How does exercise benefit heart failure patients?

Researchers in California and Utah studied patients as they performed 8 weeks of knee-extensor exercise.

First, the details.

• 6 healthy volunteers served as controls.
• 6 patients with congestive heart failure performed 8 weeks of knee-extensor training (both legs, separately).
• The heart failure patients were categorized as NYHA class II or III — slight to moderate limitation of physical activity.
• Muscle structure, and oxygen transport and metabolism (whole-body) were measured.

And, the results.

• Prior to training, oxygen uptake following cycling and knee-extensor exercise was lower in the heart failure patients vs the healthy volunteers.
• Knee-extensor training increased quadriceps muscle capillaries and mitochondrial density (how well these energy producing organelles perform their job).
• Despite not changing maximal cardiac output (the volume of blood being pumped by the heart), knee-extensor training increased the following measures of oxygen utilization.
• Maximal oxygen delivery to cells
• Arterial-venous oxygen difference (a measure of efficiency at taking oxygen out of the blood)
• Muscle oxygen diffusive conductance (efficiency of getting oxygen into cells)
• These changes increased single-leg maximum oxygen intake by 53% — a level exceeding that of the untrained controls.
• Post-training, oxygen delivery to cells during maximal cycling increased, matching the controls.

The bottom line?

The authors concluded there were “clear improvements in muscle structure, peripheral convective and diffusive oxygen transport, and subsequently, oxygen utilization support the efficacy of local skeletal muscle training as a powerful approach to combat exercise intolerance in congestive heart failure.”

So, keep exercising. The benefits in oxygen utilization are widespread. Even in the absence of direct effects on the heart, exercise helps the heart be more efficient at providing oxygen to peripheral cells, and the cells are more efficient at using that oxygen to produce energy.

9/20/11 21:04 JR