Measuring and testing – Muscular force
Reexamination Certificate
2002-04-02
2004-01-06
Noori, Max (Department: 2855)
Measuring and testing
Muscular force
Reexamination Certificate
active
06672157
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power tester for testing reaction time and muscular power. More specifically, the present invention relates to a portable power tester which can be used to determine muscular power.
2. Description of Related Art
Rehabilitation specialists are often asked to conduct an assessment of patients that have acquired a limitation to their optimal independent activity. Although the parameters of human performance vary widely, one may identify several principles which are common to all forms of independent activity. Such common principles are muscular strength, endurance, joint range of motion, and motor coordination. It is these parameters of performance that the rehabilitation specialist focuses upon. The specialist directs attention to identified parameter's which are limiting performance and evaluates the degree of the limitation.
Historically, the rehabilitation specialist has a hands on approach using his own healthy limb to resist the movement of the patient's limb. In this way, the clinician evaluates the patient's performance through feel and, at the same time, offers exercise to the limited muscle group. By repetitive hands on accommodating exercise, the limited muscle group is overloaded and adapts biologically with improved performance.
Muscle strength is a performance parameter which is quite plastic and quickly adapts to immobilization or disuse as well as to increased activity or overuse. That is, muscle strength quite quickly increases or decreases with respect to use or disuse. Disuse, such as immobilization following injury or casting after surgery, results in a significant decrease in muscle size and muscle strength. In contrast, if free weight lifting is used as the method of choice for the rehabilitation therapy, the end result is a quick response of increased muscle cell size and gain in muscle strength.
Weight lifting equipment overloads a muscle group by using gravity against which a muscle must move the weight. With free weights, no controls are present to direct the speed of movement of the limb nor the resistance throughout the range of motion that the muscle must work against. The maximum free weight resistive load that can be applied to a limb is determined by the capacity of the associated muscle group as measured throughout the range of motion of the limb. The maximum load that the limb can support varies throughout its range of motion where at some point it is at a minimum and at another it is at a maximum. Hence, the maximum resistive free weight load that can be applied is equal to the maximum supportable load in the weakest area of the range of motion.
Conventional methods of subjective assessment and reconditioning, such as subjective “through the clinician's hands” evaluations and free weight exercise, are now reinforced with technology.
Technology has been developed which provides for assessment and reconditioning of muscular deficiencies by electronic control of the rate of movement of the limb. The rate of movement control is achieved by constantly varying the amount of resistance offered the moving limb throughout the range of motion. This category of devices allow the muscle group, usually a whole limb or limb segment, to accelerate to a pre-selected speed. These constant speed devices use the methods of isokinetic or accommodating resistance.
Isometric assessment of muscular strength has been employed extensively in orthopedic, sports, rehabilitation, and industrial clinics for more than 40 years. Isometric testing typically involves a maximum voluntary contraction at a specified joint angle or functional position against an unyielding pad or handle connected to a force measuring device. In contrast to isometric testing, isokinetic testing measures strength throughout a range of motion of a body segment using a yielding, constant velocity device to which a force measuring device is attached. The isometric testing modality has become more popular due to the availability of testing products.
The first generation of isometric testing devices was developed in the early 1980s and involved measurement of only the maximal force using a cable tension meter or dial gauge. The disadvantages of these systems include the ability to measure only gross large forces, poor sensitivity at small forces, and an inability to dynamically measure forces. Additionally, the cable systems were cumbersome, setup times were long, and the number of muscle groups that could be tested was severely limited.
The second generation of these isometric testing devices used computerized testing platforms with a chair utilized for upper and lower extremity bilateral testing, spine evaluations, and lifting assessments. These systems analyzed the force curve over time, provided feedback on cogwheeling, measured fatigue, determined rate of contraction, assessed consistency of effort, calculated averages, determined bilateral deficit, etc., all related to the performance of a patient.
One disadvantage of the above-described devices is the non-integrated test chair. The chairs included in these devices were added as an afterthought. The chairs used considerable floor space due to their size, were heavy, and were wheeled or carried into place over the platform for use. In addition, the patient was removed from the chair and the chair moved several times during most exams, making the exam longer and more involved.
Another disadvantage of the above described devices is that the load cell operates in tension only, requiring multiple setups for antagonist/agonist testing. In order to provide assessments of antagonist/agonist muscle groups, cumbersome cables or straps must be used. After testing the agonists, the patient and chair must be turned around to keep the load cell in tension to test the antagonists, which increases the setup and documentation time considerably. For example, when measuring the biceps, the handle, cable, and transducer are pulled to place them in tension. When measuring the opposite motion (elbow extension using the triceps), however, the patient and chair are turned around to keep the cable/strap in tension. This requires two different setups for the chair and patient. In addition, moving in and out of the chair for every test may prove even more time consuming, burdensome, and painful for injured patients.
A further disadvantage with these above described devices is that they use two-dimensional positioning to orient the load cell with respect to the muscle group being tested, requiring complex bilateral testing setups. The positioning methods of most systems include adjustment of the load cell height, load cell angle in the vertical plane, horizontal distance from the load cell acting point, chair orientation, etc. But in most systems, the direct line of action between the plane of movement of the muscles being tested and the centerline of the transducer results in large errors in maximal force. For example, during a knee flexion test, the patient is seated in a chair and a strap is connected around the leg just above the ankle. The tranducer is lowered so the strap is horizontal. When the patient is seated in front of the transducer, the line of action is 24 degrees resulting in a strength measurement error of approximately 10 percent.
In view of the above disadvantages, there is a need for a device which provides for more convenient and accurate bilateral testing. In order to solve this problem, some devices move chair and the patient, to the right for left side testing and to the left for right side testing. This cumbersome procedure equalizes the line of action for the muscles being tested and the tranducer, but the patient is required to exit the chair, the chair is moved, and the patient is then repositioned on the chair. If multiple tests are required, the problem is compounded. Thus, there is a need for a more convenient device for bilateral testing. In addition, there is a need for a device that provides a direct line of action between the transduc
Athinarayanan Ragu
MacFarlane Pamela
Mirman Clifford
Visser Mary
Kohn & Associates PLLC
Noori Max
Northern Illinois University
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