METHOD AND DEVICE FOR ISOKINETIC QUADRICEPS EXERCISE USING PNEUMATIC MUSCLE ACTUATOR (PMA) RESISTANCE: COMPARISON TO FREE WEIGHT EXERCISE

Size: px

Start display at page:

Download "METHOD AND DEVICE FOR ISOKINETIC QUADRICEPS EXERCISE USING PNEUMATIC MUSCLE ACTUATOR (PMA) RESISTANCE: COMPARISON TO FREE WEIGHT EXERCISE"

Marsha Tate
5 years ago
Views:

1 METHOD AND DEVICE FOR ISOKINETIC QUADRICEPS EXERCISE USING PNEUMATIC MUSCLE ACTUATOR (PMA) RESISTANCE: COMPARISON TO FREE WEIGHT EXERCISE M. COWGILL, C. PHILLIPS, D. REYNOLDS, J. SERRES, K. HALL, S. MOHLER Departments of Biomedical, Industrial, and Human Factors Engineering, Wright State University, Dayton, OH

2 ABSTRACT INTRODUCTION: The history of muscle atrophy in microgravity environments is a well documented and continuing issue for space travelers. The lack of weight and pressure normally experienced due to gravity leads to reduction in both muscle mass and bone density which can be difficult to recuperate once back on earth and can lead to serious injury. The situation creates a need for a source of resistance that is not dependent on gravity. Our previous laboratory research has looked at the theoretical application of pneumatic muscle actuators (PMAs) in place of free weights working against a simulated human operator. METHODS: An exercise apparatus was created from a commercially available machine (Valor Fitness-the CC-4 Leg Machine). Modifications were made to extend the base to support the added equipment which includes a rig for attaching the Festo brand PMAs to both the base and the rod at the knee s point of rotation. Additional instrumentation included a load cell, string potentiometer, and rotational potentiometer all of which are used for both feedback and control of the system in LabVIEW. 10 subjects then participated in testing to compare two types of quadriceps exercise methods-one using free weights, the other using PMAs as described. Each exercise was performed until the subject fatigued and was only performed once. Sessions were spaced at least a week apart to avoid any training effect. Subjects were evaluated comparing their isokinetic exercise trajectory to the ideal trajectory using the root-mean-square-error (RMSE) method. RESULTS: The RMSE of the subjects in the two different quadriceps exercise methods was less than 5%. DISCUSSION: This work demonstrates that equivalent exercise performance occurs when using PMAs as a resistive device as compared to free weights. This research is applicable to a method from more effective resistance exercise in microgravity environments. 2

3 INTRODUCTION Space travelers suffer severe muscle atrophy and bone density loss due to lack of gravity Current forms of microgravity exercise do not address lack of body weight effect on muscle and bone Previous laboratory research focused on pneumatic muscle actuators (PMAs) theoretical application as a resistive device in exercise 3

4 INTRODUCTION Continued PMAs thought to be capable of producing resistance independent of gravity for better microgravity strength training Festo fluidic muscle used for research Applied to a conventional quadriceps exercise Used to replace free weights for resistance More adaptive with finer incrementing of resistance 4

5 Festo Fluidic Muscle Contracted Relaxed 5

6 METHODS Modifications made to exercise apparatus (Valor Fitness CC-4 Leg Machine) to incorporate PMAs and sensors PMAs used in parallel to increase resistance capability LabVIEW programs created to collect data and control PMA performance with interface created for subject s visual feedback 6

7 Exercise Apparatus 7

8 PMAs and Instrumentation PMAs Rotational Potentiometer Load Cell String Potentiometer 8

9 LabVIEW Interface 9

10 METHODS Continued Subjects given isokinetic workout pattern to follow with visual cues and performance feedback on computer screen Subjects asked to perform exercise at 25% of maximum strength with free weights to determine interactions between the subject and Exercise apparatus LabVIEW interface 10

11 Visual Cues and Feedback-Example 11

12 Isokinetic Profile One cycle of isokinetic workout profile 5 second hold with leg bent 5 second isokinetic motion to extended leg 5 second hold with leg extended 5 second isokinetic motion to bent leg Subject asked to repeat until fatigued (or experienced pain) or tester concluded workout 12

13 RESULTS Subjects struggled to visually match their workout profile with ideal profile Not able to achieve ideal profile under any conditions due to physiological constraints Ideal profile gave visual cues that caused subjects to complete segments of the workout profile too quickly or too slowly Many subjects unable to achieve lowering of leg in 5 seconds-probably due to visual cue confusion 13

14 Subject Performance 14

15 DISCUSSION Subjects must be evaluated for not only maximum strength but also range of motion LabVIEW interface must reflect each subject s range of motion for most accurate visual feedback of performance rather than optimal theoretical performance Subjects must work out at more than 25% of maximum strength to fatigue in less than 30 cycles 15

16 DISCUSSION Results of pilot will be applied to research program for more robust and useable results With subject customized modifications, more accurate isokinetic exercise can be performed This device and its corresponding isokinetic exercise utilizing PMAs promises to provide a more effective method of resistance exercise in microgravity environments. 16

17 Disclosure Information 84th Annual AsMA Scientific Meeting Mandy Cowgill I have no financial relationships to disclose. I will not discuss off-label use and/or investigational use in my presentation 17

DATA INTERPRETATION AND ANALYSIS

DATA INTERPRETATION AND ANALYSIS Numerical and Curve Analysis Ref: Compendium of Isokinetics George Davies Report Parameters Peak Torque Highest muscular force output at any moment during a repetition.