This document discusses the types of muscle fibers, impulse frequencies, impulse gain, impulse width, and strength of current as they relate to electric muscle stimulation (EMS) training. It notes that EMS first targets fast-twitch Type II fibers and describes optimal ranges for impulse frequencies (between 5-150 Hz), impulse gain (steep rise perceived as unpleasant but more effective), impulse width (10-500 microseconds), and strength of current (100 mA). The document provides details on how these parameters affect muscle contraction and fatigue during EMS training.
5. The Types of Fibers of the Muscle
• Type II Fibers - A high proportion of white fast-twitch fibers (type II) stands for a
maximum strength and good acceleration power skills of the athlete. These
athletes build up relatively fast muscle mass, whereas individuals with
predominantly slow Type I fibers can often provide a better stamina.
• EMS first address the fast-twitching, the type II fibers (fatigue resistant), which
are responsible i.a. for everyday motor skills, react only at higher intensities.
• A steep rise in impulse is often perceived as unpleasant, but is imperative to be
able to trigger a more effective excitation
7. Impulse Frequency
• The impulse frequency defines the frequency of the same events in a specific way
how many single impulses impact on the muscle during the contraction phase. The
unit of frequency is represented in heart (Hz).
• Under 5 Hz: there is merely a single jerk, after which the muscle relaxed again
shortly.
• Between 5Hz and 20Hz: one usually speaks of shaking. It comes up too an entire
tension of the muscle, but not limited to a total relaxation between the impulses.
• 40-80 Hz: it has already reached a high enough muscle contraction, with lower
frequencies around 40Hz fat accumulation in muscle effectively prevent than
higher frequency ranges.
• Above 100 Hz: there is a faster fatigue of the muscle.
150-200Hz: is regarded as upper limit, since from this area, the strength of muscle
contraction subsides gradually.
8. Impulse Frequencies
• Under 1,000 Hz – lower frequency therapy
• Between 1,000 and 10,000 Hz – middle frequency therapy
• Above 10,000 Hz – high frequency therapy
9. Impulse Gain
• The rising or the swelling time of an impulse, how much time an impulse
needs to achieve a set intensity.
• A steep rise of the impulse is often perceived as unpleasant, but is
imperative, to be able to trigger a more effective excitation.
10. Impulse Width
• The impulse width describes the duration of a single impulse. The longer takes a
single impulse, the deeper it penetrates into the tissue and increases the
regulation of motor units.
• 10-500 µs – the electrodes need this impulse width to warden charming effect
• Above 500µs - normally be no longer tolerated because they warden too painful.
• 250-350µs – EMS training operates in the range
11. Strength of Current
• EMS uses currents in the range of thousandths of Amps (mA). The strength of
the current determines the level of recruitment of nerve and muscle fibres.
The stronger the current is, the stronger the contraction takes place.
• There must be a sufficient current density (amperage per area) warden
triggered in deep muscle tissue to trigger a full contraction. For this reason, it
is advised to use amperage at about 100 mA.
