Electromyography (Dynamometry) Motor unit recruitment and fatigue Data report and evaluation

Transcription

1 Electromyography (Dynamometry) Motor unit recruitment and fatigue Data report and evaluation ELUP students Experiment was accomplished by: Teacher:... Date:... Subject 1 Subject 2 name:... name:... gender: male / female gender: male / female age:... age:... height:... height:... weight:... weight:...

2 Aims of the practical lesson (brief definition in a few sentences) 2 Introduction (can be continued on a separate sheet if needed) 1. Regulation and adjustment of muscle contraction strength (summary of the most important facts with regard to the analysis of the practical data) 2. Methods and materials (schematic enumeration) 3. Technical details of the practical exercises (preparation of the subject, settings of the recording system, explanation of the exercises)

3 A. Data and calculations 3 1. Motor unit recruitment Fill out the following tables using Segment 1 data both from the dominant and from the nondominant arm. During the evaluation, use the following options in the channel windows: CH1 - force; CH40- integrated EMG. Choose the parameter mean in both parameter windows. Using the I-beam cursor, select an area on the plateau phase of the first clench, read the values and insert them into the table. As the program shows the extent of muscle contraction as the force exerted by a given weight in [kg], please transform the force values in the table to [N]! Calculate the quotient force/integrated EMG as well! Repeat the same procedure with the subsequent peaks - you may not need 6 peaks to reach maximum clench force. Attach the analyzed records (printouts) to the lab report and number them accordingly! Subject 1 (name:...) Dominant forearm (right left) Nondominant forearm (right left) Mean force Mean int. Force/ Mean [CH1] force [N] EMG [CH40] int. EMG [kg] [mv/s] [Ns/mV] Mean force Mean int. Force/ Mean [CH1] force [N] EMG [CH40] int. EMG [kg] [mv/s] [Ns/mV] Subject 2 (name:...) Dominant forearm (right left) Nondominant forearm (right left) Mean force Mean Mean int. Force/ [CH1] force EMG [CH40] int. EMG [kg] [N] [mv/s] [Ns/mV] Mean force Mean Mean int. Force/ [CH1] force [N] EMG [CH40] int. EMG [kg] [mv/s] [Ns/mV] Create a graph using the force integrated EMG data pairs (x axis: force; y axis: integrated EMG)! Plot the data derived from both forearms of both Subjects on the same graph! Number of the attachment:...

4 2. Muscle fatigue 4 Subject 1 (name:...) Maximal force 50% of maximal force Mean Mean Mean int. Mean Mean Mean int. force force EMG force force EMG [CH1] [CH1] [CH40] [CH1] [CH1] [CH40] [kg] [N] [mv/s] [kg] [N] [mv/s] dominant (...) arm nondominant (...) arm Subject 2 (name:...) Maximal force 50% of maximal force Mean Mean Mean int. Mean Mean Mean int. force force EMG force force EMG [CH1] [CH1] [CH40] [CH1] [CH1] [CH40] [kg] [N] [mv/s] [kg] [N] [mv/s] dominant (...) arm nondominant (...) arm Fatigue length [CH40; T] [sec] Fatigue length [CH40; T] [sec] B. Summary and discussion of data a) What does the EMG electrode measure? What determines the amplitude of the integrated EMG signal? b) Does the dominant or the nondominant forearm have higher strength capacity? Subject 1: dominant nondominant no difference Subject 2: dominant nondominant no difference Is there any difference between the subjects in this respect? Explain the observation!

5 c) Is there any difference between the subjects maximal strength capacity? 5 yes no Explain your observations! d) In the force-integrated EMG graph, what does the slope (steepness) of the curve indicate? Order the curves according to the slope steepness (1: lowest; 4: highest) Subject 1 dominant Subject 1 nondominant Subject 2 dominant Subject 2 nondominant Compare the force per EMG unit values during approximately same strength of clench! (Use the values calculated in the first two tables!) Subject 1 dominant Subject 1 nondominant Subject 2 dominant Subject 2 nondominant Explain and interpret the order above! What do these values reflect? e) Compare the fatigue length of the forearms! (1: shortest; 4: longest) Subject 1 dominant Subject 1 nondominant Subject 2 dominant Subject 2 nondominant Explain the results!...

6 6 f) How does the EMG activity change during muscle fatigue? Explain your observations! Subject 1: decrease no change increase Subject 2: decrease no change increase... g) When holding an object, does the number of motor units remain the same? Are the same motor units used for the whole duration of holding the object? h) As you fatigue, the force exerted by your muscles decreases. What physiological processes explain the decline in strength?

7 C. Definitions 7 Motor unit:..... Muscle tone:..... Motor unit recruitment:..... Muscle fatigue:..... Dynamometer:.....