4434 Final Flashcards
3 Areas of Sensory System
- Peripheral – important for proprioception. Things like heat and cold receptors, stretch receptors, Golgi tendon organs, etc.
- Vestibular – important in balance control!
- Vision – visual acuity with advanced age
What happens to sensory receptors with age?
Decreased number and function - endocrine, cardiovascular and neuromuscular
What happens with decreased number and function of sensory receptors?
Decrease in
- Blood flow
- Astrocytes
- Immune system function
Increase in
- Inflammation
- ROS
also see DNA Damage
Why might sensory receptors lose function?
This might occur because of poor immune system, elevated inflammation, hormonal influence, accumulation of ROS
DNA damage might be because of ROS exposure and programmed cell damage to DNA
What happens to our reflexes?
- Also see decreased conduction velocity. Muscle spindle (receptor in muscle) is connected to sensory neuron – carries info to spinal cord. Also have decrease in conduction velocity because of damage with age so speed of conducted APs is lower with advanced age.
- Overall see decrease in sensitivity and processing speed
- When a stimulus have a decreased sensitivity to respond to a stimulus. Takes longer to detect stimulus and takes longer for stimulus to get to the brain and/or the spinal cord. Change is in milliseconds but this is still impactful.
- Diff ways to process sensory info. Always goes to brain and some of it goes to spinal cord as well (would be in a reflex situation)
Slower reflexes - why?
Slower conduction velocities and stimulus receptors so have slower reflexes so see increased risk of injury. Reflexes go to spinal cord. If it takes longer for receptors to detect that something is hot and longer for info to get to spinal cord and back to muscles by the time you pull hand away might already be burned. Don’t always see more injuries but have a larger risk.
Decreased proprioception - why?
Less awareness of where we and our limbs are in space. Easy for a young adult to pick up a cup without having to look at it again as we are relying on proprioception. This is a harder task for an older adult. If going to reach for the cup they watch the hand reach for that cup. Takes longer for receptors to know where is my joint in space.
Slower to adapt to new stimuli - why?
Think about balance and fall risk. Switching what surface you are walking on younger adults quickly realize this and adapt gait to new surface very quickly. For older adults takes longer to detect that difference and process it so takes longer for that adaptation to occur. Likely in the home they switch from hard floor to carpet and this is a very different response of the sensory system. switching what you are walking on is when a lot of falls in the home happen at older age. Related to slower adaption of sensory system to that new input.
Pressor response - what happens with older adults?
sensory neurons to CV control centers to influence activity so we get enough blood flow to muscle
* These receptors are less sensitive in older adults – fewer and less sensitive, slower reaction time and this response takes longer
* These chemo and mechano receptors not only feed into CV control centers in the brain but also feed back directly onto motor neurons in the spinal cord. Their feedback at the spinal cord is inhibitory. Meaning it makes it harder for those MN to be active.
* Inhibitory feedback limits output of motor units
* If you add an inhibition, firing rates would decrease! Harder to activate them. Recruitment (the other piece of force) would also go down. Makes it harder to recruit those MU (not impossible) and decreases firing rate a little bit.
* All have this feedback in our working muscles.
Based on changes in sensitivity of sensory receptors, and muscle metabolism with advanced age, how would the chemoreceptor and mechanoreceptor feedback impact muscle fatigue in an isometric contraction with advanced age?
- Have slower feedback to MN and inhibitory feedback to those MN as well.
- In an isometric contraction older adults fatigue less or have more fatigue resistance!
- If we have less sensitivity of these receptors that means we have less and slower inhibitory feedback to the motoneurons. And b/c it’s inhibitory feedback that means we have less inhibition of those MN. So in the older adult system it’s easier to activate those MN/MU.
- With less inhibition can better maintain firing rates and ability to recruit more MU. This is thought to be a contributing factor to reduced fatiguability of older muscles during isometric contractions.
- Different with faster contractions b/c of velocity component.
- Older adults are starting at a lower MU firing rate but won’t have as much of a lowering with fatigue. Not losing more firing rate with fatigue (losing some not all).
- Older adults don’t lose that protection completely, just doesn’t function as well. Take longer to reach same level of fatigue as younger adults b/c of this less inhibition.
- Threshold to feel an injury (mechanoreceptors) in older adults is higher but once it is exceeded, they will still feel it.
