Chp. 9: Aging and Postural Control

______________ is highly correlated with longevity in both humans and animals

DNA repair capacity

Taking one or more additional steps after the initial stepping response during recovery is associated with...

both aging and fall risk

Healthy older adults actually have pretty decent sway compared to young people, however, in contrast to young adults, reducing the availability of 2 senses appears to have what kind of effect?

A significant effect on postural steadiness

Ankle joint flexibility, critical for postural control, declines at what rate in aging men and women?

-Declines by 50% in women and 35% in men between the ages of 55 and 85

More current research indicates that many falls in the elderly have multiple contributing factors, including?

-Extrinsic environmental factors -Intrinsic factors such as physiological, musculoskeletal, and psychosocial factors

Many studies have identified risk factors for falls among hospitalized older adults, and they have consistently identified the following factors:

-Gait instability -LE weakness -Urinary incontinence/frequency -Need for assistance in toileting -Impaired cognition -History of falls -Use of certain medications

According to the "Guidelines for Prevention of Falls in Older Persons", there are a number of risk factors associated with falls among community living older adults. List some:

-Muscle weakness -History of falls -Gait deficits -Balance deficits -Use of an assistive device -Visual deficits -Arthritis -Impaired ADLs -Depression -Cognitive impairment -Age greater than 80yo

What classifies an older adult who is 'Physically elite'?

-Sports competition, Senior olympics -High-risk and power sports (ex. hang-gliding, weight lifting)

There appears to be an age related loss of what types of muscle fibers?

-Type 1: (slow oxidative, used for postural control and running) -Type 2: (fast twitch, used for sprinting)

In summary, data suggests that older adults with and without balance problems show changes in the motor systems affecting postural control and that these can contribute to an inability to maintain balance. Some of these motor system changes include:

1. Muscle weakness 2. Impaired timing and organization among synergies 3. Limitations in the ability to adapt movements for balance

McKee et al. (2002) followed 57 patients for 2 months and reported that ______ of community dwelling men and male veterans sustained a second hip or pelvic fracture within 1 year after initial hip fracture that caused hospitalization.

19%

In the clinic, a fall is often defined as...

A situation in which the older adult falls to the ground or is found lying on the ground. In addition it can be defined as any unintended contact with a supporting surface (like a chair or wall).

Fall rates in persons 65 years or older are at least ______ in community dwelling older adults.

33%

In the Self-Rated Fall Risk Questionnaire developed by Rubenstein, a cut point of greater than _____ points indicates increased risk for future falls.

4 points

Lower extremity muscle strength can be reduced by how much between the ages of 30-80 years old?

40%

Older adults on a stable surface had a ____ increase in sway in dual task conditions, while young adults did not

40%

Statistics show that unintentional injuries are the _____ leading cause of death in the elderly; and falls make up _______ of these deaths

5th, 2/3

What are some external factors that contribute to a persons health and longevity?

A persons lifestyle and the environment in which he or she lives

Older adults who fell after hospital discharge had significantly greater declines in independence in...

ADLs and lower performance on balance and mobility measures

What could affect the ability of an older adult to make movements such as lifting objects? (looking at changes in anticipatory postural control)

A slowing in onset of contraction or a disruption of the sequence of activation of postural synergies

Problems affecting the coordination of muscle response synergies are classified into what 3 categories?

A. Sequencing problems B. Problems with the timely activation of postural responses C. Problems adapting postural activity to changing task and environmental demands

One of the functions of the vestibular system is that it is an ....

Absolute reference system with which the other systems (visual and somatosensory) may be compared and calibrated

When it comes to anxiety of falling and older adults... what do we know?

Adults probably modulate strategies for postural control based on their level of the threat. So older adults who have a lot of anxiety about falling will move in ways that reflect these perceptions

We know that older adults don't use correct synergies in reactive balance control (they be activating proximal to distal lol). It is possible that a shift toward the use of hip movements in balance control may be due to...

Anke muscle weakness and the inability to generate large amounts of force at the ankle joint

Why is focusing on genetic components alone as the primary determinant of nervous system function with age a pessimistic view?

Because this suggests that functional loss is an invariant part of growing old. That is no fun and uncool

Wheras the stable and unstable older adults each showed more COP oscillation before coming to a stable position, this was also accompanied by...

By an increased time for the COP to come to stabilization

In studies on age-related changes to steady state balance, they found what conditions to be the best at determining the true capacity of an older adult to balance under changing steady state conditions?

Challenging quiet stance conditions, such as tandem Romberg, with eyes closed is the best.

It appears that aging may not necessarily be characterized by an overall decline in function. Rather....

Decline may be limited to specific neural structures and functions

In the research environment, how is a fall typically defined?

Defined as the inability to recover stability independently, thus requiring assistance (either by another person or by a harness) to prevent a fall.

Results show that balance impaired older adults took a longer time to regain a stable posture in what conditions than when responding to the postural task along?

Dual task conditions

EMG showed what about muscle activation time in fallers?

EMG showed time to peak in the gastroc was slower in fallers and there was increased coactivation of agonist and antagonist muscles during stepping

What is critical to understanding the capacity to maintain stability under complex and changing environmental conditions?

Evaluating the individuals ability to maintain stability under changing sensory conditions

What is a more optimistic view of the aging process?

Focusing on secondary (external) factors that contribute to longevity. In this model, with optimal experiential factors, we can expect good CNS function unless pathology occurs

Research indicates that genetic factors contribute about _____ to longevity, while health related behaviors, including lifestyle, diet, and levels of exercise, stress, and self-efficacy contribute _______

Genetic factors: 20% Health related behaviors: 80%

What is an internal factor that contributes to health and longevity?

