Primary vs Seconday Aging
Aging due to:
* Primary: genetically related, gradually declining
* Seconday: External Causes; system function will remain high until death (Under our control)
What are two secondary factors that have a large effect on aging?
- Nutrition and Exercise
What percentage of aging is genetic vs environment?
- 20% Genetics (Primary)
- 80% Environmental (Secondary)
When an older individual comes into your clinic, what do you need to think about?
- Chronological and functional age for both evaluation and treatment
General age-related changes
- Musculoskeletal
- Sensory
- Neural
- Motor behavior strategies
- Cognitive demands of motor tasks
General age-related changes may lead to…
postural instability (falls) and characteristic changes in gait
Neuromuscular Age Changes
- Lose Type 1 and Type 2 muscle fibers (Leads to a blending; one mode)
- Results in a loss of the ability to generate speed and power; results in a slower reaction time
- Decline in # of motor units and myelinated fibers
- Functional changes at neuromuscular junction (Decrease in NT effectiveness)
Fewer motor units results in…
less resolution of muscle force, impacts fine motor control causing less coordination/clumsy handling, tougher to control deceleration
Strength Age Related Change
- Muscles get smaller; muscle cells die and are replaced by connective tissue and fat
- Max isometric force decrease; LE strength decreases up to 40% between 30-80 years old
Power Age related changes
- Rate of tension development is slower (Loss of Type 2 muscle fibers which are fast twitch)
____ is more highly correlated with physical function than muscle strength
Muscle Power
Endurance Age Related Changes
- Endurance is better preserved than strength BUT muscles fatigue more rapidly
Flexibility related age changes
- Spinal flexibility declines with age; 50% less flexibility into extension due to disc height shrinking and increased facet joint contact
- Ankle joint flexibility declines 35-50% (Rely on hip strategy sooner)
- Pain and arthritis leads to less ROM
Sensory Age Related Changes
Somatosensory
* Decrease in vibration sensitivity
* Decrease in tactile sensitivity
* Delayed muscle onset to perturbation
Vestibular
* 40% loss of vestibular cells by 70 years of age; response magnitudes are smaller
Vision
* Less light transmitted to retina; effects optic flow (less ability to orient in space
* Loss of visual field and contrast sensitivity (dim light need to go to bathroom)
* Become more visually dependent for balance; due to decrease in speed of processing (sensory integration)
Neural Age Related Changes
- Reduced # of neurons, not consistent across structures
- General decrese in speed of central processing
Motor Behavior Age Related Changes
- Coordination is altered
- Quiet stance (increased spontaneous sway; often measured with amplitude and velocity)
- Perturbation response (balance recovery; more co-contraction and slower contraction of muscles; use hip strategy sooner)
- Sensory adaptability (decreased speed of processing results in reduced sensory integration/weighting)
- Anticipatory responses (inability to properly prepare for movement; younger emg activation of legs then arm; older emg activation of legs and arms - less stability)
Why would it be more beneficial to sway more in quiet stance?
Unknown but as we age it occurs. May be due to the need to draw in concious attention or increase proprioceptive input.
The more unstable the individual th emore likely they have…
more co contraction of muscles and slower response time for contraction
Cognition and Postural Control with Age
- More cognitively demanding with older adults
- Fear of falling exacerbates cognitive demands; this can impact performance as it now creates a dual task (Hick’s Law)
Examples of Risk Factors for Falls
Extrinsic environmental factors
* Stairs
* throw rugs
* slippery surfaces
* poor lighting
Intrinsic Factors
* Muscle weakness/slowness
* history of falls
* gait deficits
* balance deficits
* assistive device
* visual deficits
* arthritis
* impaired ADLs
* depression
* cognitive impairment
* gender (women > men)
* age (> 80 years)
* Number of meds
What intrinsic risk factors for falls can PT interventions help with?
- Muscle weakness/slowness
- gait deficits
- balance deficits
- impaired ADLs
Risk of Fall in the next 12 months
0-1 Risk Factor = ?%
4 or more risk factors = ?%
- 8%
- 78%
Common gait changes with age
- Decreased stride length
- Greater step width and toeing out
- Shoulders more extended/elbows flexed (due to anatomical changes with disc height)
- Increased EMG activity (faster fatigue)
- Decreased plantar flexion power at push off
- Reduced dynamic balance during gait
- Increased “hip” strategy during walking
____ m/s is needed to cross the road
1.4
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Concepts of Motor Control18
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Information processing in motor control21
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Theories of motor control23
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Intro to Motor Learning22
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Practice and Feedback15
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Neural Plasticity43
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Movement system diagnoses17
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Postural Control41
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Development of postural control38
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Control of normal mobility36
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Aging32
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Development of mobility in infants and children28
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Reach to Grasp28
