PEAK 404 EXERCISE PHYSIOLOGY LAB SKILLS. Basic Measurements, Units of Measure, And Work/Power Calculations

Transcription

1 PEAK 404 Lab Skills Page 1 1. Heart Rate at Rest (Palpation) PEAK 404 EXERCISE PHYSIOLOGY LAB SKILLS Basic Measurements, Units of Measure, And Work/Power Calculations As will be discussed as this course progresses, heart rate (HR) can be a valuable measure used to indirectly estimate an individual s current exercise effort level (% V. O 2max ) and assist in determining overall health status. Although palpation of HR is a very basic concept and is quite routine, actual measurement of the pulse can be difficult at times for certain individuals. Skills Activity 1A. Determine heart rate by palpating the pulse at the radial artery. Count the number of beats within a 10 second (or 15 second) period. Count the first beat after you start timing and the last beat just before time is elapsed. The pulse can be palpated by placing two fingers over the radial artery on the wrist (thumb side). The Pulse can also be palpated at the carotid artery in the neck just next to the laryngeal prominence (Adam s apple). Light pressure ONLY should be applied to determine the pulse (heart rate can actually be altered if too much pressure is applied over the carotid artery). Generate a presentation table that contains resting HR values for each person in your group and their fitness ratings. Table 1. Fitness ratings based on resting heart rate. Resting HR Fitness Rating < 60 excellent good average fair > 90 poor

2 PEAK 404 Lab Skills Page 2 Table 2. ample presentation table of student fitness rating based on resting heart rate. Name Resting HR Fitness Rating Joe Student 60 good Josie Student 75 average 2. Blood Pressure at Rest (Auscultation) Blood pressure is another very useful measure for overall health assessment. Resting measures are frequently used to provide information concerning the baseline function of the cardiovascular system and potential risk for cardiovascular disease and stroke. ercise measures are also useful for evaluating cardiovascular function during different types of exercise (e.g., weightlifting vs. aerobic exercise). Blood pressure literally is the pressure the blood exerts on the blood vessel wall from the inside. It can be measured directly (intravascular) in almost any blood vessel. However, it is more commonly and easily measured indirectly (noninvasive) at a peripheral artery, usually the brachial artery in the arm. The method is referred to as auscultation (sounds), sphygmomanometry or manometry, or the cuff method. In general the procedure requires the technician to listen to the sounds within the artery as blood flows through at varying cuff pressures. Initially, the cuff pressure is great enough to completely occlude the artery so no blood passes through. As pressure in the cuff is released, a point is reached at which time blood will be able to push through the artery with each contraction of the left ventricle (systole). This causes a vibration sound, which can be heard with the aid of a stethoscope. This sound is a Korotcoff sound (phase 1). As the cuff pressure is further reduced, additional Korotcoff sounds can be heard. The final two Korotcoff sounds of importance are phase 4 (a muffling of the audible pulse) and phase 5 (complete disappearance of the pulse sounds). Both these Korotcoff sounds represent the point at which blood flow through the artery is becoming more streamlined and occurring even at cardiac diastole. Phase 1, therefore, is used to indicate the systolic blood pressure (SBP), and phase 4 and 5 are used to indicate diastolic blood pressure (DBP). Skills Activity 2A. Place the blood pressure cuff (bladder) around the left arm about one inch (2.5 cm) above the crease of the elbow (antecubital fossa). The middle of the bladder should be centered over the medial (inner) surface of the arm. The stethoscope diaphragm should be placed over the brachial artery (anterior medial surface of elbow crease)

3 PEAK 404 Lab Skills Page 3 about one inch (2.5 cm) below the cuff. Often the pulse can be palpated to help locate the position of the brachial artery. NOTE: the diaphragm should NOT be under the cuff at all. Firm but light pressure should be applied to the diaphragm to hold it in place. Close off the bulb, and then inflate the cuff 30 to 40 mm Hg above the point where the pulse cannot be heard. Gradually release the pressure via the bulb valve so that the pressure decreases 2-3 mm Hg/s. Listen closely for pulse sounds. The point where two consecutive pulses can be heard (sharp tap: phase 1) is the systolic pressure. Continue to listen for the point when the sound muffles (phase 4) and then completely disappears (phase 5). ord systolic and diastolic pressures in your data table for each person in your group. For general purposes, phase 5 is used for individuals over 12 years of age as the diastolic blood pressure during rest, unless the pulse sounds do not disappear until 40 mm Hg. In this event, use phase 4 as the diastolic. For children, phase 4 is recorded as the diastolic pressure. NOTE: this procedure may take time to learn to perform successfully. Practice and be patient. Resting Blood Pressure Health/Fitness Rating: <120 / <80 very low risk (optimal) / low risk (normal, average) / moderate risk (high normal) / high risk (mild hypertension) / (moderate hypertension) 180 / 110 (severe hypertension) 3. Calculation of Work and Power During Cycle Ergometry Movement increases energy expenditure above rest. Being able to measure energy expenditure and power are crucial to a physiologist s knowledge of an exerciser s physiologic demands and limitations. Some simple formulas are listed below along with example calculations.

