Accession Number : ADA320729

Title :   Exercise Responses Associated with Altitude Acclimatization Are Retained During Reintroduction to 4,3000 M,

Corporate Author : ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA

Personal Author(s) : Beidleman, Beth A. ; Muza, Stephen R. ; Rock, Paul B. ; Fulco, Charles S. ; Lyons, Timothy P.

PDF Url : ADA320729

Report Date : 1996

Pagination or Media Count : 28

Abstract : Following 2-3 wk of altitude acclimatization, ventilation is increased and heart rate (HR), plasma volume (PV) and lactate accumulation (La) are decreased during submaximal exercise. We hypothesized that some degree of exercise responses associated with acclimatization would be retained upon reintroduction to altitude (RA) after 8 d at sea level (SL). Six male lowlanders exercised to exhaustion (EXH) at the same relative percentages of peak oxygen uptake at SL, on acute altitude (AA) exposure, after a 16-d chronic altitude (CA) exposure on Pikes Peak (4,300 m), and during a 3-4-h RA after 8 d at SL. The EXH time was the same at SL (66.0 +/- 1.6 min), AA (67.7 +/- 7.3 min), CA (79.9 +/- 6.2 min) and RA (67.9 +/- 1.9 min). At 75% VO(2peak): (1) arterial oxygen saturation (SaO2) increased from AA to CA (67.0 +/- 1.5 vs. 78.5 +/- 1.8%; P<0.05) and remained increased at RA (77.0 +/- 2.0%); (2) HR decreased from SL to CA (171 +/- 6 vs. 152 +/- 9 remained increased at RA (77.0 +/- 2.0%); (2) HR decreased from SL to CA (171 +/-6 vs. 152 +/- 9 bpm; P<(0.05) and remained decreased at RA (157 +/- 5 bpm); (3) calculated PV decreased 6.9 +/- 10.0% at AA, 21.3 +/- 11.1% at CA, and 16.7 +/- 5.4% at RA from SL baseline values, and (4) La decreased from AA to CA (5.1 +/- 0.9 vs. 1.9 +/- 0.4 mmol-l(-1); P<0.05) and remained decreased at RA (2.6 +/- 0.6 mmol-l(-1). For each individual, percent retention of acclimatization response was calculated as (RA-AA)/(CA%AA) - 100. Upon RA after 8 d at SL, the acclimatization responses were retained 92 +/- 9% for SaO(2), 74 +/- 8% for PV and 58 +/- 3% for La at 75% VO(1peak).

Descriptors :   *RESPONSE(BIOLOGY), *BLOOD PLASMA, *FATIGUE(PHYSIOLOGY), *LACTATES, *ALTITUDE ACCLIMATIZATION, PEAK VALUES, VENTILATION, SATURATION, OXYGEN, BASE LINES, HIGH ALTITUDE, VALUE, RETENTION(PSYCHOLOGY), HEART RATE, SEA LEVEL, ARTERIES, BLOOD VOLUME, OXYGEN CONSUMPTION.

Subject Categories : Medicine and Medical Research
      Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE