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Before we talk specifically about the science of Electro Muscle Stimulation (EMS), let’s lay some groundwork. 

The human body is composed of various organ systems, each of which have their own purpose and functions. The organ system we will focus on here is the muscular system. Your body has three categories of muscles: visceral, cardiac and skeletal.

  • Visceral muscles include the digestive system, bladder and, in females, the uterus. These are involuntary muscles, meaning that they more or less work without you thinking about it and cannot be engaged on demand.
  • Cardiac muscles, as the name suggests, are only found in the heart. Like visceral muscles, the cardiac muscles are involuntary and operate without you thinking about it.
  • Skeletal muscles are the muscles we see and feel when we flex, and they are the muscles we exercise during physical activity. These muscles are attached to the skeleton and come in pairs, one muscle to move the bone in a particular direction, and the other to move it back. Skeletal muscles are voluntary, meaning that you have to think about engaging the muscle in order for your nervous system to tell it to activate. In fact, these are the only muscles that can be activated by choice (whether through your own signal, or with the help of EMS).

The human body has more than 650 known skeletal muscles, each made up of muscle fibers, or muscle cells. Your body has two types of muscle fibers: slow-twitch and fast-twitch.

  • Slow-twitch muscle fibers are used for longer-distance, endurance activities such as running a marathon. These are more energy efficient and hence the “preferred” muscle fiber for the body to use in everyday activities. They are also easier to train.
  • Fast-twitch muscle fibers are used for quick, powerful movements. They can only be trained with maximum loads and fast movements. Contrary to their name, they actually kick in later during a contraction, but react faster, thus creating a large force. Fast-twitch muscle fibers are used for intense athletic activities, such as sprinting or powerlifting, but also for quickly reacting if you trip and need to prevent a fall.

When you engage in physical activity, whether lifting weights or unloading groceries from the car, your skeletal muscles contract. Each contraction begins with a signal that is sent from your brain to your motor nerves. This signal then forces your muscles to contract in order to move the object. When using EMS, the motor nerve receives the signal from the device instead of the brain, and the muscle cannot tell the difference. This is why it is possible to train muscles using EMS.


Growing muscle mass requires placing increasing amounts of stress on your muscles, resulting in an adaptation process to be better prepared in the future. This stress results in a process that facilitates muscle growth: muscle tension, muscle damage and metabolic stress.

  • Muscle tension is the act of lifting progressively heavier weights than your body has previously adapted to. Breaking through this threshold causes chemical changes in your muscles as they adapt to the increased stress over time.
  • Muscle damage is the soreness you feel after working out. This muscle damage releases inflammatory molecules and immune systems cells that cause muscle cells to jump into action.
  • Metabolic stress causes swelling around the muscle and connective tissue. This type of growth is known as sarcoplasmic hypertrophy.

During a conventional workout, you can get less than half of your muscle fibers to contract. This is terribly inefficient, especially given the stress and strain on your joints and tendons. As you will see below, EMS engages more than 2x the muscle fibers you can on your own.


Just as muscles can grow, they can also atrophy, or waste away. Atrophy is primarily caused by a lack of use of the muscle. Sometimes the lack of activity is due to an injury or illness, when it is more difficult to create muscle tension to maintain strength and healthy muscle mass.

Aging is another leading cause of muscle atrophy due to a decline in physical exercise, because your body produces fewer proteins that promote muscle growth, causing muscles to shrink (a condition called sarcopenia). The Mayo Clinic released Ten Aspects of Healthy Aging, what to expect and how to slow the decline. For six of the ten aspects, physical exercise was listed as a top priority, but this becomes more difficult and risky as we age.

With simple body weight movements and no weights or other equipment to cause impact on your joints and tendons, EMS is a safe and effective tool for physical exercise through every stage of life.



Electro Muscle Stimulation (EMS) replicates the brain signals that command your muscles to contract. Usually composed of a control unit that generates the impulses and one or more electrodes mapped directly to your muscle(s), EMS technology sends low-frequency impulses that mimic your natural brain signals to directly engage your muscle(s). This results in a muscle contraction. Sophisticated EMS devices vary the impulse characteristics for each muscle group, and vary the frequencies depending on the desired training effect, such as strength, power, cardio and recovery.

EMS technology has been around since the 1960s and goes by many names. You may have heard of Neuromuscular Electrical Stimulation (NEMS), e-stim, stim, powered muscle stimulators, or perhaps brands such as Compex and PowerDot. All of these are based on the same science and are used in a variety of contexts, from injury rehabilitation to localized strength training. In the U.S., EMS technology is regulated by the FDA as a Class II Medical Device.

You may have heard of TENS units and wonder if they are the same thing. The answer is ‘not exactly’. While TENS units and EMS devices are similar in concept, TENS units are primarily designed to stimulate nerves for pain treatment rather than muscles for training and rehabilitation purposes.



Full-Body EMS takes this science a step further, with a wearable “suit” that maps electrodes to each of your major muscle groups. The low-frequency impulses that serve as the basis for EMS technology actively engage each muscle group, simultaneously. In just 20-minutes, you can get a full-body workout that engages >90% of the muscle fibers in your body.

In addition training the whole body in just 20 minutes, Full-Body EMS also allows for the training of compound movements such as golf or baseball swings, jumping, sprinting, dribbling, or everyday functional exercises.

The benefits of Full-Body EMS are striking. Studies have shown the training to increase strength, endurance and agility in users, while decreasing back pain, body tension and depression. In addition, medical studies have shown users to gain lean muscle mass, improve physique and even increase bone density. Full-Body EMS is also known to strengthen the pelvic floor and reduce postpartum incontinence in women.



EMS technology was first developed in the 1960s. Full-Body EMS developed in Europe in the early 2000s, with the Klitschko brothers (boxing) and players from FC Bayern Munich and the German National Soccer using the technology to gain a competitive advantage in athletic competition. Soon, teams like Real Madrid were following and Full-Body EMS became a staple training method for soccer players. Usain Bolt famously incorporated Full-Body EMS into his training regime while recovering from an injury ahead of setting multiple world records at the 2008 Olympic Games. Around 2010, Full-Body EMS went mainstream in Europe and quickly expanded across the globe.

Today there are >13,000 personal training studios globally specializing in Full-Body EMS. It is loved by countless athletes (Rafael Nadal, Roger Federer, Mike Tyson), celebrities (MadonnaTom Holland), and models (Elsa HoskLindsay EllingsonAlessandra AmbrosioAshley GrahamHeidi KlumRomee Strijd).

In 1999, the U.S. FDA began regulating EMS devices (a category they refer to as powered muscle stimulators) to ensure quality and user safety. The U.S.-specific clearance process is quite involved and complicated, and the major manufacturers of Full-Body EMS equipment were so busy expanding in the rest of the world that they only began gaining FDA clearance recently.

Traditional Full-Body EMS equipment is expensive ($15k-20k) and complicated to operate. As a result, it has historically been limited to personal trainers, celebrities and professional athletes. The general public only had access to Full-Body EMS through very specialized personal trainers and studios. Katalyst set out to change this. Seeing a hunger for premium, at-home fitness products, we reinvented Full-Body EMS from the ground up and created the first FDA cleared, dynamic, immersive and content-driven platform accessible directly to consumers in the United States.