yogabook / movement physiology / muscle injuries

Muscle injuries

Muscle and tendon injuries account for between 10% and 55% of all injuries that occur in sport. In principle, they can mean longer periods of absence or even the end of an athlete’s career, especially if they have not been adequately treated. Prophylactically, warming up the musculoskeletal system and the environmental conditions are very important: cold and wetness have many disadvantages and risks for the musculoskeletal system. Typical high-risk situations for muscles are a swinging eccentric contraction and the change from a swinging eccentric contraction to a concentric contraction, as is the case when jumping off after coming up from a jump. Muscular fatigue and loss of movement coordination are also significant risk factors, which is why many injuries in team sports occur in the last third of the competition. Warm-up exercises are extremely important, but performed incorrectly they can also pose a risk. Warming up the muscle leads, among other things, to the provision of performance-adequate blood flow, which would only occur with a corresponding delay without warming up. Biarticular muscles are affected by injuries far more frequently than monoarticular muscles. Insufficiently healed muscle contusions also represent predilection sites for further injuries at the boundary between scar tissue and muscle tissue due to differences in elasticity.

In the case of muscle injuries, a distinction must be made between injuries at the attachment site on the bone, injuries in the course of the tendon itself, injuries to the muscle-tendon junction and injuries to the muscle belly. Injuries to the muscle can be divided into three types according to an older classification (see below for an improved version):

1. Overstretching/strain or tear, affecting a maximum of 5% of the fibres
2. Interruption of continuity of more than 5% of the fibres
3. Complete rupture with corresponding loss of function

The tearing of muscle fibres inevitably results in a haematoma. As the blood throughput of a muscle increases by a factor of up to 2.5 under load, muscle fibre tears during sporting activity lead to a much more pronounced haematoma than would be the case at rest. Impact trauma against a tensed muscle usually leads to superficial injuries and haematomas. If relaxed muscles suffer trauma, the injuries and haematomas are usually deep and close to the bone, which can lead to extraosseous calcifications. There is also a third type of haematoma, which can occur in the connective tissue layer between muscles.

Injury types 1 and 2 usually show no rest pain, type 3 at the latest a pronounced haematoma with corresponding pressure pain and possibly tension pain, as well as frequently a painful hypertonicity. Diagnostically, sonography can be used to assess the extent of the haematoma, the type of injury and the muscle structure. During sonography, a haematoma can be punctured and an intramuscular injection can be made, and muscle function can be observed in situ. A contrast MRI shows injuries to the muscles and tendons very well, but is used less frequently in acute cases than in chronic cases or in insertion tendopathies and also offers the possibility of examining bone injuries caused by trauma or detecting extraosseous calcifications. Scintigraphy is available as a final diagnostic tool, particularly in cases of suspected insertional tendopathy.

Immediate intervention for recent muscle injuries is carried out according to the PECH scheme in order to minimise haematoma formation and thus the expected connective tissue scar. A pressure cuff can be used to reduce blood flow and the muscle is cooled every 20 minutes. Elevating the extremity helps to reduce the blood pressure at the site of the incident. The haematoma should not spread any further after 24 hours at the latest. During this time, the event should be observed to rule out the consequences of a compartment syndrome that is discovered too late. Muscle relaxants can be administered during this time. Once the haematoma has finished forming, i.e. after 24 hours, the haematoma can be punctured under ultrasound control to promote healing. If necessary, this can be done several times in succession. Even after more than 72 hours, the haematoma may coagulate, which requires intervention, preferably by re-liquefaction and aspiration under ultrasound control. In more pronounced cases, an ultrasound scan should be performed every 2-3 days to detect and treat recurrent haemorrhages. Muscle strain should be ruled out in the first few days; at best, movement exercises without load can be carried out. After a week, you can start to gradually increase the load, whereby the occurrence of pain indicates the load limit.

Stretching exercises are only indicated from the second week after the event and should generally be performed bilaterally. Well-dosed cyclical movement patterns without shock-like load peaks such as cycling can be resumed from the third week onwards. Sport-specific training can only be resumed from the fourth week, although NSAIDs and muscle relaxants may be used in the first two weeks of supervised adapted training. Cooling can be used after exercise. The first stretching massages to the injury site should be carried out at the earliest two weeks after the event. In the case of type 3 injuries, surgical intervention should be performed within 48 hours if possible. In the case of very pronounced muscle fibre tears, the muscle should be sutured, which promotes regeneration and leads to a greater achievable maximum strength after healing than without sutures, in animal studies 80% of the contralateral strength. A poor prognosis results from immobilisation using a plaster cast, as this creates pronounced areas of connective tissue. After the surgical intervention, the muscle must be immobilised and relieved for 7 days, after which a decision is made after sonography as to when rehabilitation can begin. The question of whether a muscle has significant synergists deserves particular attention and can help decide whether surgery is indicated.

