PTA 130 Electrical Currents for Muscle Contractions

What is NMES and how is it used?

Neuromuscular Electrical Stimulation

the use of EC to produce muscle contractions, only for innervated muscles

Physiology behind motor nerves

smaller nerves produce lower force contractions

and more resistant to fatigue/atrophy

larger → stronger & quicker; fatigue rapidly prone to atrophy

Why is it better to physiologically initiate nerves than electrical stimulation?

there is a gradual increase in force → smoother, balance graded manner and asynchronous

electrical is rapid and jerky → all motor units at once (fast twitch)

What should be documented in NMES?

area treated, patient position, stimulation parameters, electrode placement, treatment duration, response to intervention

Russian Protocol

medium frequency, alternating current

freq: 2500 Hz

burst duration: 10 ms

50 bursts per sec

What should be the electrode placement?

one electrode over motor point, the other over stimulated muscle aligned parallel to muscle fiber direction

at least 2 inches apart

Treatment for edema associated with lack of contraction

ie. cast

electrodes applied to muscle around main draining veins, require motor contraction

should be applied with compression & elevation

Functional Electrical Stimulation

when performing functional activities

What to do in situation with denervated muscle?

DC, pulsed current with 10ms or longer

applied directly to the muscle to stimulate muscle cells

amplitude is increased to reach full contractions

What is done to achieve the overload principle?

increase amplitude, pulse duration, electrode size

external resistance → higher load → higher force contraction → greater strengthening

How does early ES affect post-surgical, immobilization, or other weakening pathologies?

can amplify/accelerate strength gains

ACL reconstructions

quads strength is essential to functional recovery

goal → 90 %+ of uninjured LE to allow for normal kinematic if less than 80% it can match the injured

Quad strength post-op

after 6 months → down 23%

after 12 months → down 14%

When is the best time to apply ES on a ACL patient?

through 9-12 weeks, if after then there is no difference

When should NMES be used in regards to a TKA?

used before surgery to show rapid gains

great for early strength losses and will improve outcomes

Which fiber is atrophied with age?

type 2- fast twitch

TKA

persistant quad weakness & poor activiation

quad strength ~ 40-62% compared to pre-op