KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 Learning Objectives: Physiology Concepts ● Explain how the first two laws of thermodynamics are at play in exercise physiology and describe relationship between work rate and energy expenditure. ● Describe the metabolic systems or pathways that generate energy to support work. ● Explain what determines substrate oxidation (utilization) during exercise, underlying explanation for the crossover principle, by contrasting responses to duration or workload. Technical Skills and Critical Thinking ● Explain the principles and technique for measuring oxygen consumption (VO2). ● Use VO2 and RER to calculate rate of energy expenditure (EE) and substrate use during exercise. ● Summarize data using scatterplots and histograms to show patterns and differences. Overview A direct relationship exists between energy expenditure (EE) and work rate (assuming steady-state metabolism at submaximal workloads). Energy is defined as the capacity to do work. At steady-state exercise, there is a direct relationship exists between energy expenditure (EE) and work rate, therefore, we can predict EE from work rate. Steady state exercise refers to exercise where the rate of VO2 is constant with a particular workload; the rate of VO2 matches the energy demands of that workload. Energy expenditure can be measured two ways, via indirect or direct calorimetry. Measuring the body’s rate of oxygen consumption (VO2) can assess EE and is an example of indirect calorimetry. VO2 is measured using a metabolic cart. Direct calorimetry techniques measure heat production to determine EE during exercise or movement but require expensive technology and a highly controlled environment. By measuring VO2 during steady state exercise, we can also determine whether the energy was produced from, carbohydrates or fat, which are called substrates. We assume that protein makes an insignificant contribution to the energy being used. Substrate utilization can be expressed as the mass of fuel oxidized per unit time (grams/min) or percentage that a given substrate contributes during each work rate. The respiratory exchange ratio (RER, which equals VCO2/VO2) and either VO2 or the rate of carbon dioxide produced (VCO2) are used to determine substrate utilization. Therefore, the RER and VO2 (or VCO2) can be used to determine how much carbohydrate and/or fat is being used during a given activity. RER ranges from 0.7-1.0, although values can occur outside of this range when the subject is not in a steady state. Roughly, an RER of 0.70 equates KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 to 100% of energy utilized from fat, an RER of 0.85 means 50% of energy utilized from carbohydrate and 50% from fat, and an RER of 1.00 means 100% of energy utilized from carbohydrate. The Zuntz table will be used in this lab to provide complete and precise conversion factors for substrate utilization Equipment 1. Metabolic cart (TrueOne 2400; Parvomedics) and gas collection equipment (mouthpiece headgear, & nose clip or face mask & straps to hold it) 2. RPE chart 3. Treadmill 4. Lance and lancets for finger sticks 5. Lactate analyzer, lactate strips, alcohol wipes, gloves, red biohazard disposable container 6. Glucose analyzer, glucose strips, alcohol wipes, gloves, red biohazard disposable container 7. Thumb drive to obtain Excel copy of results from metabolic cart (VO2, RER) Instructions Four students will participate as subjects (n=2-4). Two subjects will do a progressive workload protocol on the treadmill and two will do a steady-state walk, at a fixed workload protocol on the treadmill. Data collection will be done in this order: the first two subjects will do the progressive workload protocol (n=2). The second two students will do the fixed workload protocol (n=2). See data sheet on blackboard and Record data to the google sheet. 1. Subjects should report to the lab in a fasted state (overnight fast) or at least 3-to4 hours postprandial (i.e., last meal was 3 to 4 hours earlier). 2. Measure height and weight on each subject. 3. Fit the subject for a mouthpiece or facemask. Use mouthpiece for those with facial hair. 4. Perform a finger stick to measure both glucose and lactate before any exercise (resting or baseline). Follow the protocol from your instructor to perform the finger-stick properly. Record values as they are measured. 5. Assign assistance for data collection with at least one student per role below: • RPE / Glucose / Lactate value recorder • Controller to advance speed / grade (incline) on treadmill • One student or lab instructor to perform the finger stick • One student or lab instructor to assist with blood sampling (handing over alcohol wipes and meter for finger stick) KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 6. The lab instructor will calibrate the metabolic cart and initiate data collection. 