As a practical matter, many different forms of exercise, including those that are designed primarily for aerobic conditioning, will generate some degree of strength and muscle development. But since strength-building exercises exert such formidable stresses, your muscles will need a greater supply of blood in order to carry on their restorative and strengthening processes.
When blood is forced into your muscles during your weightlifting program, it helps speed up the process of repair which your muscle tissue needs to undergo. If you follow the program laid out in this book, your muscles will rebuild themselves, becoming denser and stronger than they were originally. That’s why you must be careful and follow this program to the letter. Never perform your strength exercises out of order or train the same muscle group two days in a row. If you do, your muscles won’t have sufficient time to repair themselves.