Your circulatory and respiratory systems function to supply your body with blood and oxygen through all activity levels, from rest to physical exertion. The amount of blood circulated throughout your body is based on two measurable components -- stroke volume and heart rate. The amount of each that your body is capable of producing is based on factors including fitness level, activity level, body size and medication. The amount of one component is directly related to the other and can determine your heart health.
Heart rate is defined as the number of times that your heart beats in one minute. Heart rate is measured by using a stethoscope or by feeling your pulse. Heart rates are classified by exertion levels ranging from resting to maximum rates. Typical resting heart rates vary between 40 beats to 80 beats per minute at rest. The average resting rate is 70 beats per minute, with elite athletes measuring close to 40. Maximum heart rate measurements are based on your age, subtracting your age from the number 220.
Stroke volume is defined as the amount of blood pumped in one beat. Generally, stoke volume is an estimated measurement. Actual measurements are performed on heart patients by measuring arterial pressure. Estimated average stroke volume amounts range between 50 to 70ml at rest to 110 to 130ml during cardio training. Elite athletes have estimated stroke volumes between 90 to 110ml at rest to 150 to 220 ml during cardio training.
Cardiac output is defined as the total amount of blood circulated throughout your body in one minute. Cardiac output is measured by multiplying heart rate by stroke volume. Healthy individuals with higher cardiovascular fitness levels have lower heart rates, allowing a longer time for the heart to fill with blood. The extra time for filling results in a higher stroke volume, or amount of blood that can be pumped in one beat.
On the contrary, individuals with lower cardiovascular fitness levels have higher resting heart rates. This allows less time for your heart to fill with blood, lowering the amount of blood that can be pumped in one beat.
Cardio training increases the demand on your heart and lungs to provide blood and oxygen to your body. Stoke volume and heart rate increase to meet the higher demands. Cardio workouts meeting suggested guidelines strengthen your heart and lung function, resulting in improved rates. Training goals include lowering your resting heart rate, resulting in higher stroke volume rates and reducing the risk of heart disease.