NMES - Electrical Currentsfor Muscle Contraction Flashcards
Type I or Type II = ?
- Oxidative
- Low force
- Resist fatigue
- Small diameter motor neurons
NMES
Slow twitch fibers - Type I:
- Oxidative
- Low force
- Resist fatigue
- Small diameter motor neurons
Type I or Type II = ?
- Glycolytic
- High force
- Fatigue quickly
- Large diameter motor neurons
NMES
Fast twitch fibers - Type II:
- Glycolytic
- High force
- Fatigue quickly
- Large diameter motor neurons
Voluntary or Stimulated Muscle
Has a rapid onset and synchronous recruitment of motor units = ?
NMES
- Voluntary:
- Smooth onset
- Asynchronous recruitment of motor units
- Stimulated contraction:
- Rapid (could be jerky) onset
- Synchronous recruitment of motor units
Voluntary vs. Stimulated Muscle Contractions
Greater amplitude = increase or decrease in motor units stimulated ?
NMES
- Increasing strength of stimulated contraction
- More current (amplitude) = more motor units
- Externally applied resistance
- At least _ ? _ % MVIC to strengthen an otherwise healthy muscle
- At least _ ? _ % MVIC to strengthen a weakened muscle
NMES
Voluntary vs. Stimulated Muscle Contractions:
- Targeting strength vs. endurance
- Endurance = more reps at lower force
- Strength = fewer reps at higher force
- Cameron recommends:
- At least 50% MVIC to strengthen an otherwise healthy muscle
- At least 10% MVIC to strengthen a weakened muscle
- Amplitude to produce functional movement for re-education
NMES may be benficial for the four orthopedic conditions = ?
NMES
- Orthopedic conditions:
- Post-surgery
- Pre-surgery
- Alternative to surgery
- Other conditions that lead to relative disuse
How can NMES be benficial for neurological disorders = ?
NMES
Clinical Applications - Neurological disorders:
- Spinal cord injury - Stimulation for exercise benefits
- Stroke - Neuromuscular re-education / EMG-triggered NMES
- Outright strengthening
- Neuromuscular re-education (+ benefit of sensory)
- Functional electrical stimulation (FES)
Contraindications
= ?
NMES
Contraindications:
- Demand pacemaker or unstable arrhythmia
- Over the carotid sinus
- Venous or arterial thrombosis or thrombophlebitis
- Pelvis, abdomen, trunk and low back area during pregnancy
- Do not stimulate contraction when contraction is contraindicated (wound/fracture)
Precautions
= ?
NMES
Precautions:
- Cardiac disease
- Impaired mentation or impaired sensation
- Malignant tumors
- Skin irritation or open wounds
- Be aware of the potential for Delayed Onset Muscular Soreness (DOMS)
Rehab setting
Pulse duration of ? - to - ? µs and a pulse frequency of ? - to - ? Hz appear to be the most effective parameters to optimize torque output while minimizing discomfort
NMES
Rehab Setting:
- Pulse duration of 400 to 600 µs and a pulse frequency of 30 to 50 Hz (Pulse frequency is HZ) appear to be the most effective parameters to optimize torque output while minimizing discomfort, muscle fatigue, or muscle damage.
- Optimal electrode placement, conditioning programs, and stimulus pattern modulation during long-term NMES use may improve results.
What are some keys from the research presented in class ?
NMES
Research in Class:
- Electrical stimulation may be effective for increasing voluntary muscle strength in people with stroke.
- The efficacy of electrical stimulation for people with spina bifida, cerebral palsy, peripheral nerve lesion, multiple sclerosis or spinal cord injury is NOT clear.
- It’s NOT known whether electrical stimulation with or without super-imposed voluntary strength training is superior to voluntary strength training alone in any neurological populations.
- It seems that dynamic submaximal superimposed WB-EMS training DOES NOT provide notable additional improvements in maximal strength and power parameters of the leg muscles of moderately trained, young athletes compared with a similar training intervention without superimposed WB-EMS.
Target Neuron for NMES = ?
= ?
NMES
Target Neuron for NMES = A-alpha
Strength-Duration Curve
- Short duration pulses for sensory axon = ? usec
- Long duration pulses for motor axon = ? usec
- Very long duration pulses for muscle fiber = ? ms
NMES
Strength-Duration Curve:
- Short duration pulses for sensory axon = 60-80 usec
- Long duration pulses for motor axon = 150-300 usec
- Very long duration pulses for muscle fiber = > 10 ms
Parameters
- Waveform = ?
- Spacing = ?
- Patient positioning = ?
NMES
- Parameters:
(I) Waveform = Pulsed biphasic
(II) Electrode placement =
- Spacing – At least 1 inch apart (Motor point)
- Typically, in alignment with the muscle fibers of the target musculature.
(III) Patient positioning =
- Think about comfort and application
- (gravity/resistance/moving extremities)
Pulse frequency
- Twitch = ? pps
- Tetany = ? pps
- Fatigue = ? pps
NMES
- Pulse frequency:
- Twitch = < 20 pps
- Tetany = 35 – 50 pps
- Fatigue = > 50 pps
On : Off Time
- Contraction for building strength = ? sec ON time
- ON:OFF ratios of = ?
NMES
On : Off Time:
- Contraction for building strength = 6-10 sec ON time
- ON:OFF ratio of 1:5, 1:4 or 1:3
Contraction for fatiguing spasm
- ? sec ON time
- ON:OFF ratio = ?
NMES
On : Off Time:
- Contraction for fatiguing spasm
- 2 – 5 sec ON time
- ON:OFF ratio of 1:1
Contraction for edema reduction (“pumping”)
- ? sec ON time
- ON:OFF ratio = ?
NMES
On : Off Time:
- Contraction for edema reduction (“pumping”)
- 2 – 5 sec ON time
- ON:OFF ratio of 1:1
Ramp time
- Situations may require no ramp = ?
- Situations may require extended ramp = ?
NMES
Ramp time:
- Strength building contractions = longer ramp (e.g., 2-4 sec)
- Weaker contractions can be shorter ramp (e.g., 1-2 sec)
- Some situations may require no ramp
- e.g., active dorsiflexion assist during gait
- Some situations may require extended ramp
- e.g., antagonist to spastic muscle
Treatment time
- Muscle strengthening = ?
- Muscle reeducation = = ?
- Muscle spasm reduction = = ?
- Edema reduction (muscle pump) = = ?
NMES
Treatment time:
- Muscle strengthening = 10-20 contractions
- Muscle reeducation = depends on activity
- Muscle spasm reduction = 10 to 30 min
- Edema reduction (muscle pump) = 30 min
Lab Checklist
NMES