- Onset of pressor response is delayed in older adults! But once it is on still have that feedback so in continued exercise still see increase in blood flow.
- Pain becomes harder to distinguish as it’s not just about level of damage but also perception in the brain.
What does the vestibular system tell us?
Where our head is in space. Knowing this helps with balance control. Vestibular organs just behind our ears.
What do semicircular canals do?
Help us detect head rotation. At base of ear canal.
What is in the semicircular canals?
Filled with endolymph fluid
Hair cells in cupula
- Detect motion of the head. Blue circle is canal. In the one area we have hair cells that stick up into the semicircular canals. Endolymph fluid flows through this canal (it’s viscous). It’s the movement of that fluid that causes movement of the hair cells that allows us to detect motion of the head.
Makeup of hair cells
Many stereo cilia and ONE kinocilium
- Called hair cells b/c they have a cell body and have hair like structures protruding. Also have an axon that is a sensory neuron (carries info to the brain). Each hair cell has one kinocilium (biggest one) and several stereocilia (smaller ones). Cell body sits pretty rigidly (anchored by axon it’s connected to), but hair cells stick up in that canal floating in that endolymph fluid. When fluid causes hair cells to move causes neural activity (AP’s) in the cell body that are carried along the axon to be interpreted by the brain. Neural activity is translated into direction of head movement.
How do hair cells detect movement?
- The way that these hair cells detect the direction of movement of the head is through direction of movement of the fluid which deflects these hairs in a particular direction.
- Axon is the sensory neuron that goes to the brain that translates info about direction of movement.
- If the stereocilia are pushed towards the kinocilium that results in depolarization of that hair cell
- If we stop that movement the hairs on the hair cell go back to their resting spot. The fluid isn’t moving so hairs stop moving as well. Go back to resting membrane potential. And b/c of no longer having excessive depol now decrease rate of APs in sensory neuron (back to resting rate)
- If it moves in opp direction the stereocilia pushed away from kinocilium = hyperpolarization
- When we see hyperpolarization it’s now harder to elicit an action potential. We see a decrease in the AP firing rate. Also tells the brain there is movement. Both an increase and decrease in firing rate of that sensory neuron tells the brain there is movement of the head.
Where is the kinocilium?
When we are talking about horizontal movements of the head have a canal on the right and left. The kinocilium on both sides is towards the anterior (front) side of the body on both sides.
How does endolymph fluid move compared to head?
CCW (counter clockwise) head rotation causes CW endolymph fluid movement. If you turn your head to the left (CCW) the fluid will move to the right or clockwise direction. Goes in that direction in both semicircular canals. In the left canal if head is turning CCW the fluid will move CW.
Brain and head rotation
Balance between left and right leads to sensation of head rotation.
* Dizziness that comes with age – inconsistencies on right and left.
* Endolymph fluid is still moving even though your head isn’t spinning (see this when you get off the merry go round)
Vertigo
Vertigo – Abnormal movement of endolymph fluid so get detection head is moving even though it isn’t. endolymph fluid has a specific consistency so shouldn’t move if you aren’t but if you age or get an infection that can change so it moves different and get the sense you are moving when you aren’t
Does how fast you move your head affect APs at all?
Takes a little bit for the fluid to move enough to cause that depol. Can be delayed in interpretation in where your head is but if you continue to move your head in the same direction at a faster rate will increase firing rate if in depol or hyperpol.
Changes in hair cells with advanced age
- Decrease total number of hair cells
- Decrease SENSITIVITY of hair cells that remain
- Potential changes in endolymph fluid. Changes in viscosity and gravity of it can change with age so fluid is more prone to movement without head movement,
DECREASE BALANCE BETWEEN LEFT AND RIGHT - contributed to dizziness
Things discussed like inflammation, ROS, immune system are reasons why we lose these cells and decrease sensitivity
What happens when hair cell change is uneven?
- These changes aren’t necessarily equal on both sides. Can have greater changes in sensitivity in hair cells on one side. Or greater loss overall on one side than the other. When that happens can contribute to feelings of dizziness. Brain needs info from both sides of vestibular system to properly interpret location of head in space. A decrease in the balance of info between the left and right canal.
- When you don’t have a good balance of info from left and right is harder for brain to correctly interpret where head is in space so have feeling you’re moving when you’re not. Typically, isn’t ongoing
What happens when hair cell change is uneven?
