Comparison of "Live High-Train Low" in normobaric versus hypobaric hypoxia.

Jonas J Saugy,Anna Hauser,Neil Robinson,Roberto Cejuela,Laurent Schmitt,Grégoire P Millet,Benjamin Rudaz,Jon P Wehrlin,Audric Delessert,Raphael Faiss

doi:10.1371/journal.pone.0114418

Jonas J Saugy, Anna Hauser + Show 8 more

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https://doi.org/10.1371/journal.pone.0114418

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Abstract

We investigated the changes in both performance and selected physiological parameters following a Live High-Train Low (LHTL) altitude camp in either normobaric hypoxia (NH) or hypobaric hypoxia (HH) replicating current “real” practices of endurance athletes. Well-trained triathletes were split into two groups (NH, n = 14 and HH, n = 13) and completed an 18-d LHTL camp during which they trained at 1100–1200 m and resided at an altitude of 2250 m (PiO2 = 121.7±1.2 vs. 121.4±0.9 mmHg) under either NH (hypoxic chamber; FiO2 15.8±0.8%) or HH (real altitude; barometric pressure 580±23 mmHg) conditions. Oxygen saturations (SpO2) were recorded continuously daily overnight. PiO2 and training loads were matched daily. Before (Pre-) and 1 day after (Post-) LHTL, blood samples, VO2max, and total haemoglobin mass (Hbmass) were measured. A 3-km running test was performed near sea level twice before, and 1, 7, and 21 days following LHTL. During LHTL, hypoxic exposure was lower for the NH group than for the HH group (220 vs. 300 h; P<0.001). Night SpO2 was higher (92.1±0.3 vs. 90.9±0.3%, P<0.001), and breathing frequency was lower in the NH group compared with the HH group (13.9±2.1 vs. 15.5±1.5 breath.min−1, P<0.05). Immediately following LHTL, similar increases in VO2max (6.1±6.8 vs. 5.2±4.8%) and Hbmass (2.6±1.9 vs. 3.4±2.1%) were observed in NH and HH groups, respectively, while 3-km performance was not improved. However, 21 days following the LHTL intervention, 3-km run time was significantly faster in the HH (3.3±3.6%; P<0.05) versus the NH (1.2±2.9%; ns) group. In conclusion, the greater degree of race performance enhancement by day 21 after an 18-d LHTL camp in the HH group was likely induced by a larger hypoxic dose. However, one cannot rule out other factors including differences in sleeping desaturations and breathing patterns, thus suggesting higher hypoxic stimuli in the HH group.

Highlights

Live High - Train Low (LHTL) training camps are commonly used by athletes under either normobaric hypoxia (NH) [1,2,3,4,5] or hypobaric hypoxia (HH) [6,7,8,9,10] conditions
Oxidative stress markers were elevated when individuals were continuously exposed to HH conditions compared to NH for 24 h, whereas nitric oxide (NO) in exhaled air and plasma was lower under HH versus NH [18]
No differences were found in weekly training loads monitored during the 6 months prior to the study (1161¡130 vs. 1208¡168 ECOs per week for the NH and HH groups, respectively; Fig. 2B), nor were any differences noted during the lead-in period or the post-hypoxic period

Summary

Introduction

Live High - Train Low (LHTL) training camps are commonly used by athletes under either normobaric hypoxia (NH) [1,2,3,4,5] or hypobaric hypoxia (HH) [6,7,8,9,10] conditions These two types of hypoxia are obtained by the combination of a lowered value of barometric pressure (PB) and/or a reduced inspired fraction of oxygen (FIO2) (NH: FIO2 ,20.9%; PB5760 mmHg vs HH: FIO2520.9%; PB,760 mmHg) resulting in an inspired partial pressure of oxygen (PIO2) less than 150 mmHg. NH and HH were, until recently, thought to be interchangeable since PIO2 was assumed as the only factor influencing the physiological responses to hypoxia [11].

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