Genetics

Several labs have found that many older adults used a strategy involving ______ movements rather than _______ movements significantly more often than young adults. (When they were testing in-place reactive balance control)

Hip rather than ankle movements

Among frail older adults, an inability to ______ while ______ is a predictor of future falls

Inability to walk while talking (A dual task involving gait and a secondary task)

What type of posture is associated with a decrease in spinal extensor muscle strength?

Increased kyphosis

What type of muscle contraction is more correlated to physical function?

Interestingly, muscle power has been found to be even more highly correlated with physical function than muscle strength.

When analyzing muscle response characteristics to room movements (they were studying the effects of visual flow on postural responses), researchers found that when the room moved away from the subjects, the unstable older adults did what?

Used larger ankle dorsiflexor responses, which caused high amounts of sway in the forward direction

Problems in the motor systems contributing to age-related changes in postural control include impairments in both _________ and _________ systems

Neuromuscular and Musculoskeletal

In regards to aging, muscle strength reduction is more severe in what population?

Nursing home residents with a history of falls

Older adults (>75yo) tend to fall more where compared to younger old adults (<75yo)?

Older adults fall more at home. Younger old adults fall more away from home (and suffer more serious injuries)

In response to small/slow perturbations, the onset of postural muscle activity was delayed in both unstable and stable older adults compared to the young adults. But for large/ perturbations....

Only the unstable older adults showed muscle onset delays. This suggests that stable older adults had difficulty in sensing the onset of small/slow perturbations but were able to compensate adequately for larger scaling factors

What types of pathologies could cause increased sway during quiet stance, but doesn't affect reactive balance?

Osteoarthritis and accompanying reduced joint position sensitivity

3/4 of Fall related deaths occur in what age?

Over 65 y/o

What type of training is most effective for improving physical function in older adults with muscle weakness?

Power training

In the aging process, what types of contractions are affected the most?

Rapid velocity contractions are more affected than Slow velocity contractions

Interestingly, the principal source of DNA damage leading to normal aging is...

Reactive oxygen from normal metabolism, and this is something that can be affected by diet and exercise

What is a tool used to predict falls in hospitalized elders?

STRATIFY (St. Thomas's risk assessment tool in falling elderly inpatients)

What type of ROM loss shows the greatest decline with age?

Spinal flexibility, particularly spinal extensibility, shows the greatest decline with age

Performing a secondary task caused subjects to ...

Step earlier when using a stepping strategy

Researches examined changes in functional stability limits by measuring the COP trajectory (in multiple different directions) in relation to estimated geometric stability boundaries (borders of the feet)... what did they figure out?

That functional stability boundaries were much smaller than their geometric boundaries. Suggesting that older adults are at a higher risk of instability that would require them to take a stop or maybe fall

What kind of test might be capable of identifying older adults who are at risk for falls?

The Visual Push Test

When we have something in our hand, how does the nervous system react in terms of falling?

The nervous system gives priority to to that object rather than reaching to aid in balance

What were main issues found with older adults in their reactive balance control strategies when the platform moved forward (causing backward sway)?

The older adults showed significantly slower onset in the ankle dorsiflexors, with proximal muscles being activated before distal muscles (sequencing problem)

What is a reason that measurement of sway with eyes open during normal quiet stance may not be the best way to evaluate balance dysfunction in older adults?

There are a variety of patients with neurologic disorders, such as parkinsons, who have normal, or even reduced sway in quiet stance

What are experiential factors?

These involve leading a healthy and active life, and are mostly under our control -Nutrition -Stress -Exercise

What What would classify an older adult as 'Physically independent'?

Those who are active, but engage in less physically demanding activities, such as golf, social dancing, traveling, automobile driving -Independent in all BADLs and IADLs

What would classify an older adult as 'Physically Dependent'?

Those who are dependent in both BADLs and IADLs. They require full time assistance or institutional care.

What would classify an older adult as 'Physically frail'?

Those who are usually independent in BADLs, but are dependent in many IADLs. They are capable of light housekeeping, but often require assistance to continue living independently

What traits classifies an older adult as 'Physically fit'?

Those who engage in sports, games, and hobbies, and who are capable of moderate physical work -All endurance sports and games -Most hobbies

Studies suggest that static balance should be assessed under what conditions?

Under challenging conditions such as tandem stance with eyes open versus closed. (rather than do eyes open normal quiet stance)

In terms of reactive balance control.. Horak et al. (1989) suggested that in older adults, some falls, particularly those associated with slipping, may be the result of...

Using a hip strategy in slippery conditions in which the surface cannot resist the sheer forces associated with the use of this strategy, for example, when on ice.

A number of studies have indicated that age-related increases in sway during quiet stance become larger when ______ cues are removed

Visual

There was a study examining sway under altered visual conditions. The study included 2 groups, healthy older adults and young people. Under what conditions did the healthy older adults show significantly increased sway compared to the younger group?

When healthy older adults were asked to stand on a compliant surface with their eyes closed (using vestibular inputs alone)

When does functional disability occur?

When strength falls below the threshold needed for a task

Do women or men fall more frequently?

Women

The research showed that when it comes to dual tasks, what requires additional attentional resources compared with young adults?

sensory reweighting

In addition to the musculoskeletal systems, aging results in changes to the ....

neuromuscular system, specifically the coordination of forces controlling steady-state, reactive, and proactive balance control

McKee et al. (2002, same study as the hospital stuff) found that two factors- ________ and _________ predicted falls in the 6 months after discharge

premorbid history of falls and use of a gait assistive device

Functional stability limits are ________ with age

reduced