Sports injuries and muscle relaxants

Use of muscle relaxants and their influence on driving

Sex and Age

23-year-old woman.


  • Non-pathological history: no drug allergies, no toxic habits.
  • Pathological history: no medical or surgical history of interest.

Regular treatment



Pain during the previous 24 hours when moving the left leg following repetitive exercise at the gym.

Physical examination:

  • Good general state, eupneic, afebrile, normally hydrated skin and mucous membranes, and normal coloring.
  • Cardiovascular: Rhythmic, no extra heart sounds.
  • Respiratory: Vesicular murmur present. No sound of fluid or wheezing.
  • Abdomen: Soft and palpable, no pain on palpation, no lumps or visceromegaly. Peristalsis.
    Lower extremities: Integral, symmetrical with no color changes or bruising, pain on palpating the internal left gemellus muscle with passive stretching; active contraction and counter-resistance movement extremely painful. No loss of strength or other neurovascular impairments.

Diagnostic impression:

  • Pulled left internal gemellus muscle.

Sports injuries:

Summer is approaching and an increasing number of people are engaging in sporting activities, but it is during these months that the number of sports-related injuries also increases; some of the most common of these are pulled muscles and sprains.

People should be aware that muscle injuries are very common in sportspeople with an incidence rate ranging from 10% to 55%; of these, almost 90% occur to the lower extremities, especially the ankles and the quadriceps muscles.


When talking about a pulled muscle, we are referring to the over-stretching (distension) or breakage of muscle fibers. A pulled muscle occurs when the elasticity of the muscle is exceeded and it mainly affects the superficial muscles between two joints.

A pulled or torn muscle occurs when the fibers contract suddenly at a point of fast muscle tension on a fatigued muscle, especially at the myotendinous junction.
The severity of injury of a pulled muscle is graded according to the damage to the muscle fibers:

  • Grade 1 (contractures or pulled muscles): this is a mild strain with just a few muscle fibers affected. The affected muscle is painful but contraction is normal.
  • Grade 2 (partially torn muscle): this is a moderate strain in which a large number of fibers are affected and it causes quite a lot of pain. There may be moderate swelling and a significant loss of strength.
  • Grade 3 (completely torn muscle): this occurs when the muscle is completely torn.

There are various risk factors in play when it comes to muscle injuries, most notably:

  • Insufficient training and/or warming-up.
  • Inadequate material or equipment.
  • Poor re-hydration.
  • Poor nutrition.
  • Repeated exercises (traumas).
  • Muscle fatigue.
  • Lack of sleep/rest.
  • Cold, humid atmospheres.
  • Metabolic or infectious diseases or medication.

Diagnosis and treatment:

Diagnosis is made in the clinic, and doctors should make a point of asking the patient about the injury mechanism, the presence of risk factors and the characteristics of the pain.

In some cases it may be necessary to conduct additional examinations such as a blood test, an X-ray and an ultrasound scan of the soft tissues if there is any doubt about the diagnosis.

Treatment can be pharmacological or non-pharmacological, depending on the grade and severity of the injury.

  • Non-pharmacological
    • Completely torn muscle: this generally requires surgery.
    • Partially torn muscle: complete rest during the first few hours, locally applied ice-pack, elevation of the limb, compression, active and progressive muscle exercises.
    • Contractures or pulled muscles: Relative rest, local heat, massage and a gradual and progressive return to physical exercis
  • Pharmacological: Pharmacological treatment is usually based on analgesics, preferably nonsteroidal anti-inflammatory drugs (e.g. Paracetamol, Ibuprofen, Naproxen) and in some cases the use of muscle relaxants (for short periods).

Road safety advice

When treating a patient with a muscle injury for whom muscle relaxants have been prescribed in addition to anti-inflammatories, it is important to remember that the former can have a very strong effect on driving ability.

On this issue, the Spanish Agency for Medicines and Medical Devices has made an anatomical therapeutic chemical (ATC) classification for the groups of drugs with the greatest impact on driving ability; muscle relaxants are classified as Group M, corresponding to the musculoskeletal system, the most commonly ones used in clinical practice for the treatment of pulled muscles being subgroup M03 which includes carbamic acid esters such as Carisoprodol and Methocarbamol (BA) and central nervous system relaxants such as Baclofen and Cyclobenzaprine (BX).

Doctors should remember to warn patients about road safety, especially if they are prescribing muscle relaxants:

  • With regard to carbamic acid esters, patients must be informed about the possibility of drowsiness during treatment, which should be taken into account by patients whose tasks require vigilance.
  • In the case of muscle relaxants that act on the central nervous system, patients should be informed that they can cause drowsiness in certain people and that they should take extra care when using vehicles or dangerous machinery and doing other tasks that require them to be particularly alert.

The most important thing is prevention, and this is why patients should be given certain basic recommendations to protect them from sports-related injuries, such as:

  • Adopting healthy habits, learning the correct sports techniques and using the right protective equipment.
  • Undergoing a medical aptitude test to indicate the most suitable physical activity or sport for each individual’s physical constitution.
    • Maintaining the optimal level of hydration and nutrition.
    • Stretching and warming-up before and after any physical activity.

Proper training in the techniques of the sport concerned.


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