You're likely familiar with the physical sensations that come with a workout, particularly when you push yourself to the limit. Your body temperature rises, and your skin flushes. Your pores release refreshing sweat as your heart pumps against your chest. Your breathing speeds up as you connect with your peak performance. These physiological responses result from the hard work of the heart and lungs as the cardiac system delivers the necessary blood and oxygen for strenuous exercise. 

We can measure how well this process works with a metric called VO2 max. Your measured VO2 max describes the amount of oxygen you use when exercising at full capacity . The higher your VO2 max, the more efficiently your heart pushes blood out to your organs and tissues. Conversely, research indicates that a poor VO2 max could predict future cardiac problems. Knowing and monitoring your VO2 max over time is a great way to stay on top of your heart health.

Metrics That Matter

VO2 Max

VO2 max serves as one of the best measurements of your cardiac health. In fact, the American Heart Association recommends adding it to the list of vital signs, such as blood pressure, that doctors test during patient encounters. Doctors express VO2 max as the amount of oxygen in milliliters your body consumes in 60 seconds for each kilogram you weigh (mL/kg/min).

Let's break down the process. Each breath you take pulls oxygen into the body, where it enters the bloodstream. Then, your heart pumps this oxygen-rich blood throughout the body, where it enters the muscles and triggers chemical reactions to create energy. Specifically, the oxygenated blood breaks down carbs, fats, and proteins for fuel. When we're working out, we need more fuel than usual, which is why we begin breathing deeper, faster, and harder during a tough workout. When we exercise, our heart and lungs get stronger, making it easier for the body to distribute blood and oxygen. 

As a result, when you train to raise your VO2 max, you'll be impressed by your newfound endurance. Your VO2 max test results also note your aerobic threshold. As you move your body, oxygen alone fuels your muscles in the process described above, known as aerobic metabolism. During this phase, you can exercise easily without getting winded or wearing yourself out. 

Aerobic and Anaerobic Metabolism

Eventually, your body meets its aerobic threshold (AT) and runs out of readily available energy. AT represents a percentage of your maximum heart rate. For example, if you're an athlete, your AT might be 85% of your max HR. If you're more sedentary, your AT  might max out at 65% of your max HR. 

If you don't know your maximum heart rate (MHR), use this easy equation:

205.8 - (0.685 x age)

For a 40-year-old, the equation to estimate MHR looks like this:

205.8 - (0.685 x 40)

205.8 - 27.4 = MHR of 178.4

Based on this example, at age 40, you might have an AT of 115.96 if you rarely exercise. That means you start to feel fatigued when your heart rate reaches 116 (65% of your MHR) for an extended time. As your fitness improves, your AT might be closer to 151.64 (85% of your MHR). At that point, you'll notice you feel more capable while working out, even as intensity increases.

Either way, at this point, you enter the anaerobic metabolism phase, when your body can no longer deliver oxygen fast enough to meet your energy needs. Without oxygen, your body begins to burn stored sugars to maintain metabolic function. 

When you hit the anaerobic threshold, the process of burning carbohydrates for energy produces excess lactic acid. This substance is a byproduct of glycolysis, the chemical reactions that break down sugars to fuel the muscles. You will notice the familiar fatigue, burning, and pain in the muscles that come when it's time for cooldown. With a higher VO2 max, you'll also be able to max out your AT for more effective workouts and better overall health and fitness. 

Metabolic Equivalent of Task

Another important number to know? Your metabolic equivalent of task, or MET. One MET is the amount of energy you burn while lying on the couch watching Netflix. You might burn about two METs when strolling through your favorite store, five while cleaning your house, and six or more during vigorous exercise.

VO2 max also reveals your heart rate recovery (HRR), a critical reflection of cardiovascular health. HRR is the amount your heart slows from the moment you stop exercising to precisely one minute later. According to the American Heart Association, HRR predicts mortality from coronary artery disease as well as other causes. In other words, the faster your heart returns to its normal speed after intense exercise, the better your overall cardiac health.

A VO2 max test is the most precise, available measure of these variables. During this test, you perform intense exercise in a lab setting while a special mask captures how much oxygen you expel with each breath. Now that we know which metrics we need to look at to gauge cardiovascular health with VO2 max, let's dive into what you can learn about your own body from this type of test. 

