conducted on a leg press device under standardized laboratory conditions. Pneumatic cuffs will be applied to the proximal thigh of the right leg.
Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination.
Neuromuscular function will be assessed using maximal voluntary contraction (MVC) of the knee extensors measured before and immediately after exercise. Voluntary activation will be evaluated using the twitch interpolation technique with supramaximal electrical stimulation.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 4
- Model description
- monocenter / multicenter with a new study arm
| Arm | Type | Receives |
|---|---|---|
| Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol) | Experimental | Other: BFR-CYC 3x2minBoth COPD patients and healthy participants will complete two endurance exercise conditions in a randomized, crossover design: * Blood Flow Restriction Cycling (BFR-CYC) * Non-BFR Control Cycling BFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals. Control: Time- and structure-matched protocol (3 × 2 minutes) without blood flow restriction at 65% PWR, with identical recovery periods. |
| Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol) | Experimental | Other: BFR Resistance 80% LOPBoth COPD patients and healthy participants will complete two resistance exercise conditions in a randomized, crossover design: * Blood Flow Restriction Resistance Exercise (BFR-RE) * Non-BFR Control Resistance Exercise BFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions). Control: Bilateral leg press at 40% 1RM, 3 sets of 15 repetitions, without blood flow restriction. |
| Endurance Exercise - COPD Participants (Exhaustive Protocol) | Experimental | Other: BFR-CYC 50% peak / 50% AOP (exhaustive)Patients with COPD will complete three cycling exercise conditions in a randomized, crossover design: * Blood Flow Restriction Cycling (BFR-CYC) * Continuous Cycling (CONT-CYC) * Interval Cycling (INT-CYC) |
| Resistance Exercise - Healthy Participants (LOP Comparison Arm) | Experimental | Other: BFR REsistance 48% vs. 80% LOPHealthy participants will complete two BFR resistance exercise conditions in a randomized, crossover design: * BFR at 40% LOP * BFR at 80% LOP Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination. |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Age ≥ 18 years
- Clinically healthy
- Age ≥ 18 years
- Diagnosed COPD according to GOLD-guidelines12
Key exclusion criteria (14 listed)
- Physical or intellectual impairment precluding informed consent or protocol adherence
- Non-German speaking (precluding informed consent)
- Pain during exercise of any origin
- Pregnancy
- History of thromboembolic event in the lower extremity
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 |
|---|---|---|
| BFR-CYC 50% peak / 50% AOP (exhaustive)BFR-CYC: Continuous cycling at 50% peak work rate (PWR) with bilateral thigh cuffs inflated to 50% limb occlusion pressure (LOP). A maximum duration of 30 minutes is applied as a safety limit. | Other | Endurance Exercise - COPD Participants (Exhaustive Protocol) |
| BFR-CYC 3x2minBFR-CYC: Three intervals of 2 minutes at 50% PWR, separated by 1-minute recovery periods, with bilateral thigh cuffs inflated to 50% LOP during exercise intervals. | Other | Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol) |
| BFR Resistance 80% LOPBFR-RE: Unilateral right-leg press at 40% of one-repetition maximum (1RM) with cuffs inflated to 80% LOP. Protocol: 4 sets (30-15-15-15 repetitions). | Other | Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol) |
| BFR REsistance 48% vs. 80% LOP* BFR at 40% LOP * BFR at 80% LOP All sessions will be conducted on a leg press device under standardized laboratory conditions. Pneumatic cuffs will be applied to the proximal thigh of the right leg. Participants will perform unilateral right-leg press exercise at 40% 1RM using a standardized protocol of 4 sets (30-15-15-15 repetitions) with fixed rest intervals. The protocol will be completed as prescribed (not to volitional exhaustion) unless predefined safety criteria require early termination. | Other | Resistance Exercise - Healthy Participants (LOP Comparison Arm) |
Primary outcome
Endurance Exercise:(Fixed-Duration Protocol):
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Within-subject difference change in Maximal Voluntary Contraction (MVC)
Time frame: Pre-exercise and immediately post-exercise (within minutes after completion of the exercise protocol)
Maximal voluntary contraction (MVC) of the knee extensors will be assessed before and immediately after unilateral leg press exercise performed with blood flow restriction at 40% and 80% limb occlusion pressure (LOP). MVC will be measured using an isometric setup, and voluntary activation will be evaluated using the twitch interpolation technique with supramaximal electrical stimulation. The primary outcome is the change in MVC from pre- to post-exercise, reflecting exercise-induced neuromuscular fatigue.
Endurance Exercise - COPD Participants (Exhaustive Protocol): Within-subject difference in maximal minute ventilation (VE) between BFR and traditional exercise regimens
Time frame: Continuously during exercise, at end of exercise (peak value), and within 4 minutes post-exercise
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand and response.
