A new method for muscle fatigue assessment: Online model identification techniques.
BACKGROUND
The purpose of this study was to propose a method that allows extraction of the current muscle state under electrically induced fatigue.


METHODS
The triceps surae muscle of 5 subjects paralyzed by spinal cord injury was fatigued by intermittent electrical stimulation (5 × 5 trains at 30 Hz). Classical fatigue indices representing muscle contractile properties [peak twitch (Pt) and half-relaxation time (HRT)] were assessed before and after each 5-train series and were used to identify 2 relevant parameters (Fm , Ur ) of a previously developed mathematical model using the Sigma-Point Kalman Filter.


RESULTS
Pt declined significantly during the protocol, whereas HRT remained unchanged. Identification of the model parameters with experimental data yielded a model-based fatigue assessment that gave a more stable evaluation of fatigue than classical parameters.


CONCLUSIONS
This work reinforces clinical research by providing a tool that clinicians can use to monitor fatigue development during stimulation.
UMR7287, CNRS, Aix-Marseille University, 163 avenue de Luminy, 13288, Marseille, France; Movement to Health, University Montpellier 1, EuroMov, Montpellier, France.
Maria
M
Papaiordanidou
Mitsuhiro
M
Hayashibe
Alain
A
Varray
Charles
C
Fattal
David
D
Guiraud
D000328:Adult; D000704:Analysis of Variance; D004558:Electric Stimulation / Q000009:adverse effects; D019054:Evoked Potentials, Motor / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D009862:Online Systems; D010291:Paresis / Q000175:diagnosis* / Q000209:etiology; D013119:Spinal Cord Injuries / Q000150:complications; D019415:Torque
Sigma-Point Kalman Filter; contractile apparatus; identification method; muscle model; paraplegia