Acute exercise response Flashcards
Provide an overview of macronutrients and their functions
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Macronutrients:
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Carbohydrates
- Monosaccharides (simple)
- Oligosaccharides (simple)
- Polysaccharides (complex)
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Proteins
- Composed of amino acids.
- Essential amino acids must be ingested as the body cannot synthesize them.
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Lipids
- Simple and compound lipids.
- Cholesterol.
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Carbohydrates
Functions of Macronutrients
- Carbohydrates are crucial for cellular metabolism and glycogen storage in liver and skeletal muscles. Converted to adipose cells as stored as triacylglycerol. 1g CHO = 4kcals energy
- Proteins are metabolised by deamination, with their remaining carbon skeletons useful for gluconeogenesis, fat synthesis and energy stores, though they’re not a primary energy source. 1g protein = 4kcal energy
- Lipids serve as an energy source and reserve, organ protection, thermal insulation, vitamin carrier, and hunger suppressor. 1g fatty acids = 9 kcal energy
Energy Values
- Carbohydrates and Proteins: 1g = 4kcal energy.
- Fatty Acids: 1g = 9kcal energy.
Describe physiological function and physical activity
- Physical activity level (intensity and duration) affects daily energy expenditure and the primary energy source utilized.
- over lifetime, if continually physically active, will achieve a greater level of fitness and a greater peak of physiological function
- dip will be lower than sedentary individuals
Briefly describe utilisation of molecular pathways
- Energy sources are used hierarchically:
- phosphagen system
- anaerobic glycolytic system
- aerobic system - lipid oxidation
- aerobic system - carbohydrate oxidation
Describe how energy expenditure is measured
- Indirect Calorimetry: Indicates metabolized fuels during activity. Useful in various settings to understand activity intensity.
- Can also measure Fitness Levels/VO2 Max consumption via VO2 max testing
- Clinically METs are often used
Describe VO2 in health and disease
- Higher oxygen consumption indicates greater cardiovascular fitness and efficient oxygen use in muscles and other tissues .
- Athletes in aerobic sports have extremely high VO2max levels.
- Regular physical activity can preserve VO2max levels despite max O2 consumption age decline, essential for extending lifespan and combating lifestyle diseases.
Describe neural integration of the response to exercise
- Increases myocardial contractility and suppresses parasympathetic activation.
- sends efferent motor signals to muscles required to perform activity
- Alterations in regional blood flow.
- Modulation of vascular dilation and constriction to maintain blood pressure.
- Feedback to the medulla from mechano- and chemo-receptors.
- Local metabolic factors help dilate resistance vessels, reducing peripheral resistance for greater blood flow.
Describe the pulmonary response to exercise
Phases of Pulmonary Response to Exercise:
- Neurogenic stimuli from the cerebral cortex and feedback from active limbs.
- Exponential rise to achieve a steady state relative to metabolic gas exchange demands.
- Fine-tuning steady-state ventilation through peripheral sensory feedback mechanisms.
Only part of this response (shown in green) is directly due to increasing arterial H+ concentrations (From anaerobic glycolysis) and short-term neuronal potentiation, the additional increase due to overall demands for gas exchange and other peripheral sensory feedback.
Pulmonary Responses to Exercise:
- At maximal exercise, minute ventilation can increase up to ~150 L/min.
- Pulmonary ventilation increases linearly with oxygen consumption during light to moderate intensity exercise.
- As exercise intensity increases, pulmonary ventilation increases disproportionately with oxygen consumption.
- Lung capacities do not necessarily improve with training, but oxygen exchange and uptake do, enhancing oxygen utilization per breath.
Describe the cardiovascular response to exercise
Cardiovascular Responses to Exercise:
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Heart rate regulation during physical activity is controlled through myocardial nerve supply.
- Parasympathetic withdrawal.
- Sympathetic activation.
- Heart rate increases in response to exercise intensity and stabilises during steady state exercise but can exhibit ‘cardiovascular drift’ during prolonged exercise (i.e. increased HR and decreased stroke vol due to shunting of blood to periphery and dehydration)
- Blood Pressure: Attenuation of abnormally high increases through mechanoreceptor feedback via baroreceptors.
- Systemic blood flow increases directly with exercise intensity. High increases in CO up to four times during maximal exercise –> blood flow is redistributed to active muscle
- With training, myocardial adaptations occur, including left ventricular hypertrophy for greater stroke volume and reduced heart rate at rest, as well as angiogenesis
Blood Flow Distribution:
- Exercise leads to a significant redistribution of blood flow to accommodate the increased demands of active muscles.
