Bipolar Ag/AgCl Surface EMG Electrode Pair
Provides bar-electrode differential recording (20 mm inter-electrode spacing aligned with muscle fibers).
Biomedical Engineering / sEMG Muscle Fatigue Spectral Shift
FREE TO EXPLORELABORATORY 11 · BIOMEDICAL ENGINEERING
Surface Electromyography (sEMG) Root-Mean-Square & Muscle Fatigue Shift
Measure the median frequency shift and root-mean-square (RMS) amplitude of surface EMG signals during sustained isometric biceps brachii muscle contraction as a function of contraction duration. Explore interactive physiological instrumentation simulation, biomechanics, and biomedical engineering telemetry.
BIOINSTRUMENTATION · BIOSIGNALS · BIOMECHANICS · IMAGING
Your virtual biomedical engineering laboratory.
POWER SPECTRUM MEDIAN FREQUENCY MDF—
PHYSIOLOGICAL & TEST CELL TELEMETRY
Ready to sample with Time t = 30 s.
Adjust Time t, then execute biomedical trial.
Biomedical engineering telemetry and physiological states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity biological and physiological modeling.
Biomedical assumptions and boundary condition limits
The linear spectral decline model applies during constant-force isometric contractions (10 s to 60 s). Evaluated on the biceps brachii of a healthy subject maintaining 50% MVC isometric forearm flexion against a load cell. Differential sEMG sampled at 2048 Hz (bandpass 20-450 Hz). Power spectral density calculated using 1024-point Hanning-windowed FFT epochs.
Biomedical apparatus & physiological sensors.
Precision Biomedical Biopotential Preamplifier
Amplifies microvolt myoelectric potentials (gain 1000, CMRR > 105 dB, input impedance 10 GΩ).
Electronic Isometric Dynamometer Arm Rig
Constrains forearm flexion at 90° and logs isometric force to maintain strict 50% MVC target.
Precision Analog Bandpass Filter (20-450 Hz)
Eliminates motion artifacts (< 20 Hz) and prevents high-frequency aliasing (> 450 Hz).
16-Bit High-Speed Data Acquisition Card
Digitizes raw myoelectric waveforms at 2048 samples/second per channel.
Real-Time Spectral Analysis Software Console
Computes instantaneous FFT power spectrum, RMS amplitude, and median frequency (MDF).
FOLLOW THE METHOD
A reason behind every step.
Measure the median frequency shift and root-mean-square (RMS) amplitude of surface EMG signals during sustained isometric biceps brachii muscle contraction as a function of contraction duration. Standardized parameter settings: 10, 20, 30, 40, 50, 60 s.
01
Skin Preparation and Electrode Alignment
Shave and abrade skin over the biceps brachii belly with alcohol; place bipolar electrodes parallel to fiber orientation with 20 mm inter-electrode distance.
02
Maximum Voluntary Contraction (MVC) Calibration
Perform two 3-second maximal isometric contractions; record peak force to establish the 50% MVC target level.
03
Sustained Isometric Hold Initiation
Instruct subject to maintain steady 50% MVC forearm flexion against the visual feedback load indicator for 60 seconds.
04
Epoch Segmentation and FFT Processing
Segment raw sEMG into 1.0-second epochs and compute power spectral density (PSD) using 1024-point Hanning-windowed FFT.
05
Median Frequency (MDF) Extraction
Extract MDF at 10, 20, 30, 40, 50, and 60 seconds by finding the frequency where cumulative power equals 50% of total spectral power.
06
Fatigue Rate Regression Analysis
Plot MDF versus contraction time t, fitting linear regression to calculate the spectral fatigue rate k_f in Hz/s.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into biomedical engineering insight.
Points are your recorded observations. The solid regression line validates sEMG Muscle Fatigue Spectral Shift mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
MDF = -k_f · t + MDF_0 = -0.6500 · t + 95.0000
| # | Sustained Contraction Time t (s) | Power Spectrum Median Frequency MDF (Hz) | Contraction time t (s) | Median frequency MDF (Hz) | Remove |
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