Table 4.

Correlates of dyspnea at a standardized absolute work rate during exercise

Variable	r2	P Value
V̇e, l/min	0.54*	<0.001
V̇e/V̇eCAP, %	0.56*	<0.001
VT, l	−0.43	0.004
VT, %IC	0.14	0.371
VT, %VC	0.05	0.760
FB, breaths/min	0.69*	<0.001
SpO2, %	−0.34*	0.024
$\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, mmHg	−0.32*	<0.001
EELV, %TLC	0.33*	0.032
IRV, %TLC	−0.23*	0.014
IC, liter	−0.47*	<0.001
IC, %predicted	−0.01	0.792
ΔIC (exercise – rest), liter	−0.03	0.315
Wb, J/min	0.76*	<0.001

V̇e, expired minute ventilation; V̇e/V̇e_CAP, fractional utilization of ventilatory capacity; V_T, tidal volume; IC, inspiratory capacity; VC, vital capacity; F_b, breathing frequency; S_pO₂, arterial oxygen saturation by pulse oximetry; $\mathrm{P}\mathrm{E}{\mathrm{T}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, end-tidal partial pressure of carbon dioxide; EELV, end-expiratory lung volume; TLC, total lung capacity; IRV, inspiratory reserve volume; W_b, work of breathing.

^*P < 0.05.