Is the ability of the heart lungs and blood vessels to supply oxygen to your body tissues during sustained physical activity?

While there are numerous methods for evaluating aerobic capacity, in most instances treadmill walking/running is appropriate for the majority of individuals. Normative data correlates time on the treadmill with aerobic fitness. V̇O2 is an index of the body’s efficiency at producing work. It is expressed in milliliters of oxygen consumed per minute, and adjusted for body weight in kilograms: ml/kg/min. There are many factors that can influence V̇O2max, e.g. heredity, training, age, gender, and body composition. Generally, V̇O2max declines with age (about 2% per year after age 30) and males typically have a greater oxygen consumption value than females. Nevertheless, the trend is that a higher V̇O2 max allows one to produce more energy, thereby performing more work. With this in mind, V̇O2 max is the "gold standard" measure of overall fitness.

Aerobic fitness is assessed by having the subject perform exercise at increased loads, for 12 to 15 minutes, while breathing into a mouthpiece which collects information on inspired and expired air. A treadmill, personal bike on a Computrainer, or a stationary bicycle are typically used. The test starts with an easy-moderate work load which is maintained for a 1-2 minutes. The load is increased gradually every 1-2 minutes until reaching the maximum level that the subject can tolerate and/or until physiological parameters such as heart rate, oxygen consumption, f... have hit a peak or plateau. This is done by increasing the cycling resistance or the speed and/or grade of the treadmill. The oxygen uptake, heart rate, speed and/or watts are measured at the ventilatory threshold and at maximal load, the latter would be the subject's V̇O2 max.

V̇O2 max values cannot be used in every day training, but follow-up V̇O2 tests can be used as a measure of progress. However, since heart rate, speed and/or power is typically measured during a V̇O2 max test, various heart rate, speed and/or power levels can be garnered from testing and then associated to appropriate training zones, which are then applied to everyday training. Other information such as V̇O2 economy (oxygen consumption values at a given heart rate or power output) can also be extracted from the data, compared to subsequent tests and against performance norms.

Training results in an increase in the efficiency of oxygen transport within the body. By lowering the resting heart rate (HR), and the HR at sub maximal loads, the heart pumps more blood with every heart beat. This, in addition to other physiological changes, increases the oxygen extraction capability. When an individual is tested before and after training while performing exercise at the same load, a lower HR is shown after training because more blood (thus, oxygen) is delivered in each heart beat. Such HR differences during exercise can be used to predict aerobic fitness.   The % of increase in V̇O2 max is dependent on many variables and differs considerably from individual to individual, ranging from 5-30%. In general, individuals who are the least fit see the largest changes and individuals who are highly fit see the smallest changes.

Significant amounts of research and public health data indicate that low aerobic fitness levels are correlated with an increased risk of premature death from many causes but in particular from cardiovascular disease. Accordingly, higher aerobic fitness levels are associated with numerous health benefits e.g. longer lifespan, better quality of life, reduced risks for stroke, heart disease, diabetes and cancer, improved mood and self-esteem, and improved sleep patterns. To improve or maintain cardiovascular health an individual must engage in cardiovascular exercise (run, walk, swim, bike, etc...) at least 3 times per week. Currently, however, public health data indicates that only 22-25% of Americans exercise regularly enough to achieve these positive health benefits.

V̇O2 max is also a predictor of performance, although its correlation to athletic success in endurance sports is only 30-40%, with other factors such as sustainable lactate threshold, motivation, training, etc... also playing a role. In general, however the higher a V̇O2 max the more potential for a successful performance in an aerobic endurance event.

When it comes to increasing physical performance, cardiorespiratory endurance is a term highly relevant to understand, as it affects your ability to perform better and longer. But what is it exactly and what can you do to improve it? In this post, we will give you an overview of cardiorespiratory endurance, how it is related to your physical performance and what you can do to boost it. 

What is Cardiorespiratory Endurance?

In short, cardiorespiratory endurance measures how well the body performs during long periods of exercise. It is, therefore, an indicator of how fit and healthy you are. Increasing cardiorespiratory endurance means that you will increase your physical shape, and therefore be able to exercise for longer periods and at a higher intensity level, without getting tired. Your body can keep exercising for a long time without stopping. 

More specifically, cardiorespiratory endurance is the level at which your heart, your lungs, and your muscles work together. When we exercise, your muscles need fuel, one of them being oxygen. And it is your heart, lungs and blood vessels that have to provide this to your muscles. So when a person’s cardiorespiratory endurance is measured it means that you examine how well their body takes in and utilizes oxygen. That will directly influence your physical performance. 

