Effects Of Low-Load Blood Flow Restriction Training Of The Upper Extremity In Patients With Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a common, preventable, and treatable disease characterized by persistent respiratory symptoms and irreversible airflow limitation resulting from airway and/or alveolar abnormalities, usually caused by prolonged exposure to noxious particles or gases (1). COPD represents one of the leading causes of mortality among chronic respiratory diseases and is recognized as a major global health problem, affecting approximately 10% of the adult population, with an increasing incidence associated with population aging. According to the 2017 Global Burden of Disease (GBD) Study, the global mortality rate attributable to COPD was 41.9 deaths per 100,000 population, accounting for 5.7% of all-cause mortality. The mortality rate was reported as 46.7 per 100,000 in men and 37.0 per 100,000 in women (2). The progressive and persistent airflow limitation in COPD, together with reduced parenchymal elasticity, increases ventilatory demand and imposes an excessive load on the respiratory muscles. Hyperinflation further reduces the effective contractile range of these muscles, creating a vicious cycle in which mechanoreceptor stimulation enhances ventilatory drive and exacerbates dyspnea. Increased dyspnea and impaired respiratory muscle function limit the performance of activities of daily living (ADLs), leading to substantial reductions in physical performance (3). Skeletal muscle dysfunction is a frequent systemic manifestation of COPD. Reductions in peripheral muscle strength involving the upper and lower extremities as well as the trunk significantly limit exercise capacity and functional performance, negatively affecting overall health status. Importantly, impaired muscle strength has been identified as a strong predictor of morbidity, mortality, disability, and exacerbation risk, independent of the degree of airway obstruction (4). During upper extremity activities, individuals with COPD frequently experience marked dyspnea and dynamic hyperinflation, which significantly restrict functional independence and highlight the clinical importance of upper extremity functional capacity (5). Compared with healthy peers, individuals with COPD demonstrate reduced performance during upper limb activities and report substantial difficulty. This limitation is partly attributable to altered respiratory mechanics, as upper extremity muscles also function as accessory respiratory muscles. Consequently, dyspnea intensifies during upper limb activity, often leading to premature termination of exercise (6). Given the dyspnea-inducing nature of upper extremity use and its negative impact on activity tolerance, preserving and improving upper extremity function constitutes a critical rehabilitation target in COPD. Indeed, as emphasized in the most recent joint official statement by the American Thoracic Society (ATS) and the European Respiratory Society (ERS), the inclusion of upper extremity exercise training in pulmonary rehabilitation programs is strongly supported for individuals with COPD (7). Pulmonary rehabilitation programs commonly incorporate aerobic modalities such as arm ergometry, as well as resistance-based approaches using multi-station systems, elastic bands, or free weights to target upper extremity function (8). Although aerobic exercise forms the cornerstone of pulmonary rehabilitation, its effects on muscle strength and mass are considered limited. Therefore, combined aerobic and resistance exercise approaches are recommended to more effectively address peripheral muscle dysfunction (9). However, whether currently tolerated training intensities-often limited by ventilatory constraints-are sufficient to optimally target peripheral muscle dysfunction remains controversial. Both the ATS and ERS have highlighted the need for innovative rehabilitation strategies capable of targeting peripheral muscle dysfunction at lower mechanical loads (10). Traditional moderate-to-high intensity resistance training may be effective but is often poorly tolerated in individuals with COPD due to dyspnea, early fatigue, and ventilatory limitation, thereby limiting adherence and long-term participation (11). In this context, low-load blood flow restriction training (LL-BFRT) has emerged as a promising alternative. Despite the use of low mechanical loads, LL-BFRT induces localized ischemia and increased metabolic stress, leading to significant gains in muscle strength and hypertrophy. This method may represent a viable option for individuals with COPD who are unable to tolerate high mechanical loads (12). Although evidence supporting LL-BFRT primarily derives from studies conducted in healthy individuals and predominantly targeting lower extremity muscles (12-14), data regarding its application to upper extremity muscles in individuals with COPD remain limited. Considering that upper limb activities impose greater ventilatory demand and trigger dyspnea earlier, the potential advantages of LL-BFRT in this region warrant investigation. This research gap underscores the necessity of evaluating the effectiveness of LL-BFRT-based upper extremity resistance training in COPD. Aim of the Study The aim of this study is to comparatively investigate the effects of LL-BFRT and sham-BFRT, administered in addition to an aerobic exercise program, on upper extremity muscle strength, upper extremity functional capacity, performance of activities of daily living, quality of life, functional exercise capacity, muscle oxygenation, and pulmonary function parameters in individuals diagnosed with stage II and III COPD. Interventions Participants in both groups will undergo an exercise program twice weekly for 8 weeks. Both groups will perform upper extremity aerobic exercise using an arm cycle ergometer. Each session will begin with a 5-minute warm-up at 0 Watts, followed by 20 minutes of aerobic exercise at 60-70% of age-predicted maximum heart rate. Initial resistance will be set between 35-50 Watts and maintained within this range according to individual exercise tolerance. Dyspnea will be monitored using the Modified Borg Scale. A 5-minute cool-down at 0 Watts will follow the aerobic phase. Intervention Group (LL-BFRT) In addition to aerobic exercise, participants in the intervention group will receive LL-BFRT. A pneumatic cuff will be placed proximally on the upper extremity. Occlusion pressure will be set at 30-40% of arterial occlusion pressure (AOP). Resistance will be set at 30% of one-repetition maximum (1RM). Exercises will follow a standardized 4-set protocol (30-15-15-15 repetitions) with 45-second inter-set rest periods, during which cuff pressure will be maintained. Targeted muscle groups will include the biceps brachii, triceps brachii, and anterior deltoid. After completion of each exercise, cuff pressure will be released for a 5-minute reperfusion period before proceeding to the next exercise. Dyspnea will be closely monitored using the Modified Borg Scale, and exercise will be terminated if dyspnea reaches ≥6, indicating exercise intolerance. Control Group (Sham-BFRT) Participants in the control group will receive the same aerobic exercise protocol and identical resistance exercise structure. However, cuff pressure during sham-BFRT will be set at a level insufficient to produce therapeutic blood flow restriction. Assessments Demographic data including age, sex, height, and weight will be recorded. Body mass index (BMI) will be calculated. Smoking history will be documented in pack-years. Disease duration and COPD stage (according to GOLD classification) will be determined from medical records. Oxygen therapy and inhaled treatment use will be recorded. Exacerbation frequency, defined as the number of exacerbations and hospital admissions within the past 12 months, will also be documented. This study is expected to provide evidence regarding the clinical efficacy and physiological mechanisms of LL-BFRT in improving upper extremity function in individuals with COPD and to inform exercise prescription within pulmonary rehabilitation programs.