“Hunchback”: A Silent Epidemic and Posture as Prevention

 

Introduction
Age-related “hunchback” (hyperkyphosis AKA “Dowager’s hump” or “gibbous deformity”) is a common and sometimes severe condition that affects many of the elderly and even some of the not so elderly. Characterized by an exaggerated forward curvature of the thoracic spine, this condition can profoundly impact an individual's quality of life, physical function, overall health, and even lifespan³. The good news is that hunchback isn’t necessarily an inevitable consequence of aging.

The Prevalence and Severity of Age-Related Hyperkyphosis
Depending on how it is defined, hyperkyphosis affects approximately 20-40% of older adults, and its prevalence increases with age.¹ It is typically defined as a kyphosis angle greater than 40° in the thoracic spine measured by comparing the angle of the first lumbar vertebrae to that of the 4th thoracic vertebrae, landmarks reliably seen on a lateral X-ray. Like this:²

 

 

This condition is more than a cosmetic concern; it carries significant health implications. For example, hyperkyphosis can impair mobility and physical function, increase the risk of falls and fractures, and cause pulmonary difficulties by restricting lung capacity. Most concerning of all, hyperkyphosis is known to shorten lifespan. And this is not a small effect: the risk of death was more than doubled in those with severe kyphosis, even after controlling for other important health risks.

Causes of Hyperkyphosis and the Role of Posture
The etiology of age-related hyperkyphosis is multifactorial, and can involve factors such as degenerative disc disease, vertebral fractures, and genetic predisposition. But weakness of the back extensor muscles, and by extension posture, stands out as a major contributing factor. Importantly, posture is one of the few modifiable predisposing conditions, and so offers an intervention that may allow prevention. Poor posture over time can lead to deactivation and deconditioning of spinal muscles, fatty infiltration of muscle tissue, decreased force generation capacity, and loss of strength and endurance in spinal stabilizers. These changes increase the load on passive tissues contributing to the development of hyperkyphosis. Thus, the cumulative effects of poor posture over a lifetime can significantly increase the risk of developing hyperkyphosis in later years.

Why the Poor Posture?
Our culture doesn’t prioritize posture as it once did, but in recent decades assaults on our posture have increased. Indeed, our spines are forced into the “C” shape that defines hunchback literally from both ends. From above, our addiction to cellphone screens has us strongly flexing our necks and upper spine many times a day, sometime for hours at a time. And from below, our addiction to passive sitting has us slouched in ergonomic chairs eight or more hours each day. This unprecedented attack on our spines is likely to lead to increased rates of hyperkyphotic spines in years to come as our “ergonomic” chairs and cellphones take their toll.

The Importance of Posture for Long-Term Health
Recently the importance of posture to overall health has been deemphasized, likely because of a focus on short-term outcomes that have little correlation with posture. For example, Beth Linker’s recent book "Slouch" (2024) recounts a “postural panic” in the United States during the early and mid-20th century which was the result of overblown concern for a variety of misattributed health consequences, a concern that gradually abated as we came to better understand the actual causes of infectious diseases. This “posture doesn’t matter” perspective, however, overlooks the long-term importance of posture in age-related hyperkyphosis. The effects of poor posture accumulate slowly over time, unnoticed until problems arise. This gradual progression may explain why short-term studies have failed to demonstrate dramatic effects of posture on health outcomes. However, poor posture over the long-term can lead to chronic muscle imbalances and weakness, degenerative changes in the spine, and an increased risk of vertebral fractures. It can also compromise respiratory function, and even shorten lifespan. By focusing solely on short-term outcomes, we miss the importance of posture in maintaining long-term health and quality of life as we age.

 

 

The central pillar of heaven.
And it isn’t just Western medicine and epidemiology that embrace the importance of spinal posture. For example, in Tai Chi “the central pillar of heaven” is the conduit that allows the flow of energy from the earth to heaven, emphasizing the importance of having well-grounded feet and a “suspended” head top. In practice the spine provides both the center of rotation and balance while itself remaining quiet, with the actual rotation coming from the hips, thighs, and even the feet. Spinal posture is thus important to the practice of Tai Chi, and also contributes to the health benefits of the practice. As the Tai Chi teacher Cheng Man-ching observed, “If the pillar of heaven collapses, what hope is there for one’s health?”⁴

The Feldenkrais community also emphasizes the importance of total body posture in addressing hyperkyphosis. Beginning with the observation: “even the smallest movement in one part of the body involves the entire body”⁵, the Feldenkrais method emphasizes that posture is dynamic, something that the body does, rather than a frozen position. The focus is thus on increasing kinesthetic awareness to effect changing movement habits, and thus address the stuck positioning that overtime can freeze into hyperkyphosis.