Reviewing the Research

To make this just a bit more complicated, it's impossible to point to a "good" VO2 number. A healthy range varies depending on your age, fitness level, and genetic profile. You might have a lower VO2 at age 50 than you do at age 40, even if nothing else about your lifestyle has changed. Resting heart rate, waist circumference, and weight also affect your body's ability to use oxygen during workouts.

Although you can estimate your VO2 max online or with wearables such as Garmin or AppleWatch, a clinical test gives  an accurate reading of your VO2 max, METs, and aerobic and anaerobic threshold. 

Tracking these numbers over time is a good way to monitor your cardiovascular health. Successfully increasing your VO2 max means that your body has gotten better at utilizing oxygen. A landmark study published in 2019 by the European Journal of Cardiology linked a positive change in VO2 max to a lower risk of heart disease and premature death from cardiac causes. 

Checking VO2 max regularly isn't just for athletes. The researchers’ results were even more significant with a sedentary lifestyle. People who rarely exercised before participating in the study reduced their risk of cardiac events by 9%, compared to just 1% for elite athletes. If you have a solid exercise routine already, you would likely fall somewhere in the middle. 

Even people who already have serious cardiac issues can benefit from boosting their VO2 max. A study published in the AHA journal Circulation found that increasing VO2 max leads to better clinical outcomes for chronic heart failure patients. 

A high VO2 max also correlates with better endurance, which means that raising your VO2 max will enable you to endure harder workouts for longer periods of time.  As a result, you will also lower your risk of high blood pressure, a major factor in heart health problems. The American Journal of Medicine notes that your long-term cardiorespiratory fitness directly affects your future chances of developing hypertension.

Making VO2 Max Work for You

You can cut your chance of cardiac events in the future by taking steps to improve your cardiac health today. Most experts recommend high-intensity interval training (HIIT) as a fast route to better VO2 max. According to a study published in Medicine & Science in Sports and Exercise, you can increase this metric by about 3% if you engage in HIIT twice a week for four weeks. What's more, just a 1 mL boost in VO2 max reduces your risk of death from any cause by 2.8%, and from a heart attack by 3.2%.

Unsure where to start? HIIT involves pushing your endurance limits for short bursts of your workout, then returning to a strong, steady active heart rate. For example, sprint until you reach your maximum HR and keep it up for three minutes, then jog for five minutes as you maintain a steady active heart rate before pushing it to the limit once again. 

If you're new to HIIT or to working out in general, you don't need a specific formula to improve your heart health. Simply increase the intensity of each workout how you are able. Run if you usually jog, jog if you usually walk—for as long as you can keep it up. Each time you exert yourself, try to go just a little bit further than you did during your last workout. 

The bottom line? Metrics like VO2 max, AT, and HRR provide a red flag for low cardiorespiratory fitness, which dramatically reduces your lifelong heart health. By striving to improve your numbers, you lower your risk of premature death from all causes, particularly cardiac events. You also reduce your risk of developing cancer, especially breast and colorectal cancers, according to a meta-analysis published by the Annals of Oncology.

Ready to improve your VO2 max? Connect with Fitnescity to book your VO2 max test. Understanding your baseline and measuring progress over time will give you the information you need to protect your heart now and for years to come. 

References

https://www.hsph.harvard.edu/nutritionsource/staying-active/ 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5362290/ 

https://www.ahajournals.org/doi/10.1161/CIRCHEARTFAILURE.111.965186 

https://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000461 

https://www.eurekalert.org/news-releases/593207 

https://pubmed.ncbi.nlm.nih.gov/12439086/ 

https://www.bicycling.com/health-nutrition/a27105274/higher-fitness-linked-to-lower-death-heart-disease/ 

https://www.webmd.com/fitness-exercise/what-to-know-about-vo2-max 

https://www.ahajournals.org/doi/full/10.1161/JAHA.117.008341 

https://www.sciencedirect.com/science/article/pii/S235290671930034X#

https://www.annalsofoncology.org/article/S0923-7534(19)31368-7/fulltext