"Traditional teaching suggests that there are 3 types of muscle contractions: concentric (shortening), eccentric (lengthening), and isometric (no length change).  However, when we study the Chain Reaction Biomechanics of a common activity such as walking, it becomes clear that a muscle may be simultaneously lengthening (in one plane or at one joint), while shortening (in another plane or at another joint), and possibly experiencing no change in length (in another plane of joint)."

Watch this new Vlog from Dr. Dave Tiberio to get some additional insight on an earlier Blog on this topic.