The Reliability of a Pre-Loaded Treadmill Time-Trial in Moderate Normobaric Hypoxia

The purpose of this study was to assess the reliability of a pre-loaded 1 500-m treadmill time trial, conducted in moderate normobaric hypoxia. 8 trained runners/triathletes (24±3 years, 73.2±8.1 kg, 182.5±6.5 cm, altitude specific V˙O2max: 52.9±5.5 ml·kg(-1)·min(-1)) completed 3 trials (the first as a familiarisation), involving 2, 15-min running bouts at 45% and 65% V˙O2max, respectively, and a 1 500-m time trial in moderate normobaric hypoxia equivalent to a simulated altitude of 2 500 m (FiO2~15%). Heart rate, arterial oxygen saturation, skeletal muscle and cerebral tissue oxygenation (StO2), expired gas ( V˙O2 and V˙CO2), and ratings of perceived exertion were monitored. Running performance (Trial 1: 352.7±40; Trial 2: 353.9±38.2 s) demonstrated a low CV (0.9%) and high ICC (1). All physiological variables demonstrated a global CV≤4.2%, and ICC≥0.87, with the exception of muscle (CV 10.4%; ICC 0.70) and cerebral (CV 4.1%; ICC 0.82) StO2. These data demonstrate good reliability of the majority of physiological variables and indicate that a pre-loaded 1 500-m time trial conducted in moderate normobaric hypoxia is a highly reliable test of performance.