Week 6 - Metabolism & Metabolic Adaptations Flashcards
What does metabolism refer to?
The sum of all the chemical reactions in the body
What is anabolism?
Anabolism refers to synthesis reactions, such as energy storage (e.g., glycogen stores) and tissue building or maintenance (e.g., protein synthesis)
What is catabolism?
Catabolism refers to breakdown reactions that release energy, where substrates are broken down to provide energy. Exercise is considered catabolic as it involves the breakdown of substrates to release energy
What is calorimetry?
Calorimetry is the process of measuring heat energy production, typically measured in a calorimeter
What is a kilocalorie in terms of heat?
The energy required to raise 1L of water by 1°C
What is human calorimetry used to measure?
Human calorimetry measures human heat production and is used to assess metabolism. It is valid at rest and can also measure exercise metabolism if the energy used for physical work is converted to heat
What is metabolic rate?
Metabolic rate refers to heat production relative to time, indicating how much energy is expended per unit of time
What is the difference between direct and indirect calorimetry?
Direct calorimetry measures heat production in a metabolic chamber, while indirect calorimetry measures oxygen consumption (VO2) to estimate heat production
How does indirect calorimetry work?
Indirect calorimetry measures oxygen consumption (VO2) and uses the relationship between oxygen use and heat production (1L of O2 ~ 21kJ or 5kcal) to estimate energy expenditure
What is the setup for closed circuit indirect calorimetry?
The subject breathes in and out of a closed chamber containing 100% oxygen at the start. Carbon dioxide is absorbed by soda lime to prevent interference, and a reduction in gas volume reflects the oxygen used
How does open circuit indirect calorimetry work?
The subject breathes room air while wearing a mask that measures the amount of oxygen consumed and the amount of carbon dioxide produced, along with other variables
How is energy provided in the short-term and long-term during exercise?
Short-term energy is provided both aerobically and anaerobically, while long-term energy involves the replenishment of anaerobic energy stores through aerobic processes
How do you determine which substrate (fat or carbohydrate) is being used for aerobic ATP production?
By measuring the concentrations of oxygen (O2) and carbon dioxide (CO2) in ambient and expired air and calculating the ratio of CO2 produced to oxygen consumed (VCO2/VO2), also known as the Respiratory Exchange Ratio (RER)
What is the Respiratory Exchange Ratio (RER)?
Ratio of carbon dioxide produced (VCO2) to oxygen consumed (VO2), reflecting the type of substrate being used for energy
RER = VCO2/VO2
What does an RER of 0.70, 0.85, and 1.00 indicate in terms of substrate use?
- RER = 0.70: ~100% fat metabolism
- RER = 0.85: A mixture of fats and carbohydrates
- RER = 1.00: ~100% carbohydrate metabolism
What does an RER greater than 1.0 indicate?
It indicates buffering of acid (H+) due to anaerobic metabolism, typically associated with high-intensity exercise
How does exercise intensity influence substrate use?
At low-intensity exercise, fat is the primary fuel source. As intensity increases, more carbohydrates are used for energy
How does duration affect substrate use during aerobic exercise?
Longer-duration exercise primarily uses fat as a fuel source, especially as glycogen stores become depleted. High-intensity exercise typically shifts to fat usage as intensity decreases over time due to fatigue
What are the main factors that determine metabolic adaptations to exercise training?
- Frequency
- Intensity
- Time (duration of session)
- Type of exercise training
What are the key types of metabolic changes in skeletal muscle fibers due to exercise training?
- Substrate storage (levels)
- Substrate use
- Mitochondria
- Enzyme activity
- Use of oxygen
- Lactate accumulation
What effect does sprint/interval and resistance training have on muscle ATP & PC stores?
Increase ATP & PC stores in muscle, especially with muscle hypertrophy (increase in muscle mass)
Which types of exercise increase glycogen stores in both the muscle and liver?
Endurance (E), sprint/interval (S), resistance (R), and circuit resistance (CR) training increase glycogen stores in both the muscle and liver
What are the effects of endurance (E) and circuit resistance (CR) training on fat metabolism?
Increase fat mobilisation from adipose tissue, increase plasma free fatty acids (FFAs), and increase FFAs use in muscle, leading to glycogen sparing during submaximal exercise
How does aerobic training affect muscle mitochondria?
Aerobic training (E & CR, S/I) increases the size and number of mitochondria, especially in Type I and IIa fibers, enhancing the capacity to use pyruvate aerobically and contributing to increased VO2max
What effect does resistance (R) training have on muscle mitochondria?
Resistance (R) training decreases the size and density of mitochondria, particularly in hypertrophied Type II fibers
How does endurance (E) training affect lactate accumulation during submaximal exercise?
Endurance (E) training decreases muscle and blood lactate levels during submaximal exercise and increases the lactate threshold, allowing for higher workloads before lactate accumulation
What is the effect of aerobic (E) training on lactate tolerance and buffering capacity?
Endurance (E) training increases lactate tolerance, lactate capacity, and muscle buffering capacity, allowing for better performance at higher intensities
What is the effect of endurance (E) and circuit resistance (CR) training on substrate use during exercise?
Endurance (E) and circuit resistance (CR) training increase lipid use (fat) during submaximal exercise, helping to spare glycogen and reduce fatigue, particularly in long-duration activities
