Muscle fatigue and EMG basics
Fri, Feb 26, 2027 · Week 6 · Human Anatomy & Physiology (Human Body Systems)
Today's goal: Explain muscle fatigue and how EMG measures electrical muscle activity.
What a finished product looks like
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Fatigue-mechanism summary: Muscle fatigue is the decline in force a muscle can produce during repeated use. It is caused by depletion of ATP and phosphocreatine, buildup of metabolic byproducts such as lactic acid and hydrogen ions, and eventual failure of signaling at the neuromuscular junction.
EMG prediction (labeled sketch, EMG in millivolts versus trial number):
- Early trials: moderate amplitude, higher firing frequency.
- Middle trials: amplitude rises as the nervous system recruits more motor units to keep the force up.
- Late trials: frequency drops and the signal becomes less efficient as the muscle can no longer sustain force.
Prediction in one line: as the muscle fatigues, I expect EMG amplitude to increase (more motor units recruited) while the signal frequency decreases.
Also due today: Submit your prediction sketch and summary as a single upload.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.