EMG biofeedback Flashcards
EMG biofeedback description
- The therapeutic use of instrumentation to detect and feed back electric signals from motor unit APs (MUAP) that are generated by active muscle
- these devices do not actually measure direct physiological events
- the biofeedback unit records some aspect that is highly correlated with actual physiological events
- examples of correlated aspects
- peripheral skin temp
- finger photo transmission
- electromyographic activity
Motor unit Action potentials (MUAP)
These MUAP signals are detected, amplified, rectified, filtered, integrated, and converted into audiovisual signals that are used to reinforce voluntary muscle control
- relax hyperactive muscle
- increases recruitment of hypoactive muscles
Electromyographic activity
- muscle contraction results from depolarization of muscle fiber due to binding of NT (acetylcholine) from the alpha motor neuron to receptor sites at neuromuscular junction
- depolarization results in increased permeability of muscle membrane to potassium and sodium
- this changes concentration of these ions in extracellular fluid
- can be detected by surface electrodes connected to very sensitive voltage measuring device
- EMG measures this voltage change
Electromyographic activity: changes detected by?
changes in electrochemical gradient created by the MUAP can be detected by an electrode
Electromyographic activity: motor recruitment
- As more motor units are recruited, muscle tension increases and more electrical energy is detected by the EMG electrode
- smaller motor units are recruited first
- faster contractions tend to excite larger motor units & depress smaller ones
- the firing rate and recruitment of motor units is dependent upon external force required to perform task successfully
Electromyographic activity: EMG amplitude effects
- size of motor unit
- number of active motor units
- distance of active muscle fibers from recording electrode
- size of recording area
- inteletrode spacing
- *EMG has near linear relationship with force produced during carefully controlled isometric contractions
- linear relationship does NOT hold true for concentric or eccentric contractions
EMG biofeedback purpose
- To change MUAPs into auditory and/or visual cues for the purpose of increasing or decreasing voluntary muscle activity
- to enhanced motor learning by providing feedback about performance until motor skills develop sufficiently so that feedback is no longer needed
EMG biofeedback advantages
- provides immediate reward for performance changes that may be too small to note without EMG-B
- these small changes often lead to larger changes in performance improvment
- pt is able to obtain feedback about performance without the constant supervision of the therapist
EMG biofeedback indications
Motor recruitment
- when the goal is to increase the EMG signal from the target muscle
Motor inhibition
- when the goal is to decrease the EMG signal from the target muscle
Total body relaxation
- conditions of generalized pain or stress where the goal is to decrease undesirable muscle tension to achieve muscle relaxation and stress reduction
EMG biofeedback contraindications
any condition where a muscle contraction might exacerbate the condition
EMG biofeedback safe and effective application
- Obtain informed consent
- select the appropriate muscle or muscle group needed to achieve the therapeutic goal
- Prepare the skin by cleaning with alcohol
- determine the appropriate electrode placement
- place the active electrodes over the muscle belly of the target muscle
- ensure that the active electrodes are parallel to the muscle fibers
- place the ground electrode over a bony prominenece or non contractile tissue
- set the appropriate gain/sensitivity and threshold/goal on the EMG-B unit per therapeutic goal
- remove electrodes and clean skin of any adhesive
- document electrode spacing, progress in gain and threshold settings, positioning toward function, treatment duration, etc
