Cardiorespiratory Endurance & Heart Rate

Whether you are an athlete or an individual attempting to lose weight or a post-heart-surgery cardiac rehabilitation patient, improving your cardiorespiratory endurance is a common goal. The term is often used interchangeably with aerobic capacity and may include factors such as maximal oxygen uptake, or VO2max. Many variables are affected by cardiorespiratory endurance training, but heart rate is one of the most common measures taken by health and fitness professionals when determining cardiorespiratory fitness levels.

Cardiorespiratory Endurance

Cardiorespiratory endurance is a measure of how efficiently your body is able to utilize oxygen while performing a physical task at a specific intensity level for an extended period of time. Your heart, blood vessels, blood and lungs are the primary structures affected by cardiorespiratory endurance training. As the ability of these organs to provide oxygen to your working tissues increases, cardiovascular functions such as blood pressure and heart stroke volume improve.

Heart Rate

Heart rate is a measure of how many times your heart beats in one minute. It is the most common field gauge of aerobic fitness because it is easy to measure. Place two fingers on any arterial site -- most commonly the carotid or brachial arteries -- and count the number of beats in 10 to 15 seconds. Multiply by six if you count for 10 seconds or by four if you count for 15 seconds to determine your heart rate.

Relationship

Your heart's primary job is to pump blood throughout your body. Your blood is taken up and used by your working tissues. These tissues extract oxygen from your blood so they can perform designated tasks. The more aerobically fit your heart becomes the more efficient it is at providing the tissues with the blood they need. As aerobic capacity increases, your heart muscle strengthens. This allows it to pump more blood with each beat -- a measurement referred to as stroke volume. Therefore, the number of times it must beat to pump the required amount of blood to the tissues decreases.

Measurements

Maximal oxygen consumption, or VO2max, is the chief measurement for aerobic capacity. It tells the maximum rate at which your body is able to consume and distribute the oxygen you need during activity. To determine this amount, you must multiply heart rate by stroke volume by the arteriovenous oxygen difference -- the difference in oxygen content of arterial and venous blood.

Methods to Improve

Any aerobic activity will help improve cardiorespiratory endurance and, thus, heart rate. Examples of aerobic activities include walking, jogging, cycling, swimming and inline skating. For best results, aim for 30 to 60 minutes per day, at least three days per week. Work out at a sustained heart rate of 60 to 90 percent of your maximum heart rate. Your maximum heart rate is 220 minus your age.