4. Cardiopulmonary Adaptations to training in older adults Flashcards
- aerobic capacity is the single best measure of what? (also known as what?)
- what does aerobic capacity represent?
- determined by what?
- can be measured in (2) terms)
- usually measured how (3)
- measure of cardiovascular function (also known as work capacity)
- represents ability of cardiopulmonary system to deliver oxygen and E substrates (to tissues) to perform work during maximal physical stress
- determined by measuring submaximal OR maximal oxygen uptake (VO2)
- can be measured in absolute terms (L/min) or relative terms (mL/kg bw/min)
- usually measured while subjects walk or jog on a treadmill or ride a cycle ergometer (dif protocols exist!)
why is aerobic capacity so important for aging?
- explain
- result?
- Cardiorespiratory fitness is one of the strongest predictors of independent living and mortality risk!!
- due to the age-related decline in aerobic capacity, many activities of daily living represent a higher relative intensity
IE: With a VO2max of 20 mL/kg* min, activities costing 12-15 mL/kg*min (e.g., housework, gardening), represent 75% of VO2max
RESULT:Various daily activities are difficult or impossible to perform, and individuals can become progressively less active and eventually, fitness declines and dependence increases –> vicious cycle!
cross-sectional and longitudinal studies show similar rates of increase/decline in VO2max –> ranging btw __-___% per _______ after the age of _____
- age-related increase/decline in cardiorespiratory fitness is expected to be most evident by age ___-_____
- more pronounced increase/decline in VO2max in what populations? suggesting what?
describe graph! vo2max vs age for trained vs sedentary
- decline in VO2max –> 10-15% per decade after age 40
- decline –> 70-80
- decline in sedentary individuals, suggesting the importance of optimal exercise participation during aging
- linear decrease in VO2max whether trained or sedentary
- sedentary line is lower though –> will reach threshold for dependence earlier (ie 85 yo) than trained (105)
what is the fick equation? define its components
VO2 = Q x A-VO2 diff
Q (cardiac output) = SV x HR
- determines central O2 delivery variable
A-VO2 diff (arterial-venous O2 difference)
- O2 consumption variable
- what happens to resting HR as men and women age? supine position vs sitting position
- what about max heart rate? normal vs masters athlete? WHY? (2)
resting HR in supine position is unaffected
- some age-related effects are observed in seated position –> increase resting HR, since venous return is involved
- max HR is reduced with aging (decrease 5-10 bpm/decade)
- some longitudinal studies have noted a smaller reduction in max HR with aging in Master’s athletes
WHY reduced HR?
1. decrease number and excitability of sinoarterial node cells (initiate depolarization)
2. decrease responsiveness to sympathetic stimulation
- what is often used as a measure of work intensity to determine training HR?
- why is it problematic? (4 ish)
solution?
- maximal heart rate!
1) Traditional equation (HRmax = 220 – age) underestimates HRmax in individuals over age 40
2) Tanaka equations represent more accurate equations (especially after 40)
3) Some medications affect heart rate (e.g., beta-blockers)
4) if underestimating –> individual might not be working hard enough!
SOLUTION: Rating of perceived exertion (RPE) or the Talk Test are alternative methods for determining exercise intensity
- what happens to RESTING stroke volume as we age? BUT what is something important to take into account? (2)
BUT big consequence?
- SV mostly unaffected by age BUT diastolic dysfunction (caused by enlarged atria) may be present especially at older age
- slower myocardium relaxation time (bc of changes in ion/Ca2+ channels and SA node cells) leads to REDUCED EARLY DIASTOLIC FILLING RATE in left ventricle (50% decrease by age 80)
BUT late diastolic filling is greater due to an increased blood volume in enlarged atria = CATCH-UP/compensates for lower filling rate (maintains end diastolic volume at rest!)
