Chapter 5 The Muscular System 183
those accompanying grades I and II strains.
Grade III strains involve a tearing of the
muscle, loss of function, internal bleeding,
and swelling.
Strains of the hamstrings are a frequent
problem for athletes because these injuries are
slow to heal and tend to recur. One-third of all
hamstring strains will recur within the fi rst year
of returning to a sport or an activity.
Contusions
A contusion is a bruise or bleeding within
a muscle, resulting from an impact. When an
already injured muscle is repeatedly struck,
a more serious condition, called myositis
ossifi cans (migh-oh-SIGH-tis ah-SIF-i-kanz), can
develop.
Myositis ossifi cans involves the formation
of a calcium mass within the muscle over a
period of three to four weeks. After six or seven
weeks the mass usually begins to dissolve and
is resorbed by the body. In some cases a bony
lesion can remain in the muscle.
Cramps
Muscle cramps involve moderate to severe
muscle spasms that cause pain. The cause
of cramps is unknown; in fact, there may be
numerous causes. Some of the possible causes
include an electrolyte imbalance; defi ciency
in calcium, magnesium, or potassium; and
dehydration.
Delayed-Onset Muscle
Soreness
Muscle soreness is common and typically
arises shortly after unaccustomed activity.
Delayed-onset muscle soreness (DOMS) follows
participation in a particularly long or strenuous
activity, with the soreness beginning 24 to 72
hours after the activity. DOMS involves multiple,
microscopic tears in the muscle tissue and causes
infl ammation, pain, swelling, and stiffness.
Tendinitis and Tendinosis
Tendons are the bands of tough, fi brous
connective tissue that connect muscles to bones.
Tendinitis is infl ammation of a tendon, usually
accompanied by pain and swelling.
Both acute and overuse injuries can cause
tendinitis. The condition can also occur with
aging, as the tendon wears and elasticity
decreases. Diseases such as diabetes and
rheumatoid arthritis can also promote the
development of tendinitis. Tendinitis can occur
in any part of the body, but common sites
involving injury include the shoulder, elbow,
wrist, and the Achilles tendon of the heel.
Treatment of tendinitis includes rest and
application of heat or cold. Pain relievers such
as aspirin and ibuprofen can reduce pain and
infl ammation. In severe cases, steroid injections
into the tendon can help control pain. Once the
pain is reduced, physical therapy to stretch and
strengthen both muscle and tendon promotes
healing and can help prevent reinjury.
If untreated, chronic tendinitis can progress
to tendinosis. Tendinosis, or degeneration of a
tendon, is believed to be caused by microtears
in the tendon connective tissue that decrease
the tendon’s strength. This weakened condition
increases the likelihood that the tendon will
rupture.
Although the condition is painful, no
infl ammation is present, unlike with tendinitis.
Once tendinosis has developed, recovery takes
months to years of minimal use. In many cases
physical therapy can help.
1. Describe the differences among the three
classifi cations of muscle strains.
2. Why are athletes more likely than others
to have problems with strains?
3. What is the difference between cramps
and DOMS?
4. What causes contusions? Give an example.
5. What are possible causes of cramps?
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