In principle, the recovery time of muscle fibres is three weeks, but in the case of complete ruptures, regeneration will be between twice and four times as long. The haematomas that occur with muscle fibre tears significantly delay healing. The inflammatory process by which the muscle repairs itself begins in the first minute after the trauma. The formation of non-functional scar tissue begins two weeks after the trauma and is completed after a further four weeks. To accelerate healing, various tissue growth factors can be injected into the injured area in the case of pronounced damage.

While traumatic injuries can basically contain a wide variety of entities, including mostly contusion (contusion) or laceration (open laceration), sometimes also entities such as fractures and ligament ruptures, and can therefore hardly be dealt with in a standardised manner, there are only a small number of entities for non-traumatic muscle injuries, the definition, terminology and delimitation of which is not standardised, especially internationally.

Munich consensus statement

For this reason, a conference of 30 sports medicine team physicians from various team sports, represented by the IOC, UEFA and FIFA, was held in Munich to create a more precise, standardised terminology (see also Müller-Wohlfahrt, Hans-Wilhelm et al.: 2014: „Muscle injuries in sport“), which is presented as follows (Munich consensus statement).

Functional damage without macroscopic correlate (sono, MRI)

The original English definition reads: „Acute indirect muscle disorder without macroscopic evidence of muscular injury; often associated with a circumscribed increase in muscle tone to varying extents and predisposing to tears; based on the etiology, there are several subcategories of functional muscle disorder“

1a: Fatigue-induced painful muscle stiffness (fatigue-induced muscle disorder, also: „hard tension“)
1b: „muscle soreness“ (DOMS, Delayed-Onset Muscle Soreness)
2a: spinal neuromuscular muscle lesions (spine-related neuromuscular muscle disorder)
2b: muscular neuromuscular muscle lesions (vulgo strain, muscle-related neuromuscular muscle disorder)

Structural muscle injuries with a macroscopic correlate

defined in the original as: „Any acute indirect muscle disorder with macroscopic evidence of muscle injury“

3a: Torn muscle fibre
3b: Muskelbündelriss
4: subtotaler, totaler Riss oder Avulsion

The following table shows how these entities differ:

known as	1A	1B Muscle soreness	2A	2B Tear	3A Torn muscle fibre	3B Muscle bundle tear	4 Muscle tear, Avulsion
Clinic	Pain: dull to stabbing, hardening, feeling of tension	Sluggishness, stiffness, generalised pain Pain	Pain: dull to stabbing, hardening	up to sharp, stabbing pain, hardening,	sudden, sharp, stabbing	sudden, sharp, stabbing	sudden, abrupt, then dull
Onset	Increasing during activity, possibly up to 24 h ex post	usually after 6-48 h	increasing during activity	increasing during activity	suddenly	suddenly	sudden
Reduction in strength	(-)	possibly, more subjective	pain-related	due to pain	due to pain	pain-related	pain-related, absolute failure
Localisation	partially to completely	generalised	individual muscle bundles along the entire length	spindle-shaped along the abdomen	mostly muscle-tendon junction	mostly muscle-tendon junction	Muscle-tendon or bone-tendon junction
Palpation	Band-like induration usually without oedema			Possibly palpable defect	palpable defect	palpable defect
Pressure soreness	+				localised DS	local DS
Stretching		improves	Defence reaction	improves	AI !	AI !	AI !
strain		Moderate pain		sharp pain

The muscle cramp is not included here, see its own page in pathology: /pathology-muscle-cramp

Rules

There are now a few simple rules for assessment that are very likely to apply:

If there is a hardening without significant reduced performance, it is a muscle hard tension (1A).

If the symptoms only appear gradually after a few hours and do not include any significant hardening, it is muscle soreness (1B).

If the strain tenderness is disproportionately higher than the stretch tenderness, it is a strain (2B).

Sudden, sharp, stabbing pain is usually a tear (3A, 3B) of the muscles.

If there is a sudden loss of function or a sudden reduction in strength, it is a tear (4).

If improvement occurs with stretching, it is not a tear from category 3 or 4.

If the pain affects the whole muscle, it is muscle soreness (1B).

If the maximum pain is near the tendon, it is at least a strain, possibly even a tear (2B-4).

If a dent is palpable, it is at least a strain, possibly even a tear (2B-4).

If only individual muscle bundles are painful, but over their entire length, it is a spinal neuromuscular muscle lesion (2A).

If the pain creeps in and rapidly increases to the maximum, it is a category 2 injury.

Complications

When dealing with injuries, be aware of the complications that can arise if they are not dealt with appropriately, such as stopping exercise immediately and following the rehabilitation protocol:

A cramp can turn into a strain or tear.

A strain can become a muscle fibre tear, possibly also a tendon tear or an avulsion (more common in younger age groups).

Strains tend to recur, especially if they heal poorly.