Differences in training response between patients with alpha-1 antitrypsin deficiency and COPD patients

Abstract

Background: Exercise training improves exercise capacity in patients with chronic obstructive pulmonary diseases (COPD). In a retrospective analysis, we found that COPD patients (PiMM) showed higher improvements of exercise capacity following training intervention than Alpha-1 antitrypsin deficiency patients (A1ATD, PiZZ). Objective: We investigated if this different change in exercise capacity is reflected by different skeletal muscle adaptations. Methods: 6 A1ATD (PiZZ, age: 57±7y, FEV1: 38±6%pred., Prolastin®: n=6) and 10 COPD patients (PiMM, age: 62±7y, FEV1: 28±4%pred.) prospectively performed a 3-week training therapy. Before and after, each patient underwent muscle biopsy (m.vastus lateralis) and peak work rate (PWR) test. Results: Prospective data showed that exercise capacity improved in both groups, however the improvement was smaller in A1ATD patients (PWR: A1ATD:+10±11Watt, p<0.05 vs. COPD: +19±9 Watt, p<0.001). Oxidative muscle fiber type I only increased in COPD patients (+33% [p<0.05] vs. A1ATD: -28%). A1ATD patients increased fiber type IIA by +21% whereas COPD patients decreased by -3.9%. Hybrid fibers (type I/IIA and IIA/X) decreased in both groups. Key proteins of respiratory chain and mitochondrial signaling parameters showed smaller positive adaptations in A1ATD than in COPD patients. Discussion: Training therapy of only 3 weeks is effective in A1ATD and COPD patients. However, the effects were smaller in A1ATD patients that was mirrored by less positive adaptations in skeletal muscle regarding oxidative function and mitochondrial signaling. Further studies have to be performed to detect the mechanisms explaining these differences.