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To increase muscle mass and strength in patients with chronic congestive heart failure (CHF), there is a need for implementing resistance exercises in exercise training programs. This study sought to assess the safety of rhythmic strength exercise with respect to left ventricular function in 9 patients with stable CHF, compared with 6 stable coronary patients with mild left ventricular dysfunction (control group). With use of right-sided catheterization, changes in left ventricular function were assessed during double leg press exercise at loads of 60% and 80% of maximum voluntary contraction. The exercise sessions lasted 14 minutes each, divided into work and recovery phases of 60/120 seconds. In CHF, during exercise at a 60% load, there was a significant increase in heart rate (mean +/- SEM 90 +/- 4 beats/min; p <0.05), mean arterial blood pressure (95 +/- 3 mm Hg; p <0.01), diastolic pulmonary artery pressure (20.2 +/- 2.7 mm Hg; p <0.01), and cardiac index (3 +/- 0.3 L/m2/min; p <0.05). Additionally, during leg press exercise at an 80% load, there was a significant decrease in systemic vascular resistance (1,086 +/- 80 dynes x s x cm(-5); p <0.001), an increased cardiac index (3.4 +/- 0.1; p <0.001), and left ventricular stroke work index (75 +/- 5 g x m/m2; p <0.01), suggesting enhanced left ventricular function. Compared with controls, in CHF the magnitude of changes in hemodynamic parameters during exercise, demonstrated at a 60% load, was significantly smaller (systemic vascular resistance: [mean] 1,613 --> 1000 vs 1472 --> 1,247 dynes x s x cm(-5); cardiac index: 2.4 --> 3 vs 2.8 --> 4.4 L/m2/min, and stroke work index: 60 --> 69 vs 114 --> 155 g x m/m2; p <0.05 each). Nevertheless, changes indicated an enhanced contractile function of the left ventricle in CHF. This study demonstrates stability of left ventricular function during resistance exercise in well-compensated CHF patients with optimal drug therapy, as well as the appropriateness of the chosen mode and intensity applied as these factors relate to cardiovascular stress. This conclusion cannot be extrapolated to patients with less well-compensated heart failure, or to more protracted resistance training. [ABSTRACT FROM AUTHOR]

This study sought to assess the safety of interval exercise training in patients with chronic congestive heart failure (CHF) with respect to left ventricular (LV) function. For effective rehabilitation in CHF, both aerobic capacity and muscle strength need to be improved. We have previously demonstrated in both coronary artery bypass surgery and patients with CHF that interval exercise training (IET) offers advantages over steady-state exercise training (SSET). However, because LV function during IET has not yet been studied, the safety of this method in CHF remains unclear. To assess LV function during IET and SSET, at the same average power output, 11 patients with stable CHF were compared with 9 stable coronary patients with minimal LV dysfunction (control group). Using first-pass radionuclide ventriculography, changes in LV function were assessed during work versus recovery phases, at temporally matched times between the fifth and sixteenth minute of IET and SSET. In CHF during IET, there were no significant variations in the parameters measured during work and/or recovery phases. During the course of both IET and SSET, there was a significant increase in LV ejection fraction (5 vs 4 U; p <0.05 each), accompanied by increased heart rate (6 vs 8 beats/min; p <0.05 each) and cardiac output (2.4 vs 1.8 L/min; p <0.01 and p <0.05). In CHF, the magnitude of change in LV ejection fraction during IET was similar to that seen in controls. Both LV ejection fraction and the clinical status in patients with CHF remained stable during IET. Because IET appears to be as safe as SSET with respect to LV function, IET can be recommended for exercise training in CHF to apply higher peripheral exercise stimuli and with no greater LV stress than during SSET. [ABSTRACT FROM AUTHOR]

Background: In chronic heart failure (CHF), impaired pulmonary function can independently contribute to oxygen desaturation and reduced physical activity. We investigated the effect of breathing rate on oxygen saturation and other respiratory indices., Methods: Arterial oxygen saturation (SaO2) and respiratory indices were recorded during spontaneous breathing (baseline) and during controlled breathing at 15, six, and three breaths per min in 50 patients with CHF and in 11 healthy volunteers (controls). 15 patients with CHF were randomly allocated 1 month of respiratory training to decrease their respiratory rate to six breaths per min. Respiratory indices were recorded before training, at the end of training, and 1 month after training., Findings: During spontaneous breathing, mean SaO2 was lower in CHF patients than in controls (91-4% [SD 0.4] vs 95.4% [0.2], p<0.001). Controlled breathing increased SaO2 at all breathing rates in patients with CHF. Compared with baseline, minute ventilation increased at 15 breaths per min (+45.9% [9.8], p<0.01), did not change at six breaths per min, and decreased at three breaths per min (-40.3% [4.8], p<0.001). In the nine CHF patients who had 1 month of respiratory training, resting SaO2 increased from 92.5% (0.3) at baseline to 93.2% (0.4) (p<0.05), their breathing rate per min decreased from 13.4 (1.5) to 7.6 (1.9) (p<0.001), peak oxygen consumption increased from 1157 (83) to 1368 (110) L/min (p<0.05), exercise time increased from 583 (29) to 615 (23) min/s (p<0.05), and perception of dyspnoea reduced from a score of 19.0 (0.4) to 17.3 (0.9) on the Borg scale (p<0.05). There were no changes in the respiratory indices in the patients who did not have respiratory training., Interpretation: Slowing respiratory rate reduces dyspnoea and improves both resting pulmonary gas exchange and exercise performance in patients with CHF.

