Fascics on an EMG are not the same as the twitches you feel. So a normal EMG doesn't mean that you don't twitch. It just means that there's nothing to worry about as regards ALS and a number of serious conditions.
If exercises makes twitches worse, that suggests that you may have a nutritional imbalance. It is worth looking at where your diet is providing calcium, potassium, sodium, magnesium, iron, B vitamins, etc., and hydration. Some of these compete with each other, so spacing them out across the day is advised.