Table 3—

Responses to constant work rate exercise with different inspired oxygen concentrations in healthy subjects.

Parameter F I,O2
 Endurance min7.2±1.06.9±0.79.8±1.2*9.6±1.2*10.0±1.4*
Isotime values
 Breathlessness Borg5.6±0.85.1±0.93.7±0.7*3.6±0.7*3.4±0.6*
 HR bpm151±5150±5142±7141±8144±6
V'CO2 L·min−12.04±0.242.09±0.241.90±0.221.94±0.241.96±0.20
PET,CO2 mmHg40.8±1.641.8±1.646.8±1.1*45.8±1.0*45.3±1.4*
 IC L3.10±0.193.00±0.193.06±0.243.13±0.222.99±0.16
IRV L0.95±0.110.89±0.120.94±0.090.99±0.111.09±0.08
V'E L·min−157.7±6.959.1±8.046.5±5.0*48.7±6.1*50.5±6.2*
VT L2.15±0.252.11±0.252.13±0.252.14±0.291.92±0.17
VT/IC %68.1±5.069.0±4.968.7±4.166.3±5.663.3±3.2
TE s1.20±0.101.13±0.071.38±0.09*1.30±0.071.12±0.11
VT/TI L·s−12.11±0.222.01±0.231.65±0.16*1.64±0.19*1.71±0.19*
Sa,O2 %97.3±0.599.6±0.3*99.9±0.1*99.9±0.1*100.0±0.0*
  • Isotime refers to the time at which the room air test ended

  • HR: heart rate

  • V'CO2: carbon dioxide output

  • PET, CO2: end-tidal partial pressure for CO2

  • IC: inspiratory capacity

  • IRV: inspiratory reserve volume

  • V'E: minute ventilation

  • VT: tidal volume

  • VT/IC: tidal volume as a % of IC

  • TI/Ttot:duty cycle

  • TE: expiratory time

  • VT/TI: mean inspiratory flow rate

  • Sa,O2: arterial oxygen saturation

  • *: p<0.05 versus 0.21 FI,O2