Your heart provides the beat that keeps your life going. Despite its importance, one person in the U.S. dies from cardiovascular disease (CVD) every 34 seconds. To keep your heart healthy, cardiovascular (or cardiorespiratory) fitness (CRF) is of prime importance. In fact, the American Heart Association, years ago, advocated for the routine monitoring of CRF in the clinic. Yet even with these efforts, only 12% of Americans are metabolically active, a marker of poor cardiovascular fitness across the country. But what is cardiovascular fitness, exactly? Here’s a guide to staying out of that statistical group.

What is cardiovascular fitness?

Cardiovascular fitness measures your heart and lungs’ ability to provide oxygen to your muscles as you exercise. Scientists typically employ peak oxygen uptake (VO_2max) as the gold standard for measuring CRF. Such an approach to measuring cardiovascular fitness, however, requires complex laboratory equipment that’s not easily accessible. But don’t worry, as there are other easy ways for you to measure cardiovascular fitness at home:

Here's how to measure your cardiovascular fitness at home.

• Perform a 1.5-mile jog and see how long it takes you to complete it. What constitutes good fitness will depend on your age; for example, completing the jog in 13.5 minutes for women and 11.5 minutes for men is a metric of good performance for a 35-year-old.
  
• Perform a sit-up or push-up count test: Perform as many push-ups and sit-ups as you can until you are unable to proceed any further. Strive to do at least 20 push-ups or 40 sit-ups without getting tired in a single go. 

Physical activity induces several changes in your body as it adapts to increased exertion. These adaptations play key roles in improving your body’s cardiovascular fitness:

• Activation of the sympathetic nervous system (SNS): The SNS comprises a series of nerves that mediate your body’s “fight-or-flight” response. While this response is associated with stressful situations, these nerves are also turned on during periods of exercise. As you exercise, the SNS is responsible for increasing blood flow and activating your muscles.
  
• Increased metabolism: As your SNS is activated in exercise, your body increases its energy needs. Your body’s cells meet their energy needs by ingesting oxygen and biomolecules such as sugars and fats. As you continue to exercise, your body also releases lactate, which provides a host of protective benefits.
  
• Increased circulation: Since your body consumes more oxygen, it needs a way to transport the oxygen to your body’s muscles. Your body accomplishes this by increasing your heart rate and the amount of blood circulating through your blood vessels. 

The health benefits of improving cardiovascular fitness

There are many reasons for you to improve your cardiovascular fitness. For one, maximizing your cardiovascular fitness, or CRF, increases your metabolic health and reduces the risk of multiple health conditions:

• Reduced type 2 diabetes (T2D) risk: The research on cardiovascular fitness has clearly shown its ability to reduce T2D risk. For instance, a 2020 study of 168 participants determined that those who had higher peak oxygen consumption during exercise were the least likely to have metabolic syndrome. Much of these correlations stem from the benefits that exercise brings, including improved well-being, improved glucose and blood pressure control, and reduced fat.
  
• Reduced risk of CVD: Improving the heart’s ability to pump blood to the rest of your body also improves heart health. A 2021 systematic review of 45 eligible studies determined that high-intensity, high-load resistance training yielded the greatest improvements in CRF among obese participants. (See our guide: Is strength training beneficial for metabolic health?) Another 2021 meta-analysis of 21 studies had similar results, suggesting that cardiovascular fitness could be a powerful predictor of mortality among CVD patients.

Improved cardiovascular fitness also has benefits for your cognitive and mental health. These findings are vital at a time when depression and other mental health disorders are on the rise as a result of the COVID-19 pandemic:

• Improved cognition: A 2021 study done on 501 middle-aged adults determined that those with the highest cardiovascular fitness had the lowest CVD risk and the highest cognitive function. These adults had the highest visuospatial scores and were best able to problem-solve. A 2020 study of 167 teenagers aged 14 and 15 observed a positive correlation between CRF and cognitive and social functioning. That finding contributed to cardiovascular fitness being the best contributor of both traits. People who continue to improve their CRF over time also see a reduced risk of incident dementia, according to a 2019 longitudinal study.
  
