Exercise Responses Associated with Altitude Acclimatization Are Retained During Reintroduction to 4,3000 M,
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).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1996
- Accession Number
- ADA320729
Entities
People
- Beth A. Beidleman
- Charles S. Fulco
- Paul B. Rock
- Stephen R. Muza
- Timothy P. Lyons
Organizations
- United States Army Research Institute of Environmental Medicine