The term can also be referred to as aerobic capacity, cardiovascular fitness, and aerobic fitness. 

Whether you want to strengthen your physical performance, get in shape or lose weight, it is important to look at how you can increase your cardiorespiratory endurance. But let us first look into how it is tested and measured.

Measuring your Cardiorespiratory Endurance

The test of cardiorespiratory endurance is done by measuring maximum oxygen uptake (VO2 max) and metabolic equivalent (MET.) VO2 determines the maximum amount of oxygen that the body is capable of using during high-intensity activities. Both heart rate and oxygen consumption are measured in the test of VO2. Test candidates are measured while exercising, typically at a treadmill or stationary bicycle. The higher the number in the VO2 test, the higher the maximum oxygen uptake. 

MET is the ratio between the energy expended during physical activity and the energy expended while resting. What you want to know, is how much energy a person is using while sitting at rest. That number is one MET and by multiplying, the number can tell us how much energy a person consumes during different levels of exercise. The tests can be done at a clinic, laboratory, or hospital. 

If you are physically very fit or an athlete, you can also test yourself in a submaximal exercise test. This can give you the same indications. Submaximal exercise tests are for example: 

• Astrand treadmill test
• 2.4 km run test 
• Multistage bleep test 

These tests will give you an indication of how your good your heart and lungs are at bringing oxygen to your muscles during exercise. The higher results, the longer you will be able to perform. It is linked to your respiratory strength and the stronger, the better the endurance.   

The cardiorespiratory system and why it is important for your physical performance 

Your muscles need oxygen and when we are active and are training, they need more. The process of making sure they will have enough oxygen includes your heart, lungs, and blood vessels. The word cardiorespiratory explains to us, that we are dealing with both the cardiovascular system and the respiratory system. 

The cardiovascular system is the system that keeps your heart beating and pumps blood out into your body. The system is controlled by the heart and includes veins, capillaries and arteries. All of these together pump blood and oxygen around the body. 

The respiratory system enables us to breathe. The system is controlled by your lungs but also includes your nose, mouth, and diaphragm. The system takes in air and hereafter transfers the oxygen into the blood which then pumps it into your muscles and organs. 

By strengthening cardiorespiratory endurance your body will be able to take in and carry more oxygen. This will result in an increased number of red blood cells and hemoglobin. Your heart rate will also become stronger and be able to pump out larger volumes of blood and distribute the oxygen better.

Physical performance 

But how is it related and important to your physical performance? The slower these two systems are, the less efficient they are. And the slower they are, the tougher it is for your body to pump the oxygen around. It will eventually impact your endurance and performance. You will need more energy to pump the oxygen around in your body, which means that you can perform at a shorter period and you will loose breath faster.

How can you boost cardiorespiratory endurance?

By exercising regularly, you can improve your cardiorespiratory endurance and continuously increase the difficulty of the aerobic or cardio activity that you are performing. You have to push yourself to reach a higher heart rate when you exercise. 

4-6 times of exercise per week, at around 60 minutes at a time of medium intensity training is efficient. If you perform high-intensity training, 30-40 minutes is enough. 

Each time you workout you should strive to go a little further and have continuous progression in your performance. Adding variation is also important to remember, as this pushes your body and makes sure that you train different muscle groups. 

There are several different types of exercises you can do and perform to improve your cardiorespiratory endurance, and also different types of activities. Just keep in mind that the best cardiorespiratory workout is one that gets your heart rate up and makes you sweat. We have listed some good ideas here: 

Exercises: 

• Run and jump in one spot 
• Jumping jacks
• Side hops
• Hopping squats
• Burpees 
• Mountain climbers

Activities: 

• Running 
• Swimming 
• Power walking 
• Dancing 
• Basketball and soccer 
• Rollerblading 
• Rowing 

Other benefits of improving your Cardiorespiratory Endurance: 

Improving cardiorespiratory endurance is good for your overall health. Not only does it enable you to physically perform for longer and at a higher level, but it also has a positive correlation with the health of your heart and a negative correlation with risk factors. This means decreasing your risk of heart diseases. Also, the risk of high blood pressure and diabetes can be minimized, since you strengthen the health of lungs and heart which altogether has a positive influence on your physical wellbeing. 

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