When we train in zone 2, we use oxygen to maintain a low-intensity cardio workout. Transport of oxygen throughout the body requires the coordinated functions of the heart, lungs, blood vessels, and blood.
The heart is our main pumping mechanism, circulating oxygenated blood throughout the body to the working tissues. As the body begins to exercise, the heart must pump more blood to meet this increased demand.
Stroke volume is the volume of blood being pumped out with each beat. The heart pumps out approximately 70ml of blood each beat. Stroke volume and heart rate together determine cardiac output, which is the volume of blood being pumped through the heart in a given time.
The training effect of zone 2 is that stroke volume increases while exercise heart rate decreases, signaling greater cardiorespiratory endurance. That’s the long-term magic of taking things slow in your training.
“Zone 2 cardio makes your heart stronger and it will require fewer pumps to pump blood, making it more efficient,” says Niren. “Your body also expands its vascular system, better enabling it to deliver oxygenated blood to different parts of the body.”