2) Lab 5 Group Data Sheet EMG (Group #2)

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San Francisco State University *

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483

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Mechanical Engineering

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Apr 3, 2024

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Lab #5 Topic: Neuromuscular Activation and Fatigue (EMG) Purpose: Using an EMG Device (Biopac System) to record EMG response to increased mechanical work by skeletal muscle. The Biopac system is used to observe, record, listen to and correlate motor unit recruitment and to record EMG when inducing fatigue. Part A: 1) Lab Lecture - Key words: Electro-myogram (EMG): measures the speed and strength of signals traveling in the body created by the muscle fiber action potential. Central Fatigue: occurs during long-duration, low intensity types of activities. Motor Unit: a neuron and the muscle fibers it innervates. Classified based on size, fatigability, amount of force generated, and fiber type. Peripheral Fatigue: occurs during medium-duration, and submaximal types of activities. Size principle (Henneman’s size principle): motor neurons activate muscle fibers. Shoots to small motor neuron’s first and goes up by size. Group Participants: Participant 1 : Jacob Cilia Participant 2 : Abel Benavides Participant 3 : Jaime Montejo Participant 4 : Ana De Alba Participant 5 : Mari Johns Participant 6: Joshua Martinez-Recoder Participant 7: Jennifer Quintero 2) Practice Blood Pressure and Pulse Assessment : (record BP & Pulse on all your group members) Subject Name BP (mmHg) HR Technician Name Maria 118/78 68bpm Jennnifer Jennifer 120/78 67bpm Maria Ana 118/76 69 bpm Jennifer Mari 120/60 78 bpm Joshua Joshua 126/70 80 bpm Jacob Jacob 120/79 68bpm Joshua Part B: 1) Mechanical Handgrip Dynamometer: (manual devices) - 3 trials each Subject First Name Right Hand 3 Trials Avg Force generated Left Hand 3 Trials Avg. Force generated Absolute Grip Strength (Table 1) BW in kgs Relative Grip Strength (Table 2) Jacob 2 8 3 2 3 5 31.67 kg 3 0 3 0 2 7 29 kg 35 kg 74kg 0.473

Jaime 4 5 4 4 4 3 44 kg 4 7 4 8 4 6 47 kg 48 kg 90 kg 0.533 Mari 2 5 2 1 2 1 22.33 kg 2 0 2 2 2 1 21.6 kg 25 kg 63.5 kg 0.394 Jennifer 2 2 2 1 2 1 21.33 kg 1 8 1 5 1 6 15.67 kg 22 kg 86 kg 0.256 Maria 1 3 1 6 1 5 14.67 kg 1 5 1 3 1 3 13.67 kg 16 kg 63.5 kg 0.252 2) Create a Hypothesis: Based on your knowledge of what we will observe and measure in this lab, form some type of hypothesis. The hypothesis can be anything that relates to the variables and procedures in this lab. Hypothesis- The dominant hand will on average generate more force than the non-dominant hand. Share a scientific article as a Reference for your hypothesis: • APA Reference: Li, X., He, W., Li, C., Wang, Y. C., Slavens, B. A., & Zhou, P. (2015). Motor unit number index examination in dominant and non-dominant hand muscles. Laterality , 20 (6), 699–710. • In short (see abstract), what were the article's findings? Briefly discuss: The article found that between dominant and non-dominant hand the dominant hand measured more average force. EMG readings showed that the dominant hand had significantly larger force during the pinch test, but the study found no correlation with an increase of motor unit recruitment between each hand. Part C: Equipment Preparation: Procedures & Setup: Subjects needed: minimum of 2 per group - Read procedures carefully before starting; make sure your understand generally what needs to be done in the activities; Important: Always take pictures of each data set BEFORE you close the program each time (unfortunately we cannot retrieve it)! 1) Equipment needed: (Instructor: make sure you have at least 40 electrodes per class, that is based on 2 subjects per group, 3 groups, 3 Biopac systems & computers) • Biopac System L02 –Electromyography (EMG) II application, • 1 Biopac electrode lead set SS2L (black, red, white), • 1 Biopac system handgrip dynamometer (SS25L), • Biopac Headphones (not essential, if available) and • vinyl electrodes (6 electrodes needed per subject), • 1 abrasive pad per subject

