Cost-Effective Method for Testing Muscle Stiffness in the Bicep Using Vibration-Induced Stimulation

Abstract

The purpose of this paper is to present the experimental data concerning alternative methods of gathering muscle stiffness information and the procedures utilized for this experiment. In an effort to reduce cost and size of current muscle stiffness detection methods, accelerometers are utilized to gather vibrational data. During the initial stages of testing, the first method used was inaccurate and inconsistent due to certain steps which were revised for the second method. Implementation of the second method removed inconsistency within each individual test. Results were found to be satisfactory, so after further testing in order to increase sample size, plans for device design are soon to be undertaken.Current methods of measuring muscle stiffness and degradation, such as Magnetic Resonance Elastography (MRE), are both highly invasive and expensive. The purpose of this study is to develop a method of determining muscle stiffness using surface vibrational testing which will be both cost-effective and non-invasive. Thus far, the test subjects have been males in the age range of 20–22 years old. This pool will be expanded in future testing, but for now this data suffices for preliminary research. This method makes use of three accelerometers in contact with various locations on the surface of the bicep. Using a medical hammer, a vibration is induced on the unstressed bicep in proximity with the sensors which will then determine the difference in vibration from one sensor to the next. The test is repeated with the bicep stressed using a 10 lb. weight. The vibration difference between the sensors is used to determine the speed in meters per second and a muscle stiffness value in kilopascals for both unstressed and stressed. Our method of testing during the initial phases differed from this where instead of a medical hammer being used by the experimenter, the subject would induce the vibration with his own index finger. This proved to be inconsistent, and the use of the medical hammer was introduced in successive tests. We believe that the simplicity of this device will serve as an affordable alternative to current methods of determining muscle deterioration/rehabilitation. In further proceedings, once the sample pool has been expanded, we hope to be able to make approximations for the stiffness of an individual’s biceps based on unstressed readings and other varying physical factors such as height, weight, and gender. Current subjects’ demographics have spanned 20–22-year-old males. In future proceedings, subject demographics need to be expanded in order to obtain a more diverse range of data. However, with the data that has been collected thus far, the results shown here reflect expectations. Due to strength differences across test subjects, the standard deviation for the stressed tests is significantly larger than that of the unstressed. This is visualized in figure 2 where the error bars indicate that the data points are tightly packed for the unstressed (0 lbs.) test and vary significantly for the stressed (10 lbs.) test. Broadening the sample pool in future testing will help in refining and predicting levels of stiffness among similarly situated subject groups. As expected, the mean velocity and stiffness increases when moving from unstressed to stressed; the lower bound of the stressed data point also does not overlap with the upper bound of the unstressed data point in either graph. The graphs also bear a strong resemblance to one another which is another testament to their validity.