IMPORTANT PARAMETERS OF EMS
What do we have to know if we want to start training with Electrostimulation?
Electrical Muscle Stimulation (EMS) or Electrical Muscle Stimulation (EEM) is the activation of the musculoskeletal system in response to an electrical stimulus.
These impulses activate the action potential coming from the central nervous system to generate natural muscle contraction.
Before naming which are some of the aspects that we have to take into account for the use of this tool in our training sessions, it is very important to know how a muscle contrition develops. This will help us to better understand and develop our sessions, fully understanding what happens at each moment of a contraction.
The process of how a muscle contraction occurs can be outlined as follows:
- After depolarization, the future action potential is delivered through the axons of the motor neurons of the spinal cord to the motor endplate of the muscle in question.
- At the motor endplate, the axon releases acetylcholine, the main neurotransmitter for motor neurons that innervate skeletal muscles.
- When acetylcholine is released, neurotransmitter receptors on the motor end plate are activated, causing the different ion channels to open.
- The opening of these channels allows the entry of large amounts of Na + into the cell, thus initiating an action potential.
- The action potential spreads throughout the sarcolemma and into the muscle fiber thanks to the T tubules.
- When the action potential reaches the interior of the fiber, there is a large release of Ca ++ ions from the sarcoplasmic reticulum into the cytosol.
- Ca ++ ions bind to troponin C, which allows actin and myosin to interact.
- Actin and myosin, in the presence of ATP, cause the sarcomere to slip and shorten, producing muscle contraction.
- After a fraction of a second, the calcium ions are pumped back into the sarcoplasmic reticulum by a Ca ++ pump located in the membrane and remain stored in the reticulum until a new muscle action potential arrives; This removal of calcium ions by the protein calsequestrin causes muscle contraction to cease.
Once we understand the process of a muscle contraction, we are going to see what are some of the aspects that we have to control if we want to carry out an optimal training with an electrostimulator.
Aspects that we have to take into account.
Conductance is the facility offered by a medium for the passage of electric current. Some body tissues are more conductive than others and are classified into:
- Low conductive fabrics. Bones, fat, calloused skin, hair or nails.
- Medium conductive fabrics. Normal skin, tendons, thick fasciae, and cartilage.
- Good conductive fabrics. Lymph, blood, intra and extra cellular fluids, muscles, connective tissue and nervous tissue.
- Electricity generating fabrics. Certain regions of the heart such as the sinus node.
Here we can find the different forms of the pulse such as triangular and rectangular mainly. This will determine if the input of the stimulus is made abrupt or more progressive. In triangular pulses, what is known as accommodation can occur.
The closer you get to the vertical, the less accommodation you will have. Therefore, the rectangular currents have a more vertical rise and it will take less time to reach the maximum intensity.
The intensity is measured in amperes which is the basic unit of intensity of electric current, the units used to measure the amplitude levels that cause muscle contraction are of the order of milliamps.
It is one of the most important parameters since it will allow us to regulate what type of muscle fibers are going to be activated. The frequency tells us the number of times per second that an impulse will be produced.
It is important to control all aspects and use them appropriately for each objective.