Electrical currents for muscle contractions

Question 1

When will you see NMES?

Answer 1

If it’s an electrical current used for muscle contraction.

Question 2

What types of fibers are stimulated with NMES?

Answer 2

Type II fast twitch

Question 3

How can NMES strengthen muscles?

Answer 3

Overload principle

Specificity

Question 4

What are some clinical applications for NMES?

Answer 4

Increasing strength after surgery
Non surgerical
-Decrease pain, increase strength, improve functional performance
-OA, RA, PFPS
Neurological
-stimulate intact PNS in patients with CNS injuries

Question 5

What type of current is used for Denervated muscles?

Answer 5

Continuous DC
Requires pulse durations > 10ms
Can be used in patients with Bels Palsy

Question 6

What type of NMES is used in inntervated muscles?

Answer 6

Pulsed biphasic

Russian

Question 7

Where do you place the electrodes for NMES?

Answer 7

One electrode over motor point

other electrode over stimulated muscle aligned parallel to muscle fiber direction

Question 8

What are the amplitude and pulse duration parameters for NMES?

Answer 8

Amplitude - Contraction >= 10-50% MVIC of unijured limb

Pulse duration - 150-350us (shorter small muscles, larger large muscles)

Question 9

What frequency do you want to use for NMES?

Answer 9

20-30pps for small muscles,
35-50 pps for larger muscles
>50-80 pps may increase muscle strengthening but also increase fatigue (longer rest times)

Question 10

What are the on/off and ramp times for NMES?

Answer 10

Muscle Strengthening
-ON: 6-10 seconds
-OFF: 50-120 seconds
-ON/OFF ratio:  1:5 - 1:3
-Ramp up/down:  1-4 seconds
Relieve muscle spasms and edema on:off ratio of 1:1
-On and off times of 2-5 seconds

Question 11

How long is a normal treatment time for NMES?

Answer 11

Muscle strengthening about 10 min
Allow for 10-20 contractions
No more than 20 min in single session