• 1 alcohol wipe per subject for skin preparation • maybe electrode gel (not essential, but can improve conductibility). 2) Procedures and Setup - Getting ready a) First boot computers with the Biopac software and hardware - open program “Biopac Student Lab 4.0” b) open the L02 - Electromyography II application software c) give the data collection-set an appropriate name - like: Kin483SP23 or use “a nickname for your group” d) attach Biopac handgrip dynamometer and electrode set to correct port (follow instructions on screen) e) click “next” and follow the instructions for electrode placement, preparation, calibration and data collection f) before pressing “next” which will start the activity! - make sure you understand what the subject has to do! Segment 1: Placing electrodes on both arms & Calibrating • Clean your electrode sites on forearm (dominant arm & non-dominant arm - you will need 6 electrodes) - attach electrodes on dominant arm first and place the handgrip dynamometer in front of your dominant arm. • Click “next” and calibrate - follow instructions (clench for 2 seconds when prompted) • use dominant hand to clench digital handgrip dynamometer for 2 seconds at maximal Peak Force and release to generate maximal Peak Force data. Note your maximal grip force generated. If calibration went ok. - click “next”: • Before proceeding: change the table variables: use - Channel & variables: Ch 41 - Max / Ch41 - Mean / Ch 40 - P-P / Ch 41 -T) on your screen according to the lab sheet table variables (see below Data Table) • Only then proceed with Phase 1 of 2 - using your dominant hand first: Phase 1: • Generate 4-5 2-second cycles of “grip-release”, “grip-release”, “grip-release “generating increasing increments of grip force up to Peak Force or maximal force. • Force (kg) Increments for Peak #1. For subsequent peaks, add the increment (i.e., 5, 10, 15 kg or 10, 20, 30 kg). - the program will tell you • Click “Next” - go to next data collection module: Use dominant hand still, but this time clench as hard as you can (max force) and hold ... until the force has declined to 50% of your max force (if max force initially was 30 kg, keep clenching at maximal ability, until the EMG shows the decline of the line to 15 kg) - SUSPEND The software now will prompt you to switch to non-dominant arm!

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Phase 2: Repeat steps of Phase 1 for non-dominant arm THEN, use the DATA TABLE to record the following: • A) Force (kg) and EMG (mv) of each increment (Peak 1-4 or 5, depending how many 2 sec increments (cycles) the subject did use to generate Peak Force (close or above to Max Grip Force) • B) and Max force (MVC) - time until fatigue/ 50% of MVC • Note: To get readings for the Max Force, Mean Force, Peak-to-Peak, Delta T click the 2 nd tool on the right-hand side of the screen • Use that tool to highlight these areas to get data for A) and B): A): incremental 2- second grip-releases AND B) highlight the beginning of MVC are to when 50% is reached or subject stops. • b) • Clean Up: Make sure to clean all the equipment (manual hand grip dynamometer, digital hand grip dynamometer, EMG cables, table top) before returning it to your instructors. Discard the abrasive pads and computers are shut down and BIOPAC hardware is turned off before they leave lab. Part 4: DATA COLLECTION Subject 1 Name: Jacob Age: 24 Sex: Male Height: 1.778m (5’10”) Weight: 74kg Data Table 1: Increasing Handgrip Force / Clench Force Data: Forearm 1 (Dominant) Forearm 2 (Non Dominant) Subject 1: J acob Max Force Mean Force at Peak (kg) Integrated EMG (mV) Max Force Mean Force at Peak (kg) Integrated EMG (mV) CH 41-Max Ch 41 - Mean Ch 40 – P-P 41-Max CH 41 – Mean Ch 40 – P-P Max Grip Force ALL n/a n/a n/a n/a PEAK #1 14.1kg 7.7kg 0.36 12.73 kg 0.42kg PEAK #2 23.85kg 14.4kg 0.49 17.4 kg 0.62kg PEAK #3 25.3kg 17.5kg 0.51 22.56 kg 0.69kg PEAK #4 24.1kg 15.6kg 0.61 22.68 kg 0.66kg PEAK #5 Table 2: Maximal Force until 50% - Record decline in force until 50% of MVC • Record force (kg), EMG (mv), and time to fatigue (s) Forearm 1 (Dominant) Forearm 2 (Non-Dominant) Maximum Clench Force (kg) 50% of max clench Force (kg) Time to Fatigue (s) Maximum Clench Force (kg) 50% of max clench Force (kg) Time to Fatigue (s) Ch41-Max Calculate Ch41-T Ch41-Max calculate Ch41-Time Subject 1 25.3kg 12.65kg 4s 22.68kg 11.28kg 2s

