sports medicine-muscle contraction

Sports Science

Contraction of muscles

As we discussed earlier, muscle is composed of specialized cells capable of contracting when appropriately stimulated. Three different types of muscle cells exist:

-Cardiac muscle. This forms the heart.
-Skeletal muscle (voluntary muscle) which moves the bones of the skeleton.
-Smooth muscle (involuntary). This type of muscle is found in many internal organs. It lines the digestive tract, bladder and blood vessels. We have no voluntary control over this type of muscle hence it is sometimes referred to as involuntary muscle. In this unit of work we will concentrate on skeletal muscle.

Skeletal muscles are controlled by signals, transmitted along nerve fibers, from the brain and spinal cord. The muscle is organised into small functional units called motor units.
A large muscle, such as the bicep, is controlled by thousands of nerve cells. Each nerve cell makes contact with a number of muscle cells. The point of contact is known as a neuromuscular junction.
The nerve cell and the muscle cells it makes contact with is called a motor unit.
When the nerve transmits a signal the whole motor unit is stimulated and the muscle cells contract together
Muscles with large motor units have coarse movements
Muscles with small motor units give fine, graded movements

The image on the right shows a motor unit responding to a nerve impulse. Click to see the detail inside the muscle cell.

How does a muscle regulate the force it will exert to perform a task?

Surely the force required of the muscles is less when playing the piano than it is during weight training.

The Muscles produce force by recruiting motor units. When the bicep needs to apply a small force, just to lift the hand to play the piano, a small number of motor units are activated. However, when lifting heavy weights nearly all the motor units in the biceps muscle will be activated.

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Sports Science Contraction of muscles As we discussed earlier, muscle is composed of specialized cells capable of contracting when appropriately stimulated. Three different types of muscle cells exist: -Cardiac muscle. This forms the heart. -Skeletal muscle (*voluntary muscle) which moves the bones of the skeleton. -Smooth muscle (involuntary). This type of muscle is found in many internal organs. It lines the digestive tract, bladder and blood vessels. We have no voluntary control over this type of muscle hence it is sometimes referred to as involuntary muscle.* In this unit of work we will concentrate on skeletal muscle.
Skeletal muscles are controlled by signals, transmitted along nerve fibers, from the brain and spinal cord. The muscle is organised into small functional units called motor units. A large muscle, such as the bicep, is controlled by thousands of nerve cells. Each nerve cell makes contact with a number of muscle cells. The point of contact is known as a neuromuscular junction. The nerve cell and the muscle cells it makes contact with is called a motor unit. When the nerve transmits a signal the whole motor unit is stimulated and the muscle cells contract together Muscles with large motor units have coarse movements Muscles with small motor units give fine, graded movements
The image on the right shows a motor unit responding to a nerve impulse. Click to see the detail inside the muscle cell.
How does a muscle regulate the force it will exert to perform a task?
Surely the force required of the muscles is less when playing the piano than it is during weight training.
The Muscles produce force by recruiting motor units. When the bicep needs to apply a small force, just to lift the hand to play the piano, a small number of motor units are activated. However, when lifting heavy weights nearly all the motor units in the biceps muscle will be activated.
Continue