Skeletal Muscle Lab Report

Introduction
The objective of this experiment was to look at and measure a muscle contraction, as well as to understand how fatigue affects muscle strength. Humans are made up of multiple different types of muscle, one of which is skeletal muscle. Skeletal muscle is a collection of muscle fibers that position and move the skeleton (Silverthorn & Ober, 2016). The muscles are then arranged into motor units, which are made up of a motor neuron and all the muscle fibers that are controlled by that motor neuron (Silverthorn & Ober, 2016). These motor units act in an all-or-none manner to create a contraction (tension in the muscle). Therefore, to create varied types of contractions with different forces and lengths, the muscle is made up of different

As the force increases the amplitude of the EMG activity also appears to increase. The corresponding table of values (Table 1) is located beneath the figure, showing that increase of force during the trials results in an increased EMG activity. In Figure 2, the effect of prolonged contractions is shown by the decrease in both muscle force and EMG activity for the dominant hand. The maximum muscle force of the dominant hand is 34.03 kg, while the half-max fatigue time is 15.995 seconds. Next, Figure 3 shows the EMG activity and force of the grip strength for the non-dominant hand. It is shown that as the force increases the amplitude of the EMG activity also appears to increase. Underneath Figure 3, is Table 2 corresponding values of absolute integral of EMG activity and the absolute integral of the area under the force curve. Figure 4 shows the effect of a prolonged contraction on the non-dominant hand. The maximum muscle force of the non-dominant is 33.519kg, while the half-max fatigue time for the non-dominant hand is 15.062

After a prolonged contraction, there is a decrease in muscle force and EMG activity.
Discussion
To begin, the EMG intensity was shown to increase as the force that was applied increased in the dominant hand. This trend was also seen in the non-dominant hand. From the data, one can see that as the force increases the EMG activity increases. This must mean that they are directly proportional to each other. In contrast to the literature values (Incelet al., 2002) the values obtained for the non-dominant hand were slightly higher than those of the dominant hand. However, this may be due to the subject’s initial grip strength for the dominant hand was lower and the amount of strength increased each trial was lower. Whereas, for the non-dominant, the difference in strength was increased by a greater amount for each trial. In other words, the increased amount of strength in each trial was relative to the first trial done on each hand. Therefore, if they started lower they will finish lower in comparison if they started at a higher grip