We prospectively assessed whether baseline central hemodynamics and exercise capacity can predict improvement of VO2 at ventilatory threshold (VT) after exercise training in patients with severe chronic congestive heart failure. Eighteen patients (mean +/- SEM; age 52 +/- 2 years), half of them listed for transplant, underwent 3 weeks of exercise training (interval cycle and treadmill walking; 5 x/week) and 3 weeks of activity restriction in a random-order crossover trial. Baseline data were not significantly different for groups with exercise training first and activity restriction first: cardiac index at rest (2.1 +/- 0.1 L/m2/min), maximum cardiac index (3.1 +/- 0.2 L/m2/min) (Fick), and echocardiographic ejection fraction (21 +/- 1%). The same was true for cardiopulmonary exercise data (cycle ergometry; up 12.5 W/min): VO2 at VT (9.3 +/- 0.4 ml/kg/min), maximum VO2 (12.2 +/- 0.7 ml/kg/min), VT in percentage of predicted maximum VO2 (31 +/- 2%), heart rate at VT (95 +/- 4 beats/min), and decrease of dead space-to-tidal volume ratio from rest to VT (33 +/- 1 --> 29 +/- 1). Improvement of VO2 at VT after training (2.2 +/- 0.4 ml/kg/min; p <0.001) was not related to baseline central hemodynamics (r = <0.10 for each), but was greater in patients with a lower baseline VO2 at VT (r = -0.65; p <0.01), peak VO2 (r = -0.66; p <0.01), VT in percentage of predicted maximum VO2 (r = -0.74; p <0.001), heart rate at VT (r = -0.63; p <0.01), and smaller decrease of dead space-to-tidal volume ratio from rest to VT (r = 0.65; p <0.01). Ejection fraction after exercise training (24 +/- 2%) and activity restriction (23 +/- 2%) did not differ significantly compared with baseline, and patient status (heart failure and cardiac rhythm) remained stable. Three parameters accounted for 84% of the variance of improvement in VO2 at VT: VO2 at VT in percent predicted maximum VO2, decrease of dead space-to-tidal volume ratio, and heart rate at VT. The findings suggest that there was a greater increase in VO2 at VT after exercise training in patients with greater peripheral deconditioning at baseline. The improvement was unrelated to central hemodynamics. Clinically stable patients with severe chronic congestive heart failure, potential heart transplant candidates, and those awaiting transplantation may benefit from involvement in a short-term exercise training program.

Background: Patients with chronic heart failure (CHF) are characterized by abnormal gas exchange and ventilatory responses to exercise., Hypothesis: This study compares variables obtained from cardiopulmonary exercise testing in 35 patients with CHF with 35 age- and weight-matched healthy subjects. A second goal was to obtain cardiopulmonary variables measured at ventilatory threshold to distinguish patient changes from those of healthy subjects., Methods: Exercise testing was carried out using bicycle ergometry with ramplike protocol (work rate increments 12.5 W/min). Gas exchange and ventilation were measured breath by breath., Results: Compared with healthy subjects, the VO2 in patients was lower at identical work rates (p < 0.004) and at ventilatory threshold (p < 0.0001), and the slope of the VO2 curve during incremental exercise was flatter (p < 0.05). With the exception of heart rate, the variables for VO2, VCO2, ventilation, O2 pulse, ventilatory equivalents for O2 and CO2, and VD/VT (physiologic deadspace to tidal volume ratio), as well as lactate differed significantly at identical work rates. With the exception of VD/VT, all cardiopulmonary variables showed significant differences in their slopes during exercise. By means of a discriminant analysis, VCO2 and ventilation proved to be the most distinguishing variables at ventilatory threshold between patients with CHF and healthy subjects., Conclusions: These results indicate the clinical usefulness of cardiopulmonary exercise testing when assessing functional impairment due to CHF. For treatment evaluation, not only VO2 but also VCO2 and ventilation responses to exercise should be considered.

Sixty-nine healthy normals from the 3rd to the 6th decade were stressed to exhaustion by means of a cardiopulmonary exercise test on a bicycle ergometer. Peak VO2, VCO2 and ventilation differed significantly between the four decades: peak VO2 (mean +/- SD) was 3,393 +/- 516; 3,061 +/- 444; 2,817 +/- 801 and 2,589 +/- 687 ml/min (p < 0.001). The mean value for respiratory gas exchange ratio (R) at ventilatory threshold (VT) was 0.86 and for ventilatory equivalent O2 (EqO2) 0.24. Mean VO2 at VT was 1,662 +/- 521; 1,462 +/- 308; 1,474 +/- 559 and 1,268 +/- 232 ml/min (p < 0.05). The VO2 of the four age groups at VT was between 47 and 49% of peak VO2 (n.s.), and both parameters correlated significantly (r = 0.67, p < 0.001). The average increase of VO2 in relation to work rate (ml/W/min) was 11.5 +/- 1.2 for the total exercise and was below VT lower (9.4 +/- 1.9) than above VT (12.9 +/- 1.2) (p < 0.001).