RESUMEN
Chronic obstructive pulmonary disease [COPD] is a chronic debilitating disease with disabling symptoms. It has recently become apparent that skeletal muscle dysfunction is common in patients with COPD, and may play a role in reducing exercise tolerance. The peripheral muscles seem to be more affected than the respiratory muscles, especially those of the lower limb in comparison to those of the upper limb. In this thesis the relation between skeletal muscles dysfunction and the severity of COPD was studied. The form of dysfunction emphasized in this study was the muscle strength; being measured as amplitude and envelope or as torque. Thirty COPD patients and ten control subjects were included in this study. All were submitted to the following a- thorough history taking. b-Clinical examination. c- Chest X-ray. d- Arterial blood gases, e- Resting spirometry, f- Isokinetic dynamometry, g- Quantitative Interference pattern electromyography. Results were tabulated and statistically analyzed. There was statistically significant difference between the COPD patients and the control group regarding the strength of the muscle represented in this study by: quadriceps muscle in isokinetic dynamometry and Vastus medialis, in particular, in EMG. There was also a significant correlation between smoking index represented by pack years and the weakness of the muscle. Ex. smokers were found to be more affected. The COPD patients, whether they showed manifestations of hyperinflation or chronic bronchitis, had significant correlation with muscle weakness by surface EMG. However, the correlation was not significant regarding the isokinetic dynamometry, measuring the torque of the muscle, although it was evident that the isokinetic dynamometry was much lowered in COPD in relation to the control group. So, COPD patients diagnosed by clinical assessment, radiology and resting spirometry, showed significant impairment of the strength of their quadriceps muscle; especially, the vastus medialis muscle. The weakness of peripheral muscles was attributed to severity of COPD, and smoking habits