title: Skeletal muscle strength during exposure to hypobaric hypoxia.
abstract: To assess the effects of acute exposure to hypobaric hypoxia and acute mountain sickness (AMS) on skeletal muscle strength, 10 healthy young men were studied before, during, and after a 48-h sojourn at a simulated altitude of 4,572 m (15,000 feet). Measurements were made of isokinetic (180 degrees, 36 degrees, and 0 degrees/s) knee extensor strength; isometric strength of upper torso, knee, and trunk extensor muscles; and strength endurance of knee extensor and elbow flexor muscles during a bout of repeated isokinetic contractions. There were no significant differences between strength measurements at sea level and after 2 and 24 h of hypoxic exposure. After 48 h of exposure, means of strength measurements were increased relative to sea-level values but the difference was statistically significant in the case of only one test; namely, isometric strength of the upper torso. Strength endurance was unchanged throughout the exposure. Symptoms of AMS were absent after 2 h, most pronounced after 24 h, and although somewhat reduced, still present to a significant extent after 48 h of hypoxia. Thus, despite the occurrence of AMS, muscle strength was unimpaired during acute hypoxic exposure.
mesh_terms: D000328:Adult; D000531:Altitude; D001274:Atmospheric Pressure; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000503:physiopathology*