Introduction
       Music has become increasingly popular in modern day society and many people have begun to associate music with their everyday tasks in life. It has become almost second nature for many individuals to pair music with their exercise. It has been found that music has a tendency to increase the intensity of the exercise, the endurance of the individual, and increase motivation to continue exercise.1 Psychological fatigue is a common form of fatigue. It is considered to be the fatigue brought on by mental exhaustion instead of muscular exhaustion. By studying the ability of music to extend the time before psychological fatigue sets in, insight as to the extent of which the mind can be impacted by an external stimulus can be obtained.
    It has been found that there are four methods in which music may impact exercise performance including; 1.) a reduction in the sensation of fatigue, 2.) an increase in the levels of mental arousal, 3.) improvement of motor coordination, and 4.) an increase in relaxation. 4 It is thought that the sensation of muscle fatigue can be altered by the presence of music because it prevents the exerciser from focusing solely on physical cues by directing their attention elsewhere. 4 The second hypothesis claims that mental arousal is altered when exposed to music; meaning that the music is ‘psyching up’ the individual resulting in increased performance.4 The hypothesis that there are increased motor skills resulting from exposure to music suggests that some types of rhythms can fine tune motor skills and subsequently improve exercise performance.4 The final hypothesis suggests that during high intensity exercise and fatigue contributing hormonal/byproduct release (such as acidosis) - music is able to slow down release of  such byproducts, which increases performance.4 The final hypothesis’ mechanism remains unclear. 
    Many other studies have also examined the link between music and psychological fatigue, primarily observed in athletes. As athletes spend a large amount of time working to improve their muscular fitness in the weight room, they attempt to maximize effort. A study  investigated the use of music as an ergogenic aid to promote enhanced physical performance. It was previously thought that music aids in distracting the mind; allowing the individual to dissociate from exercise. The study suggested that the use of self-selected music improved the takeoff velocity and rate of force development.1  According to the study, these increased factors directly contribute to an increase in anaerobic performance and an increase in acute physical power performance. This study along with others also concluded that using self-selected music leads to increased physiological arousal that stems from stimulated feelings of vigor, tension, as well as fatigue. 3,5 Increased fatigue is a result of music causing alteration of mood that allows individuals to disconnect from the discomfort of exercise, and shift attention to external information to maximize performance in the weight room.3
        Further research suggests that different kinds of music have varying effects on an individual's fatigue. It has been suggested that athlete output as a result of slow and fast rhythm classical music changes under different style tempo music. They determined, however, that while the fast rhythm classical music did seem to boost the participants endurance this was likely due more to the fact that the music acts as a distraction from the physical activity at hand. This leads the fast pace music to be more of a distraction and in turn increase the endurance of the participants, at least temporarily. 
    A group of undergraduate researchers’ at Clarkson University took their own experiences with music exposure and exercise and the phenomena was probed; “does music exposure psychologically prolong muscular fatigue; or physically? Better yet, does music exposure have an effect at all?”. Therefore, a study was developed involving various exercises which incorporated multiple muscles throughout the body. For this study, the goal was to examine the effect of music on individuals ability to prolong an exercise and overcome the effects of psychological fatigue, which is the first form of fatigue to set in. During the study, fatigue is considered the point where a participant is no longer able to continue an activity at the same intensity that they had previously performed it at.  
   This was done through four different tests including; an ECG recording of the test subject is used to obtain heart rate variability during music and non-music conditions to see if there is an increased sympathetic activation. It has been suggested that sympathetic branch activation may contribute to increased athletic performance by increasing the heart rate . Sympathetic activation is indicated by increased heart rate as a result of the "fight or flight response" seen when humans are exposed to threatening conditions or stressors such as exercise. Heart rate increase when exposed to music could suggest that there is sympathetic activation that otherwise wouldn't have been present during the exercise. Use of the goniometer reveals angle change in a joint maintained or lost during an exercise. In this study, data obtained from the goniometer shows how long it took the participant to fatigue respective to a ten degree angle change. A hand dynamometer has been used to account for individual grip strength. The final method used was EMG device which accounted for muscle fiber recruitment to the targeted muscle in Hz. 
    It is expected that these tests will show a difference in physical ability between participants when they are listening to music versus when they are not. When someone is listening to music we expect their heart rate to be increased, the time that they can hold a specific angle while doing a bicep curl to increase, the time and force of the grip strength measured with the hand dynamometer should increase, and finally the force of the contraction of the muscle should increase. If all of these values increase it is reasonable to assume that the participants ability to perform a physical task has improved in the presence of music.  It has been concluded that individuals who use music have higher endurance levels than those who do not use music, however all individuals throughout the conduction of this study reported that they preferred the experimentation when music was used to reduce discomfort.1     

