Year: 1999
Type: conference-abstract
Abstract: 815 We hypothesized that the incidence and severity of acute mountain sickness (AMS) would increase when subjects exercised compared to when they were sedentary at high altitude, and that subjects would breathe less and retain more fluid as they became ill with AMS. Seven male subjects exercised (EX) 4 times for 30 min in the first 6 hrs of a 10 hr exposure to simulated high altitude (PB=429, 4572 m) at 50% of their altitude specific maximal workload. On another day they completed the same altitude exposure but were sedentary (SED). Measurements included resting ventilation (VE), arterial oxygen saturation (SpO2), fluid input, urine volume, hemoglobin, hematocrit and serum protein. Symptoms of AMS were worse in EX than SED, with peak AMS scores of 4.4±1.0 and 1.3±0.4 in EX and SED, respectively (p<0.05). Resting VE and SpO2 were not different between EX and SED. SpO2 during exercise bouts in EX was significantly lower (76.3±1.7%) than during either SED (81.4±1.8%, p<0.01), or at rest in EX (82.2±2.6%). Fluid intake was similar between trials, but in EX urine volume dropped 64% from baseline to 3 to 6 hrs compared to a 16% drop in the same time period during SED (p=0.06). Those with the most severe AMS had the greatest drop in urine volume (r = −0.89, p < 0.01). In EX the normal hypoxia-induced contraction of plasma volume was absent, and symptom score was negatively related to urine volume. Our findings suggest that AMS is exacerbated by exercise at altitude. Further investigation using this model may allow identification of the pathophysiologic mechanisms of AMS.
Language: English
Topic: High Altitude and Hypoxia
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2041877247