Muscle loss in chronic obstructive pulmonary disease (COPD) impairs patients' exercise capacity and health related quality of life (HRQoL). Exercise training, as part of a programme of pulmonary rehabilitation (PR), is important in the treatment and demonstrates clinically important improvements in symptoms burden, exercise capacity and HRQoL. However, weakness and fatigability of the ambulatory muscles hinder patients' ability to achieve optimal exercise intensity. This study explores a novel rehabilitation intervention, low-intensity interval cycling with blood flow restriction (IC-BFR), ultimately aimed at mitigating muscle loss and improving uptake and adherence in PR programmes designed for COPD patients. However, its application in COPD patients has been limited. We investigated the acute physiological responses of IC-BFR in healthy age-equivalent adults.

Fifteen healthy participants (male: n = 6, female: n = 9, age: 58.5 ± 5.7 y, BMI: 25.8 ± 2.9 kg/m2, V̇O_2peak 33.7 ± 10.9 ml/kg/min) volunteered for this study which had local ethics approval. Participants initially performed a ramp-incremental cycling test to determine V̇O_2peak and gas exchange threshold (GET) followed by a familiarisation session. In a randomised, crossover design, participants performed two experimental trials: interval cycling exercise with BFR and without (CON). Exercise involved three sets of three 2-minute low-intensity intervals at a power output equivalent to 90% of GET. Intervals were separated by 2-minute recovery. Each set was separated by a 5-minute inactive period. BFR was applied during each interval only. Heart rate (HR), oxygen saturation (%O_2sat), blood pressure (BP) and rate perceived exertion (RPE) were monitored throughout exercise. Central BP and arterial stiffness (AIx) were assessed pre- and immediately post-exercise. Blood samples were obtained pre-exercise and at 24-, 48-, and 72-hours post-exercise and assessed for biomarkers of muscle damage (creatine kinase, CK) and inflammation (C-reactive protein, CRP; interleukin-6, IL-6). Data were analysed using a Linear Mixed Model test which accounted for the repeated measures design and missing data. Data are presented as mean ± SD.  Significance was accepted at p < 0.05.

HR increased (p < 0.001) throughout exercise in both conditions but was not different between conditions (p = 0.518).  %O_2sat remained unchanged (p = 0.190) throughout exercise and was not different between conditions (p = 0.194).  Systolic (p < 0.001) and diastolic (p < 0.012) BP were greater during the interval phases of exercise in BFR compared to CON. However, during the recovery phases systolic (p < 0.125) and diastolic (p < 0.626) BP were the same.  Central systolic (p = 0.073) and diastolic (p = 0.064) BP and AIx (p = 0.485) did not change.  RPE was higher (p = 0.033) throughout exercise in BFR compared to CON. There were no changes in CRP (p = 0.073), IL-6 (p = 0.091), or CK (p = 0.160) in either condition.

BFR applied during interval exercise increased BP and RPE to a greater extent compared to CON. There were no other effects of BFR or muscle damage and inflammation. IC-BFR is well-tolerated in healthy adults, paving the way for its potential implementation in COPD PR programmes.