1. Leg Ergometer for Blood Flow Studies
Amy Weaver, Laura Bagley,
Lacey Halfen, Deborah Yagow, Lein Ma
BME 200/300
October 19, 2007

2. Client: William Schrage
Dept. of Kinesiology
Advisor: Wally Block
Dept. of Biomedical Engineering

3. Overview Research Facilitating Ergometer
Blood Flow Research and Analysis
Existing Leg Ergometers
Quantifiable Client Specifications
Alternative Resistance Approaches
Improvements on last semester’s device
Monark exercise bicycle
Proposed Design: Servo motor with brake
Construction and Testing

4. Research Facilitating Ergometer
Device to facilitate blood flow analysis during exercise
Femoral artery is imaged using an ultrasound
Test subject will use the ergometer to maintain a kicking motion against a constant workload
Leg must passively return to original position

5. Blood Flow Research Measure blood flow in femoral artery
Examine how smaller blood vessels regulate upstream (femoral) blood flow
Infuse drugs into the femoral artery to isolate blood pathways

6. Significance of Research
Metabolic, neural, and mechanical influences on control of blood flow
Altered by age or disease
Cardiovascular disease associated with blood flow abnormality
Can exercise restore normal blood flow?
Drug companies can develop pills to mimic effects of exercise

7. Background: Existing Devices
Part of an exercise bike and a car seat
Rollerblade boot with the toe cut out
Device was unreliable, and had variable forces
Start with specifics of bike and its problems. Mayo information is least important.
Altered Monark stationary bike in use at Mayo Clinic

9. Last Semester’s Prototype
Frame built from pipe
Car seat fastened to frame
Snowboard binding to connect foot to resistance
Bicycle components used as resistance

10. Client Specifications
Constant wattage (range W)
Kick rate KPM
Chair positioned 30º from vertical
Adjust for heights 5’4” to 6’4”
Flexible range of motion while kicking
180˚ leg extension
Passive return to rest position

11. Client Specifications
Output to computer through A/D converter
Adjustable workload
Under $2,000
Easily portable (with wheels)
Minimum lifespan of five years

12. Consistent Design Components
From Previous Device
Seat
Snowboard boot
Frame
New Additions
Ball joints
Lightweight pedal bar
Force transducer in pedal bar to determine kick rate

13. Updated Bike Retain bike wheel from last semester
Improve seat attachment
Weld seat to ergometer frame
Improve wheel attachment
Weld bike frame to ergometer frame
Add side support bars
Remove excess parts
Handle bars

14. Modified Monark Electric or friction brake models
Convenient data display for RPM, Power, etc.
$900-$7,000
Utilize only the flywheel and braking device
Pedal bar attaches Monark pedal to boot

15. Proposed Design: Servo Motor
Crank arm connects pulley to pedal bar
Brake attached to pulley via belt
Servo motor to adjust magnetic brake force
Console used to electronically adjust motor settings
Kicking motion propels crank arm around

16. Design Matrix Criteria Weight Servo Motor Monark Modified Bike
Ease of Use for Client 35
0.9
0.6
0.4
Constant Power Output 25
0.8
0.5
Force Adjustability 20
0.1
Ease of Construction 10
0.3
Cost
0.7
Total
100
82.5 50
44.5

17. Future Work Obtain parts for servo motor design Order pedal bar sensor
Build attachments to frame
Perform client monitored trials with various subjects
Ensure passive leg return
Verify wattage consistency

18. References
Maximal Perfusion of Skeletal Muscle in Man (Per Andersen and Bengt Saltin) 1984
Chi-hua Fitness Co., Ltd.
Joe Halfen, Director of Quality, Octane Fitness