Marathon runners native from the Altiplano were studied during a high altitude marathon (4220 m Cerro de Pasco) and during a laboratory exercise test (VO2max). We hypothesized that living in chronic hypoxia does not limit the training-induced benefits on the autonomic modulation of the heart assessed by the analysis of heart rate variability (HRV). Two groups of trained (Tg, n = 13) and sedentary (Sg, n = 11) subjects performed an active orthostatic test. Eight of the Tg also performed the exercise trials and repeated the orthostatic test 6-8 (Post1) and 20-24 h (Post2) after the end of the marathon. Heart rate (HR) was monitored continuously over the race. Runners exhibited a high VO2max (61.5 ± 2.4 ml/min/kg) despite a low HRmax (176 ± 11 bpm), and [Lactate]max (11 ± 2.1 mmol/l). VEmax was 144.9 ± 30.6 l/min (n = 6). Mean HR during the marathon was 168 ±17 bpm (n = 4). [Lactate] at the end of the race was 4.4 ± 1.5 mmol/l (n = 5). The performance ranged between 2:45:00 and 3:22:05. Tg exhibited a higher total power of HRV and a lower resting HR than Sg secondary to a higher and dominant parasympathetic modulation on sympathetic activity. At Post1, total power of HRV decreased, whereas resting HR increased from basal level, mainly because of a rise in sympathetic modulation. From Post1 to Post2, sympathetic modulation fell and all HRV parameters were restored. Responses to the active Standing position never changed. The high level of performance especially over the marathon evidences the degree of adaptation of runners native from the Altiplano, probably at the pulmonary or muscular level. Living in chronic hypoxia does not limit the training-induced benefits on the autonomic control of the cardiovascular System and does not impair the regulation induced by exercise in Andeans. This project was supported by POLAR Electro Oy, Kempele, Finland.
© Copyright 2006 High Altitude Medicine & Biology. Mary Ann Liebert. All rights reserved.