EMS should feel intense, similar to a muscle spasm, but shouldn’t be painful. You may notice that your movements have more resistance. You may also feel more sore than normal after your workout, since you were recruiting more of your muscle fibers. EMS should be used under the supervision of a professional. EMS should feel intense, similar to a muscle spasm, but shouldn’t be painful. You may notice that your movements have more resistance. You may also feel more sore than normal after your workout, since you were recruiting more of your muscle fibers. EMS should be used under the supervision of a professional.