Accession Number : ADA185730

Title :   Maximal Cardiorespiratory Responses to One- and Two-Legged Cycling during Acute and Long-Term Exposure to 4300m,

Corporate Author : ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA

Personal Author(s) : Fulco, Charles S ; Rock, Paul B ; Trad, Laurie ; Forte, Vincent, Jr ; Ruscio, Bruce

PDF Url : ADA185730

Report Date : 14 Jul 1987

Pagination or Media Count : 21

Abstract : During exposure to high altitude, maximal oxygen consumption (V02max) is diminished immediately in proportion to the reduction in oxygen content of the inspired air. As the exposure lasts beyond a couple of days, there is an increase in arterial oxygen saturation. However, V02max does not increase possibly due to a reduction in cardiac output. The purpose of this investigation was to study the contribution of the increase in oxygen content to the working muscles without the potentially confounded problem of a reduced cardiac output. Seven male subjects (aged 17 to 24 years) performed one- and two-legged V02max tests on a cycle ergometer at sea level (SL), after 1 hour at 4300m simulated altitude (SA) and after two weeks of residence at the summit of Pikes Peak, CO. (PP;4300m). Cardiac output limits maximal performance during two-legged but not one-legged cycling. Since only one-legged V02max increased as more oxygen was made available to the working muscles then the altitude-induced reduction in cardiac output can be implicated as being responsible for the reduction in V02max during two-legged cycling.

Descriptors :   *HEART, *HIGH ALTITUDE, *RESPIRATORY SYSTEM, *RESPONSE(BIOLOGY), *PHYSIOLOGICAL EFFECTS, *EXPOSURE(PHYSIOLOGY), ARTERIES, CYCLES, ERGOMETERS, EXPOSURE(GENERAL), LIMITATIONS, LONG RANGE(TIME), MUSCLES, OUTPUT, OXYGEN, OXYGEN CONSUMPTION, REDUCTION, SATURATION, SEA LEVEL

Subject Categories : Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE