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  1. Overview • Need for Ergometer in Research • Blood Flow Research and Analysis • Quantifiable Client Specifications • Ergometer Construction • Challenges and Solutions • Testing and Conclusions

  2. Need for Ergometer in Research • Device to facilitate blood flow analysis during exercise • Femoral artery is imaged using ultrasound • Test subject will use the ergometer to maintain a kicking motion against a constant workload • Leg must passively return to original position • No commercially available device

  3. Blood Flow Research • Metabolic, neural, and mechanical influences on control of blood flow • Altered by age or disease • Discovery of natural chemicals’ role such as adenosine and its effects on blood flow • Cardiovascular disease associated with blood flow abnormality • Can exercise restore normal blood flow? • Drug companies can develop drugs to mimic effects of exercise

  4. BloodFlow 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 http://www.gehealthcare.com/usen/ultrasound/images/cmeadi_fig3_500.jpg

  5. Existing Devices: Cycle • Custom-made cycle for use in MRI • Wood and plastic • Image blood flow during exercise • Compare healthy individuals to those with vascular disease Cycle ergometer prototype for use in MRI at Stanford

  6. Existing Devices: One-leg • Part of a Monark exercise bike and a car seat • Rollerblade boot with the toe cut out • Device was unreliable, and had variable forces Altered Monark stationary bike in use at Mayo Clinic

  7. Client Specifications • Constant wattage (range 0-100 W) • Kick rate 30-60 KPM • Chair positioned 30º from vertical • Adjust for heights 5’4” to 6’4” • Flexible range of motion while kicking • 90˚ - 180˚ range • Passive return to rest position

  8. Client Specifications • Output to computer through Powerlab and a BNC cable • Adjustable workload • Under $2,000 • Easily portable (with wheels) • Minimum lifespan of five years

  9. Design Progress • Frame built from steel pipe • Car seat fastened to frame • Adjustable for proper subject placement • Snowboard binding to connect foot to resistance • Aluminum bar to connect boot to crank arm • Ball joints allow for lateral deviation during kick • Crank arm connects pulley to aluminum bar

  10. Resistance Mechanism • Brake attached to pulley via belt • Servo motor adjusts magnetic brake force • Console used to electronically adjust motor settings through servo motor • Kicking motion propels crank arm

  11. Kick Rate Sensor • PowerLab interface for kick rate data • Sensor to detect rotations of the pulley • Each drop in voltage corresponds to one kick • Distance (time) between voltage drops determines kick rate

  12. Testing • Subject size and pedal bar length • Passive leg return-EMG screenshot • Consistent work load and power output • Ten minute stability test • New crank arm • Force transducer in pedal bar Future Work

  13. EMG Testing No EMG activity (passive return) Rectus Femoris Vastus Lateralis Vastus Medialis Low Resistance High Resistance

  14. New Crank Arm Multiple holes to allow for adjustable range of motion 12"

  15. Budget

  16. References • Maximal Perfusion of Skeletal Muscle in Man (Per Andersen and BengtSaltin) 1984 • Chi-hua Fitness Co., Ltd. http://www.chihua.com.tw/English/MAIN.htm • Joe Halfen, Director of Quality, Octane Fitness • Custom MRI cycle tracks blood flow during exercise http://ability.stanford.edu/Press/mricycle.html • Role of adenosine in regulating the heterogeneity of skeletal muscle blood flow during exercise in humans http://jap.physiology.org/cgi/content/full/103/6/2042 Additional Thanks To: • Lab of Pulmonary Medicine • Ken Ma • ECB Shop