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Consider the specific cardiovacular adaptations with chronic exercise training - Left ventricular hypertrophy –
greater stroke volume per beat –> reduced heart rate at rest - angiogenesis to deliver more
blood and oxygen to tissues
note: Ceasing exercise training results in rapid declines to adaptations in short time frame
Describe the MSK response to exercise
- Exercise invokes various responses from the musculoskeletal system, which are critical for performance and adaptation.
Musculoskeletal Responses to Exercise:
- Muscle cells utilise different fuels to meet metabolic demands
* depends on activity which will dictate which type of muscle fibre is being used
* Fast twitch à carbohydrate via glycolytic pathways or via carbohydrate oxidation
* Slow twitch à fats via lipid oxidation
* Immediate increase of Glucose through Glut 4 receptors that relocate to the cell surface
and uses it for carbohydrate oxidation or stores it as glycogen
* Release of various myokines and extracellular vesicles to distribute signals to different
tissues
* With chronic exercise training:
* Angiogenesis occurs within muscle due to increased blood flow
* Muscle hypertrophy and mitigation of sarcopenia
* Increased motor control to specific muscles** or mitigates sarcopenia.
Muscles and Myokines:
- Muscles release myokines, enabling crosstalk between muscle and other organs
- Can have endocrine, autocrine, or paracrine actions
- affecting blood vessels, lipid and glucose metabolism, bone formation, and endothelial function
Descrube teh endocrjne response
Endocrine Responses to Exercise:
- Individual hormone responses to acute exercise are complex due to the interdependence of hormones and systems.
- Hormones are typically released as needed, with physical activity affecting both resting and exercise-induced hormone production and release.
Hormone Responses:
- Epinephrine/Norepinephrine: Increases sympathetic activity and cardiac output; modulates glycogen catabolism and fatty acid release. Training enhances sympathoadrenal adaptations= bradycardia, smaller rise in BP during aerobic exercise.
- Growth Hormone: Stimulates lipolysis and inhibits carbohydrate breakdown, with no effect on resting values but attenuated rise during exercise.
- Adrenocorticotropin hormone (ACTH): Mobilizes free fatty acids, showing an increase during exercise with training for glycogen sparing.
- Gonadotropic hormones: Affect male and female sex organs, with trained females showing depressed values and varied testosterone levels in males, usually reduced but may increase with prolonged resistance training
- Insulin and Glucagon: Insulin lowers blood glucose and promotes synthesis, becoming more sensitive with training. Note: normal decrease in insulin activity with acute exercise is greatly reduced with training – better overall regulation. Glucagon raises blood glucose levels, with a smaller increase during exercise post-training.
Describe the inflammatory response
In the Systemic Circulation:
- Release of cytokines such as IL-6 (from muscle) and circulating IL-17, IL-23.
- Acute anti-inflammatory response during and post-exercise.
- Reduction of chronic inflammation through the creation of an anti-inflammatory environment following habitual exercise.
In the Muscle:
- Increase in reactive oxygen species within the muscle. note that this is part of adaptation and is not harmful
- Accumulation of innate immune cells like macrophages and neutrophils post-exercise, aiding in the repair of injured muscle. – reason for DOMS
Describe the risks of sedentary lifestyle
:
- neurological: risk of dementia, amyloid beta levels, brain insulin resistance
- cardio: increased risk of CVD, atherosclerosis, blood pressure
- vascular: decreased VO2 max, shear-rate and peripheral blood flow, microvascular function
- musculo: increased risk of sarcopenia, increased H2O2 emissions, increased NMJ damage
- metabolic: decreased VO2, insulin sensitivity, glucose uptake and metabolism reduction, mitochondrial efficiency
- liver: risk of T2D, hepatic insulin resistance, triglyceride accumulation
- Lifelong exervise: improves sleep quality, synchronised circadian clock, maintaining body weight, better response of hormonal activity, anti-/pro-inflammatory balance, maintenance of muscle mass
note good vascular health common feature of very long life
What is the role of GP and other specialists in physical activity promotion?
- Physical activity baseline check for every patient using a simple questionnaire.
- Encouragement to discuss physical activity with patients, using inviting terminology.
- Guidance on referrals for further exercise prescription or discussion.
- ex phys, physio, cardiac and pulmonary rehabilitation
