EMS is an acronym for electrical muscle stimulation. Basically this local muscle stimulation takes your brain's place in sending
the message to muscles to contract. Therefore, there is no voluntary effort. The result is an involuntary isometric contraction
the intensity of which is dependent on the magnitude of the stimulation.
Many elite track athletes use EMS primarily for two reasons: to enhance performance and to facilitate recovery. Recovery programs utilize a short-duration pulsing type of stimulus, each contraction lasting about one second. Strength programs incorporate contractions up to ten seconds in duration. EMS is usually applied at the end of the day following all training. Typically EMS is used three or four times per week on the same days as high-intensity power work, placing great demand on the central nervous system.
So how does EMS measure up in the lab? Well, a study conducted at the Vienna International Workshop on functional Electrostimulation in 1998 evaluated me effects of EMS on improving the strength of the knee extensors in patients with chronic heart failure. After eight weeks, the patients increased their maximal isometric strength by 20 percent. Another study at the University of Berlin evaluated the functional value of EMS vs. repetitive training of the hands and fingers in the rehabilitation of stroke patients. Twelve patients received EMS for 20 minutes twice daily, and in a separate phase conducted repetitive hand-training for the same duration. The researchers found that EMS did not improve biomechanical or functional motor parameters of the hand and arm. Although, they did find that repetitive hand-training significantly improved the aforementioned parameters. The researchers concluded that EMS may do little to improve strength in the gym because of the skill component associated with lifting weights.
But what about muscle growth, you ask? I doubt it. Remember that some exercise scientists now believe the growth response may be induced by an optimal combination of tension and fatigue. This is why bodybuilders train with heavy weights (tension) to the point of failure (fatigue). In theory, one may be able to achieve the same result with EMS but not many individuals could tolerate the high setting needed to approximate an intense set of barbell curls - it would be just too painful, especially on bodyparts such as hamstrings and biceps. In addition, EMS is an isometric (without movement) contraction whereas training with weights involves positive (concentric) and negative (eccentric) movement. Many exercise scientists also believe that eccentric contractions are crucial to inducing a growth response in the muscles. If you want my advice here it is: Stick to the old tried and true barbells and dumbbells. Achieving true muscle mass requires a ton of effort in the gym. As a wise man once said, "If it's too good to be true, it probably is."