Muscle tissue is made up of fibers that are capable of lengthening and shortening. They have a certain amount of elasticity to them, and if they are forced past the point of elasticity it is possible to separate or tear the fibers. This damage is referred to as a strain. Each muscle is attached to the bones by a tendon. Tendon tissue is not nearly as elastic as muscle tissue, so when the muscle is lengthened past the point of no return, the region where the injury is most likely to occur is where the muscle and tendon meet. Muscle strains are classified into a simple system:

Grade 1 strain: Some of the fibers have been stretched past their limit or mildly torn. Although there is tenderness and pain with movement, it is possible to move the area without limitations. Usually ice and rest will help a grade 1 strain recover.

Grade 2 strain: Many of the muscle fibers have been torn and it is painful when the muscle actively contracts. Many times a depression can be felt where the injury occurred. There may be some swelling or discoloration due to the capillaries being damaged. This injury is more severe and will take much more time to heal than a grade 1 strain. In this case it is beneficial to wrap the injured area with an ace bandage. Ice, elevation, and compression are needed. It may help to see a doctor for an examination and x-ray to be sure nothing else is damaged.

Grade 3 strain: This involves a complete tear of the muscle or tendon tissue. With a complete tear there is a loss of movement. Initially this is very painful, but the pain may diminish due to the nerve fiber being separated. A great deal of discoloration will occur. This injury should been seen by a doctor immediately.

Although you are not likely to experience any severe injuries in the Krav Maga program, one of the most common minor acute injuries you should be aware of is muscle soreness. A certain level of soreness is inevitable when beginning a training program, or when doing an exercise to which you are not accustomed. There are two types of muscle soreness. The first is the soreness you feel immediately after an exercise, which usually is accompanied by fatigue. The second is known as delayed onset of muscle soreness, or DOMS, which is most intense after twenty-four to forty-eight hours and gradually subsides over a few days. This soreness is thought to be caused by microscopic tears or damage to the muscles and tendons from being overworked, and it can lead to swelling and stiffness.

Muscle soreness can't be prevented, but it can be lessened by implementing a proper warm-up and increasing the intensity of your training sessions slowly over time. You can treat muscle soreness with light activity. Twenty to thirty minutes of light to moderate cardiorespiratory exercise can help the body feel loosened up, and the increase of blood flow can decrease the amount of pain felt. Some experts recommend stretching as a modality, and even ice. If the pain inhibits you from performing daily activity, you may take an over-the-counter painkiller such as ibuprofen or acetaminophen.

Muscle cramps are very common among athletes, avid exercisers, and individuals in the beginning stages of an exercise program. Cramps are involuntary muscle contractions that can occur in any muscle but are most common in the feet, calves, hamstrings, and abdominal musculature. Very little is known about cramps and why they occur, but research indicates cramps occur due to loss of electrolytes such as sodium, calcium, potassium, and magnesium, which are all essential in muscle contraction. When a cramp comes on, the best thing to do is relax the muscle as much as possible. Take some deep breaths, calm yourself down, and drink plenty of fluids to rehydrate your body. Some experts recommend massage and stretching the muscle that has cramped.

A contusion is a fancy name for a bruise. Bruising is usually caused by a blow from an outside object. Krav Maga is a contact activity, so it is likely that some bruising will occur. This is common in the beginning stages so don't be alarmed. Try to keep your punches and kicks light until you feel your technique is developed. Once you use the correct alignment, the bruising will diminish and you can make stronger contact without turning black and blue the next day.