Ch 12 DPT 634 Electro for Muscle contraction

Question 1

Amplitude (intensity)

Answer 1

The magnitude of current or voltage (see Fig. 11-25).

Question 2

Biphasic waveform

Answer 2

Current that moves only in one direction. Biphasic currents may be pulsed or alternating.

Question 3

Electrical muscle stimulation (EMS)

Answer 3

Application of an electrical current directly to muscle to produce a muscle contraction.

Question 4

Fast-twitch type II muscle fibers

Answer 4

Large muscle fibers that contract to produce quick, powerful movements, but fatigue quickly; also called “fast twitch.”

Question 5

Frequency

Answer 5

The number of cycles or pulses per second. Frequency is measured in Hertz (Hz) for cycles and in pulses per second (pps) for pulses (see Fig. 11-10).

Question 6

Functional electrical stimulation (FES)

Answer 6

Application of an electrical current to produce muscle contractions applied during a functional activity. An example of FES is the electrical stimulation of dorsiflexion during the swing phase of gait.

Question 7

Motor point

Answer 7

The place in a muscle where electrical stimulation will produce the greatest contraction with the least amount of electricity; generally located over the middle of the muscle belly.

Question 8

Neuromuscular electrical stimulation (NMES)

Answer 8

Application of an electrical current to motor nerves to produce contractions of the muscles they innervate.

Question 9

On-off time

Answer 9

On time is the time during which a train of pulses occurs. Off time is the time between trains of pulses, when no current flows. On and off times are usually used only when electrical stimulation is used to produce muscle contractions. During on time, the muscle contracts, and during off time, it relaxes. Off times are needed to reduce muscle fatigue during the stimulation session.

Question 10

Overload principle

Answer 10

A principle of strengthening muscle that states the greater the load placed on a muscle and the higher force contraction it produces, the more strength that muscle will gain.

Question 11

Pulse duration

Answer 11

Time from the beginning of the first phase of a pulse to the end of the last phase of a pulse. Pulse duration is generally expressed in microseconds (microseconds 106 seconds) (see Fig. 11-9).

Question 12

Pulsed biphasic waveform

Answer 12

Series of pulses where the charged particles move first in one direction and then in the opposite direction (see Fig. 11-6, B).

Question 13

Pulsed current (pulsatile current)

Answer 13

An interrupted flow of charged particles where the current flows in a series of pulses separated by periods when no current flows.

Question 14

Ramp up/ramp down time

Answer 14

The ramp up time is the time it takes for the current amplitude to increase from zero, at the end of the off time, to its maximum amplitude during the on time. A current ramps up by having the amplitude of the first few pulses of the on time gradually be sequentially higher than the amplitude of the previous pulse. The ramp down time is the time it takes for the current amplitude to decrease from its maximum amplitude during the on time back to zero (see Fig. 11-22).

Question 15

Russian protocol

Answer 15

A medium frequency AC with a frequency of 2500 Hz delivered in 50 bursts/second. Each burst is 10 ms long and is separated from the next burst by a 10 ms interburst interval (see Fig. 11-5). This type of current is also known as medium-frequency burst AC (MFburstAC); when this term is used, the frequency of the medium-frequency current or the bursts may be different from the original protocol.

Question 16

Slow-twitch type I muscle fibers

Answer 16

Small muscle fibers that are slow to contract but do not fatigue easily; also called “slow twitch”