# Omg Lab Report

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LABORATORY REPORT Activity: Recruitment and Isotonic and Isometric Contractions Name: Carolyn Chrzastowski Instructor: Professor Waite Date: 07.19.2015 Predictions When the arm goes from resting to flexing, the amplitude and frequency of sEMG spikes will increase During flexion, the amplitude and frequency of sEMG spikes will ___ during extension. be greater than Recruitment of motor units will be greatest when the load is 20 pounds Materials and Methods Comparison of motor unit activation during muscle tone and concentric and eccentric isotonic contractions Dependent Variable amplitude and frequency of sEMG spikes Independent Variable muscle movement Controlled Variables total number of motor units…show more content…
6. Describe how frequency of sEMG spikes changed with increasing muscle load. The frequency of sEMG spikes started increasing as the muscle load increased until it reached it's optimal point at a 5 lb threshold and then started to slowly decreased thereafter. 7. Based on changes in amplitude and frequency of sEMG, did motor unit activation increase, decrease, or stay the same with increasing muscle load? The motor unit activation increased with muscle load based on the changes in amplitude and frequency of sEMG because the motor units which are activated are contracting at a greater frequency. 8. Do you think that the force of isometric contraction increased, decreased, or stayed the same as muscle load increased? The force of the isometric contraction increased as the muscle load increased. 9. Which would be a better predictor of increase in force of contraction, change in sEMG amplitude of spikes or change in sEMG frequency of spikes? Change in sEMG frequency of spikes. Discussion 1. Discuss the importance of muscle…show more content…
During arm extension, what type of contraction would the triceps brachii be exhibiting: concentric isotonic contraction, eccentric isotonic contraction, isometric contraction. concentric isotonic contraction 7. As muscle load is increased, which muscle fiber type is recruited first, second, and last? First is the slow oxidative fiber, then is fast oxidative glycolytic fibers, and last is fast glycolytic fibers. 8. Describe the importance of this order. Include affect on force of contraction and fatigue. This order is set up in order to increase the amount of force necessary for the work load while also limiting fatigue. The slow oxidative fibers are set up to help with weaker amount of force but are very resistant to fatigue. Then the stronger motor units, although less resistant to fatigue are next, if more force is needed. 9. Restate your predictions that were correct and give data from your experiment that support them. Restate your predictions that were not correct and correct them, giving with supporting data from your experiment that supports your corrections. My first prediction was correct that when the arm goes from resting to flexing, the amplitude and frequency of sEMG spikes will