Muscle Fatigue Lab Report

For the study conducted this week, the group formed two hypotheses over two different tests that were ran. For the first test, which was ran using a hand dynamometer to measure grip strength, it was hypothesized that while listening to two different types of music, classical and rock, and measuring the executed force with the hand dynamometer every 15 seconds, that when listening to rock music, the individual will show less fatigue of the forearm muscle throughout the song than when listening to classical music. This test was then split into two different trials with the first consisting of the subjects listening to rock music and the second consisting of the subjects listening to classical music. Results for part one of the first test indicated
For this study, the lab group examined the muscles of the forearm and fingers in particular. Muscle fatigue can occur by way of two different mechanisms. Which mechanism is used is determined by the muscle group(s) targeted and the task being performed. Fatigue can occur when there is a buildup of excess metabolites within the muscle fibers, indicating metabolic fatigue, or when there is there is improper stimulation of motor commands in the motor cortex, indicating neural fatigue (Enoka). During the time that muscular endurance and strength is being tested, there is an accumulation of H+ molecules in the intracellular space which can cause a drop in pH by up to 0.5 pH units. With the accumulation of hydrogen ions in this space, it has been shown that this can lead to a reduction of force and power production from the muscle. An increase in H+ ion concentration also correlates with the reduction of isometric force and shortening velocity. This abundance of H+ ion the intracellular space is from the breakdown of glycogen through the anaerobic pathways into lactic acid. Lactic acid is further broken down into lactate and H+(Allen). This increase in hydrogen ion presence and therefore the drop in pH also effects and can induce muscle fatigue by way of energy metabolism inhibition. The inhibition of these processes can cause a low amount of ATP to be produced. Without enough ATP being present in the cells, energy-requiring processes such as cross-bridge cycling and sarcoplasmic reticulum Ca2+pumping, are halted until enough ATP can accumulate to complete the function (Westerblad). Once the cell has produced enough ATP to complete the process, the cell can then return to its normal resting state and the process repeats itself once again as soon as repeated use of the muscle is occurring. These processes were observed