Week 10: Exercise and Ageing Flashcards
Define ageing
– Sum of all changes and conditions that occur with the passage of time
– A complex interaction between physiological, genetic, molecular, behavioural and environmental factors which can act simultaneously
WHO def:
– Elderly: 60-74 years
– Old: 75-84 years
– Very old: 85+ years
Provide a startling statistic about elderly populations in relation to Aus’s healthcare system
In 2016, approx 3.7 million people (15% of Australia’s total projected population of 24.3 million) are older Australians (65 years or more) –> i.e people are living longer → large proportion of people not part of the workforce anymore; greater need for healthcare system puts burden on society
Describe the physiological changes that occur with ageing in the cardiovascular system
- Parameters affected include the Fick equation, heart rate (HR), cardiac output (CO), blood pressure (BP), and structural modifications
- The Fick equation links oxygen consumption (VO2) to cardiac output and arteriovenous oxygen difference, affected by age
1) Changes in electrical and receptor components regulating HR occur with aging, leading to decreased receptor numbers and diminished HR modulation.
2) Diminished HR modulation contributes to an overall decrease in cardiac output, affecting maximal oxygen consumption (VO2 max) during increased demand. - Structurally, the heart undergoes changes, including increased heart weight and elevated blood pressure.
3) Changes in cardiac function, such as left ventricle (LV) arterial stiffening, contribute to increased blood pressure, while overall contractility and response to catecholamines decrease.
4)These changes result in a reduction in maximal stroke volume, impacting the heart’s ability to pump blood effectively.
5) Variations in the thickness of the heart wall are observed, with an increase in thickness in the top left quadrant, associated with hypertrophic changes in aging hearts.
6)The lower left quadrant indicates significant variation, highlighting the heterogeneous nature of cardiovascular changes with aging.
7) Beyond the heart, aging affects peripheral blood flow, leading to a decrease in overall circulation.
8)Reduced maximal heart rate, alterations in electrical and receptor functions, and declining contractility collectively contribute to diminished cardiovascular performance with age.
Describe the physiological changes that occur with ageing in the respiratory system?
- Reduced Exercise Capacity: The decrease in vital capacity, FEV1.0, and VO2 max suggests a diminished ability to take in oxygen and transport it to working muscles during exercise. This can result in reduced exercise tolerance and capacity in the elderly.
- Impaired Respiratory Muscle Function: With decreasing lung and chest wall elasticity, the ability of respiratory muscles to contract efficiently is compromised. This can lead to increased fatigue during respiratory efforts and may contribute to difficulties in maintaining optimal ventilation.
- Decreased Maximal Heart Rate: The reduction in maximal heart rate can impact the cardiovascular response during exercise, limiting the heart’s ability to pump oxygenated blood efficiently. This contributes to a reduced overall capacity for physical exertion.
- Respiratory Efficiency Issues: Changes in lung volumes, such as increased residual volume, may lead to impaired respiratory efficiency. This can result in difficulty expelling air and may contribute to a sense of breathlessness and respiratory discomfort.
- Risk of Respiratory Conditions: The age-related changes in lung elasticity and function may increase susceptibility to respiratory conditions such as chronic obstructive pulmonary disease (COPD) and other respiratory disorders. These changes can exacerbate the impact of pre-existing conditions or make individuals more vulnerable to respiratory infections.
- Impact on Daily Activities: The decline in respiratory function may affect activities of daily living, such as climbing stairs or performing household chores, leading to a decrease in overall functional independence.
- Quality of Life Considerations: Cumulatively, these respiratory changes can influence an individual’s quality of life, affecting their ability to engage in physical activities, social interactions, and other aspects of daily life.
Describe the physiological changes that occur with ageing in bone
- Overview: Aging leads to deterioration in the composition, structure, and function of bones, predisposing individuals to osteoporosis.
- Bone Dynamics: Bone, a dynamic organ with mechanical and homeostatic functions, undergoes continuous self-regeneration through remodeling, involving the removal of old bone and replacement with new bone.
- Balance Disruption: Aging disrupts the balance between bone formation and resorption, tilting towards greater resorption than formation. This imbalance results in bone mass deficiency and reduced strength.
- Osteoclast Activity: Osteoclast cells, responsible for bone resorption, become more active with age, surpassing the rate of bone formation, leading to weakened bones.
Risk Factors:
* Non-Modifiable: Genetics, peak bone mass accrual in youth, alterations in cellular components, age over 50, comorbid medical conditions (e.g., hyperthyroidism).
* Modifiable: Poor nutrition (low calcium, insufficient protein, inadequate vitamin D), low BMI, lack of physical activity, drug use (excessive alcohol, smoking).
Effects of Bone Structure Changes:
* Osteoporosis: Major cause of hip fractures in the elderly, characterized by bone mass deficiency and insufficiency fractures.
* Spinal Compression Fracture: Common at the thoracolumbar junction, contributing to a curved and shortened spine, leading to pain, reduced mobility, and musculoskeletal problems.
* Reduced Bone Density of Vertebrae: Combined with intervertebral disc fluid loss, results in a curved and shortened spine, poor posture, and musculoskeletal issues.
