biomechanics of skeletal muscle and electroymography n biomechanics of skeletal muscle -readings:...
TRANSCRIPT
Biomechanics of Skeletal Muscleand Electroymography
Biomechanics of skeletal muscle- Readings: Hamill pp 76-81, 103-109
Electromyography- Readings: Hamill pp 81-85; Cram pp 32-37, Ch 3;
DeLuca website tutorial (http://www.delsys.com ),
Musclestructure
The motorunit
Factors Influencing Production of Muscular Tension
Motor unit size Muscle Fiber Type
- Selective recruitment of fiber types:• SO FOG FG
Length - tension relationship Force-velocity relationship
Muscle Fiber Types
Recruitment proceeds from smallest fibers to largest (the size principle)
Three-component
model of muscle
contraction
Length-tension
relationship
Force-Velocity
relationship
Electromyography: The analysis of muscle electrical activity
The electromyogram Recording the Electromyogram Factors affecting electromyogram Analyzing the electromyogram Applications of electromyography
The EMGsignal
Recording the electromyogram Electrodes –
- Size- Number- Placement
Signal conduction – wires or telemetry? Signal conditioning
- Amplification- Filtering- Analog to digital conversion- Integration- Frequency analysis
Filtering: Effect of different cutoff frequencies on EMG
Factors affecting the electromyogram
Analyzing the EMG signal
The concept of Frequency decomposition
Converting EMG from
time domain to frequency
domain
What is the time block, Or window over which Frequency analysis isdone?
EMG in the Frequency Domain
Applications of electromyography
Timing of excitation Degree of excitation
- Normalization procedures
Muscle force-emg relationship Muscle fatigue Clinical gait analysis Ergonomics Limitations of EMG
Timing and degree ofexcitation
EMG-forcerelationship
Electromechanical delay
Windowing is a critical step in converting EMG signal from time to frequency domain
The fatigue indexFrom EMG –Review the AssumptionsInherent in thisprocedure
Website article reading assignment
Go to website: http://www.delsys.com and download tutorial article on “surface electromyography detection and recording”
Be prepared to answer the following questions:- What is differential amplification?- What is common mode rejection ratio?- Where should electrodes be placed?- Where should electrodes not be placed?- How large should electrodes be?- Name 3 applications of EMG signal
Further readings on Electromyography
•Journal articles with specific review assignments:•Hildenbrand & Noble. (2004) J Ath Trng. Abdominal muscle activity using different exercise equipment. •Caterisano, et al (2002) J Str & Cond Res. EMG of Hip and thigh muscles during back squat.•Anders (2006) ACE FitnessMatters. EMG of gluteus maximus during various hip extension exercises.
•Additional detailed tutorial on methodology (optional):
•Electromyography in biomechanics. J Appl Biomech, 19:135-163. (can be foundDeLuca, C. J. (1997) “The use of surface electromyography in biomechanics” on delsys.com website). Click on “library”, then “tutorials”, then article title.