Isometric - An isometric contraction is one where a muscle contracts but no net movement occurs. Picture two identical people arm wrestling. Theoretically, their strength would be the same so no net movement would occur despite muscle contraction.
In practical terms, isometric contractions are part of everyday movement and sport. Isometric strength maintains posture and is crucial to stabilization during movements to allow for concentric and eccentric contractions to apply force to the levers of the skeleton.
Post surgical rehabilitation often begins with isometric contractions. The body part is put in a position and the athlete is instructed to hold that position. Patients of upper arm surgeries often find themselves standing against a wall and pushing in different positions to initiate contractions of muscles that have become weak from surgery.
Isometric contractions work very well to correct compensations and help atrophied muscles increase neurological drive. Initial gains in strength do not come from the creation or growth of muscle fibers. Initial strength gains come from increased neurological efficiency of the movement. In other word, the initial gain of strength that comes from working out or doing rehabilitation exercises comes from increased neurological signal to muscles to fire. Isometric contractions work very well to work on this neurological signal increase which allows for an increase in muscle recruitment.
How can isometric contractions be used? I like to incorporate isometric contractions for athletes that struggle with strength at end range of motion. I will have a baseball player externally rotate his shoulder to full end range then have him resist for multiple sets. Isometrics may also be used when a particular movement is dysfunctional due to weakness. If I see an athlete's knee collapse while squatting, an isometric exercise for the glutes at the point of collapse may be just enough to provide feedback for improved movement.
Concentric - Concentric contractions are probably the most familiar type of contraction. This is a contraction where the muscle shortens through the movement; think bicep curl. Since concentric contractions make up so much of exercise and rehabilitation, we won't spend a whole lot of time on it. There are some ways to manipulate concentric contractions for further gains. I like to combine isometric and concentric contractions. I like to have an athlete prone (face down) and externally rotate. I then apply a downward force while the athlete moves the arm through a range of motion in a different plane. Concentric contractions can also be manipulated with the pace of contraction, either faster or slower.
Eccentric - Eccentric contractions occur in the deceleration phase of movement and are indicative of muscle fiber lengthening. Eccentric contractions occur as our bodies decelerate as in slowing down after running through first base or slowing the arm after ball release. Recent research has shown that eccentric strength training can be good for tendonitis injuries. Eccentric contractions are crucial to the "loading" phase of movements which we will discuss later. Eccentric muscle contractions occur as a result of the "loading" phase of a lot of standard movements. However, specific eccentric focused exercises may be warranted for specific deceleration movements such as slowing down from a sprint or the follow through of a throw.
Understanding the types of contractions helps to understand the purpose and application of strength training movements. In future posts I plan to get into more detail on each type and how to better utilize them for training and rehabilitation.
That's all for now...from the training room
No comments:
Post a Comment