Methods

Twelve participants will be participating in this study; chosen from all different backgrounds with varying levels of athleticism and participation in athletic activities. All the participants were informed that they must create a playlist of music that they considered to be motivational. To eliminate participant bias, the volunteer is not given further information as to what the aim of the study is. The chosen participants came into the laboratory twice to fulfill the experiment. On the first day, they completed the tasks with/without music and the second time they completed the experiment under the opposite condition completed on the first day (no music/music). Three participants would serve as the control group and would perform all of the experiments twice with no music either time. In order to eliminate the confound of previous muscular fatigue or delayed-onset muscle soreness, the subjects came in a minimum of one day apart from each experiment. The participation pool was not limited by gender or age, in order to record a more representative pool of data regarding the impact of music upon muscular fatigue across all categories. Unfortunately, the sample size was limited due to lack of time.
    Heart rate can easily be measured on the ECG, but heart rate variability was a separate metric that had to be extracted from the ECG readings and is a good indicator of the autonomic nervous system's balancing act of the sympathetic and parasympathetic branch activation. The method of analyzing heart rate variability used was a frequency domain analysis, which ultimately determines how much of a recorded signal lies within standardized frequency ranges. In terms of heart rate variability, each of the two frequency ranges represents a specific physiological phenomenon. The two most commonly used metrics for this are high frequency (HF) which represents signals of the .15-.40 Hz range, and low frequency (LF) which represents signals of the 0.04-.15 Hz range. In our study, we only analyzed LF values as this is indicative of sympathetic branch activation, and we are interested in seeing the fluctuation of the sympathetic branch in response to music. The parasympathetic branch does not play a prominent role when it comes to working out and resistance training. As for analyzing the heart rate variability, we selected to use a time interval range from 600 ms to 1.2s and the option to "include ectopic beats", as the HRV software was very picky about discriminating which beats were supposedly ectopic and the calculations were not very representative of the subject's data.
    Data from the EMG recording was processed using the root mean square method, which is used to analyze the raw EMG signal of isometric voluntary muscle contraction. Ultimately, this method greatly smooths out individual spikes seen in the EMG recording and allows for much more clear indication of a change in the activity of the muscle over time.
Procedure 1: ECG Recording (heart rate variability) -
The participant was prepared for ECG, and the recording was taken as outlined in the protocol for laboratory experiment #5. The volunteer should be instructed to relax for a minute while not listening to music, and their ECG trace will be recorded. When the volunteer returns a minimum of one day later for a conduction of the experimental protocol, under the same conditions. However, this time the individual will be instructed to listen to their music of choice for a minute before recording, and then for the minute of recording. The particular phenomenon of interest for this recording would be heart rate variability. Heart rate variability is defined as the time interval between beats. Heart rate variability was calculated by a program online, with the metric of interest being the low-frequency power percentage as this is representative of sympathethic branch activation. Heart rate would also be calculated for the music and non-music group, which is done by counting the number of QRS complexes in a 15 second period, and multiplying this number by four.
Procedure 2: Goniometer -
The participant was prepared to use the goniometer, and the recording was taken as outlined in the protocol for laboratory experiment #2. The goniometer was placed over the elbow joint. In this exercise, the volunteer is asked to perform a bicep curl. Prior to data collection, a baseline angle should be obtained by having the subject complete a partial bicep contraction, maintaining what they believe to be is a 90 degree angle between the forearm/arm. The researcher will time the individual (in seconds) under exposure to music/no music to see how long the subject can sustain the position of the roughly estimated 90 degree bicep curl contraction. The subject will be timed until there is a 10-degree difference in forearm/arm angle orientation while using a 5-10 pound dumbbell to offer resistance.
Procedure 3: Hand Dynamometer -
Volunteer picks up and loosely grips hand dynamometer in a fist of the dominant hand. The subject is exposed to the music for a minute of their choice prior to beginning the exercise. The volunteer will be asked to grip the dynamometer at maximum strength for 3 seconds in order to get a 100% baseline. The subject is then instructed to grip the dynamometer for 20 seconds at 60, 80, and 100% maximal grip strength. (If a volunteer is not instructed to listen to music prior to running experiment, then they will simply perform the trial accordingly). What will be recorded is the time that they are able to stay within a 4% range (as indicated in lab protocol 3) of the intended percentage of their maximal grip strength. This procedure tests for possible increase in motor skills when exposed to music, considering that certain rhythms may allow for the individual to stay within the desired range more accurately. Music can also serve to distract the subject from the fatigue associated with prolonging their maximum grip strength at to remain within the desired range. The maximum force of grip strength, as well as the duration of maximum, will be averaged between the control and experimental groups. 
Procedure 4: EMG -
Volunteer was prepared for EMG by skin abrasion and electrode gel placed on earth electrode wristband, the reading was taken as outlined in the protocol used in laboratory experiment #4. Now the volunteer is explicitly faced away from the monitor and is instructed to use their dominant hand to lift 5, 10, 15 pound weights, respectively with their elbow placed on the corner of a lab bench. Subject is instructed to simply lift the weight as if they were performing a bicep curl. They are instructed to not flex their muscle while performing the task, but rather lift the weight and avoid excess muscle exertion. Subject will lift each weight twice, with a brief pause between each curl as instructed by the researcher. Data should be recorded throughout the entirety of the test run. When the volunteer returns again they will be instructed to listen to the songs of their choosing and the same process of lifting the weight toward the body will be repeated. 

Results

Effects of music on Amplitude of Hand Grip Strength (Hand dynamometer)

   The average maintained 80% grip strength over a twenty second time interval for participants during both the music and non-music condition is displayed in figure 1. The average maintained 100% grip strength over a twenty second time interval for participants during both the music and non-music condition is displayed in figure 2. Each individual participant in the study that were not sorted into the control group is represented on the x-axis, numbered one through eight. Their individual trial run in the presence of self selected music is represented by the blue bars, while their trial run that they preformed is represented by the red bars. Six of the eight individuals did see an increase in the average percentage maintained at an 80%, while the other two did not, when exposed to music. While only four of the eight individuals saw an increase in the average percentage maintained at 100% while exposed to music. The average difference in maintained percentages between the trials with music and without music was found to be 13.1 for the 80% grip strength and 6.5 for 100% grip strength.