Single limb exercises in patients with chronic obstructive pulmonary disease : feasibility, methodology, effects and evidence

Abstract: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. COPD is a slowly progressive, inflammatory disease in the airways and lungs, caused mainly by smoking. The inflammation leads to a narrowing of the small airways (airway obstruction) and a destruction of tissue in the lungs. This gives a decreased expiratory airflow which leads to dyspnea, the primary symptom of the disease. The chronic airflow limitation also is associated with the development of limb muscle dysfunction. Decreases in both limb muscle strength and endurance have been shown which, in turn, is associated with exercise intolerance, one of the key disabling factors of the disease. Pulmonary rehabilitation including exercise training is the cornerstone of treatment and is strongly recommended. However, it is still unclear how to optimize exercise training for this group of patients. Also how to address the increase in dyspnea which limits the exercise stimulus, and how to assess muscular strength, need further study. Partitioning the exercising muscle mass, known as single limb exercises, is a novel exercise strategy aimed at reducing the negative consequences of chronic airflow limitation in patients with COPD.The aim of this thesis was to study the current evidence of single limb approaches in patients with COPD, to examine the feasibility and effects of a high-repetitive single limb exercise (HRSLE) regimen in patients with COPD and to examine whether elastic resistance could be used to evaluate muscular strength.This thesis is based on five papers. In order to study the evidence on single limb exercises, a systematic review of randomized controlled trials was performed. The review showed that single limb exercises, performed as one-legged cycling appeared to be more effective than two-legged cycling with regard to exercise capacity but not dyspnea, and might be included in exercise programs for patients with COPD (Paper I). Thirty healthy older women and men participated in a validation study comparing elastic resistance maximal strength with isokinetic dynamometry measurements. Excellent levels of agreement and no differences between the two pieces of equipment were found which indicates that elastic resistance could be used to evaluate muscular strength (Paper II). A study protocol was created for a randomized controlled trial designed to identify the effects of HRSLE in combination with COPD-specific patient training (experimental group) in comparison to patient information alone (control group) (Paper III). HRSLE was performed as resistance training, using a single limb at a time, elastic bands as resistance and a high number of repetitions (25 repetitions in 2 sets) with the aim of increasing limb muscle endurance. After eight weeks of exercise, the differences between the groups were in favor of the experimental group on lower- and upper-extremity functional capacity, upper-extremity endurance capacity and muscular function. No differences were seen between the groups on endurance-cycle capacity or health-related quality of life (Paper IV). In patients with COPD, the HRSLE regimen was considered feasible with a high attendance rate, excellent compliance and high relative exercise intensity. No severe adverse events occurred. The physiotherapists conducting the HRSLE in the clinical setting also found it to be feasible (Paper V).This thesis shows that single limb exercises performed as one-legged cycling may be useful and effective for patients with COPD. Eight weeks of HRSLE was feasible and effective with regard to exercise capacity but without effect with regard to health-related quality of life. Elastic resistance could be used as exercise equipment to improve limb muscle function in patients with COPD and to evaluate muscular strength in healthy older adults.