During a PEMF session that is either a low-to-high intensity or simply a high-intensity device, the animal is likely to experience the pulse with involuntary muscle contractions. This has typically been compared to the sensation with electrical stimulation (E-stim) devices that are more broadly known, but these two sensations are very different!
While E-stim devices apply a foreign electrical current to the muscles, PEMF amplifies the energy that is already in the nervous system. The experience of a high-intensity PEMF machine is the magnetic field stimulating the nerve paths within that muscle which then, in turn, causes the muscle to contract.
Muscle contractions, by themselves, are caused by a chain of chemical reactions; one of which is called the action potential (AP). The action potential occurs only in muscle and nerve cells and plays a significant role in the contraction effect of PEMF. Occurring within the cell membranes, AP indicates that the cell membrane is open and that ions can flow through it. Once the entire membrane is open, the charge of the ions is so great that the process reverses and the cell membrane begins to close. The shifting of these ions from inside to outside the cell, and how they change their electrical charge, is what causes a muscle contraction.
The muscle contractions we see during a PEMF session are not always the same on both sides of the spine. One side may react more strongly than the other. The electromagnetic fields cause the muscle tissue to “pulse” or twitch in low energy or damaged areas. These areas of sensitivity can pulse more strongly with less magnetic field strength (MFS) than the rest of the area that is in contact with the magnetic field.
We mentioned above that the action potential happens in nerve cells and muscle fibers. When we watch a horse during a PEMF session, we see the most visible pulsing along the topline, shoulders, and hindquarters, since those areas are heavily muscled. There is hardly any visible skin vesiculation in the extremities since they consist of bone, tendon, ligament, and have very little other soft tissue. These areas are also put through a lot of stress in performance horses as they carry the bulk of compensation throughout the body.
Example: The horse is falling to the inside while completing a circle to the left.
This is a common issue in performance horses. They are often stronger in traveling one direction than the other, making them a “righty” or a “lefty.” It is also common in racehorses who are accustomed to only going to the left (in America) and not using both sides equally.
With the PEMF loops draped over the back or the hindquarters, it is not uncommon to see completely different pulsing on the right side of the body than the left, indicating an imbalance. There are many potential causes for the horse riding unbalanced and not utilizing their body correctly. Those causes are best presented by a vet or a qualified trainer who can enlist the aid of a PEMF professional to support in the care of the horse. PEMF can aid in relaxation so that the horse is better able to receive care.
Ideally, as a PEMF professional encountering this, we prefer to pulse that area on the back or hindquarters until the visible pulsing in the fascia and tissue has almost or completely equaled out between the two sides. If it needs more time, they can return to it at the end of the session or stay in that region during the first part of the whole body session. Fascia is a very sensitive tissue and does not need a lot of power to help it to relax. Set the power to where you see hardly any visible pulsing. Base your MFS setting off of the strongest pulsing you see. The MFS may need to be adjusted several times as the fascia relaxes.
The basis of PEMF is understanding the subtle electromagnetic energy that every organism on this earth possesses. Understanding that electromagnetic activity happens in every cell, not just within the nervous system, is the first step. The second step is seeing how those electrical beings interact. Starting with the smallest pieces of the puzzle will build a strong foundation for your understanding of PEMF.
 To locate the citation referenced here, visit info.pulseequine.com/research.