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

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

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

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

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

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

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

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

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 180˚ leg extension Passive return to rest position

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

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

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

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 http://www.robbinssports.com/sporting-goods-store/fitness-and-exercise-exercise-bikes-c-24_272.html

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

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

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

References Maximal Perfusion of Skeletal Muscle in Man (Per Andersen and Bengt Saltin) 1984 Chi-hua Fitness Co., Ltd. http://www.chihua.com.tw/English/MAIN.htm Joe Halfen, Director of Quality, Octane Fitness