Age-Related Changes in the Musculoskeletal System, Balance Mechanisms, and Sensory Functions Relevant to Fall Prevention
By Stephen O'Hare, President, Pedors Shoes
Falls are a significant public health concern, particularly among older adults. Understanding the underlying anatomical and physiological changes associated with aging can help in developing effective fall prevention strategies. Here we present a basic understanding of the musculoskeletal system, balance mechanisms, and sensory functions relevant to fall prevention.
Additionally, we explore age-related changes that affect balance and mobility, shedding light on the factors contributing to increased fall risk among older individuals. By comprehending these mechanisms and changes, healthcare professionals and the families of seniors can implement targeted interventions to reduce falls and improve the quality of life for older adults.
1. Anatomy and Physiology of the Musculoskeletal System
The musculoskeletal system is made up of 206 bones, cartilage, ligaments, tendons and muscles, which form a framework for the body. Tendons, ligaments and fibrous tissue bind the structures together to create stability, with ligaments connecting bone to bone, and tendons connecting muscle to bone.
Bone remodeling and density changes with age. It is well known that the underlying mechanisms of osteoporosis in older adults are different than those associated with estrogen deprivation. Age-related bone loss involves a gradual and progressive decline, which is also seen in men. Markedly increased bone resorption leads to the initial fall in bone mineral density. With increasing age, there is also a significant reduction in bone formation.
The three main types of muscle include:
Skeletal muscle – the specialised tissue that is attached to bones and allows movement.
Smooth muscle – located in various internal structures including the digestive tract, uterus and blood vessels such as arteries.
Cardiac muscle – the muscle specific to the heart.
Age-related changes in muscle mass and strength
One of the most striking effects of age is the involuntary loss of muscle mass, strength, and function, termed sarcopenia. Muscle mass decreases approximately 3–8% per decade after the age of 30 and this rate of decline is even higher after the age of 60. Weight resistance training becomes increasingly important in seniors as they age to help preserve muscle mass and limb and maintain core body strength.
2. Joints and Connective Tissues
Joints allow our bodies to move in many ways. Some joints open and close like a hinge (such as knees and elbows), whereas others allow for more complicated movement — a shoulder or hip joint, for example, allows for backward, forward, sideways, and rotating movement.
As you age, joint movement becomes stiffer and less flexible because the amount of lubricating fluid inside your joints decreases and the cartilage becomes thinner. Ligaments also tend to shorten and lose some flexibility, making joints feel stiff.
Bones become more brittle and may break more easily. Overall height decreases, mainly because the trunk and spine shorten. Breakdown of the joints may lead to inflammation, pain, stiffness, and deformity. Joint changes affect almost all older people. Regular exercise and a stretching regimen prolongs flexibility as we age.
3. Balance Mechanisms
The five major vestibular structures are located in the inner ear and include: the utricle, the saccule, and the lateral, superior, and posterior semicircular canals.
The vestibular system monitors the motion and position of the head in space by detecting angular and linear acceleration. The 3 semicircular canals in the inner ear detect angular acceleration and are positioned at near right angles to each other.
As with most systems in the body, aging causes a degenerative effect within the vestibular system. Aging in the vestibular system is a multifactorial process, affecting both the peripheral organ and central circuits, from the peripheral end-organ to the brainstem to the cerebellum to the cerebral cortex. It follows that diseases that affect any one of these brain areas will disrupt one or more facets of vestibular functioning.
While the cause of dizziness in the elderly is a multisystem process, the data suggest that aging causes a reduction in peripheral vestibular function and also the cortical efficiency with which these signals are used for balance, which together play a significant role in the increasing the risk of falls in the elderly.
4. Visual System
The visual system helps regulate the other systems involved in maintaining balance, this means that any defect in the visual system can lead to frequent falls and a balance disorder. Visual dysfunctions that cause blurred or double vision are common in balance disorders, but can also be its root cause.
The vestibular system and the visual system work together by sending signals from the eye muscles to the balance organs in the inner ear. When you turn your head, your eyes go in the opposite direction. This is called the Vestibular Ocular Reflex.
Visual impairment was associated with reduced balance function. One study found that postural sway for male participants with visual impairment, regardless whether their eyes were open or closed, was similar to that of sighted participants with their eyes closed.
5. Somatosensory System
Proprioception is the ability to perceive the position and movements of joints and the perception of force in space allows us to better understand our movement and posture. Proprioception is closely related to balance.
Balance is achieved by not only proprioception, mentation, a vestibular system, vision and muscle strength but also through psychological factors. Of these factors, proprioception has an important role in balance, postural and motor control.