Adam Grillo

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INTRODUCTION: Fitts’ law is a descriptive model of human movement that states the time required to rapidly move to a target areas is a function of the ratio between the distance to the target and the width of the target. This means for simple tasks such as a simple bicep curl, the distance and targeted area are short and easy to hit. If one side of the body goes through this simple task, the opposite side will have a better idea of what to expect through what is called bilateral transfer. However unilateral transfer of muscle activity, were someone works solely on one side of the body, has been shown to also have similar affects to the opposite limb. During most simple tasks the first and initial movement time (MT) is called reaction time (RT). This is the interval of time between the presentation of a stimulus and the initiation of the muscular response to that stimulus. Research has shown a low resting heart rate (HR) to be a good indicator of physical fitness as well as alertness. If this is the case, individuals with a lower HR should have a quicker RT to a stimulus. PURPOSE: The purpose of this study was to figure out if one side of the body’s RT/MT could be decreased by stimulating muscle activity in the opposite side.METHODS: Ten male students (M; age 24.7 +/-3.4 yrs) five left handed (LH) and five right handed (RH) of the UTA Kinesiology department, volunteered to participate in this study. Each subject had resting heart rate (HR) taken and soon after were asked to find out their one repetition max (1RM) for a fully extended bicep curl. Each subject had an electromyogram (EMG) pad placed on the belly of either the left or right bicep, a ground lead on the C7 vertebra, and an electro-goniometer placed on the arm with the EMG pad. The subject then performed a simple bicep curl as quickly as possible and the EMG and electro-goniometer RT readings were recorded. This was done 2 to 5 times with 30 seconds of rest in between each curl. The subject was then asked to hold 50% of the 1RM in the opposite hand while performing the same quick bicep curl. The same set up and process was then performed on the opposite arm on which the subject started with. RESULTS: For the LH subjects: Right CON RT (CON: 46.97 +/-13.8 msec; 50%1RM: 48.16 +/-13.5 msec); Left CON RT (CON: 49.65 +/-11.6 msec; 50%1RM: 51.29 +/-11.1 msec) did show a faster reaction time for the right side over the left on both groups, however showed no significant difference when comparing right to right and left to left (p > 0.05). Although for the RH subjects: Right CON RT (CON: 52.02 +/-10.9 msec; 50%1RM: 46.46 +/-10.0 msec); Left CON RT (CON: 60.43 +/-16.8 msec; 50%1RM: 50.56 +/-15.2 msec) showed significant difference in comparing both right to left and same arms to each other (p < 0.05). Resting HR between the two groups was compared in order to see if fitter individuals had a quicker RT (RH: 67.4 +/-10.0 bpm; LH: 62.4 +/-9.5 bpm), showing the LH subjects to have a slightly lower average resting HR. CONCLUSION: The results of this study indicate that even though LH individuals seem to have a lower base RT on both arms, when muscle activity is unilaterally transferred RH individuals benefit from this extra activity whereas LH individuals are slightly hindered.


Kinesiology | Life Sciences

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