- Key Outcome: The culmination of these changes is osteoporosis, insufficiency fractures, spinal compression fractures, and reduced bone density, contributing to significant health challenges in the aging population.
Describe the physiological changes that occur with ageing in skeletal muscle
- age related decrease in Type II fibre attributed to Type I neurons innervating old type II fibres –> increased percent type I fibres
- size of both Type I and II decrease
- loss of 10% per decade after age 50
Strength vs. Muscle Mass:
* Strength declines more rapidly than muscle mass with aging.
Muscle mass is a primary determinant of strength in the elderly.
Reversibility:
* These age-related changes in skeletal muscle are reversible to some extent.
Study Findings:
* Studies on nursing home residents, up to age 96, show:
* Increases in muscle size.
* Increases in muscle strength.
* Improved residual functional capacity.
Clinical Implications:
* Clinical conditions contribute to a “ceiling effect” on abilities.
* Decreased ability to perform rapid movements.
* Reduction in maximum heart rate.
Power Equation and Impact on ADLs
* P=FD
* Decreased strength leads to reduced force and speed, affecting the ability to perform Activities of Daily Living (ADLs).
Height Decrease:
* Aging contributes to a decrease in height.
* Compression in vertebral spaces and reduction in the size of vertebrae can occur.
increased Fat Mass:
* Aging is associated with an increase in fat mass.
Reflexes slow with age:
* decreased MU activation with age –> MU remodelling and death occurs
* less efficent MUs because of less precise control, less force, slowing of muscle –> loss of balance and speed of movement
Define Sarcopenia, Osteopenia, Osteoporosis
Sarcopenia = age related decrease in muscle mass and function
Osteopenia = low bone mineral density (BMD)
Osteoporosis = skeletal bone disease due to decreased bone mineral density and bone mass
What are the consequences of sarcopenia and osteopenia/osteoporosis
- consequences of sarcopenia
- Metabolic disturbance glucose disposal chronic disease such as T2D
- dysfunctional remodelling of MU -> NMJ instability –> collateral reinnvervation
- increases/stabilisation in adiposity due to ageing
- consequences of osteopenia/osteoprosis
- Loss of balance → tripping and without power, to stop yourself, will hit the ground → result in hip fracture
- loss of bone mass –> increased likelihood of fracture during falls
- reduction in gait velocity, reduced mobility and functional performance
- Impairment in getting in and out of bed and chair, climbing stairsdependency institutionalisation
- Increase risk of falls injury hospitalisation and institutionalisation
What is the disuse theory of ageing
- the theory that some decline in physiological and psychological abilities with aging may be due to the lack of use of those abilities
- three main factors: physiological aging, disuse atrophy, chronic disease
- exercise can decelerate downward spiral
- 30 years of ageing = 3 weeks of bederest in light of VO2max (Darren et al, 2001)
Define successful ageing
- defined as high physical, psychological and social functioning in old age without major diseases (Rowe & kahn, 1987;1997)
- three components of successful ageing: abscence of disease/disability, engagement with life, high cognitive and physical function
Describe the relationship between sarcopenia/muscle strength and the future risk of mortality
- sarcopenia associated with significant increase in mortality risk, independent of BMI
Describe how exercise can be used to counteract the changes to bedrest and immobilisation
- higher exercise intensities and frequences are associated with greater improvements, especially in strength and muscle endurance –> safe and effective even in VERY elderly populations
Describe the effects of immobilisation and bedrest, and consider how these changes are different/similar to ageing
- effects of im. and bedrest
- decrease strength loss greater than decrease in skletal muscle and fibre atrophy = decreased muscle specific force
- all muscle fibre types show some degree of atrophy
- loss of fibres and size of fibres, particular type I attributed to less CSA, rather than loss of MU or muscle fibres
- comparison to ageing
- Aging involves gradual changes over time, influenced by factors like hormonal shifts and reduced physical activity; Immobilization accelerates these processes due to the absence of mechanical loading on muscles and bones
- Joint stiffness and contractures are common in both scenarios. Aging-related joint changes are often a result of wear and tear over time, while immobilization-induced changes occur more rapidly due to lack of movement
- Aging involves complex hormonal changes, while immobilization contributes to metabolic alterations primarily through reduced muscle activity
Discuss some of the changes following aerobic and resistance exercise in older adults. Focus specifically on where adaptations are similar, different and where they can work together.
- aerobic training
- can increase aeorbic capacity
- reduce body fat
- limited effect on muscle mass, strength and power and on bone
- resistance training
- increase aerobic capacity
- augement the effect of AT on adiposity
- increase skeletal muscle mass, strength and power
- increase bone mass
Musclar Adaptation to Disuse
- less recruitment of MU –> decresaes in contractile stregnth of muscle
- Initial muscle fibre composition: Slow postural muscle, like soleus, atrophy at A greater rate than faster muscles
- Length of period of inactivitY: There is a rapid rate of atrophy in the firsT few weeks of inactivity, which then reduces
- Position during inactivity: Most atrophy occurs when the muscle is fixed in the shortened position –> Not fixed = less atrophy
- Muscle situation: Lower limb muscles atrophy faster than upper limb muscles