Resistance Exercise:(Healthy and COPD): Ventilatory Response (Ventilation, VE)
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.
11 secondary outcomes
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Muscle Oxygenation (NIRS)
Time frame: Continuously during exercise and immediately post-exercise
Resistance Exercise - Healthy Participants (LOP Comparison Arm): Perceived Exertion / Dyspnea (Borg Scale)
Time frame: At baseline (pre-exercise), after each set, immediately post-exercise, and at 2 and 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Cardiorespiratory Response (Vo2 , VCO2)
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol):NIRS
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Blood Lactate Concentration
Time frame: At baseline (pre-exercise) at peak and 3 min wpost-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Perceived Exertion and Dyspnea (Borg Scale)
Time frame: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Endurance Exercise - COPD Participants (Exhaustive Protocol): Exercise Tolerance (Time to Exhaustion)
Time frame: During exercise (recorded at end of exercise)
Endurance Exercise:(Fixed-Duration Protocol): Cardiorespiratory Response (Vo2 , VCO2)
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Endurance Exercise:(Fixed-Duration Protocol): Borg Scale (Dyspnea/Perceived Exertion)
Time frame: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Resistance Exercise:(Healthy and COPD): Cardiorespiratory Response
Time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise
Resistance Exercise:(Healthy and COPD): Dyspnea (Borg Scale/ Perceived Exertion )
Time frame: At baseline (pre-exercise), during exercise (at regular intervals), at end of exercise, and within 4 minutes post-exercise
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Jul 2026.
- Derived from this study: PubMed 42648900Kuhn M, Clarenbach CF, Klay A, Kohler M, Baur DM, Senn O, Radtke T, Haile SR, Mayer LC, Sievi NA, Kohlbrenner D. Acute cardiorespiratory responses to low-load blood-flow restriction vs high-load resistance exercise in COPD: a randomised crossover trial. Thorax. 2026 Aug 26:thorax-2026-225047. doi: 10.1136/thorax-2026-225047. Online ahead of print.
- Derived from this study: PubMed 39148127Kuhn M, Clarenbach CF, Klay A, Kohler M, Mayer LC, Luchinger M, Andrist B, Radtke T, Haile SR, Sievi NA, Kohlbrenner D. Exploring immediate cardiorespiratory responses: low-intensity blood flow restricted cycling vs. moderate-intensity traditional exercise in a randomized crossover trial. BMC Sports Sci Med Rehabil. 2024 Aug 15;16(1):172. doi: 10.1186/s13102-024-00951-0.
- Individual participant dataSharing planned: No
Related trials for COPD
Active, not recruiting
Symptoms and Functions in Patients With COPD and Chronic Bronchitis Switching From CIG to THS
COPD, Smoking
Not yet recruitingPhase 2/3
An Open-Label Extension Study to Evaluate Inhaled Treprostinil SMI in Participants With Pulmonary Hypertension Associated With Chronic Obstructive Pulmonary Disease (PH-COPD)
Pulmonary Hypertension Associated With Chronic Obstructive Pulmonary Disease
Not yet recruiting
The Aim of the Study is to Decipher the Alterations in Signalling Pathways of Skeletal Muscle Stem Cells (Satellite Cells (SCs)) in Individuals With COPD, as Well as to Examine the Effect of Exercise Training on SCs.
COPD (Chronic Obstructive Pulmonary Disease), Sarcopenia in Elderly
Not yet recruitingPhase 2
Study of Treprostinil Administered Via Soft Mist Inhaler (SMI) in Participants With Pulmonary Hypertension Associated With Chronic Obstructive Pulmonary Disease (PH-COPD)
Pulmonary Hypertension Associated With Chronic Obstructive Pulmonary Disease
Active, not recruitingPhase 1
A Study for GSK3862995B in Healthy Participants and Participants With Chronic Obstructive Pulmonary Disease
Pulmonary Disease, Chronic Obstructive
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.
Christian Clarenbach, Dr. med principal investigator
University of Zurich
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing BFR-CYC 50% peak / 50% AOP (exhaustive), BFR-CYC 3x2min and BFR Resistance 80% LOP in people with COPD, run by University of Zurich at 1 site in Switzerland.
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 4 inclusion and 14 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: looking for participants now, as of the sponsor's last update on 7 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Christan Clarenbach, Dr. med (044 255 22 21, Christian.clarenbach@usz.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Endurance Exercise:(Fixed-Duration Protocol): (time frame: Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise). The study lists 4 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 NCT05163600, which also lists 2 linked publications.
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 7 Jul 2026.