The Acute Cardiorespiratory Response to Blood-flow Restricted Versus Traditional Exercise Training Regimens (CaRe BFR)

NCT05163600 | Recruiting

• 1 other identifier: 2021-02038
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

COPD

Outcome Measures

Primary Outcomes (4)

• Endurance Exercise:(Fixed-Duration Protocol):

  Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.

  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.

  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.

  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.

  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)

  Continuously during exercise and immediately post-exercise

• Resistance Exercise - Healthy Participants (LOP Comparison Arm): Perceived Exertion / Dyspnea (Borg Scale)

  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)

  Continuously during exercise and at end of exercise, with recovery measurements obtained within 4 minutes post-exercise

• Endurance Exercise - COPD Participants (Exhaustive Protocol):NIRS

  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

  At baseline (pre-exercise) at peak and 3 min wpost-exercise

Study Arms (4)

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.

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.

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)

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.

Other: BFR REsistance 48% vs. 80% LOP

Interventions

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.

Endurance Exercise - COPD Participants (Exhaustive Protocol)

BFR-CYC 3x2min OTHER

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.

Endurance Exercise - COPD and Healthy Participants (Fixed-Duration Protocol)

BFR Resistance 80% LOP OTHER

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).

Resistance Exercise - COPD and Healthy Participants (BFR vs Control, Fixed Protocol)

BFR REsistance 48% vs. 80% LOP OTHER

* 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.

Resistance Exercise - Healthy Participants (LOP Comparison Arm)

Eligibility Criteria

• Age: 18 Years - 90 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age ≥ 18 years
• Clinically healthy

You may not qualify if:

• 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
• Age ≥ 18 years
• Diagnosed COPD according to GOLD-guidelines12
• 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

Sponsors & Collaborators

• University of Zurich: lead

Study Sites (1)

University Hospital Zürich

Zurich, Canton of Zurich, 8091, Switzerland

RECRUITING

Related Publications (1)

• Kuhn 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.

  PMID: 39148127 DERIVED

MeSH Terms

Conditions

Pulmonary Disease, Chronic Obstructive

Condition Hierarchy (Ancestors)

Lung Diseases, Obstructive; Lung Diseases; Respiratory Tract Diseases; Chronic Disease; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Study Officials

• Christian Clarenbach, Dr. med

  University of Zurich

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Christan Clarenbach, Dr. med

CONTACT

044 255 22 21; Christian.clarenbach@usz.ch

Manuel Kuhn, PhD Student

CONTACT

0798526722; manuel.kuhn@usz.ch

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: PD Dr. med Head of Pneumology

Model Details: monocenter / multicenter with a new study arm

Study Record Dates

• First Submitted: December 3, 2021
• First Posted: December 20, 2021
• Study Start: May 20, 2022
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026
• Last Updated: July 7, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

CH (1)