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kin142 lab guide Units 19-22.docx

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Biomedical Physio & Kines
BPK 142
Craig Asmundson

UNIT19: Cardiovascular Response to Submaximal Exercise - total heart volume and total blood volume - want to know: amount of blood pumped out from the right ventricle to the lungs, and from the left ventricle around the rest of the body, with each beat or stroke of the heart o stroke volume (SV) of blood  active in absorbing oxygen from the lungs while unloading carbon dioxide to the air, and carrying absorbed oxygen and food around the body effectiveness of system - depends on degree of dimensions (volumes) - greater dependence on power of system (rate of circulation of volumes of blood) - DETERMINING GOOD ENDURANCE PERFORMANCE = SIZE OF CARDIACOUTPUT (Q) o Rate that heart pumps blood per min – given in product of stroke volume (SV) or blood pumped per min of heart, and HR (bpm) Q = SV × HR Typically, for a male at rest, SV is 80 millilitres and HR is 70 beats per minute. Thus, at rest: 80 ml/b × 70 ml/min = 5,600 ml/min = 5.60 L/min *can be 35 litres per minutes during maximal aerobic exercise in a world-class, male, endurance athlete. CIRCULATORY SYSTEM - Set of adjustable tubes flow of blood causes pressure to increase (depending on Q + FLEX OF TUBES) Flow (Q) = Mean Arterial Blood Pressure / TPR Electrocardiography (ECG) - Heart muscle contracts from electrical signal from right atrium (SINOATRIAL NODE ( PACEMAKER)) - 3 positions used to produce ecg o Left wrist, right wrist, left ankle (EINTHOVEN LEADS) o Right ankle = reference electrode o Fifth electrode (exploring) used to p/u signals @ various points over chest Electrodes: - Use conducting gel rubbed over area of skin to make good contact - Held in place by being on adhesive patch 1 - LEAD 1. o The negative terminal of the ECG machine is connected to the electrode on the right arm, the positive terminal to the left arm electrode. Accordingly, when the right arm is negative with respect to the left arm there is a positive or upward deflection of the recording pen - LEAD II. o The negative terminal is connected to the right arm electrode, the positive terminal to the left leg electrode - LEAD III o The negative terminal is connected to the left arm electrode, the positive terminal to the left leg electrode. 12 Lead system used in medicine - Can examine HR, rhythm, waveform @ rest As the wave of depolarization moves across the atria and ventricles, the magnitude and direction of the ionic current flow periodically changes IF: - Left fibre bundle diseased o Conduction cannot take place o Left ventricular contraction delayed o Abnormal ECG waveform - Cardiac impulse blocked @ AV Node o Ventricles beat at own rate, abnormal wave 2 Exercise electrocardiography is used to determine:  if the oxygen demands of the working heart are > than the oxygen supply to it  an accurate measure of the heart rate (esp during exercise) Other methods = palpation of the carotid (neck) or radial (wrist) pulse OR auscultation with a stethoscope over the chest wall [both inaccurate though] Blood Pressure Measurement - high + low pressure in major artery due to contraction/relaxation of heart - measured using blood pressure cuff, pressure reading manometer, stethoscope o blood pressure cuff + recording manometer = SPHYGMOMANOMETER Pulse Pressure (PP) = SBP – DBP mm Hg Mean Arterial Pressure (MAP) = [(SBP – DBP) / 3] + DBP mm Hg Equipment for Indirect Measurement of Blood Pressure - DIRECT method = putting catheter into artery + recording pressure using pressure transducer - Sphygmomanometer o Compression bag enclosed in a cuff, inflating bulb, pump o Manometer = app pressure read o Controlled exhaust to deflate system - Bag and Cuff o Inflatable bag surrounded by cuff o Inflatable bag should be 20% wider than diameter of limb used - Manometers o MERCURY GRAVITY MANOMETER o ANEROID MANOMETER * Determination of Blood Pressure Subject - Comfortably seated in chair in quiet room with legs uncrossed - Recognize biological factors: anxiety, emotional turmoil, meals, tobacco, bladder distension, climate variation, exertion, pain - Avoid exertion, exposure to cold, eating smoking HALF HOUR BEFORE - No postural change for 5 min before Technique 1. Choose