Subject 2 Name : Mari Johns Age: 22 Sex: Female Height: 62 in (1.57m) Weight: 63.5 kg Data Table 1: Increasing Handgrip Force / Clench Force Data: Forearm 1 (Dominant) Forearm 2 (Non Dominant) Subject 2: Max Force Mean Force at Peak (kg) Integrated EMG (mV) Max Force Mean Force at Peak (kg) Integrated EMG (mV) CH 41-Max Ch 41 - Mean Ch 40 – P-P 41-Max CH 41 – Mean Ch 40 – P-P Max Grip Force ALL n/a n/a n/a n/a PEAK #1 5.31 kg 3.39kg 0.09 3.95kg 3.40kg 0.11 PEAK #2 8.89kg 6.13kg 0.12 7.04kg 5.1kg 0.24 PEAK #3 13.84kg 9.99kg 0.30 9.05kg 6.57kg 0.30 PEAK #4 15.97kg 11.98kg 0.35 12.53kg 9.23kg 0.32 PEAK #5 20.19kg 15.84kg 0.37 15.76kg 12.86kg 0.34 Table 2: Maximal Force until 50% - Record decline in force until 50% of MVC • Record force (kg), EMG (mv), and time to fatigue (s) Forearm 1 (Dominant) Forearm 2 (Non-Dominant) Maximum Clench Force (kg) 50% of max clench Force (kg) Time to Fatigue (s) Maximum Clench Force (kg) 50% of max clench Force (kg) Time to Fatigue (s) Ch41-Max Calculate Ch41-T Ch41-Max calculate Ch41-Time Subject 2 20.62 10.31 17s 14.52 7.26 17s Part 6: LAB QUESTIONS:| • Is the Grip Strength of the dominant arm different than the non-dominant arm? Yes, No? Why do you think it is or isn’t? Yes, the grip strength of the dominant arm generates more force than the non-dominant arm. I think this is because the dominant arm is used more often and more often used to hold, lift, and such rather than the non-dominant arm. This makes the dominant arm stronger than the other. • Contemplate - When holding a different - bigger/larger/heavier object – then the handgrip dynamometer in our lab activity, how will this effect a) the number of motor units recruited? When holding a larger/heavier object than the handgrip dynamometer, more motor units are recruited by a motor neuron. This is to accommodate the heavier object and uses larger motor units. b) Are the same motor units (think fiber types) being recruited for the duration of the activity? Different motor units are being recruited when holding a larger object for a duration of an activity. When holding an object, it may start off as a medium motor unit, but transition to a large one as the muscle fibers fatigue. Which can lead to central fatigue. • As you fatigue, the force exerted by your muscle’s decreases. What physiological processes may explain the

decline in strength? Offer some ideas (think: central & peripheral fatigue) • Muscle fatigue leading to a decline in strength is due to the physiological processes of both central and peripheral fatigue. For central fatigue a reduced neural drive and motivation has an impact on muscle activation and effort. As for peripheral fatigue it is often a result of metabolic changes, energy depletion, impaired excitability contraction, and mechanical factors such as muscle damage or intense muscle contractions. Both of these factors are the most common influences on decreased muscle strength during muscle fatigue. • Looking at your data sets and the procedure of the first segment, where you were asked to initiate incrementally increasing % of grip force - can you identify whether you are using Slow(S), Fast-Fatigue resistant (FR), or Fast-fatigable (FF) motor units during your grip clench? Give a couple examples (eg. Discuss a couple “plateaus” - & think what muscle you studied) • Based on the data from the grip test involving the incremental increase of grip force the motor unit recruitment progressed from Slow (S) to Fast-Fatigue Resistant (FR) and then to Fast-Fatigable (FF) units. Due to their high fatigue resistance and steady output at a lower level, S units were used at the initial plateau of the test. Secondly as force requirements rose, FR units came into play and offered intermediate fatigue resistance, allowing the grip to keep going. In the final stages FF units were recruited for maximal force generation. FF units are more prone to fatigue to ensure efficient force generation. This order of motor unit recruitment pattern manages fatigue and is a crucial part in being able to sustain the grip throughout the trials. • Define - Motor unit: Composed of a motor neuron and the muscle fibers it controls. When the neurons send a signal, the muscle fibers in that unit contract. Motor units come in different sizes and are used depending on the type of movement. They are recruited to generate the required force needed to make contractions happen. • Define - Motor unit recruitment: The activation process of motor units in order to produce a force leading to a movement. It involves the sequential activation of motor units, starting with smaller, lower-threshold units for lighter tasks and progressing to larger, higher-threshold units for more forceful contractions. • Define - Fatigue: Defines the decline in muscle performance or unit generating frequency following any related muscle contractions. It causes a decrease in muscle strength, power or endurance and it can be a result of various factors such as metabolic changes, energy depletion, neuromuscular fatigue, and psychological factors like motivation and attention. The two types of fatigue are peripheral fatigue or central fatigue. • Define - EMG: Electromyograph y is a technique used to measure muscle electrical activity. Using electrodes placed on the skin it can detect the electrical signals generated during muscle contractions. EMG provides useful insight into aspects such as muscle activation patterns, muscle fatigue, neuromuscular function and muscle recruitment. • Lastly: After participating in today’s activity, do some research to find a scientific peer-reviewed research study evaluating/assessing hand grip strength and correlated their results to some type of health or performance variable? In other words, find research that says that “handgrip strength” of a person can tell us

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something about another health or performance aspect. • Studying hand grip strength can provide valuable information into several aspects of human health and performance. This article specifically focuses on hand grip strength of older adults. Using the Dynamometer older adults between ages 60-75, were studied with the aim of assessing the decline of muscle strength in hands and forearms, which is vital in quality of life. The results showed a correlation between decreased muscle strength and those with chronic disease and/or older age. In conclusion the results proved the practicality and effectiveness in using hand grip strength tests to assess muscle strength in geriatric adults. Citation: Hadeel Halaweh (2020) Correlation between Health-Related Quality of Life and Hand Grip Strength among Older Adults, Experimental Aging Research, 46:2, 178-191 Photos of Biopic EMG readings: Subject 1 Subject 2