The Challenge of Improving Posture
Despite the importance of good posture, few interventions have been shown to reliably improve it. This challenge stems from the unique and largely ignored nature of postural muscles and their training requirements. Because postural muscles are designed for endurance and maintaining static positions they differ fundamentally from phasic muscles, an entirely different type of skeletal muscle that is responsible for dynamic movements.

Postural Muscles Position Us While Phasic Muscles Move Us
Postural muscles play a crucial role in maintaining equilibrium and posture control, which involves a complex interplay of neuromuscular mechanisms.⁶ These muscles are primarily composed of slow-twitch (Type I) muscle fibers, which are rich in mitochondria and myoglobin, allowing for sustained activity and endurance, endurance that is required to continuously maintain upright posture and stabilize the body against gravity. Phasic muscles, by contrast, are primarily composed of fast-twitch (Type II) muscle fibers, and are well designed for rapid and powerful contractions, but fatigue more quickly than postural muscles. These muscles activate on demand for specific movements, contributing to dynamic actions and force generation. Phasic muscles have a lower resting metabolic rate but are prone to atrophy when not regularly exercised. Because of these fundamental, histological and physiologic differences between postural and phasic muscles, traditional strength training approaches, which focus on high-intensity, short-duration exercises, are not as effective for training postural muscles which require low-intensity, prolonged activation, and frequent engagement throughout the day. And, actually, this makes sense, because this sort of training exactly mimics postural muscle’s functional role in maintaining posture in everyday life.

Active Sitting?
This is where active sitting emerges as a particularly promising approach to preventing, and possibly reversing, hyperkyphosis. Active sitting stands in opposition to the almost universal way we spend our seated time, which is sitting passively in a standard “ergonomic” office chair. Because all muscles largely go dark when sitting passively held up by a backrest, armrests, and lumber support, it’s not surprising that over time, lulled in the coddling embrace of “ergonomic” chairs, postural muscles weaken and atrophy. Active sitting, on the other hand, involves the use of novel alternatives to “ergonomic” chairs that encourage balanced posture and movement that continuously engages the core and postural muscles. Examples of active sitting include balance ball chairs, wobble stools, and other chair designs that specifically promote movement. Active sitting may help address hyperkyphosis in a few ways. Because sitting actively requires continuous engagement of postural muscles it naturally exercises these muscles in a way that’s consistent with the needs of postural muscles: low-intensity, prolonged activation, and frequent engagement throughout the day. By incorporating active sitting into one’s day, it’s possible to engage postural muscles for extended periods, accumulating significant training time that can improve not only strength, but also coordination. And, because the dynamic nature of active sitting also can improve body awareness and posture control, posture in other activities can also improve. Finally, unlike structured exercise programs, active sitting can be seamlessly integrated into most people's daily lives, making adherence seem effortless. In sum, because active sitting trains postural muscles in a way that aligns with their physiological requirements, active sitting offers a simple approach to improving posture and thus preventing, and possibly reversing, hyperkyphosis.

Summing Up
Age-related hyperkyphosis is a common and sometimes severe medical condition that can impair quality of life and overall health in older adults. While its causes are multifactorial, posture plays a crucial role and represents one of the few modifiable risk factors. The importance of good posture to long-term health has been underestimated due to a focus on short-term outcomes in research and clinical practice. Addressing hyperkyphosis requires a shift in how we approach postural training, because traditional exercise methods are not optimal for the unique requirements of postural muscles. Finally, active sitting seems a promising intervention, because it offers a way to engage and strengthen postural muscles that matches their physiological function. By improve spinal posture, strength, and coordination, active sitting is one way to reduce the risk of hunchback and its attendant health consequences.

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¹Age-related hyperkyphosis: update of its potential causes and clinical impacts-narrative review
²The Clinical Relevance of Hyperkyphosis: A Narrative Review
³Hyperkyphotic posture predicts mortality in older community-dwelling men and women: a prospective study
⁴Like a Long River: Some Tai Chi Thoughts. Wolfe Lowenthal, 2005
⁵The Brain's Way of Healing: Remarkable Discoveries and Recoveries from the Frontiers of Neuroplasticity, Norman Doidge, 2016
⁶Human Postural Control