Guide to Muscle Injury

Guide to "Muscle Injury":

There are several classification criteria that can be taken into consideration. We confine ourselves to treating only the strained muscles and other muscle injuries which are more common in sports. As a first step in the classification we have to divide the nature of trauma : direct or indirect.


  • Muscle injury by direct trauma, which according to the classical interpretation, require the existence of a force acting from the outside.
  • Muscle injury from indirect trauma, caused by more complex mechanisms, which include harmful forces that develop within the muscle structure, which occur because of problems of the muscle itself or imbalances of the musculoskeletal system. Essentially, the primary causes are:
    1. Agonist-antagonist muscle imbalance
    2. Eccentric contraction

Explosive Concentric Contraction

The consequence of muscle trauma, except for the contracture and the stretching, it is always an anatomical damage of the muscle fiber, with involvement of the connective part and possibly tendon and vascular structures. The diversity of the nomenclature used in the classification is clinically given by the extent of damage caused by the trauma.

Classification of muscle damage:

  •  Injuries caused by direct trauma (contusion)
    • mild
    • moderate
    • severe
  • Injuries caused by indirect trauma
    • contracture
    • stetch
    • strappo
    • 1st degree strain
    • 2nd degree strain
    • 3rd degree strain (partial or total breakage)

Classification of injury from direct trauma

Muscle injury from direct trauma are of contusive nature. In terms of anatomicopathological profile, however, the rupture produced by these muscle injury does not differ substantially from a muscle injury due to external causes.  From the functional point of view in practice, the muscle contraction resulting from the trauma causes articular limitation, linked to a reduced muscle extensibility. Muscle injury from direct trauma are classified in three degrees, according to the gravity, indicated by practicable range of motion (Reid 1992)

  • mild muscle injury: more than half of the range of motion is allowed;
  •  moderate degree of muscle injury: it is granted less than half but more than 1/3 of the range of motion
  • severe muscle injury: it has allowed less than 1/3 of the range of motion

Classification of injuries from indirect trauma

  • Contracture
  • Elongation
  • Stretch
  • Distraction
  • Strain
  • Break
  • Laceration

These terms refer to different degrees of severity, due to the different clinical  and anatomopathological manifestations of the lesion.

Contracture. It is the most benign form and doesn't show anatomical lesions. It manifest itself with  muscle pain during or,very often, at distance from the sport activity, with a variable latency (after a few hours or days later), not well localized, due to a maintained tetanic contraction imputable to a state of muscle fatigue.

Stretch. It manifest itself with acute pain, often well localized, during athletic movement. The athlete is forced to stop his activity, although very often doesn't occur instantaneously functional impotence.Anatomopathologically doesn't appear relevant interruption of the fibrils, however, are clear biochemical changes that can be recognized as intracytoplasmic changes, myofibrils disorganization, possible sub microscopic lesions in the sarcomere and mitochondrial..

Strain. The subject feels acute pain, violent during athletic movement, due to a real anatomical lesion with laceration of a variable number of myofibrils. As result of the strain will always have a hematoma, more or less important according to the number of myofibrils involved and to the integrity of the muscle. Based on these considerations, the extent of damage is distinguished on a scale of three degrees:

  • 1st degree strain: irreversible damage of some muscle fibers within a bundle, but not the whole bundle;
  • 2nd degree strain : fracture of one or more muscle groups, disorganization of connective tissue and intramuscular hematoma;
  • 3rd degree strain: muscle rupture, partial or total, with widespread hematic extravasation, intra-or extra fascial.