Muscle Contraction Sample

Concentric Contraction —Shortening of Muscle.
In a concentric contraction, the force generated by the muscle remains less than the muscle's maximum. A contraction is considered concentric when the joint is moved against resistance, by a muscle crossing that same joint; this also creates muscle torque, generating power. The resistance is typically caused by an object, subjected to gravitational pull, or other type of external force (e.g. weight stack).

Eccentric Contraction—Muscle Actively Lengthening.
In an eccentric contraction, the muscle fibers get longer. An eccentric contraction helps control the speed, or direction, of a movement by resisting movement caused by another force. As muscle load increases, the muscle reaches a point where the external force, on the muscle, is greater than the force generated by the muscle itself. This forces the muscle to lengthen.

Isometric Contraction—Muscle Actively Held at a Fixed Length.
The third, and final, type of muscle contraction is isometric contraction. Isometric contraction occurs when the muscle is activated, then held at a constant length. The force, generated during an isometric contraction, is dependent on the length of the muscle at the time of contraction.

Muscle Contraction

Muscle Injury

The body immediately begins to heal itself once an injury has occurred. Rest allows the natural healing process to take place, enabling the body to rebuild cells. The more severe the injury, the longer it will take to heal, so the length of the rest should be appropriate.

To help reduce pain, that can be caused by muscle spasms and other conditions, ice should be applied. Cold temperature can “overload” the pain receptors. Numbness may be a result of ice application, especially for periods of 20 minutes or longer. The deeper the tissue injury, the longer ice should be applied (20-30 minutes).

Compression can help reduce the area, from which swelling may occur. Normal pain may result, due to compression.

Elevation can help reduce high fluid volume, and blood, and release the saturated fluid back into the circulatory system.

Ligament Sprains
A ligament is a band of tissue that connects one bone to another. There are three degrees of sprains:

1st Degree: Stretching of ligamentous fibers.
Symptoms: Swelling, mild pain, stiffness.

2nd Degree: Tearing, or separation, of ligamentous fibers.
Symptoms: Moderate pain, joint stiffness, and swelling.

3rd Degree: A complete rupture of the ligament.
Symptoms: Severe pain, initially, mild or no pain shortly thereafter, due to damage to nerve fibers. May require surgical repair.

Ligament Sprain Care
For 1st and 2nd degree sprains, resting the ligament will allow the ligament to heal. Restoring stability to the joint may be recommended. The time allotted for restoration may be lengthy, due to scar tissue development.

Muscle Strains
A muscle is made up of muscle fibers that consist of many thinner fibers, called myofibrils. Each myofibril is made up of thick, and thin, myofilaments.

There are three degrees of muscle strains:

1st Degree: A few fibers have been torn or stretched.
Symptoms: Using the muscle causes unusual pain.

2nd Degree: Some muscle fibers have been torn.
Symptoms: Using the muscle causes great pain. Evidence of slight capillary bleeding and swelling may be present.

3rd Degree: A complete tear within the belly of the muscle.
Symptoms: Using the muscle creates severe pain. Surprisingly, the pain may go away due to separation of the nerves; very difficult to use the muscle. Surgery is required.

Hamstring Strain
Type I Strain: Soreness.
Care: Ice, compression, heat, and mild stretching.

Type II Strain: May hear, or feel, a “pop”. Applying pressure to hamstring is difficult and causes severe pain. Swelling is noticeable.
Care: Ice, compression, physical therapy.

Type III Strain: Extreme pain when muscle is in use. Swelling should be present.    
Care: Ice, compression, surgery, and crutches.    

Quadriceps Strain
Type I Strain: Tightness, mild pain.
Care: Ice, compression.

Type II Strain: Twinge in the rectus femoris muscle. Slight swelling.
Care: Ice, compression, isometric exercises.

Type III Strain: Immediate swelling, bulging in the quadriceps; considerable pain.
Care: Ice, compression, rest. Surgery in some cases.

Muscle Strain Care
Due to the likelihood of re-injury, continuous use is not recommended. Rest for a period of 7-9 weeks. Surgery may be required for 3rd degree strains.

Perforating fibers are embedded within the bone and provide a strong anchor for the tendon, which are fibrous cords of connective tissue. When muscle activity causes the tendon to move repeatedly, it could become irritated. Due to the tendons continuous contact with surrounding structures, such as muscles, the tendon can be damaged.

Symptoms: Redness, pain, swelling, and “crackling” sound.