Daniels scale: what it is, characteristics, and functions

The Daniels scale or Daniels test is a tool used to measure the strength of the muscles in the human body, especially in patients with neuromuscular disorders or injuries located.

We must bear in mind that the muscular system allows us to relate to the environment, since it is in charge of the movement, and therefore, the person responsible for our body adapting to the immediate spatial demands of the environment that around us. That is why the human being has 650 different muscles, which correspond to 40% of the weight of an adult individual, a figure that is not negligible.

So that, assessing muscle strength in patients undergoing physiotherapeutic treatments is an essential question. In addition to identifying and monitoring disease progression, scales such as Daniels' can be useful for cultural events, since it allows the evaluation, for example, of the participants in sports Paralympians.

For all the compelling reasons that we have discussed previously, here We explain what the Daniels scale is and in which areas it is applied.

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Daniels scale: classifying muscle strength

As we have said before, this and other scales are used to measure the strength of the muscles in the human body. As we do not want to start building the house from the roof, first it is necessary to establish, at least briefly, what muscle strength is and how it works.

On muscle strength

Muscle strength is defined as the ability of a muscle or series of muscles to exert tension against a load during muscle contraction exercise. As simple as this "book" definition may be, various sources state that muscle strength can be dissected into three different variants:

Maximum force: the highest value of force that the neuromuscular system can show in a contraction.
Explosive force: the realization of the maximum degree of force possible in a minimum time interval.
Strength resistance: it is the endurance capacity of a certain muscle group when a constant and long effort of force is made.

As we can see, we are before muscular efforts that are classified according to their resistance, duration and speed of execution. Each of these types of forces has uses at specific moments in the individual's life and in various sports disciplines.

Muscle effort can be performed isotonic or isometric, and there are three types of muscle contractions (agonists, antagonists, and synergists). Although we are not going to dwell on this complex terminology because of the risk of deviating too much from the subject to be discussed, we throw the terms so that the conceptual world that encloses the force muscular.

A scale of a numerical nature

Returning to the subject that concerns us here, the Daniels scale It was first published in 1946 and was written by Americans Lucille Daniels, Marian Williams and Catherine Worthingham (For this reason, in English it is also known as “Daniels and Worthingham Scale”). The work, known as "Functional Muscle Tests: Manual Examination Techniques" continues to be available today, both in online format and on well-known sales portals.

The scale itself follows a specific numbering, with six well differentiated levels from 0 to 5. These are the following:

0: the muscle does not contract, complete paralysis.
1: the muscle contracts, but there is no movement. The contraction can be palpated or visualized, but there is no movement.
2: the muscle contracts and performs all the movement, but without resistance, since it cannot overcome gravity.
3: the muscle can carry out the movement against gravity as the only resistance.
4: the muscle contracts and performs the full movement, in full range, against gravity and against moderate manual resistance.
5: the muscle contracts and performs the movement in full range against gravity and with maximum manual resistance.

This numerical scale is accompanied by a qualitative evaluation, which assigns the parameters "Normal", "Good"; "Fair", "Poor", "Traces of activity" and "Nil" to the values mentioned above.

The division of this scale, quoted word for word, allows physical therapists to assess the ability of a muscle to generate contraction, which leads to making a movement, holding it or stopping it.

Even so, in some cases, the strength of the patient is a biased parameter, as this can be variable (for example, that the individual uses less force than he is really capable of) and subjective. On these occasions other more sophisticated tools are required.

An example of this is electromyography, a graphic recording technique of the electrical activity produced by skeletal muscles. We no longer rely on a mere observation, since the electromyogram is obtained from the insertion of electrodes on the muscle or the skin surface that is above it.

It is important to recognize that the Daniels scale is part of a complete assessment of the patient's neuromuscular status, but it does not provide answers to all the variables to be measured.

This test exemplifies both muscle strength and function, but Other parameters such as the following must also be taken into account: arcs of movement (observation of active and passive movement), balance and stability (observation of responses motor skills) and the evaluation of the patient's coordination and gait (by means of manual ocular tests, oculopedic tests and observation).

In addition, it has certain reservations: above all, sections 4-5 of the scale are partially subjective, as they depend a lot on the examiner and the force that he applies to the limb to be evaluated. This has led various professionals to classify this type of scale as a method with little sensitivity and little validity, due to a high load of uncontrollable subjectivity.

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Application of muscle strength tests

Neuromuscular diseases are a set of more than 150 neurological pathologies, mostly of a progressive nature and of genetic origin, whose main characteristic is the loss of muscular strength. Despite being considered as serious diseases, it is estimated that today there are more than 60,000 people affected by this type of disorder in Spain alone.

More than 50% of these diseases appear during childhood, and unfortunately, there are still no treatments effective or cure, although detecting them in time allows the application of different therapies to alleviate their symptom. In addition to a loss of mobility that generates a variable degree of disability in the individual, the loss of Personal autonomy and the incapacity for self-realization produce various psychosocial effects on the patient.

For all these reasons, quickly identifying these disorders is essential to address them in a multidisciplinary way (both in a medical and psychological field). The performance of tests such as those of the Daniels scale are an adequate basis for the detection of various diseases or for the quantification of the damages produced after a traumatic event for the system highly strung.

Not everything is reduced to genetic diseases, because for example, loss of muscle strength can occur after a stroke, brain mass injuries, spinal cord trauma and many other pathologies. In this case we are dealing with acquired muscle disorders, as there is no apparent genetic predisposition on the part of the individual to suffer them.

Resume

As we have seen, muscle strength tests or Manual Muscle Tests (MMT) are a series of relatively useful tools to assess the state of the patient's musculature at a time concrete.

Although their relative effectiveness is well established, these types of practices must be penetrated with more effective and objective methods., such as electromyography, strain gauge or dynamometry, as well as meters of many other parameters not directly associated with muscle strength itself.

The Daniels scale has several benefits, due to the simple cataloging of the patient based on a score numerical, but it is questioned for certain reasons, such as the high subjective component of the evaluator in question. Of course, with the number of tools available today, an observational assessment cannot be the only support for a diagnosis.

Bibliographic references:

Ciesla, N., Dinglas, V., Fan, E., Kho, M., Kuramoto, J., & Needham, D. (2011). Manual muscle testing: a method of measuring extremity muscle strength applied to critically ill patients. JoVE (Journal of Visualized Experiments), (50), e2632.
Hislop, H. J., & Montgomery, J. (2002). Examination of the muscles of the upper limb. Muscle functional tests. Madrid: Marbán Libros, 4, 57-166.
Montoya-Leal, V., & Pérez, V. Z. (2016). Quantitative assessment for occupational reintegration. Health Uninorte Magazine, 32 (2), 319-336.
Mora, I. S. (2000). Muscular system.
Daniels, L., & Worthingham, C. (1973). Muscle functional tests.-Manual expiration techniques.
Tweedy, S. M., Williams, G., & Bourke, J. (2010). Selecting and modifying methods of manual muscle testing for classification in Paralympic sport. European Journal of Adapted Physical Activity, 3 (2), 7-16.
What are muscle diseases? Aesem.org. Picked up on September 10 in https://www.asem-esp.org/que-son-las-enm/