appropriate cuff o <25cm use small adult or child size cuff o 25-35 cm use adult cuff 3 2. Position cuff o Wrap deflated cuff around upper arm o Lower margin 2.5 cm above elbow o Arrow placed over brachial artery of arm o Put stethoscope directly over brachial artery  Medial and underneath biceps tendon (middle of elbow joint on anterior surface) o Listen to korotkoff sounds 3. Position stethoscope 4. Listen to korotkoff sounds o Turbulent blood flow 5. Practice o Locate and be familiar with the sounds o Pump bag go 100 mm hg pressure 6. Determine systolic pressure o With the stethoscope in place, the pressure in the bag is raised approximately 30 mm Hg above the point at which the radial pulse disappears, and then released at a rate of two to three mm Hg per second. Faster or slower deflation will cause systematic errors. As the pressure falls, the Korotkoff sounds become audible over the artery below the cuff. These sounds pass through four phases as the pressure declines, until the sounds disappear:  Phase I— That period marked by the first appearance of faint, clear tapping sounds which gradually increase in intensity.  Phase II— The period during which a murmur of swishing quality is heard.  Phase III— The period during which sounds are deeper and increase in intensity.  Phase IV — The period marked by the distinct, abrupt muffling of sound so that a soft, blowing quality is heard.  Phase V — The point at which sounds disappear. The muffling and disappearance are commonly referred to as the fourth and fifth points. Sometimes, particularly in some hypertensive patients, the usual sounds heard over the brachial artery (when the cuff pressure is high), disappear as the pressure is reduced, and then reappear at a lower level. This early, temporary disappearance of sound is called the auscultatory gap and occurs during the latter parts of phase 1 and phase II. Because this gap may cover a range of 40 mm Hg, one can seriously underestimate the systolic pressure or overestimate the diastolic, unless its presence is excluded by first palpating for disappearance of the radial pulse as the cuff pressure is raised. When all sounds have disappeared, the cuff should be deflated rapidly and completely. One to two minutes should elapse for the release of blood trapped in the veins before further determinations are made. 7. Determine diastolic pressure— There is some controversy as to whether to make the fourth phase or the fifth phase the true diastolic pressure point. We will use the fifth phase (the point at which the Korotokoff sounds disappear), as the true diastolic pressure point. Submaximum Tests of Cardiorespiratory Fitness—Astrand Test  Variety of step, bicycle ergometer + treadmill tests used to access cardioresp fitness (predicts VO2max)  Calculate size of work rate stimulus + heart rate response to it  Submaximal effort = 65-85% of max HR 4 Prediction of VO2max from Submaximum Bicycle Ergometry Using the Astrand Test  Astrand test predicts maximal aerobic power (VO2max) from HR measured @ end of 6 min submaximal work rate on bicycle ergometer Equipment:  Monarch bicycle ergometer  An electrocardiograph, or heart rate monitor  Pre-gelled disposable electrodes.  Stopwatch for recording exercise duration.  Ruler for measuring ECG intervals. About the Monarch Bicycle Ergometer:  Work rates expressed in kilopond-meters/mi o Kilopond = force of gravity acting on 1 kg (watts)  One watt = 6.12 kp·m·min-1  General subjects = 60revs/min  Trained cyclists = 90-100revs/min Given a pedaling frequency of 50 rev/min, and 6.0 m/rev, work rate may be determined simply by the tension setting. For example, a tension setting of 2.0 kiloponds will produce a work rate of (50 rev/min) x (6.0 m/rev) x (2.0 kp) = 600 kp·m·min-1. Procedure 1: 1. The subject should refrain from energetic physical activity for two hours before the test, and not smoke for one hour before the test. The test should not be performed earlier than about one hour after a light meal or earlier than about 2- 3 hours after a heavier meal. 2. Adjust the cycle seat height so the subject's leg is almost fully extended at the knee when the ball of the foot is applied to the pedal at its lowest position. 3. Prepare the subject for heart rate measurement using either an electrocardiograph or a heart rate monitor. 