Cardiac Output And Blood Pressure
Cardiac output and blood pressure are two important measures of the health and function of the cardiovascular system. You need to understand these measures as a fitness professional in order to design and deliver safe, effective exercise sessions, and in the case of blood pressure, Glyco Care Glucose Supportglucose metabolism be able to conduct and interpret blood pressure measurements for your clients. Cardiac output (known as ‘Q’) is a measure of the amount of blood that is pumped out of the heart in one minute. ‘Q’ specifically refers to the amount of blood pumped out of the left ventricle as this is the ventricle that supplies blood to the muscles and organs of the body. Cardiac output is made up of two components, heart rate (HR) and stroke volume (SV). Heart rate (HR) refers to the number of times the heart beats every minute (bpm). This can be easily measured through the use of heart rate monitors or taking ones pulse (counting the ‘pulses’ at the radial artery for example over a one minute period).
Heart rates increase as the intensity of activity increases, as shown in the adjacent picture. This is because the working muscles demand more energy, so the heart beats increasingly faster in order to deliver the nutrients and O2 needed to meet these increased energy demands. The normal resting heart rate range for an adult is between 60-100 bpm. However when a resting heart rate is greater than 100bpm it is called ‘tachycardia’ and when it’s below 60bpm it is called ‘bradycardia’. These can both indicate possible heart conditions or complications and if you notice these in a personal training client of your's you should advise your client to have a medical check. The exception to this is that bradycardia may be present in extremely fit (international level multisport, triathlon, ironman etc) individuals and not something to be concerned about. Stroke volume (SV) refers to the quantity of blood pumped out of the left ventricle with every heart beat.
The exact volumes are not easily measured, so they are often estimated based on what we know about stroke volume and the factors that it affects such as blood pressure which we can measure. Q. Therefore to calculate Q we must first establish HR and daily glucose support SV. An example at rest is shown below. An increase in HR, SV or both will increase someones Q. SV on the whole does not fluctuate too much, with only relatively small increases with exercise. Increases in Q with exercise are vital, as it is essentially your CV system trying to meet the demands of the body for the supply of oxygen rich blood and the removal of waste. However it is highly unlikely that you will ever have to measure a client’s Q, but because Q affects blood pressure, which you will measure, its important that you know what HR & SV are and how they along with Q influence blood pressure.
Blood pressure (BP) is a measure of the force being exerted on the walls of arteries as blood is pumped out of the heart. BP measurements are usually taken on the upper arm with a ‘sphygmomanometer’ and a stethoscope as pictured on the adjacent diagram. The sphygmomanometer consists of an inflatable cuff with a pressure gauge. When inflated the cuff blocks the flow of blood to the arm below the cuff. As the cuff is allowed to slowly deflate, the measurer listens through the stethoscope to sounds as the artery opens and allows blood flow to continue again. The measurer is listening for two specific sounds as the blood flows through the artery, as shown on the below image. The first sound heard as the artery opens enough for the first pumps of blood to come through is known as the ‘systolic’ pressure. This measures the force the heart has to pump against to get the blood to flow around the body.
The second sound recorded is known as the ‘diastolic’ pressure. This measure is recorded at the point where the measurer stops hearing the ‘pump’; essentially it measures the pressure in the arteries as the heart relaxes. The systolic number is placed over the diastolic number and is always the higher of the two numbers. For example blood pressure of 110 (systolic) and 70 (diastolic) is read as 110/70mmHg. The measurement of blood pressure is expressed in millimetres of mercury (mmHg). High blood pressure at rest is an indicator that the cardiovascular system is in a less than ideal state of health. ‘Normal’, healthy BP is regarded as 120/80mmHg or thereabouts. BP is also used as a ‘risk factor’ for many diseases and illnesses, such as heart disease. Doctors and fitness professionals alike use blood pressure to screen for potential problems before making judgements as to what exercise a person can safely take part in. Cardiac output as you know is made up of heart rate and stroke volume.