- These changes aren’t necessarily equal on both sides. Can have greater changes in sensitivity in hair cells on one side. Or greater loss overall on one side than the other. When that happens can contribute to feelings of dizziness. Brain needs info from both sides of vestibular system to properly interpret location of head in space. A decrease in the balance of info between the left and right canal.
- When you don’t have a good balance of info from left and right is harder for brain to correctly interpret where head is in space so have feeling you’re moving when you’re not. Typically, isn’t ongoing
What happens with endolymph fluid with age?
Fluid can become more viscous which means when it moves causes greater deflection of hair on the hair cells so even a small movement of that fluid when your head isn’t moving will be detected as a change in position when you’re not moving but can also contribute to slower response b/c it does move more slowly.
* If the hair cells are less sensitive it takes longer to detect a movement. The decrease in sensitivity is different across the 2 sides which contributes to the dizziness (i.e., might not get same hyperpol on the 2 sides).
* All movements of the head are impacted with age.
Visual pathway changes with age
Decreased
- Strength of smooth muscle of eye
- Pupil size and reactivity
- Elasticity of lenses (cataracts)
- VISUAL ACUITY
- Important to control of balance is visual acuity
- In darkness pupils get larger and in bright they get smaller. Harder to adjust pupil to light due to reduction in strength of smooth muscle
- Lens isn’t moving as much so see fluid build up behind the lens (cloudy) so pupils and lens are less adaptive
- Visual acuity – your vision. Average adult vision is 20/20 so what the average adult can read from 20 feet away you can too but this is reduced as we age.
- We rely on vision (if it’s available) more than any other sense, especially during balance control. We rely on vision so much that it can be to a fault sometimes. We will ignore vestibular or proprioception info and believe our vision over other systems. When function of visual system is reduced can have major repercussions on balance control
What contributes to balance?
- Do use all of these sensory systems to control balance. Neuromuscular system is involved as well.
o These systems being the 3 talked about in this lecture – peripheral receptors (proprioception), vestibular and vision - These sensory systems bring info from our environment and affect our neuromuscular system. If our head isn’t where we expect it to be in space we will adjust our muscle contractions to bring it back to where we want it to be in space. Diff outcomes for balance.
Falls and their causes (5)
Leading fatal injury in older adults
- Females are more likely to fall than males but interestingly males are more likely to have a catastrophic fall (more likely to die as a result of the injuries from a fall).
o Muscle weakness/function
o Chronic conditions
o Medications
o Cognitive distraction
o Impaired sensation
May be because of decreased reaction time (when you change what you’re walking on), decreased proprioception (changing surfaces), decreased sensitivity of sensory receptors (in all the systems just discussed), vestibular function (not knowing where you are in space), decreases in vision.
Balance definition
Maintain center of mass within the base of support
Ground reaction force
Force exerted on the body by the ground
Your foot puts pressure on ground, ground is also putting force onto your body and this is the ground reaction force.
Each arrow represents a force. Any point on that foot, any place it’s in contact with the ground will see that ground reaction force pushing back up
Center of pressure
Point where resultant (sum) of all ground reaction forces acts
- Center of pressure doesn’t have to be on one foot
- Can get one between your feet. Each foot has a COP of its own but balance with both feet on the ground usually talking about COP of the body which would fall between the feet assuming the weight is equally distributed between the 2 feet.
- COP is not static. It moves around as you shift your weight.
- Even if feet aren’t moving but weight is being shifted it moves.
Center of Mass/Gravity
The point on an object around which the mass is equally distributed
- If symmetrical object can find a balance point where you can actually balance the object at the center of mass
- Center of mass on our body is around the belly button
- Position of center of mass will change as you change your position
- Hands above head so more mass higher so COM is higher. Lean forward – shifts forward.
- COM of your body can fall outside of your body b/c it’s all of the body parts that are taken into account.
- In quiet stance can chance COP which will change COM. COM is following it. Because they are so tightly linked sometimes see them used almost interchangeably in literature. Are tightly linked but not identical.
Base of Support
Region bounded by contact with the support surface
Stability
Lowest when COM is at edges of BOS
What happens if the COM goes outside the BOS?
- Adjust BOS
- Fall
- If standing quietly the base of support is around our feet and COM would be somewhere in the middle of that. COP would also be within that area (in that base of support) if we are completely still.
