788-4 Does Low Level Training Increase Peak Aerobic Capacity in Patients with Congestive Heart Failure?

Abstract

Conventional high level exercise training at a workload consistent with 75% of peak oxygen consumption (pVO 2 , ml/min/kg) in patients with congestive heart failure (CHF) improves peak aerobic capacity and limb vasodilatory capacity. However, training at this workload may promote left ventricular dilatation in patients with CHF by prolonged exposure to substantially elevated filling pressure (PCWP). Whether training at low level, I.e., at a workload consistent with <50% pVO 2 , would result in limited increases in PCWP while still improving peak aerobic capacity and peripheral vasodilatory function is unknown. Accordingly, 15 patients with stable advanced CHF underwent measurement of 1) the PCWP response to low vs high level exercise, and 2) the change in peak aerobic capacity and limb vasodilatory capacity resulting from participation in a low level training program. PCWP was measured by right heart catheterization at rest, and during low and high level exercise. Patients then performed 12 weeks of low level training, utilizing a semi-recumbent bicycle. Pre- and post-training evaluations included pVO 2 , calf and forearm peak hyperemic blood flow (PHBF, ml/min/100 ml), and resting heart rate (HR, b/min). 1)PCWP rose to 20 mmHg during low level exercise (Δ54% vs rest), and 34 mmHg during high level exercise (Δ162% vs rest). 2)Pre- and post-training data are as follows: pVO 2 calf PHBF forearm PHBF HR pre-train 99 18 23 99 post-train 14.1 36 20 80 p value 0.02 <0.01 NS 0.02 1) The rise in PCWP is significantly less during low level exercise than during high level exercise. 2) Training at a workload consistent with ≤50% of pVO 2 significantly improves peak aerobic capacity. 3) PHBF in the trained calf increases 100% from baseline, while it does not change in the untrained forearm. Enhanced vasodilatory responses in exercising muscle may be an important contributor to improved peak aerobic capacity. Thus, low level training produces benefits similar to high level training with only a moderate rise in PCWP, and may therefore provide less of a stimulus for ventricular dilatation.