TABLE 1

Selected sensory and physiological parameters at rest, iso-time, and peak exercise for constant-load cycle exercise tests with room air and hyperoxic conditions

ParameterRestIso-timePeak
Room airHyperoxiaRoom airHyperoxiaRoom airHyperoxia
Dyspnoea Borg units0.1±0.40.2±0.74.4±3.12.5±2.1**5.6±3.05.4±3.6
Leg discomfort Borg units0.0±0.10.1±0.24.5±2.72.9±1.8**5.7±2.56.4±2.7
SpO2 %95±299±1***91±398±1***90±498±1***
Heart rate beats·min−182±1477±13*125±20116±20***127±18124±20
Heart rate % pred54±1052±10*82±1177±12***84±1182±13
VE L·min−118±517±569±1955±15***72±2262±15***
VE/MVV %17±716±665±2151±14***68±2258±16***
VT L0.79±0.200.75±0.21*1.51±0.451.41±0.45**1.51±0.511.35±0.39***
fB breaths·min−124±924±947±1240±10***50±1547±12
EELV % TLC61±860±854±755±855±855±10
EILV % TLC80±977±890±788±791±986±11***
PETCO2 mmHg34±535±532±537±6***32±535±6***
  • Data are presented as means±sd. Iso-time was defined as the highest equivalent time achieved during both room air and hyperoxic conditions. The mean work-rate for the constant load exercise tests was 67±27 W, and the median iso-time was 6.0 (4.0–14.0) min. SpO2: arterial oxygen saturation measured by pulse oximetry; VE: minute ventilation; MVV: maximal voluntary ventilation; VT: tidal volume; fB: breathing frequency; EELV: end-expiratory lung volume; TLC: total lung capacity; EILV: end-inspiratory lung volume; PETCO2: partial pressure of end-tidal carbon dioxide. Significantly different from room air: *: p<0.05; **: p<0.01; ***: p<0.001.