Article reviewed and approved by Dr. Ibtissama Boukas, physician specializing in family medicine
The objective of sheathing is often of an aesthetic nature, but we must not forget its role in the prevention of back pain and the improvement of sports performance. For these reasons, many physicians, physiotherapists (physiotherapists) or sports coach use various tests to assess the strength and endurance of the trunk muscles.
What is sheathing, exactly, and how can you assess it (especially when you have low back pain)? The Shirado and Sorensen tests are presented in this article, and are compared to other modalities aimed at evaluating static and dynamic sheathing.
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Gaining, what is it?
When we talk about sheathing, most people think of the plank exercise where you stand on your elbows in a prone position on the floor (keeping your back straight). Although this exercise works the core muscles, the concept of sheathing should not be limited to this exercise only.
Cladding is also referred to as “core stability” in English. It defines a set of exercises aimed at improving the strength of the superficial and deep muscles of the trunk (including the postural, abdominal, oblique, extensor muscles of the spine, etc.). Contrary to some popular belief, sheathing is not intended for the sole purpose of strengthening the rectus abdominis (the famous chocolate bar!).
In general, cladding exercises involve the weight of the body and fight against the effect of gravity. These are typically isometric exercises (ie static, ie the length of the muscle fibers do not change), but dynamic components of movement can also be added to the exercises.
Link to back pain
The dysfunction of the trunk muscles is closely linked to the development of back pain according to studies. More specifically, weakness or reduced endurance of the muscles of the abdominal strap seems to be a risk factor for chronic low back pain. In the same way, a good isometric endurance of the lumbar muscles would seem to prevent the appearance of lumbar problems.
Thus, many studies have been performed to assess and quantify trunk muscle strength and endurance in patients with back pain. Although there are no standards or reference tests for the evaluation of sheathing, many clinicians use the Shirado and Sorensen tests within their therapeutic management.
The following sections present each of the tests in detail, and offer alternatives aimed at the same objectives.
Shirado test
The Shirado test is a static abdominal endurance test used in the evaluation of patients with low back pain. The objective of this test is to measure the endurance of the muscles of the abdominal belt via an isometric effort (a muscular contraction without change in fiber length).
La Shirado test procedure is the following :
The initial position of the patient is: lying on the back, arms crossed on the chest, hips and knees flexed at 90° and the calves resting on a raised support.
The test consists of straightening the patient's chest so that his shoulder blades lift off the ground, and his abdominals are contracted isometrically. The legs do not move during the Shirado test.
The patient holds the position for as long as possible (maximum three minutes) while the examiner calculates the time elapsed since the start of the test.
A momentary drop in trunk flexion is tolerated, but only twice. At the third warning (or if the patient can no longer maintain the position), the stopwatch is stopped.
In the presence of lumbar or other pain, the test is stopped and the examiner notes the time elapsed since the adoption of the initial position.
If the participant manages to maintain the position for more than three minutes, the test can be stopped and the time (180 seconds) constituting the maximum value of the test noted.
In survey comparing the results of healthy subjects and those suffering from back pain, the mean maintenance value was 155 seconds (± 79) in the asymptomatic population, whereas those with low back pain held on average 41 seconds (± 23).
Sorensen test
Sorensen's test was first described in 1964 as a test assessing the isometric endurance of the hip and back extensor muscles (paraspinal, spinal erectors, multifid, etc). The test as described by Sorensen consists of "measuring the number of seconds during which the subject is able to maintain the upper body without support (from the upper edge of the iliac crest) horizontally, while he is placed in ventral decubitus, buttocks and legs fixed by three wide straps, and arms crossed against the chest”.
More specifically, here is the Sorensen's test procedure :
The equipment needed for the test is a bed (or massage table), a stopwatch, and three to four straps.
The starting position is as follows: the patient assumes a prone position on a bed, with the upper edge of the iliac crest at the edge of the bed and the upper trunk unsupported. The arms, meanwhile, are crossed over the chest. The lower limbs are stabilized by straps.
The patient is asked to maintain the upper body in a horizontal position, the time being calculated with a stopwatch.
The test ends if the patient can maintain the position for 4 minutes (240 seconds) or if they can no longer maintain the defined position before the 4 minutes have elapsed.
The downtime is recorded.
Note: An alternative to the Sorensen test would be to lie face down on the floor, then place a pillow under your stomach. The test would be to raise the sternum off the ground so as to achieve lumbar extension, then measure the time elapsed before the patient can tolerate the position. The advantage of this option is that it does not overload the lower back as much, nor does it cause hyperlordosis.
Nicholaisen and Jorgensen assessed back muscle endurance using the Sorensen test. They found that the isometric endurance of patients with low back pain was significantly lower than that of normal subjects. Similarly, patients with severe low back pain performed worse than those with mild back pain.
Sorensen's test has some drawbacks in some patients with low back pain. In fact, adopting the initial evaluation position is sometimes impossible because of the lumbar pain caused. This usually arises from hyperlordosis caused by extension of the hip and knee. This can overload the lower back region, causing pain there and impairing the optimal execution of the test.
alternatives
To measure trunk muscle endurance, various modalities can be used. In addition to the Shirado and Sorensen tests, here are tools for evaluating static and dynamic sheathing.
Frequency analysis by electromyography (EMG)
Computerized dynamometers : These devices provide a significant amount of measurements relating to the strength of the muscles evaluated, their power, endurance, etc. Arithmetic variations are also included (like mean, median, etc.) allowing for better analysis.
Although they have several advantages, the major disadvantages of the machines are their high price. Also, their installation and application are generally long and arduous. For these reasons, they are used more in a research context, and not in the clinic with patients.
Conclusion
Ideally, gain assessment tests should be easy to perform in a clinical setting, and no special equipment should be required. The Shirado and Sorensen tests meet these criteria, hence their popularity among health professionals and sports trainers.
Also, the tests themselves should not reproduce pain in the population suffering from back pain, especially if they are used in a therapeutic context. Primarily, they should not cause painful lumbar hyperextension, nor overload the lumbar spine. It is with this in mind that there are alternatives to these tests, especially for the Sorensen test. On the other hand, these tests, when they are well tolerated, remain interesting for evaluating the endurance of the trunk muscles in low back pain populations.
Anas Boukas( Physiotherapist, physiotherapist, consultant )
My name is Anas Boukas and I am a physiotherapist. My mission ? Helping people who are suffering before their pain worsens and becomes chronic. I am also of the opinion that an educated patient greatly increases their chances of recovery. This is why I created Healthforall Group, a network of medical sites, in association with several health professionals.
