Background: Skeletal muscle wasting commonly occurs in patients with chronic obstructive pulmonary disease (COPD) and has been associated with the presence of systemic inflammation. The present study investigated whether rehabilitative exercise training actually decreases the levels of systemic or local muscle inflammation or mainly reverses the abnormalities associated with muscle deconditioning.
Methods: Fifteen COPD patients [(mean±SEM) FEV1: 36±4% predicted] undertook high-intensity exercise training 3 days/week for 10 weeks. Before and after the training programme the concentration of TNF-alpha, IL-6 and CRP in plasma was determined by ELISA, whereas vastus lateralis mRNA expression of TNF-alpha, IL-6, total IGF-I and its isoform mechano-growth factor (MGF) as well as MyoD, were assessed by real-time PCR. Protein levels for TNF-alpha, IGF-I and MyoD were measured by Western-blot.
Results: Rehabilitation improved peak exercise work-rate (by 10±2%; p=0.004) and mean fiber cross sectional area (from 4061±254 to 4581±241 µm2; p=0.001). Plasma inflammatory mediators and vastus lateralis expression of TNF-alpha and IL-6 were not significantly modified by training. In contrast, there was a significant increase in mRNA expression for IGF-I (by 67±22%; p=0.044), MGF (by 67±15%; p=0.002), and MyoD (by 116±30%; p=0.001) The increase observed at the mRNA level was also extended to protein level for IGF-I (by 72±36%; p=0.046) and MyoD (by 67±21%; p=0.012).
Conclusions: Pulmonary rehabilitation can induce peripheral muscle adaptations and modifications in factors regulating skeletal muscle hypertrophy and regeneration without decreasing the levels of systemic or local muscle inflammation.
- exercise training
- myogenic regulatory factors