Muscle function test

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The muscle function test according to Vladimir Janda is an examination method that provides information about the strength of individual muscles or muscle groups that form a functional unit and about the extent of lesions of peripheral motor nerves. It also enables the analysis of simple motor stereotypes , forms the basis for the analytical physiotherapy and is at the same time an aid for determining the performance of a tested body part. Janda assumes in his muscle function test that a certain amount of muscle strength is always required to move a body part through space. Basically, the following levels of muscle strength can be distinguished:

  • The musculature is able to overcome a resistance that opposes the movement from outside.
  • The muscles can only overcome gravity .
  • The muscles can only overcome parts of the body if gravity is excluded.
  • There is only muscle tension, but there is no movement.

The muscle function test is an analytical method. It basically only serves to determine the strength of individual muscle groups, but it is also an investigation of certain, precisely defined, relatively simple motor stereotypes.

Assessment levels

Janda describes muscle strength in terms of six basic levels. Each basic level is assigned a special percentage of maximum muscle performance:

  • Level 5 : N (normal) Full, normal muscle strength (100% of the norm), normally strong muscle does not mean that the muscle is normal in all functions (e.g. fatigue).
  • Level 4 : G (good) Approx. 75% of normal muscle strength, i.e. H. Medium resistance can be overcome with full range of motion.
  • Level 3 : F (fair) Approx. 50% of normal muscle strength, i.e. H. Movement can be carried out against gravity to the full extent of movement.
  • Level 2 : P (poor) Approx. 25% of normal muscle strength, i.e. H. Execution of the movement in full range of motion possible, but not against gravity.
  • Level 1 : T (trace) trace of tension; about 10% of normal muscle strength.
  • Level 0 : Z (zero) No muscle contraction possible when trying to move.

We only work with the use of Arabic numbers. The percentages or abbreviations are not used. If the tests result in a value between 2 levels, the corresponding number is provided with a “+” or “-”.

Examination of shortened muscle groups

The term muscle shortening or, better, "reduced elasticity" is used to describe a condition in which, for various reasons, the muscle that is at rest has been shortened. The muscle is therefore shorter than normal when at rest, and it cannot be passively stretched to the extent that it would correspond to the full range of motion of the associated joint. This condition is not caused by increased activity of the nervous system or active muscle contraction. One form of shortening is muscle contracture , as it occurs when the balance of forces between antagonistic muscle groups changes.

It has been proven that certain muscle groups tend to shorten while others tend to weaken. In contrast to muscle weakening, the investigation of shortening has received too little attention so far, whereby shortened muscles can play a major role in a variety of movement disorders.

When examining shortened muscle groups, one must work just as precisely as with the muscle function test. Accordingly, the same evaluation standard is used here.

For a large part of the shortened muscles, it is very difficult to quantify the degree of shortening precisely, and therefore only a general assessment is usually sufficient. However, in order to still achieve a reliable test, the prescribed starting position, fixation and direction of movement must be meticulously adhered to. As with the muscle function test, the muscle must not be pressed. It is logical that muscle shortening can only be assessed correctly if the joint mobility is not restricted in any way.

Sample exercises to test muscle function and shortening

Muscle function

Extension of the hip joint

Starting position: prone position, small pillow under the stomach, head on forehead, arms lengthways next to the body, legs in basic position, toes sticking out over the edge of the bench.

  • Level 5 :
    • Fixation: the pelvis is fixed on the side to be tested with the finger and hand, while the thumb palpates the greater trochanter (large hillock, upper end of the femoral neck).
    • Movement: Hyperextension of the leg in the hip joint from 10–15 ° behind the frontal plane.
    • Resistance: with hand on the lower third of the rear thigh muscles: arching against the direction of movement
  • Level 4 :
    • Fixation: the greater trochanter is felt with the finger
    • Movement: Hyperextension of the leg in the hip joint from 10–15 ° behind the frontal plane.
    • Resistance: none
  • Step 3 : Lying on the side on the leg to be tested, the upper leg is held in abduction by the tester
    • Fixation: holding the pelvis on the iliac crest
    • Movement: Hyperextension in the hip joint from the zero position (10–15 °)

Shortening

Extensibility of the pectoralis major muscle (PMA / PMS / PMC)

Starting position: supine position on the edge of the bench on the side to be examined. Legs bent, the soles of the feet propped up on the bench. Arms relaxed next to the body, head in central position.

  • Level 2 : arm sinks to the horizontal. The range of motion increases with pressure
  • Stage 1 : Arm does not reach the horizontal by itself, but only under pressure from above.
  • Level 0 : Arm remains above the horizontal even with pressure.

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