Sub-maximal aerobic exercise training reduces haematocrit and ameliorates symptoms in Andean highlanders with chronic mountain sickness.

Macarlupu JL; Vizcardo-Galindo G; Figueroa-Mujica R; Voituron N;
Richalet JP; Villafuerte FC

Experimental Physiology. 106(11):2198-2209, 2021 11.

ABSTRACT: Excessive erythrocytosis 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 haematocrit within sea-level range, and thus we hypothesise that
aerobic exercise training (ET) might reduce excessive haematocrit and
ameliorate CMS signs and symptoms. Eight highlander men (38 +/- 12 years)
with CMS (haematocrit: 70.6 +/- 1.9%, CMS score: 8.8 +/- 1.4) from Cerro
de Pasco, Peru (4340 m) participated in the study. Baseline assessment
included haematocrit, CMS score, pulse oximetry, maximal cardiopulmonary
exercise testing and in-office plus 24 h ambulatory blood pressure (BP)
monitoring. Blood samples were collected to assess cardiometabolic,
erythropoietic, and haemolysis markers. ET consisted of pedalling exercise
in a cycloergometer at 60% of V O 2 peak for 1 h/day, 4 days/week for 8
weeks, and participants were assessed at weeks 4 and 8. Haematocrit and
CMS score decreased significantly by week 8 (to 65.6 +/- 6.6%, and 3.5 +/-
0.8, respectively, P < 0.05), while V O 2 peak and maximum workload
increased with ET (33.8 +/- 2.4 vs. 37.2 +/- 2.0 ml/min/kg, P < 0.05; and
172.5 +/- 9.4 vs. 210.0 +/- 27.8 W, P < 0.01; respectively). Except for an
increase in high-density lipoprotein cholesterol, other blood markers and
BP showed no differences. Our results suggest that reduction of
haematocrit and CMS symptoms results mainly from haemodilution due to
plasma volume expansion rather than to haemolysis. In conclusion, we show
that ET can effectively reduce haematocrit, ameliorate symptoms and
improve aerobic capacity in CMS patients, suggesting that regular aerobic
exercise might be used as a low-cost non-invasive and non-pharmacological
management strategy.