• Reduced mental health risk: A 2019 longitudinal study of 88 demonstrated that women diagnosed with exhaustion disorder who had at least medium cardiorespiratory fitness were more likely to reduce the severity of exhaustion disorder. Having low cardiovascular fitness also increases the risk of mental health disorders, namely depression and anxiety. 

Whether these benefits stem from improved physical health requires further investigation. How the human body mediates these benefits with improved cardiovascular fitness also requires further investigation. Nevertheless, the research remains clear on cardiovascular fitness's benefits. Improving your heart’s ability to pump oxygen to the rest of your body improves your overall health and reduces the risk of disease. 

How to improve cardiovascular fitness

With higher cardiovascular fitness metrics correlated with improved disease outcomes, the next step is knowing how to achieve optimal cardiovascular fitness for your health.

• Adopt a high-intensity interval training (HIIT) regimen: HIIT is a training regimen that alternates between lower-intensity movement and high-intensity work. The workout provides a viable alternative for people with busy schedules to achieve similar improvements in cardiovascular fitness as those who perform other kinds of workouts. HIIT is therefore an excellent exercise option provided you don’t have an existing condition such as CVD, diabetes, or high blood pressure.
  
• Implement a diverse workout routine: For those who cannot adopt HIIT, there are other exercising options to try. A brisk walk, run, or participation in sports can improve cardiovascular fitness by lowering blood pressure and heart rate. Adopting resistance training also improves CRF, according to a 2022 systematic review and meta-analysis of 37 eligible studies of older adults. On top of that, resistance (aka strength) training reduces fat and improves muscle strength. (Learn more about strength training for beginners.)
  
• Exercise at different times of the day: Setting aside a time of the day to exercise doesn’t have to be stringent or intimidating. For one, exercising before or after you eat a meal can yield similar benefits to your metabolic health as well as your cardiovascular fitness. While the time of day you exercise can yield unique sets of benefits, any time of day is a great time to exercise. 
  
• Try a plant-based diet: Contrary to popular opinion, a plant-based diet can take many forms, and doesn’t mean you have to eliminate meat — just eat less of it. (All vegetarian diets are plant-based, but not all plant-based diets are vegetarian.)  Leading medical organizations recommend the Mediterranean diet as one of the healthiest plant-based diets. Why? A 2020 systematic review of 11 eligible studies determined that participants who adopted the Mediterranean diet had higher cardiovascular fitness values relative to other diets. Eating the Mediterranean diet alone provides many metabolic and cognitive benefits including the provision of antioxidants and improving insulin resistance. The mechanisms involved with the diet’s benefits to exercise outcomes are not fully understood. Nevertheless, having a plant-based diet could fortify and boost the cardiovascular fitness gains you’re making from exercise. (And even if you need to eat more meat in a body-building regimen, integrating vegetables into your diet will help you maintain a healthy, balanced diet.)

The good news is that these recommendations can be accomplished even when you have a busy schedule. Just a half-hour of physical exercise can go a long way for you to work towards increasing your cardiovascular fitness. 

Key Takeaways

What is cardiovascular fitness? Cardiovascular fitness, also known as CRF, is defined as your body’s circulatory system optimally delivering oxygen to your muscles and your muscles using that oxygen for sustained physical activity. Maximizing your cardiovascular fitness provides a host of physical benefits that reduce the risk of cardiovascular disease (CVD) and type 2 diabetes (T2D). On top of that, having good cardiovascular fitness improves cognitive health and keeps your brain mentally sharp throughout the day. The best part is that there are many ways for you to maximize your cardiovascular fitness. What training regimen you adopt depends on the goals you set for your body. Irrespective of what regimen you adopt, you can feel secure knowing that your cardiovascular fitness will improve as you exercise. Just make sure to complement your exercise regimen with a healthy diet, which will help fortify your CRF gains.

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