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Types of Muscle Contraction | |
Muscle Contractions can be divided into:
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Tension staying on the same, Length getting shorter/longer. Energy fluctuating.
Isotonic contractions are those which cause the muscle to change length as it contracts and causes movement of a body part. There are two types of Isotonic contraction:
Concentric contraction
Concentric contractions are those which cause the muscle to shorten as it contracts. An example is bending the elbow from straight to fully flexed, causing a concentric contraction of the Biceps Brachii muscle. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.
Eccentric contraction
Eccentric contractions are the opposite of concentric and occur when the muscle lengthens as it contracts. This is less common and usually involves the control or deceleration of a movement being initiated by the eccentric muscles agonist.
For example, when kicking a football, the Quadriceps muscle contracts concentrically to straighten the knee and the Hamstrings contract eccentrically to decelerate the motion of the lower limb. This type on contraction puts a lot of strain through the muscle and is commonly involved in muscle injuries.
eccentric contraction 시 hamstring이 quadriceps의 concentric contraction으로 발이 앞으로 나갈려는 것을 강하게 붙드는 바람에 상해를 입을 수 있다. 즉 큰 힘 weight 을 무리하게 버틸 때 근섬유는 상처를 입는다. 이 상처를 자연치료하도록 적당히 쉬어 줄 때 전보다 더 강한 근육이 형성되는 것이다. 당길 때는 무리한 힘을 쓰는 것이 아니므로 근 섬유가 상처를 입지 않는다. 없는 힘으로 무리해서 당길 수는 없는 것.
Tension fuctuating, Length staying on the same. Energy fluctuating.
Isometric contractions occur when there is no change in the length of the contracting muscle. This occurs when carrying an object in front of you as the weight of the object is pulling your arms down but your muscles are contracting to hold the object at the same level. Another example is when you grip something , such as a tennis racket. There is no movement in the joints of the hand, but the muscles are contracting to provide a force sufficient enough to keep a steady hold on the racket.
The amount of force a muscle is able to produce during an isometric contraction depends on the length of the muscle at the point of contraction. Each muscle has an optimum length at which the maximum isometric force can be produced.
한 손에 물통을 들고 여기게 계속 더 많은 물을 부어 나간다면 팔은 움직이지 않고 정지 해 있으나 근육은 contract를 하게 된다. 이때 상서를 입게 해서 근육을 강화해 나갈 수 있다. 지금은 이런 운동을 하지 않는다.
Tension fluctuating, Length getting shorter/longer. Energy staying on the same.
Isokinetic contractions are similar to isotonic in that the muscle changes length during the contraction, where they differ is that Isokinetic contractions produce movements of a constant speed. To measure this a special piece of equipment known as an Isokinetic Dynamometer is required. Examples of using isokinetic contractions in day-to-day and sporting activites are rare. The best is breast stroke in swimming, where the water provides a constant, even resistance to the movement of adduction.
특별히 제작한 운동기구가 필요하다. 움직이는 속도를 일정하게 유지 하면서 오그렸다 폈다 하는 운동이다.
http://www.youtube.com/watch?v=T3OiOJ6-x34
http://www.youtube.com/watch?v=i2VG3HGBrBw
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