If a bicyclist has a heart rate of 110 beats per minute and a stroke volume of 85 mL per beat, what is their cardiac output?

• A. 9.35 L/min
• B. 8.5 L/min
• C. 7.0 L/min
• D. 10.0 L/min

Answer: (A)

To determine the cardiac output, one must use the formula:

Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV)

In this scenario, the heart rate is given as 110 beats per minute and the stroke volume is 85 mL per beat. First, it's essential to convert the stroke volume from milliliters to liters to maintain consistency in the units for calculating cardiac output, as cardiovascular metrics are usually expressed in liters per minute.

1. Convert stroke volume:

85 mL = 0.085 L

2. Apply the formula:

CO = HR × SV

CO = 110 beats/min × 0.085 L/beat

3. Perform the multiplication:

CO = 9.35 L/min

Therefore, the cardiac output is calculated to be 9.35 liters per minute, which corresponds with the first option. This value represents the overall volume of blood the heart pumps in one minute, an important measure of a person's cardiovascular efficiency during activities such as cycling.