Maximal Cardiorespiratory Responses to One- and Two-Legged Cycling during Acute and Long-Term Exposure to 4300 Meters Altitude
Abstract
During exposure to altitudes greater than about 2200 m, maximal oxygen uptake (vo2max) is immediately diminished in proportion to the reduction in the partial pressure of oxygen in the inspired air. If the exposure lasts longer than a couple of days, an increase in arterial oxygen content (calcium peroxide), due to a hemoconcentration and an increase in arterial oxygen saturation, occurs. However, there is also a reduction in maximal cardiac output (Q(max)) at altitude which offsets the increase in CaO2 and, therefore, Vo2(max) does not improve. The purpose of this investigation was to study the contribution of the increase in CaO2 to the working muscles without the potentially confounding problem of a reduced Q(max). The approach used was to have seven male subjects (aged 17 to 24 years) perform one- and two-legged Vo2(max) tests on a cycle ergometer at sea level after 1 hr at 4300 m simulated altitude and during two weeks of residence on the summit of Pikes Peak, CO. Cardiac output limits maximal performance during two-legged cycling but does not limit performance during one-legged cycling. Since only one-legged Vo2(max) increased as more oxygen was made available to the working muscles, the altitude-induced reduction in Q(max) can be implicated as being responsible for the reduction in Vo2(max) during two-legged cycling. Keywords: Altitude acclimatization, Reprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1988
- Accession Number
- ADA201907
Entities
People
- Allen Cymerman
- Charles S. Fulco
- Laurie Trad
- Paul B. Rock
- Vincent Forte Jr.
Organizations
- United States Army Research Institute of Environmental Medicine