Biceps Muscles Lab Report

Figure 1. An EMG Tracing of Triceps and Biceps Muscles Co-activation. EMG signal produces an electrical activity of the muscle fibers active at a moment time. The electrical activity is measured in millivolts per milliseconds. The top channel shows the bicep EMG, while the bottom EMG correlates to the triceps contraction traces. Shown on the top graph, there are two periods of bicep activation, each last approximately 1.5ms. When the biceps are activated, it produces increasing amplitude peaks, and when the biceps are inhibited, the amplitude decreased dramatically. The same idea applies to the triceps. In bottom channel illutrates two triceps activation periods, where a larger amplitude was exhibited when activated and when inhibited, the amplitude decreased. When one muscle is active, the other muscle is mostly inhibited and vice versa. This is known as the co-activation phenomenon and is demonstrated in the figure.

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A).
As weights were added to the arm, the amplitude of the top channel of the EMG trace for the bicep muscles increased as each individual book was added. In this experiments of lifting objects, the bicep muscles that were doing much of the work is known as flexors while the triceps were doing less of the work in the opposition force of contractile. For the top channel that correlates with the bicep trace; a …show more content…
Co-activation is seen in this experiment where the bicep, the flexor, resembles the agonist and the triceps, the extensors, resemble the antagonist. When the bicep muscle is active by being in its flexed position; its motor neurons are excited whereas the motor neurons in opposition of the triceps are somewhat inhibited. However, these triceps muscles still contribute to minor activities compared to that of the bicep muscles; but together they work in a co-activation fashion for contractile