Lecture notes Advanced Biomechanical Analysis

Biomechanics -Electromyography - 13/03/23
 Fatigue testing – look at frequency
 Set a threshold as the value showing the muscle as ON
o ‘When the amplitude rises above 2 standard deviation of background noise’
 Force Estimation –
o Raw Amplitude:
 Timing/patterns are usually clear, and amplitude can be compared within a
muscle/sessions
 Comparisons can’t be made between muscles/sessions
o Normalised to Maximum Voluntary Contraction (MVC):
 Amplitudes can be more meaningfully compared
 But MVC results are variable and isolated MVCs can be difficult to set up.
 Some people can’t attempt MVCs
o Normalised to Peak (or mean) Value Within a Trial:
 Doesn’t require MVCs
 But every muscle will have values up to 100% irrespective of how active it
was
o Normalised to A Reference Task (Submaximal):
 Can be a more consistent baseline
 Level can be tailored to client
 But what level should you pick and it can be hard to control the required
level
 dEMG (decomposition)
o Tries to extract individual motor units from EMG signal eg. Delsys Galileo
o Explore motor unit recruitment and firing rates
 Frequency : Fatigue




 Signal Processing –
o Select a raw EMG signal
o Full-wave rectify it (absolute value in simple math)
o Linear envelope (using RMS – Root Mean Square or a low-pass filter)