I also have not heard of a "muscle hit". Are you referring to cramping? Physiologically, it does not seem possible to have a muscle hit without including all other organs (skin, muscle, vitals, cardio-vascular). Muscles can build lactic acid with exertion, this is usually a byproduct of hypoxia (insufficient oxygen supply to the muscle for the required work), or probably more frequently from dehydration. Breathing cool anhydrous air or nitrox promotes a greater insensible water loss on exhalation. This is the reason we put heated humidifiers on intubated patients in critical care units. This water loss can be significant and can easily tip the balance to dehydration if the diver is already dry. Remember coffee, tea, coca-cola are all diuretics which will cause dehydration. If you are experiencing these symptoms, consult a specialist in dive medicine before diving again. Second, lots of water before diving and after. Skip the soda or other like beverages for fluid replenishment.