Effects of continuous vs. interval aerobic training on PetCO2 response during graded exercise test in patients with coronary artery disease

Abstract

Background: Previous studies have demonstrated in patients with coronary artery disease (CAD) that lower values in end-tidal CO2 pressure (PetCO2) during graded exercise test (GET) have been associated with ventilation perfusion (V/Q) mismatch.

Purpose: 1) to evaluate the effects of the continuos (CT) and interval aerobic training (IT) on PetCO2 responses during GET in CAD patients; and 2) examine the relationships between PetCO2 at ventilatory anaerobic threshold (PetCO2VAT) and cardiorespiratory parameters after interventions.

Methods: 37 patients with CAD (59.7±1.7 years) were divided into 2 groups: CT (n=20; 28.1±1 kg/m²) and IT (n=17; 28.5±1 kg/m²). All patients performed a GET on treadmill to determine VAT and peak oxygen consumption (VO2 peak).

Results: CT and IT groups showed increased in relative aerobic fitness (ΔVO2peak = 4.1± 0.4 and 4.4±0.3 ml/kg/min CT and IT, respectively; p<0.05).

Significant relationships were observed to: 1) CT (PetCO2VAT and VO2peak r=0.49; PetCO2VAT and VEVCO2VAT r= -0.80; P=0.01); and 2) IT (PetCO2VAT and VO2peak r=0.39; PetCO2VAT and VEVCO2VAT r= -0.45; P=0.01).

Conclusion: CT and IT demonstrated the same responsiveness in increase PetCO2 values during GET in CAD patients. These results suggest that the factors related to both an increased cardiorespiratory fitness and ventilatory efficiency after interventions may be responsible to increased PetCO2 during GET.