SO structural changes in heart mitigate lower filling rate –> same preload when older and younger!
what happens to stroke volume during SUBMAXIMAL AND MAXIMAL EXERCISE?
trained vs untrained
older vs younger
WHY? (5)
- reduced in older trained and untrained men compared to younger adults
*as exercise intensity increases, SV decreases
1) Reduced preload (left ventricular filling) –> doesn’t keep up during exercise (vs at rest)
2) Increased afterload (bc peripheral changes = increase peripheral resistance)
3) Reduced left ventricular contractility –> SA node, Ca2+ release
4) increased left ventricular stiffness –> less able to stretch
5) Prolonged contraction time
what happens to cardiac output in older vs younger adults?
a) during supramaximal exercise? (2)
b) at maximal exercise intensity
a) CO for a given intensity will be similar or slightly lower in older vs younger adults
- can be maintained at the expense of an increased heart rate compensating for a reduced stroke volume
b) older adults (vs young endurance athletes) have age-related decrease in max CO due to lower max HR and lower stroke volume
*depends on fitness level
a-VO2 difference an aging
- what happens?
- what plays an important role after age 65%?
- why? (5 ish)
- lower a-VO2
- decline in ability of mitochondria to consume O2 plays an important role!
- aging vascular system is less able to redirect blood from inactive tissue to working muscle (lower vascular tone)
- lower O2 uptake by muscle mitochondria:
a) decrease mitochondria density, volume, respiration capacity (promotes ATP prod)
b) decrease oxidative enzyme activity
c) decrease capillary-to-fiber surface ratio (less gas exchange ratio)
early studies on _________ training in older adults demonstrated that cardiovascular fitness (ie WHAT?) improved by around ___% after ___-____ months of training
- more recent studies indicate that similar improvements in ________ occur after ___ weeks of _________ training
- CONCLUSION?
on endurance training –> ie VO2max –> improved by about 20% after 6-12 months
- improvements in VO2max occur after 12 wks of aerobic training
older adults are capable of improving their CV function in response to aerobic training!
Effects of aerobic training interventions
- following ____ months of aerobic training that progressed from low (____% HRR) to high (____% HRR) intensities of _________ exercise –> increase in VO2max of ___% was possible for both older women and men btw ___-____ yo
- THEREFORE, even though WHAT, WHAT?
- 12 months of aerobic training –> 40% (for 1st 6 months) to 75% HRR (for last 6 months) of continuous exercise –> increase in VO2max of 30% –> 60-70yo
THUS: even though low intensities of exercise can produce small but significant increases in VO2max –> higher training intensities can result in more pronounced increases in VO2max! –> intensity matters!
MA of controlled clinical trials evaluating effect of aerobic exercise on VO2max in adults aged 60 years +
- 80 studies used ________ as primary training modality
- improvements in VO2max were observed at what intensity, frequency and duration&
WALKING!
- >=60% VO2max
- >=3days/wk
- >= 16 wks
EFFECTS OF AEROBIC TRAINING ON HR AND SV:
> ___ months of mod-intensity aerobic training (>___% VO2max) is associated with LOWER/HIGHER HR at rest and submaximal workload
- what happens to max HR after training? and SV?
WHY? (3)
> 3 months at >=60% VO2max –> lower HR
- Max HR generally remains unchanged after training BUT an increase in SV can be observed (especially at higher intensities)
- increase sensitivity to circulating catecholamines (ie NE)
- decrease peripheral vascular resistance (important for determining MAP)
- increase peak rate of ventricular filling rate (increase end-diastolic volume)
EFFECTS OF AEROBIC TRAINING on a-VO2 difference
- after > ___ weeks of (what intensity) aerobic training, what happens to a-VO2 difference at rest and during submaximal and maximal exercise in older adults?
HOW?
> 12 weeks –> INCREASES!
HOW: increase mitochondrial density, volume and function –> enables working muscles to extract more O2 from blood
*especially important for older adults with the lowest levels of cardiorespiratory fitness (greater benefits for them!)
