ELECTROMYOGRAPHY II

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Apr 3, 2024

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ELECTROMYOGRAPHY II Motor unit recruitment and Fatigue DATA REPORT Student’s Name: Anne Marie Elie, Raina Hemmings, Anthony Malone, Sophia Ferreira Lab Section: L03 Date: 02/15/24 Subject Profile Name: Anthony Malone Height : 5,5 Gender: Male / Female Age: 22 Weight: 176 Dominant forearm: Right / Left I. Data and Calculations Motor Unit Recruitment A. Complete Table 2.1 using Segment 1 and Segment 3 data. In the "Force (kg) Increments" column, note the force increment assigned for your recording under Peak #1; the increment was pasted to the Journal and should be noted below from Data Analysis—Step 2. For subsequent peaks, add the increment (i.e., 500, 1000, 1500). You may not need eight peaks to reach max. Take measurements on plateaus of the Integrated EMG data. Table 2.1 Increasing Clench Force Data Assigned Force Increment Peak # SS25L/LA = Kg SS56L = kgf/m^2 Seg. 1 Forearm 1 (Dominant) Seg. 3 Forearm 2 Force at Peak Integrated EMG (mV) Force at Peak Integrated EMG (mV) 1 28 16.8143 0.2047 2 31 19..4403 0.2323 3 35 27.8493 0.3829

4 42 40.600 0.5617 5 33 24.9681 0.2846 6 37 32.1044 0.3695 7 45 40.3949 0.4479 8 50 47.7613 0.4971 Fatigue B. Complete Table 2.2 using Segment 2 and Segment 4 data. Table 2.2 Maximum Clench Force Data Seg. 2 Forearm 1 (Dominant) Seg. 4 Forearm 2 Maximum Clench Force 50% of Max Clench Force Time * to Fatigue Maximum Clench Force 50% of Max Clench force Time * to fatigue calculate calculate 41.8876 20.9438 25.9400 38.5045 19.25225 25.4000 *Note : You do not need to indicate the Delta T (time to fatigue) polarity. The polarity of the Delta T measurement reflects the direction the "I-beam" cursor was dragged to select the data. Data selected left to right will have a positive ("+") polarity, while data selected right to left will have a negative ("-") polarity. Page 16 Biopac Student Lab 3.7.6 II. Questions C. Is the strength of your right arm different than your left arm? Yes No D. Is there a difference in the absolute values of force generated by males and females in your class? Yes No What might explain any difference? The difference can be a result of males typically having a higher muscle mass as a whole and their general ability to generate more force compared to females. Females however tend to have greater muscle fatigue ability compared to males. E. When holding an object, does the number of motor units remain the same? Are the same motor units used for the duration of holding the object? The number of motor units will remain the same while holding an object however the same motor units will not be used throughout the time of holding the object. The body will continually switch out the motor units while keeping the same amount in contraction to maintain the contraction/tension and conserve energy.

F. As you fatigue, the force exerted by your muscles decreases. What physiological processes explain the decline in strength? This decline in strength is related to the Short-duration maximal exertion that was performed by squeezing as hard as you can for a period of time. During this form of activity, there are increased levels of inorganic phosphate along with a decrease in the release of Calcium. This could cause a decrease in the force you exert from your muscle because not only is the increase of Calcium levels in the cytosol the first step in muscle contractions but the increase in the levels of inorganic phosphate are related to the degradation of ATP. G. Define Motor unit: defined by a group of muscle fibers innervated by the same nerve group. It is made up of motor neurons and skeletal muscle fibers innervated by the motor neurons' axonal terminal H. Define Motor unit recruitment : successful activation of the same and additional motor units with increased strength of the voluntary muscle concentration I. Define Fatigue : defined as a lack of energy and motivation; overall tiredness J. Define EMG : measures muscle response or electrical activity in response to nerve stimulation of the muscle K. Define Dynamometry : the process of obtaining quantifiable measurements of muscular strength, power, and endurance. End of Lesson 2 Data Report

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