Calibration Laboratory Purposes: To calibrate the treadmill and cycle ergometer and determine whether correction factors are needed during the use of this equipment To calibrate the physician scale and stadiometer Equipment needed: Cycle ergometer Treadmill Tape measure Ruler / Yard stick Metronome Standard weight Marking tape
Magic marker Timer Level Counter Physician scale Stadiometer
Calibration determines the validity of the machines. Think about why it is important in a research setting and a clinical setting. Calibration of physician’s scale 1. Make sure there is nothing on the step of the scale. What should it read? 2. Obtain two known weights of varying masses 3. Place each weight on the scale, separately then combined 4. Does the scale read the correct weight 5. Remove weights, does the scale still read zero? Calibration of the stadiometer How would you calibrate this? 1. Obtain a stick of known height 2. Place stick perpendicular to the step of the scale 3. Measure the height of the stick with the stadiometer Cycle ergometer calibration Calibration of resistance (kp) 1. Inspect the resistance on the cycle while no subject is pedaling. What should the resistance be? Make adjustments if needed 2. Hang a known weight from the belt; recheck the resistance and make adjustments if needed 3. REMOVE WEIGHT 4. Pedal for a few minutes on the cycle ergometer 5. Recheck the calibration (steps 1-4) 6. Does the calibration hold after a subject pedals for a while 7. If adjustment is needed, how much?
Calibration of the RPM 1. Cover the RPM display from the subject pedaling 2. Set the metronome to 50 and have the subject pedal to this cadence (each time the metronome sounds the subject’s foot is in the down swing) 3. Once you are confident that the subject is maintaining the cadence, check the RPM display 4. Is there a difference? 5. Continue steps 1-4 with the metronome at 75 and 90 6. Is there a difference at 75 and/or 90 RPM? 7. Is the difference constant or does it change at different RPM’s? Treadmill (TM) calibration Calibration of TM elevation 1. Make two marks (using tape) 30 cm apart on the edge of the running board (NOT ON THE BELT) 2. When the TM is at 0% grade, place the level on the running board. According to the level, is the TM actually at 0% grade? 3. Measure the perpendicular height from the floor to mark 1 and from the floor to mark 2. What do expect these measurements to be: equal or unequal? 4. Set the elevation to 5% 5. Measure the elevation (from the flat floor to mark 1 and from the flat floor to mark 2—still perpendicular) 6. Is the TM elevation accurate at 5% grade? 7. Check 10% and 15% elevation as well (step 5) 8. Is the TM elevation accurate at 10% and 15% grade? 9. If they are not accurate, what is the difference? Does the difference increase as the elevation increases or not? Calibration of the TM speed 1. Measure and record the length of the belt… how did you measure the length of the belt? Are you sure it’s accurate? 2. Place a mark both on the belt and on the running board. (HINT: I suggest you place the mark on the running board near the back end of the TM) 3. One tester will set the TM speed and record the results 4. Other testers will stand near the back of the belt with a counter and a timer 5. Once the speed is set (2.0 mph and 0%), count a given number of revolutions (let’s say 10) and measure the time it takes for the TM belt to revolve 10 times 6. Perform the same procedure at 5 mph at 0% grade 7. Perform the same procedure at 5 mph at 5% grade 8. Perform the same procedure at 5 mph at 0% grade with a subject running 9. Perform the same procedure at 5 mph at 5% grade with a subject running 10. Repeat steps 6-9 using 8 mph
Calibration Lab – Homework Directions: Please answer the following questions using data gathered in class. You may confer with your partners but must do your own calculations. This is for your benefit! You will see these calculations again… hint. Please hand in your answers separate from your partners. Please type your answers on a separate sheet. Do not hand in this sheet. You may write any calculations in pen/pencil. 1. Why is this laboratory important? 2. Provide a table for both the elevations and speeds you checked on the TM. Include the expected value and the value you measured. Each table must have a title. Your two tables should have the following format: (if you need help using Word ® or Excel ® please ask, your tables must be typed!) Table 1. Data for calibration of treadmill elevations Condition Elevation Height of 1st Height of 2nd checked (%) mark (cm) mark (cm) w/o subject 0% 14 14.5 w/o subject 5% 18 19.5 Etc… Table 2. Data for calibration of treadmill speeds TM condition Subject Revolutions counted 2.0 mph; 0% No 10 rev 5.0 mph; 0% No 5.0 mph; 0% Yes 5.0 mph; 5% No 5.0 mph; 5% Yes Etc…
Difference (cm) 0.5 1.5
Calculated grade (%) 1.67 5.0
Time 37.23
Calculated speed 2.04
3. Are the TM elevations valid? 4. Are the differences in measured and display elevation (if any) constant at various elevations? Explain. 5. Are the TM speeds valid with the subject? without the subject? 6. Are the TM speeds valid at various elevations? With and without a subject? 7. Are the differences in measured and display speeds (if any) constant, or does it depend on the elevation or subject interaction? 8. What resistance should register on the cycle ergometer when it is static? 9. Does the resistance require calibration when a known weight is hung from the belt? If so, how much? 10. Does the calibration hold after the subject pedals for a while? 11. Provide the data collected on the calibration of the RPM in a table. 12. Are the differences in measured and display RPM’s (if any) constant at the different RPM’s. Explain.
13. Graph the measured vs. “true” heights from the stadiometer. Graph should include a title, labeled axes, line of best fit, and R2. Explain how close are they in agreement? Figure 1. Calibration of stadiometer height
Calibration of Stadiometer Height
R2 = 1 150
True (cm)
100 50 0 0 50 100 Measured (cm) 150
14. Graph the measured vs. “true” weights from the physician scale. Graph should include a title, labeled axes, line of best fit, and R2. Explain how close are they in agreement?