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.
Age ≥ 18 years
Clinically healthy
Physical or intellectual impairment precluding informed consent or protocol adherence
Non-German speaking (precluding informed consent)
Pain during exercise of any origin
Pregnancy
Crossover
BFR-CYC 50% peak / 50% AOP (exhaustive)
Other interventionBFR-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 3x2min
Other interventionBFR-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% LOP
Other interventionBFR-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% LOP
Other intervention* 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.
Endurance Exercise:(Fixed-Duration Protocol):
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)
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
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)
Minute ventilation (VE) will be continuously assessed during cycling exercise across all conditions to evaluate ventilatory demand.
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.
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.
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.
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.
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