- Want to keep COM within that base of support. COP will also move. COP is a pretty good proxy for the COM. And often ppl use it b/c it’s easier to measure than the location of the center of mass – all you need is a pressure mat or force plate. Need motion capture system to know where COM is.
- In the center we are really stable. Hard to knock someone off balance if their COM is far away from the edges of the base of support. If out near the edge than it’s easy to knock them off balance.
- COM is going outside so can move foot to recapture COM in base of support. If you don’t do that or don’t do it quickly enough you fall
What happens with older adults when COM goes outside BOS?
- With older adults their COM is going outside BOS and decrease in sensitivity in sensory systems (have a harder time detecting it) and then b/c of muscle weakness/reductions in muscle strength have a harder time bringing COM back into base of support fast enough. Get closer to edge of BOS before the change is detected.
Difference between COP and COM
- One key diff between COP and COM – mathematically the COP can’t go outside the base of support. It’s ground reaction forces so those have to be within the contact area. COM can go outside BOS.
- When talking about falls it really has to be COM going outside base of support.
- Movement and sway can be either COP or COM.
Why is larger BOS good?
Larger BOS is good b/c you have more space until you hit the edge of BOS. Typically the smaller your BOS, the closer you get to the edges. Have further for COM to travel before it hits BOS.
Quiet Stance
Even when standing still there is some sway in A-P and M-L directions
- Even young healthy people when just standing still will see some sway/movement.
- Sway is movement of COM in anterior/posterior and medial/lateral directions.
- We can’t stand perfectly still will always see a little bit of sway/movement in our COP and COM.
What 5 factors contribute to sway?
- Physiological factors (e.g., heart beat, breathing)
- Psychological factors (e.g., attention)
- Posture
- Muscle tone
- Sensory feedback - visual, vestibular, proprioceptive
All of these are impacted with advanced age.
reduced sensory feedback (visual, vestibular and/or proprioception) lead to increased sway.
How can we improve (reduce sway) in older adults?
o Continuously training them -
o Increase base of support (walker or cane) – b/c BOS is all points of contact with the ground
Proprioceptive feedback with touch experiment for sway
- Can enhance sensory feedback in older adults – easiest to enhance is proprioceptive
- This was done in healthy young adults – standing on a force plate looking at COP as a proxy and looking at how much is displaced (move) within that BOS
- Solid is eyes closed – have more sway when eyes are closed
- Give the slightest bit of proprioceptive feedback – barely touching a force sensor – not leaning on it but are touching it. That gives one additional point of contact for proprio (where is my body in space relative to the ground) and when they do that there is a reduction in sway. But you can see pink bars are lower than green so it improves both.
- Then let them have free contact with it. If it was a pressure related thing would expect harder they pushed on it the better they’d get and that didn’t happen so proves it’s just the proprioceptive feedback improving things here
- A cane for an older adult adds to base of support as BOS is also around cane now, not just feet. Also allows more proprioceptive feedback through the hand about where the body is in space. Have more space that COM can travel before it reaches its limits and b/c of proprio feedback have reduce amount of sway
Vibratory Insoles
These insoles have small devices in them that provide very low level vibrations to bottom of feet. Have a remote control in their pocket to turn it on or intensity up. Don’t have to be perceptible (don’t have to feel them) but by providing vibration under soles of feet are activating sensory receptors in soles of feet or at least getting them closer to threshold of activation and this is a way to enhance sensory feedback through soles of the feet.
Displacement of that COP becomes smaller with that vibration. Movement of COP and therefore COM is not getting as close to the boundaries of the baes of support. Improving balance by adding vibration to insoles in shoes of older individuals. Also used in those with peripheral neuropathies.
List one way you could theoretically improve balance control in older adults through manipulating the vestibular or visual system.
- In healthy older adult have increased sway – want to move from sway on right to sway on left
- Vestibular system – loss of hair cells and decreased sensitivity of hair cells – if you could somehow regrow them or train them to be more sensitive this could help improve balance. The endolymph fluid (consistency changes with age) and imbalance between two semicircular canals so if we could balance out fluid consistency on both sides this would help.
- As a preventative measure before you get to that decline take measures to avoid the loss of hair cells. Protecting auditory canals with ear plugs.
