Frozen Shoulder, Mayo Clinic
Frozen shoulder - Symptoms and causes - Mayo Clinic
Rotator cuff injury, Mayo Clinic
Rotator cuff injury - Symptoms and causes - Mayo Clinic
A precise understanding of the causes of frozen shoulder and rotator cuff injuries, Eam Taekyoung/Postural expert
Mayo Clinic believes that 'frozen shoulder' occurs when the joint capsule thickens and tightens around the shoulder joint, restricting the movement of the shoulder joint. It's believed that it can occur when the shoulder is immobilised for a long period of time, especially after surgery or an arm fracture. However, it's not clear why this happens in some people.
It is also believed that most rotator cuff injuries are caused by gradual wear and tear of the tendon tissue, which can be irritated or damaged by repetitive overhead activities or prolonged heavy lifting. As a posture expert, I don't think the above causal analysis is wrong, but I think it is not sufficient.
Sedentary socialisation During the Paleolithic era, humans lived a hunter-gatherer lifestyle, so the ability to run was paramount to survival, and our bodies were optimised for running. However, the fact that the centre of gravity of the head is tilted at about 12 degrees when looking forward, and the average marathon runner's spine is also tilted at about 12 degrees, suggests that modern humans still have a Paleolithic running body. However, as we have progressed through agricultural and industrial societies, we have spent an increasing amount of time sitting in a hunched posture rather than running. More recently, rapid digital socialisation, typified by the use of smartphones, has accelerated this trend. When walking or running, steps per minute and heart rate (cadence) are almost the same. In a marathon, the average steps per minute and heart rate per minute are both around 150. Both of these values get smaller and smaller as your speed decreases. This means that your cardiovascular system is beating at roughly the same frequency as the number of repetitions of the load on your legs. This, in turn, means that the left and right muscles and the cardiovascular system are optimised to tense and relax in equal cycles. Therefore, the healthier an individual is, the more likely he is to have a complete cycle of tension and relaxation in his left and right lumbar muscles, which is the same cycle as his steps. This means that the longer an individual remains in a posture, such as sitting in a slouched posture with both the left and right lumbar muscles tense, the more his muscles and cardiovascular system will deteriorate.
Characteristics of people around 50 years old
Frozen shoulder tends to occur around the age of 50. Rotator cuff injuries also occur mostly in middle-aged people, with the exception of those caused by overexertion. In general, we reach our maximum muscle mass in our 30s and then it gradually decreases. From your 50s onwards, you"ll lose 1 to 2 per cent of your muscle each year, and by your 70s, you"ll have lost almost half of it. Maintaining as much muscle mass as possible in your 30s can help you avoid sarcopenia as you age. However, the rate of muscle loss can vary greatly between individuals, depending on factors such as genetics, lifestyle, and overall health. Muscles work in conjunction with ligaments and tendons to connect bits of bone that don't hold together on their own and maintain the shape of the body. If you were to remove all of the "muscles, ligaments, and tendons" at once, your body would collapse like a deflated balloon. As muscle mass decreases, the strength to support the body's bones decreases, and as the strength to support the bones decreases, the body becomes more slumped and deformed, and as the body becomes more slumped and deformed, the blood vessels and nerves that are naturally responsible for the body's logistics are unable to maintain their normal shape and condition, which can lead to a sharp increase in various diseases. At the age of about 50, the decline in muscle mass that started at about 30 has been going on for about 15 years. This is a time when a steady decline in the amount of physical activity and range of motion of the body's muscles is quite advanced.
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| Maximize your mobility: Keeping your muscles as you age (petoskeynews.com) |
The effects of slouched posture For people who do a lot of running in their daily routine, the zigzag movement of the legs and shoulders remains the same contributing factor when walking. However, for people whose main activity is sitting, the head is often in a downward gaze, which causes the head to gradually protrude forward at an imperceptible rate. However, as this head protrusion increases, the zigzag movement of the shoulders becomes less and less necessary. The protruded head provides the partial forward movement force that the shoulder was responsible for, so the shoulder doesn't need to be involved. The decreased zigzag movement of the shoulder atrophies the repetitive activity of contraction and relaxation of the muscles associated with the shoulder, thoracic and lumbar spine, and eventually leads to a state of constant contraction of the associated muscles. As the forward projection of the head increases, the strides become smaller and smaller and more frequent shuffling. In order to prevent the body from collapsing under the excessive moment generated by the head, the soles of the feet move forward quickly to prevent collapse. Many elderly people who are severely stooped often walk with a hobble.
In the context of the frozen shoulder, the shoulder joint capsule is a 360-degree joint. The joint capsule at the base of the joint is loose, which means that it stretches smoothly when the muscles contract to move the arm forward or sideways. When the capsule at the base of the joint becomes contractile and stiff, it causes pain when you move your shoulder.
Slouched posture also reduces the use and range of motion of the Scalene muscles, intercostal muscles, and pectoralis manor, which have the ability to lift the ribs and expand the chest space. However, it constantly strains the trapezius and rotator cuff muscles and reduces their range of motion. The rotator cuff unites four muscles: supraspinatus, infraspinatus, deltoid, and subscapularis.
Better understand the causes of frozen shoulder and rotator cuff injuries
Let"s summarise what we"ve seen above.
👉 Sedentary socialisation increases the amount of time we spend in a slouched posture.
👉 Sitting in a slouched posture keeps both the left and right muscles of the lumbar spine in a state of tension, which reduces muscle and cardiovascular function.
👉 The age of about 50 years marks about 15 years of progression in the loss of muscle mass that began at about 30 years of age, and a steady decline in the amount of physical activity and range of motion of the body's muscles.
👉 As the forward projection of the head increases, the shoulder has less and less of a 'forward mobilising function' to perform, and therefore less and less of a zigzagging motion of the shoulder to cause a 'forward mobilising function'. This reduction can lead to atrophy of the repetitive activity of contraction and relaxation of the muscles associated with the shoulder, thoracic and lumbar spine, and eventually to persistent contractures of the associated muscles.
👉 Slouched posture reduces the use and range of motion of the Scalene muscles, intercostal muscles, and pectoralis manor. However, it continuously strains the trapezius and rotator cuff muscles and reduces their range of motion.
These are the underlying mechanisms by which frozen shoulder and rotator cuff injuries (other than those caused by overexertion) occur in middle-aged and older people.
Solution
A proper remedy starts with an accurate understanding of the cause. The key is to increase the amount of time you spend looking up. For more information on how to do this, see the links below.
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