7. Protocol – metabolic cart will serve as the official clock. ● Progressive Workload Treadmill Protocol (data sheet on page 4) o Before the subject begins, be sure to have collected blood glucose and lactate measurements at rest. o Synchronize the start of the walking test with the start of metabolic-cart measurements. The lab instructor can help with a countdown. o Stage 1: Subject walks at 2.0 mph and 0% grade for 3 minutes RPE is obtained from subject at ~2:45 min or just before stage ends. At the 3 min mark, advance the stage by increasing speed and grade of treadmill. o Stage 2: Subject continues walking at 3.0 mph and 4% grade for 3 min. Obtain RPE before the stage ends, and at 6 min advance to Stage 3. o Stage 3: Subject continues walking at 4.0 mph and 8% grade for 3 min. Repeat RPE measurement before the stage ends. o When test ends, have the subject stop for a finger stick to measure glucose and lactate. Record values as they are called out. o If needed, have the subject walk to cool down a bit before next subject. ● Fixed Workload Treadmill Protocol (data sheet on page 5) o Before the subject begins, have them sit and perform a finger stick for blood glucose and lactate at rest. Use same sterile procedures. o Have subject start walking at 3 mph and 0%. o The grade and speed will remain at these settings. o Near the end of every 3 min segment, obtain the RPE from the subject. collect data for the following. Use data sheet below for recording. o After 9 min (maximum), have subject stop; repeat the finger stick for blood glucose and lactate. Data Management and Work-up 1. Data needed from metabolic cart • Oxygen consumption (VO2): Found on printout from metabolic cart. Bracket the values by workload “stage” (3-min periods). • Respiratory exchange ratio (identified as “RER” column on printout from metabolic cart). Bracket the values by workload “stage.” Summarizing the Data and Presenting Results for Interpretation 1. For this report, only use data from your lab section. The sample size should be 2 per treatment (4 participants in total). KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 2. Create a table for the physical characteristics of the participants in each treatment (progressive and fixed). List mean and SD values for age, height, and weight of the participants. 3. Create another table for metabolic and physiological responses at each stage. For participants within a treatment, list mean values at each work stage for VO2, RER, Calories/min, and initial and final blood glucose and blood lactate. a. For Calories per min at each stage, use the average VO2 and RER per stage (or nonprotein RQ) to locate the conversion factor in the Zuntz table (Zuntz, 1901), i.e. kcal per L VO2. A copy of the Zuntz table is posted on Bb for this lab. b. Multiply the conversion factor from the table by the VO2 in L/min for that stage. 4. To obtain the substrate oxidation data, follow these steps: a. Average the last two readings of a stage (obtain 30 sec readings on printout from metabolic cart print out) to obtain a “per minute” mean for each subject. In other words, you will be using the last minute of each stage and looking at that minute as two-30 second intervals. b. Then calculate the mean per minute for the two participants within a treatment. This represents the steady-state metabolism for that stage. Do so for each of these variables: i. VO2 ii. RER iii. substrate use (% carbohydrate, %fat oxidized) 5. Three graphs will be created: a. Plot VO2 (Y axis) vs. time (X-axis). There will be two lines on this graph (progressive and fixed workload). b. Plot RER (Y axis) vs. time (X-axis). There will be two lines on this graph (progressive and fixed workload). c. For the progressive workload data only, plot the % of substrate (fat and carbohydrate) used at each stage (3-min means). There will be two lines on this graph. KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 Progressive Workload Name: Prog 1 Sex: Male/Female Age: _________ Height (cm): _________ Weight (kg): _________ Minute Speed (Mph) Pre0-0:59 2 1-1:59 2 2-2:59 2 3-3:59 3 4-4:59 3 5-5:59 3 6-6:59 4 7-5:59 4 8-8:59 4 PostFixed Workload Grade (%) RPE Lactate (mg/dl) Glucose (mmol/dl) RPE Lactate (mg/dl) Glucose (mmol/dl) 0 0 0 4 4 4 8 8 8 Name: Fixed 1 Sex: Male/Female Age: _________ Height (cm): _________ Weight (kg): _________ Minute Speed (Mph) Grade (%) Pre0-0:59 1-1:59 2-2:59 3-3:59 4-4:59 5-5:59 6-6:59 7-5:59 8-8:59 Post- 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 0 0 0 0 0 0 0 0 0 KN 352 Lab 1: Exercise Metabolism Instructions – Fall 2023 Condition_ Lactate_P Glucose_ RPE_Stag P or F re Pre e1 Sex Age Height (in) Weight Volunteer 1 M 22 172 88 F 7.3 106 8 Volunteer 2 F 21 168 45 F 2.9 102 9 Volunteer 3 M 23 175 89 P Volunteer 4 M 21 172 81.8 P 10.7 9.9 96 102 6 8 VO2 RER Calories/m in *Condition: P = progressive, F = fixed Table 2 Fixed (n=2) Stage 1 Stage 2 Stage 3 Progressiv e (n=2) Stage 1 Stage 2 Stage 3 VO2 RER Calories/m in VO₂ VO₂ VO₂ RPE_Stag RPE_Stag Lactate_P Glucose_ RER_2:00 RER_2:30 (L/m)_2:0 (L/m)_2:3 (L/m)_Sta e2 e3 ost Post – 2:30 – 3:00 0 – 2:30 0 – 3:00 ge 1_AVG 12 14 3.2 110 1.34 1.37 0.71 0.73 1.35 9 11 2.1 103 0.61 0.6 0.73 0.74 0.6 6 11 10 14 4.3 7.6 103 106 0.9 0.24 0.89 0.25 0.62 0.69 0.64 0.66 0.89 0.24 Intial Blood G. Intial Blood Lact. Final Glucose Final Lact. Intial Blood G. Intial Blood Lact. Final Glucose Final Lact. VO₂ VO₂ VO₂ VO₂ VO₂ RER_Sta RER_Sta RER_5:00 RER_5:30 (L/m)_5:0 (L/m)_5:3 (L/m)_8:0 (L/m)_8:3 (L/m)_Sta – 5:30 – 6:00 ge 1_AVG ge 2_AVG 0 – 5:30 0 – 6:00 0 – 8:30 0 – 9:00 ge 2_AVG 0.72 1.34 1.19 0.77 0.79 1.26 0.78 1.22 1.16 0.73 0.56 0.54 0.82 0.84 0.55 0.83 0.5 0.54 0.63 0.67 1.52 0.92 1.5 0.91 0.7 0.66 0.72 0.71 1.5 0.91 0.71 0.68 2.45 2.25 2.43 2.38 VO₂ RER_Sta RER_8:00 RER_8:30 (L/m)_Sta – 8:30 – 9:00 ge 3_AVG ge 3_AVG 0.79 0.79 1.18 0.79 0.85 0.85 0.52 0.85 0.92 0.99 0.92 1.02 2.44 2.31 0.92 1
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