4 PEAK 404 Lab Skills Page 4 Work is the product of force times the distance it is applied. Work = Force x Distance or W = F x D One kilogram of force applied over a distance of 100 meters would equal 100 kg m (kilogram meters) of work. W = 1 kg x 100 m W = 100 kg m A device that measures work is called an ergometer. A stationary bike that allows the measurement of work performed while riding is a cycle ergometer. A tensioned belt applies a measured force against a flywheel. The flywheel travels a distance of 6 meters for every revolution of the pedals. A person pedaling 100 times (revolutions of the pedal) will perform an amount of work equal to the force of the belt times the distance the flywheel turns during the time they pedal. Work = 1 kg x 6 meters/rev x 100 rev Work = 600 kg m Power is used to describe the amount of work performed per unit of time. Power = Force x Distance or Power = Work Time Time The rider of a cycle ergometer will pedal against a known resistance, with a particular cadence (pedal revolutions/min), and for a designated period of time. When these values are known, both work and power can be calculated. While Work = 1 kg x 6 meters/ rev x 100 rev/min x 5 minutes Work = 3000 k gm P = 1 kg x 6 meters/rev x 100 rev/min P = 600 kg m/min

5 PEAK 404 Lab Skills Page 5 Conversion Factors allow one to move from one type of unit to another. The unit for work is called a joule (1 kg m = 9.8 joules). 600 kg m x 9.8 joules / kg m = 5880 joules The unit for power is called a Watt (1 Watt = 6.12 kg m/min) 600 kg m/min x 1 watt / 6.12 kg m/min = 98.0 Watts Skills Activity 3A. Calculate the work in kg m and joules and power in kg m/min and Watts for the following situations: 1) Tension at 1.5 kg, pedaling cadence at 40 rev for 1 minute 2) Tension at 2.25 kg, pedaling cadence at 80 rpm for 3 minutes 3) Tension at 3.0 kg, pedaling cadence at 50 rpm for 5 minutes 4. Heart Rate and Blood Pressure Measurement During ercise Heart rate and blood pressure changes during exercise are the physiologist s gauge of how hard the exerciser is working, be it a normal response or an abnormal response. The normal response can be used to indicate fitness while the abnormal response can be a cue for the exerciser to seek medical advice. The skills of measuring these physiologic responses are the physiologist s tools of the trade and must therefore be practiced routinely. Skills Activity 4A. Each group will have one subject perform cycle ergometry, while the other group members will be responsible for data collection. Heart rate will be measured by palpation and blood pressure will be determined by auscultation (as described in part 2 of this lab). Once the subject has been appropriately prepared (blood pressure cuff placement), the subject will quietly sit on the Monark Cycle Ergometer for 3.0 min, during which resting measures will be made during the last 15 seconds of each minute, and then recorded. Next the subject will ride the cycle ergometer for approximately 6.0 min, with increases in work rate occurring at the end of each minute. Specifically, each subject maintains pedal cadence at 50 rpm. ercise begins with a resistance of 0.5 kg and increases of 0.5 kg increments up to 3.0 kg at

6 PEAK 404 Lab Skills Page 6 beginning of 6.0 min. Heart rate and BP measurements should be made during the last minute of each stage. overy measurements should be made for 2 minutes of post exercise cycling at 0 kg m and for 2 minutes of quiet rest. (1) ord the stages, work rates, HR, and BP on the data table below. (2) Plot HR (dependent variable Y axis) vs. work rate (independent variable X axis) on one line graph and (3) plot both SBP and DBP (dependent) vs. work rate (independent) on another line graph. Each graph should be on a single page and labeled appropriately. Each should be titled, Figure - Influence of on. Be specific about the type of exercise used to influence a physiological function. Although these skill activities are not graded, they will serve to give you practice in the skills needed to be successful in this class. Practice them often, especially when your group must wait to use equipment. Rest 1 Rest 2 Rest Work Rate HR SBP DBP Compare your answers in part 3A to the following. 1. W=360 kg m, W=3528 joules, P=360 kg m/min, P=59 Watts 2. W=3240 kg m, W=31752 joules, P=1080 kg m/min, P=176.5 Watts 3. W=4500 kg m, W=44100 joules, P=900 kg m/min, P=147 Watts