Sub-maximal aerobic exercise training reduces hematocrit and ameliorates symptoms in Andean highlanders with Chronic Mountain Sickness.

Macarlupú JL; Vizcardo-Galindo G; Figueroa-Mujíca R; Voituron N; Richalet JP; Villafuerte FC;

Experimental physiology [Exp Physiol] 2021 Sep 23. Date of Electronic Publication: 2021 Sep 23.

New Findings: What is the central question of this study? What is the effect of sub-maximal aerobic exercise training on signs and symptoms of chronic mountain sickness (CMS) in Andean highlanders? What is the main finding and its importance? Aerobic exercise training effectively reduces hematocrit, ameliorates symptoms, and improves aerobic capacity in CMS patients, suggesting that a regular aerobic exercise training program might be used as a low-cost non-invasive/non-pharmacological management strategy of this syndrome.
Abstract: Excessive erythrocytosis (EE) is the hallmark sign of Chronic Mountain Sickness (CMS), a debilitating syndrome associated with neurological symptoms and increased cardiovascular risk. We have shown that unlike sedentary residents at the same altitude, trained individuals maintain hematocrit within sea-level range, and thus we hypothesize that aerobic exercise training (ET) might reduce excessive hematocrit and ameliorate CMS signs and symptoms. Eight highlander men (38 ± 12y) with CMS (hematocrit: 70.6 ± 1.9%, CMS score: 8.8 ± 1.4) from Cerro de Pasco-Peru (4340m) participated in the study. Baseline assessment included hematocrit, CMS score, pulse oximetry, maximal cardiopulmonary exercise testing, and in-office plus 24h ambulatory blood pressure (BP) monitoring. Blood samples were collected to assess erythropoietic, hemolysis, and cardiometabolic markers. ET consisted of pedaling exercise in a cycloergometer at 60% of VO 2peak for 1h/day, 4 days/week for 8 weeks, and participants were assessed at weeks 4 and 8. Hematocrit and CMS score decreased significantly by week 8 (to 65.6 ± 6.6%, and 3.5 ± 0.8, respectively, p<0.05), while VO 2peak and maximum workload increased with ET (33.8 ± 2.4 vs. 37.2 ± 2.0ml/min/kg, p<0.05; and 172.5 ± 9.4 vs 210.0 ± 27.8W, p<0.01; respectively). Except for an increase in HDL-C, other blood markers and BP showed no differences. Our results suggest that reduction of hematocrit and CMS symptoms result mainly from hemodilution due to plasma volume expansion rather than to hemolysis. In conclusion, we show that ET can effectively reduce hematocrit, ameliorate symptoms, and improve aerobic capacity in CMS patients, suggesting that regular aerobic exercise might be used as a low-cost non-invasive/non-pharmacological management strategy.