Questions and Answers
Why is it important to lightly abrade the skin and clean the area with alcohol swabs prior to attaching EMG electrodes?
This reduces the electrical resistance of the skin.
Why is the EMG waveform irregular unlike the discrete waveform from an ECG?
An electromyogram records skeletal muscles, which don't contract at the same time.
How did the EMG trace change when you added weight to the volunteer's arm?
The data had a higher amplitude, indicating more motor neurons were being recruited to resist the load.
Did this experiment help you decide which of the factors proposed to explain fatigue are important?
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From your data, do you think that verbal encouragement or brief rests limited the extent of muscle fatigue?
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During sustained skeletal muscle contraction, true fatigue might occur due to a lack of ______.
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What explanations can you think of for pseudo-fatigue?
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Do you need to reform your hypothesis based on your experience testing each of the factors in the lab today?
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Study Notes
Importance of Skin Preparation
- Lightly abrading the skin and using alcohol swabs decreases skin electrical resistance.
- Proper preparation enhances electrode performance for accurate EMG readings.
EMG vs. ECG Waveforms
- EMG waveforms are irregular due to asynchronous contractions of skeletal muscles.
- ECG waveforms are regular because cardiac muscles contract in unison.
Effects of Added Weight on EMG Trace
- Adding weight results in a higher amplitude EMG trace, indicating increased motor neuron activation.
- More motor neurons are recruited to counteract the load force as weight increases.
Muscle Fatigue and Experiment Observations
- Heavier contractions lead to more pronounced muscle fatigue compared to lighter contractions.
- The experiment provides insights into the relationship between contraction intensity and fatigue.
Impact of Verbal Encouragement and Rest
- Verbal encouragement and brief rests can partially reduce muscle fatigue during sustained exertion.
- These factors help maintain performance levels during grip strength tests.
Locations of True Muscle Fatigue
- True fatigue can occur due to:
- Depletion of calcium ions (Ca2+).
- Accumulation of lactic acid in muscle tissue.
- Desensitization of muscle receptors leading to decreased responsiveness.
Understanding Pseudo-Fatigue
- Pseudo-fatigue, experienced with eyes closed, mimics actual fatigue but can be easily overcome.
- Lack of visual feedback may lead to a subjective feeling of fatigue, despite actual force capacity being maintained.
Hypothesis Validation and Adjustments
- The original hypothesis remains valid; findings indicate more fatigue with visual feedback.
- Rest periods contribute to reduced fatigue perception, highlighting the importance of visual and mental cues in muscle performance.
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Description
Explore the essential concepts of electromyography (EMG) through these flashcards. Learn about the importance of skin preparation for accurate readings and the differences between EMG and ECG waveforms. Perfect for students in physiology or biomedical engineering.
