Strains make up 30% of injuries

Strain, also known as pulled or torn muscle, is an injury of the muscle fibers, causing intense pain, swelling, and difficulty to move the affected area. Muscle fibers in charge of muscular contraction, the physiological process where muscles shorten or relax, can break or torn apart. It can also injure the connective tissue.

Recent epidemiologic studies show that muscle injury makes up 30% of all injuries. Muscle injuries are very frequent in sports, especially soccer. Strains are frequent among high performance athletes. It is also common on people who practice physical activity from time to time.

The risk of suffering from an injury practicing professional soccer is of 6 to 9 injuries per 1,000 hours of exposure. The risk of injury during a competition is of 4 to 6 times more frequent than that of trainings; during these, pulled muscles causes more days lost, with an incidence of 1.7 injuries per 1,000 hours. Strains are classified according to its mechanism of injury:

  • Strain by compression: caused by an external mechanism (direct trauma or skin and tissue rupture).
  • Strain by stretching: caused by an internal mechanism because of a sudden and strong contraction (over stretching).

These last one are subdivided in:

  • Muscle tear (grade I): the injury occurs when a muscle stretches to its elasticity limit.
  • Partial muscle tear (grade II): larger injury caused when the muscles stresses more than its elasticity limit. The patients experience a pull with intense local pain. If muscle is superficial, 12 to 24 hours after, blood accumulation can appear, looking like a bruise.
  • Total muscle tear (grade III): it is less frequent. Its clinical manifestation is similar to a partial tearing, but in this one the total loss of muscle function persists.

The most common causes of muscle tear are traumatisms (straight hits), improper training, a lack or excess of work, not stretching or warming up properly, and fatigue at the end of a competition. Another risk factor is malnutrition, because this weakens the capacity of muscle fibers to contract, making them susceptible to injury. Dehydration is also a risk factor.

Various investigations sustain that muscular tears are frequent in sports, causing higher leave periods. In a descriptive and epidemiological study performed during 2008 – 2009 season, 27 teams belonging to first and second Spanish division with a total of 728 players were included. The objective was to quantify injuries in soccer practice, including the typology and localization. Also including additionally, to show the average medical leave days that different injuries caused on Spanish professional soccer.

In said investigation, a total of 2,184 injuries were found. Making an incidence of 8.94 per 1,000 hours of exposure. The most frequent was muscular overload injury (n=516), followed by muscle tear (n=353), these caused a higher number of leaves (267.2 leave days by team and season). Within the 353 registered injuries by tear muscle, femoral biceps stands out as the muscular groups with higher injury frequency with an average of 3.3 injuries per team and season; however, if we take into account the severity of the injury, the rectus femoris stands out with an average f 76.6 accumulated leave days per team and season.

According to the high incidence of this injury and considering it is a cause of a high number of leaves, it is convenient to implement preventive measures to decrease the frequency in high performance teams, as well as in individuals that practice a sport not very frequently.

Some recommendations to prevent strains are:

  • Keep regular physical activity.
  • Before exercise, warm up between 5 and 10 minutes with light running or on a bike. Repeat this at the end of exercise session.
  • Stretch before and after physical activity.
  • Suspend exercise if you feel a pull or swelling in any muscle group.
  • Keep hydrated during physical activity.


Reviewers: Cassandra Saldaña Pineda (Knowledge Management Unit), and Brenda Giselle Álvarez Rodríguez and Perla Karime Olais Vega (Public Health Research Unit).



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