- Targeting things like inflammation and ROS that contribute to that loss of hair cells. Can be preventative or at least preventative of further decline. Won’t improve balance once balance has decreased but it could prevent further decline of that balance if you prevent further hair cell loss.
- Visual system –
o Train the visual system – train the muscles (smooth muscles around the eye that control pupil dilation to allow in proper amount of light are weakened) so train eyes to strengthen these muscles so you have better visual acuity.
o Laser eye surgery – anything that will improve visual acuity! Or cataracts surgery.
o Removing the fog will mean better sensory input so better vision.
o Getting glasses/contact lenses – if it’s the right prescription.
o Better lighting – changing of pupil size to allow in correct amount of light is a problem with older adults so they are much more compromised in dim lit situations.
Changes in the brain with age
- Decrease blood flow (worse if we don’t use those neurons)
- Changes in hormones (decrease in hormones that can help maintain health of those neurons)
- Increase inflammation
- Increase ROS
- Genetics/DNA – biological clock theory
- Decrease in number and function of neurons on both sides of the synapse.
In addition to that, those neurons that remain some but not all will have a reduction in function. This reduction in function comes in part b/c of changes in synaptic transmission (changes in communication) - reduction in amount of NT available to be released and we can have reduction in number of receptors on the receiving (post synaptic) neuron. Need these receptors b/c without them the NT is useless. Don’t completely lose receptors but lose some and makes that transmission a little less efficient. Loss of receptors makes that neuron less sensitive.
- Loss of receptors make that post synaptic neuron less receptive to NT so takes longer for it to respond to the pre synaptic neuron. Have a reduction in amount of NT b/c you’re losing neurons but within the vesicles that contain NT also see a reduction in the amount.
- Poor overall health would see increased inflammation/ROS (not getting rid of them), reduction in blood flow not washing out harmful things
- Glial cells are housekeeping cells like astrocyte cells and are also subjected to death and damage
Why do we lost NT?
o Neural cells don’t divide throughout life so susceptible to bio clock that tells them when to die off.
o Can have neurodegenerative diseases but even in absence of disease we still lose brain cells
o Inflammation - ROS
Hippocampus
Memory
Frontal Cortex
Executive function - decision making, attention, etc.
Hippocampus and frontal cortex
- These are 2 areas that overall, on average tend to decline a little faster than other brain regions in terms of volume.
- Decrease in brain volume can contribute to decrease in sensory function – happens at the receptors but do lose some of the regions of the brain where that sensory processing happens
- Have multiple pathways in our brain. Might have a preferred pathway but there are alternatives/other pathways. When neurons die can’t access that same pathway. No longer the most efficient way to retrieve that memory for example.
- Do have redundancies in our pathways. No GPS for our brain. So it takes some time to figure out the new path. Learning to take a new path can take some training. This is important in healthy aging and cognitive functions.
- Don’t completely lose cog functions but they might be slowed down.
What happens to cognitive function as we age?
- Decline in cognitive function
- E.g., verbal memory, reasoning, perceptual speed. Happens at varying speeds
- Some functions preserved (e.g., verbal ability)
Things like verbal and numeric ability are increasing but most will start to decline into advanced age. Numeric has a slower rate and reasoning and spatial orientation have a more rapid decline
Healthy Aging
Minor, noticeable, (sometimes) measurable decline in cognitive abilities
Mild Cognitive Impairment (MCI)
Slight, noticeable, measurable decline in cognitive abilities. At increased risk of developing dementia.
Usually it’s memory that they notice (cognitive function they notice the most).
More than minor, but cog function declines are slight. This is often when they start being noticeable to others who are close to you. Measurable on clinical tools. At higher risk for developing dementia.
Dementia
Collective term for decline in mental abilities that interfere with daily life.
– When ppl have dementia it is measurable and noticeable. Cog declines interfere with daily life/function. Not just not knowing where car is rather where am I and how do I get back
- Dementia might not have the self-awareness to be worried. Once it is dementia often ppl aren’t aware of decrements they are experiencing. Someone else realizes decrements for them.
Alzheimer’s Disease
Specific disease that accounts for 60-80% of dementia cases
Amyloid Beta Plaque
Protein aggregates interfere with neuron function
Amyloid Beta - growth and repair of neurons
- Formation of amyloid beta plaques – amyloid beta is a protein we all have in the brain and typical function is to help in growth and repair of neurons. In some forms of dementia these ABP start to aggregate. They form these balls of protein or plaques so no longer functioning in the way they normally would function to grow and repair neurons.
