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-   -   Hamstring Exercises - Videos & Description (http://www.muscleandbrawn.com/forum/showthread.php?t=6092)

BendtheBar 05-08-2011 02:11 PM

Hamstring Exercises - Videos & Description
 
1 Attachment(s)
Hamstring Exercises - Videos & Description

* Dumbbell Romanian Deadlift
* Lying Leg Curl
* Romanian Deadlift
* Smith Machine Stiff Leg Deadlifts
* Standing Leg Curl
* Stiff Leg Deadlift
* Sumo Stiff Leg Deadlifts

http://muscleandbrawn.com/forums/att...1&d=1304881788

In human anatomy, the hamstring refers to one of the three posterior thigh muscles, or to the tendons that make up the borders of the space behind the knee. In modern anatomical contexts, however, they usually refer to the posterior thigh muscles, or the tendons of the semitendinosus, the semimembranosus and the biceps femoris. In quadrupeds, it refers to the single large tendon found behind the knee or comparable area.

As shown in the diagram, the human hamstring occupies the posterior of the body of the femur.

Etymology

The word ham originally referred to the fat and muscle behind the knee. String refers to tendons, and thus, the hamstrings are the string-like tendons felt on either side of the back of the knee. Another commonly accepted origin is that legs of ham used to be hung by a hook through the space between the thighbone and the tendons behind the knee. Ham/pork used to be more common in England than beef and lamb.

The four muscles of the posterior thigh (semitendinosus, semimembranosus, biceps femoris long & short head) flex (bend) the knee, while three of the four extend (straighten) the hip. The three 'true' hamstrings cross both the hip and the knee joint and are therefore involved in knee flexion and hip extension. The short head of the biceps femoris crosses only one joint (knee) and is therefore not involved in hip extension. With its divergent origin and innervation it is sometimes excluded from the 'hamstring' characterization. [3]

Functions

The hamstrings cross and act upon two joints - the hip and the knee.

Semitendinosus and semimembranosus extend the hip when the trunk is fixed; they also flex the knee and medially (inwardly) rotate the lower leg when the knee is bent.

The long head of the biceps femoris extends the hip as when beginning to walk; both short and long heads flex the knee and laterally (outwardly) rotates the lower leg when the knee is bent.

The hamstrings play a crucial role in many daily activities, such as, walking, running, jumping, and controlling some movement in the trunk. In walking, they are most important as an antagonist to the quadriceps in the deceleration of knee extension.

Imaging

Imaging the hamstring muscles is usually performed with an ultrasound and/or MRI.[4] The biceps femoris is most commonly injured, followed by semitendinosus. Semimembranosus injury is rare. Imaging is useful in differentiating the grade of strain, especially if the muscle is completely torn.[5] In this setting, the level and degree of retraction can be determined, serving as a useful roadmap prior to any surgery. Those with a hamstring strain of greater than 60mm in length have a greater risk of recurrence.[6]

Use in surgery

The distal semitendinosus tendon is one of the tendons that can be used in the surgical procedure ACL reconstruction. In this procedure, a piece of it is used to replace the anterior cruciate ligament (ACL). The ACL is one of the four major ligaments in the knee.

Training

In strength training, the hamstrings are trained in isolation with the leg curl exercise, as well as a part of several other lower body exercises. Hamstring plays an essential role in characterizing body flexibility, which is assessed by performing a sit and reach test. .


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