For many decades Transcutaneous Electrical Nerve Stimulation (TENS) was used to manage pain and Neuromuscular Electrical Stimulation (NMES) was used to strengthen muscles. Recent studies found these modalities are not so black and white. While many people that have been in physical therapy may have had an experience with TENS and NMES devices, but were not educated on the difference between these types of stimulus.
TENS vs NMES
TENS and NMES target different nerve groups of the body. TENS is specifically targets the sensory nerves, which are responsible for sending pain signals to the brain. NMES targets the muscle itself, specifically through the motor nerves. This allows the NMES machine to create a muscle contraction to recruit more muscle fibers when training; warming up or recovering. Sensory and motor nerves fire at different frequencies, which is why NMES and TENS devices affect the body differently.
TENS – Transcutaneous Electrical Nerve Stimulation
TENS is the use of an electrical current to stimulate the nerves for therapeutic purposes. TENS stimulates the sensory nerves, suppressing the pain signals that are being sent to the brain to give the user relief. In other words, TENS “tricks” the brain to ignore the pain for a short duration of time by applying a non-painful stimulus to the same area.
NMES – NeuroMuscular Electrical Stimulation
NMES uses electric muscle stimulation (EMS) to cause excitement in the muscle tissue. This stimulus is designed to mimic the same type of signal the brain sends to the muscle when working out. There are two types of muscle fiber: slow twitch and fast twitch. Both muscle fibers contract at different frequencies. Electric Muscle Stimulators often offer various pre-programed settings which target the specific muscle types differently by adjusting the frequencies and work to rest cycles. The NMES parameters are much different then TENS, which facilitate more muscle fiber recruitment. The more you increase the intensity of the device, the more muscle fiber you recruit. This is how users see big strength gains, increases in vertical and reduce the risk for injury.