- When in these aggregates start to interfere with function of otherwise healthy neurons and leads to death of those neurons and before they die those plaques lead to disruption of healthy functioning. Taking away certain brain pathways.
Tau tangles
Degrade structure of neuron’s
Tau protein - maintain structure of microtubules
- Tau is also a type of protein in the brain that is necessary for helping to maintain structure of microtubules. Help form tubules that help maintain structure of that axon. In this case, the proteins become tangled and proteins miss form. So instead of these blue lines that help form structure of microtubules they get tangled up. Can no longer provide the structure, so microtubules lose their structure and then neurons lose their function. If the axon loses its structure can’t propagate AP’s properly. Die b/c they become so dysfunctional.
Functions of sleep (4)
- Energy conservation
- Clearing “waste”
- ↑ immune system activity
- Memory consolidation
Sleep and aging (4)
- Becoming tired earlier
- Wake up earlier
- More sleep disturbances
- Less deep sleep
- Waste products – things like metabolic byproducts of neurons in the brain. Waste in the brain. Gives house keeping cells and blood flow time to clear things out. Clear out ROS
- More immune system activity for chronic inflammation – more ROS – she didn’t get into this really
- Better able to consolidate recent memories that happened throughout the day
- Shift in bio clock of sleep/wake cycles
- With these reductions in sleep time/quality have less of these functions of sleep available to older adults. Affects many functions including cognitive function.
Which theory of aging would best explain the physiological reason for changes in sleep patterns with advanced age?
Endocrine theory best explains these. Responsible for maintaining cyclical patterns in our body and homeostasis. Those changes in hormonal fluctuations that happen with advanced age are a major contributor to reductions in sleep time and quality.
How to limit cognitive decline?
- Improve sleep – get more
- More sleep will result in better cog function. Recommended for older adults to take naps
- Can do some training – eat well (change diet)
- Exercise
- Can improve or limit decline in cog function. Can slow this rate of decline! Can improve cog functions – if you train for that cog function can improve it.
Increased sleep and preventing cognitive decline in older adults
Can help with memory consolidation, can directly impact memory (recent memory). Improves immune system function so less inflammation and clearing of waste products which removes ROS. This improves cog function by slowing the decline in function or loss of neurons b/c we know ROS and inflammation contribute to cell death.
Improved nutrition and preventing cognitive decline in older adults
Increase foods high in antioxidants can reduce ROS and we know that there is a connection between ROS and inflammation so by decreasing ROS decreases inflammation and a reduction in these 2 reduces the disruption or loss of function of those neurons so keeping that road intact. Slows that decline!
Playing cognitively challenging games and preventing cognitive decline in older adults
o Use it or lose it - if never activating a neural pathway your glial cells will stop maintaining that pathway. Using these pathways consistency helps maintain blood flow to those neurons and maintain the health of that pathway. If you lost a pathway – practicing new games will help you find more efficient new pathways.
o If you train on a cog tasks can improve function on that cog tasks. Doesn’t really translate to other cog tasks, only the one you are practicing.
Exercise and preventing cognitive decline in older adults
Long-term when you exercise you see improved immune system function, reduced ROS (better able to clear them out), improve blood flow (to the brain), decreased inflammation all of this helps maintain health of neurons in the brain and slows down loss of those neurons or loss in function of those neurons.
Cognitive benefits of Physical Activity
- Any cardiovascular training is beneficial even walking
- Higher levels = greater cognitive benefits
- Resistance training can be beneficial
- Not all cognitive functions improve
- Higher levels – more of it or more intensity does seem to be better
Cognitive benefits of Physical Activity Study (graph)
- Graph – looking across lots of studies and improvements in cog function with exercise. If ppl accumulated at least 52 hours of PA within the intervention there was an improvement in cognitive function. PA can have a benefit on cog abilities. Most work in this area looks at cardiovascular aerobic exercise. Much less work looking at resistance training in older adults for cog benefits.
- The figure with all the cog functions where most decline – some will improve but not all. Seems to be diff for diff ppl or interventions. Some will generally improve as long as there is at least 52 hours of accumulated activity and it does depend on when the people are starting.
- Will hit 52 hours at different points depending on the study design.
