BACKGROUND: Pulmonary VO(2) on-kinetics during light-to-moderate-intensity constant-work-rate exercise, an experimental model mirroring energetic transitions during daily activities, has been shown to speed up with aerobic exercise training (AET) in normal subjects, but scant data are available in chronic heart failure (CHF). METHODS AND RESULTS: Thirty CHF patients were randomized to 3months of light-to-moderate-intensity AET (CHF-AET) or control (CHF-C). Baseline and end-protocol evaluations included i) one incremental cardiopulmonary exercise test with near infrared spectroscopy analysis of peak deoxygenated hemoglobin+myoglobin concentration changes (?[deoxy(Hb+Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO(2) on-kinetics phase I duration, phase II ?, and mean response time (MRT) assessment, and iii) circulating endothelial progenitor cell (EPC) measurement. Reference values were obtained in 7 age-matched normals (N). At end-protocol, phase I duration, phase II ?, and MRT were significantly reduced (-12%, -22%, and -19%, respectively) and peak VO(2), peak ?[deoxy(Hb+Mb)], and EPCs increased (9%, 20%, and 98%, respectively) in CHF-AET, but not in CHF-C. Peak ?[deoxy(Hb+Mb)] and EPCs relative increase correlated significantly to that of peak VO(2) (r=0.61 and 0.64, respectively, p<0.05). CONCLUSIONS: Light-to-moderate-intensity AET determined a near-normalization of pulmonary VO(2) on-kinetics in CHF patients. Such a marked plasticity has important implications for AET intensity prescription, especially in patients more functionally limited and with high exercise-related risk. The AET-induced simultaneous improvement of phase I and phase II, associated with an increase of peak peripheral oxygen extraction and EPCs, supports microcirculatory O(2) delivery impairment as a key factor determining exercise intolerance in CHF.
Speeding of pulmonary VO(2) on-kinetics by light-to-moderate-intensity aerobic exercise training in chronic heart failure: Clinical and pathophysiological correlates
Simone Porcelli;
2013
Abstract
BACKGROUND: Pulmonary VO(2) on-kinetics during light-to-moderate-intensity constant-work-rate exercise, an experimental model mirroring energetic transitions during daily activities, has been shown to speed up with aerobic exercise training (AET) in normal subjects, but scant data are available in chronic heart failure (CHF). METHODS AND RESULTS: Thirty CHF patients were randomized to 3months of light-to-moderate-intensity AET (CHF-AET) or control (CHF-C). Baseline and end-protocol evaluations included i) one incremental cardiopulmonary exercise test with near infrared spectroscopy analysis of peak deoxygenated hemoglobin+myoglobin concentration changes (?[deoxy(Hb+Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO(2) on-kinetics phase I duration, phase II ?, and mean response time (MRT) assessment, and iii) circulating endothelial progenitor cell (EPC) measurement. Reference values were obtained in 7 age-matched normals (N). At end-protocol, phase I duration, phase II ?, and MRT were significantly reduced (-12%, -22%, and -19%, respectively) and peak VO(2), peak ?[deoxy(Hb+Mb)], and EPCs increased (9%, 20%, and 98%, respectively) in CHF-AET, but not in CHF-C. Peak ?[deoxy(Hb+Mb)] and EPCs relative increase correlated significantly to that of peak VO(2) (r=0.61 and 0.64, respectively, p<0.05). CONCLUSIONS: Light-to-moderate-intensity AET determined a near-normalization of pulmonary VO(2) on-kinetics in CHF patients. Such a marked plasticity has important implications for AET intensity prescription, especially in patients more functionally limited and with high exercise-related risk. The AET-induced simultaneous improvement of phase I and phase II, associated with an increase of peak peripheral oxygen extraction and EPCs, supports microcirculatory O(2) delivery impairment as a key factor determining exercise intolerance in CHF.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
