Dual morphometrical changes of the deltoid muscle in patients with COPD

The present study was specifically aimed at evaluating if the structure of the deltoid muscles is modified in patients with chronic obstructive pulmonary disease (COPD). Twenty-eight male volunteers (61+/-13 yr) were assigned, according to pulmonary function, to either the COPD (n=14, FEV(1)=22-74%pred) or control group (n=14, FEV(1)=83-121%pred). Biopsies from non-dominant deltoid muscle were obtained and processed for morphometric analysis of the fibre types. Both type I and type II muscle fibres were distributed in the typical mosaic pattern. The mean value of the fibre size was within the normal range. However, three differentiated modes were observed in the deltoid from COPD patients: a central mode of normal sized fibres, a mode of atrophic fibres and a mode of hypertrophic fibres. This observation was evident even within single fascicles and especially prevalent in the most severe COPD patients. We conclude that factors with opposite effect (promotion of either atrophy or hypertrophy) exert relevant roles in the histomorphometrical characteristics of the deltoid muscles in COPD patients.