- CV training – any type – can be beneficial to cog function. Resistance training prob as well but we have less work in this and not all cog functions improve
Physical Activity with Cognitive Component
- When you combine PA with a cog component this is when you have biggest benefits on cog function.
- Things like dance classes. Aerobic PA but there is a huge cog component (stay in time, remember steps, etc.).
- Even if you have a group of older adults who can’t stand and dance (not comfortable or safe) can do seated dance so they still have to remember what comes next and keeping time.
- Another example is boxing – combo of cog training (skills) have to keep time, produce a series of movements and remember them and getting aerobic and strengthening activity as well.
- Best outcomes come with combo of aerobic and cognitive component!
Physical Activity
Movement carried out by the muscles that requires energy
Exercise
Sub-category of physical activity
- Planned, structured, movement intended to improve or maintain physical fitness
PA guidelines for older adults
PA
- Moderate to vigorous aerobic physical activities such that there is an accumulation of at least 150 minutes per week
- Muscle strengthening using major muscle groups at least twice a week
- Physical activities that challenge balance
- Several hours of light PA, including standing
Sleep
- Getting 7 to 8 hours of good-quality sleep on a regular basis, with consistent bed and wake-up times
Sedentary behaviour
- Limiting sedentary behaviour to 8 hours or less which includes
- No more than 3 hours of recreational screen time
- Breaking up long periods of sitting as often as possible
Does meeting the guidelines impact longevity?
If older adults actually meet PA guidelines they do live longer - lots of data supporting this!
- Years of life gained (how many additional years are these ppl living) if they are at diff percent of meeting the activity (aerobic) guidelines.
- Even if only hitting 50% of guidelines there is still a large benefit to life expectancy!
- About 3 years if you meet them!
- Still some improvement if exceeding guidelines but the return on investment gets smaller and smaller. Increase from meeting to doubling is much less than from not meeting to meeting.
- This is based on just the aerobic 150 minutes!
- Biggest improvements you get are when you go from doing nothing to doing something!
What is the impact of activity duration and intensity on mortality?
- To be meeting PA guidelines it’s generally recommended 30 min a day for 5 days.
- Looking at % reduction in mortality - how much is your chance of dying reduced.
- Increasing duration of daily PA will give you some improvement in mortality but it’s not a linear relationship. As you get to higher durations get smaller returns on your investment. Really plateaus after about 60min a day.
- Vigorous intensity PA has a greater effect on all cause mortality! Greater intensity the greater the benefit on mortality.
- Prob won’t start at 30 minutes of vigorous but anything at mod is beneficial as well
- If we go from doing nothing to meeting PA guidelines across the week see decrease in hazard ratio of mortality. Again going from doing nothing to something is where you see the most improvement. Beyond that you see less and less added benefit to mortality
Barriers to exercise for older adults (9)
- Poor health (most frequent)
- View exercise as recreation rather than “medicine”
- Vague instructions from health care providers
- Believe exercise does more harm than good
- Environment
- Too much time
- Transportation
- Cost
- “Unladylike”
Motivators for exercise in older adults (5)
- Self-efficacy
- Social support
- Education about physical activity benefits
- Prompts (e.g., phone check-ins)
- Music
- 1- if they feel motivated and confident they can do it are more likely to stick with it – best motivator
- 4- goes along with social support
- 5- many older adults who participate in things like dance do it b/c they enjoy the music
3 Studies that show benefits of just walking
- Longitudinal follow-up of 39,000 older women
- Light-to-moderate physical activity associated with reduction in risk of heart disease
- At least 60 minutes walking per week predicted lower risk of heart disease
- Did risk of heart disease 1, 3, and 5 years out. Would be greater reduction if they did more and met those guidelines, but beneficial even if they aren’t meeting them.
- 1002 women aged >65 years, functional limitations, but mobile
- 1-year follow-up
- Walking > 8 city blocks per week, twice as likely to still be mobile than those walking less
- At risk of being in a wheelchair.
- Greater or equal to 8 blocks
- A city block is usually 100-200m. So less than 2km a week and still were twice as likely to still be walking a year later.
- Small increments can have impact on functional health and heart disease
- Having a dog is one of the best ways to motivate older adults to walk.
- Dog owners have higher stats in all the categories (number of steps, time walking and time walking at a moderate cadence).
- 23 minutes a day is huge when on the last slide we talked about 60 minutes a week being beneficial!
