Changes in nocturnal urinary catecholamine excretion in long-term intermittent Exposure to normobaric hypoxic training

Abstract

Objectives The hypoxic training is seemed to be effective methods that improve endurance performance in athlete. But on another front, it is difficult to gain the benefit if athletes are failed to keep their conditions. Therefore, evaluation of biomarkers that enable monitoring individual conditions during hypoxic training is desired. Since nocturnal urinary catecholamine (NU-CA) is known to non-invasive biomarker that reflects sympathetic nervous activity, we examined the changes of NU-CA levels in LHTL/LHTL+intermittent hypoxic training(IHT) . Materials and Methods The male college-level middle and long distance runners were divided into three groups; 1) LHTL (stayed normobaric hypoxic room during their sleep, trained at normoxia), 2) LHTL+IHT(stayed same conditioned room and trained partially at normobaric hypoxic room), and 3) control (live and train at normobaric normoxia). The accomodation and training room for LHTL+IHT group were normobaric hypoxia (O2 conc. =14.4%=3000m above sea level). The term of intervention was 31 days (day-0 to day-30). Noctual urine was collected on 1, 2, 3, 5, 7, 9, 17, 29th day and NU-CA levels were measured by using High Performance Liquid Chromatography (HPLC). Results and Discussion The percentage of area under the curve (%AUC) of noradrenaline/dopamine showed significant increase in LHTL+IHT group compared to LHTL group. There were no significant differences between LHTL and control groups. These results suggest that NU-CA levels may partially available to monitor athelete’s conditions in hypoxic training depending on its training intensity. We also discuss why NU-CA was changed in trainings by compared other quationaire prameters, such as,fatigue and arousal.