LAB 6: Muscle Physiology

Motor Unit
A motor neuron and all of the muscle fibers it innervates

Motor Unit Recruitment
The gradual activation of more motor units to increase the force of contraction of a muscle

An increase in the frequency of stimulation for each active motor unit
Increase the force of contraction of a muscle

What can you conclude about the effect of load on muscle fatigue?
Muscles fatigue more rapidly as more motor units are recruited to support heavier loads
With a larger percentage of muscle fibers in use, there are fewer available fibers to allow for recovery time which results in fatigue

What are some physiological factors that could account for observed fatigue?
Damaged or previously fatigued muscles
Lack of ATP
Accumulation of lactic acid

What trend do you observe for the measurements as the subject gradually increases the force of muscle contraction?
P-P and mean values increase as subject increases force of muscle contraction

What is the relationship between maximum voltage for each clench and the number of motor units in the forearm being activated?
The number of motor units increases as maximum voltage increases

What is the source of the signals that were detected by the EMG electrodes?
Action potentials travelling along muscle fibers

Is there a difference in the circumference between the dominant and non-dominant forearms?
Not really, we use both of our hands fairly equally