Introduction: Ventilatory responses during exercise have emerged as significant predictors of morbidity and mortality in heart failure (HF) patients. While exercise training (ET) has been shown to improve ventilatory responses in systolic HF patients, no study to date has examined the effect of ET on ventilatory responses following ET in diastolic HF (DHF) patients.

Purpose: Therefore, the goal of the present investigation was to assess the ventilatory responses after randomization to an endurance ET intervention or non-exercise control condition in older DHF patients.

Design: Fifty-eight elderly subjects (> 65 yr) with isolated DHF (clinical symptoms of HF, ejection fraction > 50%, and no coronary, valvular, or pulmonary disease) were randomly assigned to control (CG) or exercise group (EG).

Method: All patients were stable and well compensated outpatients with NYHA II-III symptoms. At baseline and 4-month follow-up, all subjects performed an incremental upright bicycle ergometer test until exhaustion. Gas exchange measures were collected along with continuous electrocardiography. Patients who were randomized to the EG underwent 4-months of structured aerobic exercise training consisting of three 30- to 40-minute sessions per week at 50% to 75% of HR reserve, while the CG continued with usual care. All tests and measurements were performed in both groups at entry and after the study period. The volume of oxygen consumption (Vo₂) and carbon dioxide production (Vco₂), minute ventilation (VE), and end-tidal oxygen and carbon dioxide pressure (PET o₂ and PET Co₂) were collected and plotted against exercise time. The ventilatory equivalents for oxygen and carbon dioxide (VE/Vo₂ and VE/Vco₂) and the respiratory exchange ratio (RER = Vco₂/Vo₂) were calculated and co-plotted against exercise time. Tidal volumen (TV) was calculated from VE and RR. The VE/Vco₂ slope was calculated by plotting the rate of ventilation against Vco₂, forming a regression line, and calculating the slope of the regression line.

Results: There were no statistical differences between CG and EG at baseline in any of the variables studied. At follow-up Vo₂ peak (28%), VE (38%), RR (3%), TV (26%), and VE/Vo₂ (6%) were significantly higher (P < .05) in EG than CG. However, there were no significant difference in the VE/Vco₂ slope between CG and EG after ET (33.3 vs 33.8, P = .44, respectively).

Conclusions: Although limited by a relatively small sample size, it appears that ET had no significant benefit on ventilatory responses or efficiency in elderly DHF patients. Therefore, the ET induced increase in functional capacity observed in DHF patients appears to occur independently of ventilatory adaptations.