Respiratory Exchange Ratio

Transcription

1 Respiratory Exchange Ratio Respiratory Quotient (RQ) reflects the composition of fuels oxidized by the cells during exercise. At the cellular level, RQ is the volume of CO (VCO ) produced divided by the volume of oxygen consumed (VO ) during the same period of time. Since these values are measured at the mouth and not in the lungs, R or Respiratory Exchange Ratio is the term utilized to represent fuel oxidation by indirect calorimetry. When an individual is utilizing 100% carbohydrate for energy, R = 1.0. For fats, R ~ 0.7. At rest and during nonmaximal exercise, a combination of fats and carbohydrates (CHO) are utilized as substrate. On a mixed diet, R at rest is 0.8. For a starving individual, R may be as low as During maximal exercise, R = 1.0 or greater. Although the formula for R and RQ are the same, R does not equal RQ at the onset of exercise, during hard exercise and post exercise. At the onset of exercise CO is often stored in cells and under anaerobic conditions oxygen consumption does not accurately represent the amount of ATP formed. Recall the oxygen deficit that occurs at the onset of exercise. During very intense exercise, the blood bicarbonate system which buffers lactic acid produces additional nonrespiratory CO causing R to be greater than 1.0. I. Equipment Metabolic Carts Heart rate monitor Blood Pressure Cuff Bicycle Ergometers Stethoscope II. Procedure A. Pre-exercise 1. Prepare the subject for exercise - take height and weight, connect heart rate monitor and blood pressure cuff. Complete the top part of the data collection sheet.. Connect subject to the metabolic cart. After 5 minutes in the seated position, record heart rate, blood pressure, and other metabolic data outlined on the data collection sheet. B. Exercise 1. Begin exercising at the specified resistance (50 W) pedaling at 60 rpm for minutes (first workload).. Take HR every minute and BP at 1 and minutes of each workload. RPE should be recorded at the end of each workload.. Every minutes the workload will increase until the subject reaches volitional max or develops symptoms. 1

2 C. Recovery 1. The subject will pedal at 60 rpm at 0.5 Kg resistance for minutes and remain stationary in a seated position for the remaining minutes.. Record HR every minute and BP at 1, and 5 minutes of recovery. III. Data Analysis 1. Complete the data sheet utilizing the EXCEL or other program. a. Find the R value on the printout from the metabolic cart and use the Zuntz Table to find --kcal/liter of oxygen consumed and --% fat utilization Record on data sheet. b. Compute the % relative intensity on data sheet for each workload at minute based on actual measured VO max.. Graphically plot the relationship of R (y) over time (x). Plot R for each minute.. Graphically plot the relationship of R (y) against % of VOmax (x) for the last minute of each workload. 4. Graphically plot the % fat utilization (y) against workload for the last minute of each stage. 5. Based on the R value for each workload (rd minute) calculate the number of kilocalories burned during the minutes at each stage. (The Zuntz table provides the number of kilocalories burned based on substrate utilization). Multiply the minutes in each stage by the number of kcal burned (Zuntz Table) based on the R value attained at the end of each stage. Example: R =.91; Zuntz table - kcal = 4.96 kcal/l O VO =.6 (printout) kcal/min = 4.96 kcal/l O x.6 L O /min. Report a total number of calories burned for the entire time of exercise. 6. Calculate the number of kilocalories burned as fat and the number burned as CHO for each stage as well as the total calories, include recovery. Use the Zuntz table.

3 7. What happens to fat utilization as exercise intensity increases? Explain. 8. What happens to R as exercise intensity increases? Explain. 9. What causes R to be greater than 1.0 during high intensity exercise? 10. What did you find with regards to total kilocalories burned and calories burned as fat as workload increased? (CALCULATIONS FOR # 5 AND 6) 11. What effect would training have on the graph depicting fat utilization and workload? Explain the effect of training, why it occurs and which direction it would shift the curve. 1. Using the ACSM equation for estimating caloric expenditure (1 L O = 5 kcal) during exercise, how many kilocalories were burned during exercise? Is there much of a difference between estimated and measured using the Zuntz table? Show your work (computer printout). Multiply the O consumption in by 5 kcal. Use the VO at the end of each minute.

4 Name Sex M F Age MPHR bpm Weight lb. kg Height in cm Condition Min HR bpm BP mm Hg RPE VO VCO R Kcal/L O %Fat %Rel Int. Rest 0 50 W W W 1 00 W 1 4

5 Condition Min HR bpm BP mm Hg RPE VO VCO R Kcal/L O %Fat %Rel Int. 50 W 1 00 W 1 50 W W 1 Recovery

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