MAXIMAL FORCE AND ENDURANCE TO FATIGUE OF RESPIRATORY AND SKELETAL-MUSCLES IN CHRONIC HYPOXEMIC PATIENTS - THE EFFECTS OF OXYGEN BREATHING

The consequences of chronic hypoxemia on maximal force and endurance t ime to sustained 80% of maximal isometric contraction of two skeletal muscles (adductor pollicis and vastus lateralis) and diaphragm were st udied in patients with chronic obstructive pulmonary disease (COPD). C ompared to normal subjects, COPD patients have lower values of F-max f or the two skeletal muscle groups and P-max (diaphragm). Endurance tim e was also shorter for the diaphragm and adductor pollicis. Chronic hy poxemia was associated with an accentuation in integrated EMG changes in both low and high frequency bands for adductor pollicis and diaphra gm. Inhalation of oxygen enriched gas mixture for a 15-min period incr eased markedly F-max and P-max values, prolonged the endurance the EMG changes in the low frequency band for adductor pollicis. The present observations provide evidence for altered maximal performances of skel etal muscles in chronic hypoxemic patients and also point out the virt ues of oxygen breathing in these patients. (C) 1995 John Wiley & Sons, Inc.