The Three Key Components of Aerobic Energy Production (PART 1: Oxygen Supply)

Last week, we explored why developing your aerobic system is just as vital as strength training in our program here at Pursuit. In the coming weeks, we’re going to break down the three key components of aerobic energy production:

• Oxygen Supply
• Oxygen Utilization
• Substrate Availability

Today, let’s dive into the first one : Oxygen Supply and how to improve it.

What Is Oxygen Supply?

Oxygen supply refers to how much oxygenated blood your heart can pump out and how efficiently that blood is delivered to your working muscles through your vascular system.
This process is driven by cardiac output, which is the amount of blood your heart pumps per minute. Improving cardiac output means improving both how much blood your heart can pump with each beat, and how effectively your vascular system delivers that blood throughout the body.

When we increase oxygen supply, we not only improve endurance and recovery, but also support overall heart health—lowering resting heart rate, reducing average blood pressure, and promoting longevity (George et al., 2018).

How Do We Improve Oxygen Supply

To begin, we can use the Cardiac Output Method , which we covered in a previous post: 🫀 Building the Hedge Against Disease.

This method involves longer-duration, low-to-moderate intensity training, often referred to as Zone 2 efforts. Training in Zone 2 typically means staying within a heart rate range of 130–150 BPM, depending on your fitness level, and working at a pace where you can still carry on a conversation.

This style of training promotes a specific adaptation called eccentric cardiac hypertrophy , which is an enlargement of the left ventricular cavity of the heart. A larger cavity means your heart can hold and pump more blood per beat, improving stroke volume and overall cardiac efficiency (D’Andrea et al., 2007; Utomi et al., 2013).

If your heart rate climbs too high during this type of training, the heart doesn’t have enough time to fully fill between beats, so we want to stay in that sweet spot to allow for maximum benefit.

Why It Matters

Not only does this training improve how well your heart functions, but it also stimulates the growth of new blood vessels—improving oxygen delivery to your muscles. This leads to better recovery, reduced soreness, and more resilience on those higher-intensity training days (Vega et al., 2017).

Cardiac Power Intervals

Another effective strategy for increasing oxygen supply is through Cardiac Power Intervals . These are high-intensity efforts followed by rest.

Unlike the Cardiac Output Method, which promotes eccentric hypertrophy, these intervals stimulate concentric cardiac hypertrophy —where the walls of the heart become thicker and stronger (Spence et al., 2011). Instead of increasing the size of the chamber, this adaptation improves how forcefully the heart contracts with each beat.

This improves cardiac endurance at higher heart rates and increases the density of mitochondria in the heart muscle, allowing the heart to use oxygen more effectively even during intense efforts (Chong et al., 2020; Nunes et al., 2020).

Putting It All Together

Whether you’re building a bigger heart with Zone 2 work or training it to pump harder with high-intensity intervals, both approaches help improve how well your body delivers oxygen—and that’s the first major piece of the aerobic performance puzzle.

Next up on the list is Oxygen Utilization , where we’ll talk about how your muscles actually use that oxygen once it arrives!

— The Pursuit Team

References

Chong, J., Baltodano, J., Pedrozo, Z., & Wang, Y. (2020). Mitochondrial function in cardiac hypertrophy and heart failure . Journal of Clinical Investigation , 130 (2), 721–732. https://doi.org/10.1172/JCI129165

D’Andrea, A., Riegler, L., Cocchia, R., Scarafile, R., Salerno, G., Gravino, R., … & Calabrò, R. (2007). Left ventricular myocardial velocities and deformation indexes in top-level athletes . Journal of the American Society of Echocardiography , 20 (3), 243–253. https://doi.org/10.1016/j.echo.2006.07.026

George, K. P., Oxborough, D., Forster, J., & Lord, R. (2018). Physiological hypertrophy in endurance athletes: the athlete’s heart . Heart , 104 (6), 456–467. https://doi.org/10.1136/heartjnl-2016-310514

Nunes, R. B., Alves, J. P., Kessler, L. P., & Dal Lago, P. (2020). Aerobic exercise improves mitochondrial function and oxidative stress in heart failure . European Journal of Applied Physiology , 120 (1), 1–12. https://doi.org/10.1007/s00421-019-04216-1

Spence, A. L., Carter, H. H., Naylor, L. H., & Green, D. J. (2011). A prospective randomized longitudinal MRI study of left ventricular adaptation to endurance and resistance exercise training in humans . Journal of Physiology , 589 (22), 5443–5452. https://doi.org/10.1113/jphysiol.2011.216135

Utomi, V., Oxborough, D., Whyte, G. P., Somauroo, J., Sharma, S., Shave, R., … & George, K. (2013). Systematic review and meta-analysis of training mode, imaging modality and body size influences on the morphology and function of the male athlete’s heart . Heart , 99 (23), 1727–1733. https://doi.org/10.1136/heartjnl-2012-303465

Vega, R. B., Konhilas, J. P., Kelly, D. P., & Leinwand, L. A. (2017). Molecular mechanisms underlying cardiac adaptation to exercise . Cell Metabolism , 25 (5), 1012–1026. https://doi.org/10.1016/j.cmet.2017.04.025