4. Record and measure the resting HR of a subject after he/she has sat quietly for three minutes. 5. Astrand and Ryhming do not specify any warmup. However, 3 minutes of unloaded pedalling may minimize the risk of injury, and should not affect the accuracy of the prediction of VO2max. 6. Start the subject pedalling at 50 rpm on a bicycle ergometer with no brake resistance. Continue this baseline work rate for 3 minutes. Then immediately increase the work rate to 450, 600, 750, or 900 kp·m·min-1 for females and 600, 900 or 1200 kp·m·min-1 for males depending on the size and probable aerobic fitness level of the subject. Record the heart rate during the last t en seconds of each minute. 7. Maintain the steady work rate chosen for 6 minutes. 5 8. If after one or two minutes it is apparent that a heart rate of less than 120 beats per minute is going to be the steady state heart rate, increase the work rate to achieve a heart rate of 140 – 150 beats per minute and continue the work for the full 6 minute period. Record the steady state heart rate. Average the heart rates for the 5th and 6th minutes. 9. If heart rate varies more than 5 b/min between the 5th and 6th minutes, the subject should continue exercising at the same work rate until the difference between heart rate measured at 2 consecutive minutes is less than or equal to 5 b/min. Allow the subject to recover for 5 – 10 minutes. 10. Estimate the VO2max of the subject from the Astrand Tables (Tables 19-2 and 19-3) and correct the value with the age adjustment factor (Table 19-1). 11. Use your subject's predicted VO2max in ml·kg-1·min-1 in Table 19-4 to get a rating of your subject's aerobic fitness level. Note that these Swedish norms were created from a population with a more optimal level of aerobic fitness than the typical North American population. Procedure 2 Equipment: - ECG machine plus electrodes and alcohol - Blood pressure cuffs and stethoscopes - Monarch bicycle ergometers - Heart rate monitors - Stopwatches - Rulers - Kleenex Technique 1. Practice measuring blood pressure - Get a partner, and then choose the correct size blood pressure cuff for you and your partner. Follow the procedures described for measuring blood pressure at rest when sitting. Record data for you and your partner in Table 19-5. 2. Watch the demonstration of one subject being attached to the electrocardiograph. Obtain one piece of the resultant trace each. Calculate the heart rate of the subject from your piece of trace – Table 19-6. 3. Perform the Astrand test. Use either an electrocardiograph or a heart rate monitor to measure the subject's heart rate. 4. Put a blood pressure cuff around the subject's arm. 5. Measure blood pressure and resting heart rate while the subject is seated at rest on cycle ergometer. 6. Start the subject pedaling at 50 rpm with no brake resistance. Continue for 3 minutes. 7. Monitor heart rate in the last ten seconds of each minute of rest and exercise. 6 8. Increase the work rate to either 450, 600, 750 or 900 kp·m·min-1 for females and 600, 900 or 1200 kp·m·min-1 for males depending on size and probable aerobic fitness. Maintain the steady state work rate chosen for 6 minutes. Follow all of the Astrand Test procedures described with the first procedure. 9. Monitor blood pressure immediately at the end of the six minutes of exercise. It is very difficult to measure blood pressure while a subject is exercising. Pump the blood pressure cuff up to 190 mm Hg 10 seconds before the end of the six minutes of exercise. At the end of six minutes of exercise, the subject should stop pedaling. The measurer should drop the pressure in the cuff until the first Korotkoff sounds are heard, indicating systolic pressure. Then drop the pressure in the cuff very rapidly down to approximately 90 mm Hg and start searching for the pressure where the Korotkoff sounds disappear, indicating diastolic pressure. Heart rate and blood pressure recover quickly when a subject stops exercising so speed of measurement is essential if accurate data is to be obtained. 10. Take off the brake resistance and have the subject cool down at 50 rpm for 3 minutes. Monitor heart rate at the end of each minute, and blood pressure at the end of the three minute cool down period. 11. Calculat
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