October, 6, 2023 Flashcards
Pg. 54 RQ practice problems
what is a MET
(practice questions on bottom of page 55)
A MET, or Metabolic Equivalent of Task, is a physiological measure used to estimate the energy expenditure or metabolic rate associated with various physical activities. It provides a way to standardize and compare the energy cost of different activities in terms of resting metabolism.
One MET is resting VO2 expressed in mls/min or in mls/min/kg. For the average 70kg adult, 1 MTE is 250 mls/min assuming that each kg of body consumes 3.5 mls O2 per minute
what fuel source will run out first between carbohydrates and fats
carbohydrates as it is measured in grams while fat in the body is measured in kilograms (a thousand fold more)
Does Diet influence RQ?
Yes, diet can influence the Respiratory Quotient (RQ), which is a measure of the ratio of carbon dioxide produced (VCO2) to oxygen consumed (VO2) during metabolic processes. The RQ reflects the composition of macronutrients being metabolized, and changes in diet can impact this ratio. Here’s how diet influences RQ:
Carbohydrate-Rich Diet: A diet that is high in carbohydrates can lead to an RQ that is closer to 1.0. Carbohydrates are primarily oxidized in the body, and their complete metabolism results in a balanced ratio of CO2 production to O2 consumption (i.e., RQ ≈ 1.0). This is because the metabolic breakdown of glucose generates an equal number of CO2 and O2 molecules.
Fat-Rich Diet: A diet rich in dietary fats, particularly long-chain fatty acids, can lead to a lower RQ. Fats are primarily oxidized through beta-oxidation, and this process produces more CO2 compared to the amount of O2 consumed. As a result, the RQ for fat metabolism is less than 1.0, often approaching 0.7. This means that fat oxidation generates more CO2 for the same amount of O2 consumed.
Mixed Diet: In practice, most diets are a combination of carbohydrates, fats, and protein. The specific dietary composition can influence the overall RQ, with the balance of macronutrients contributing to the ratio. The RQ will vary over the course of a day as individuals consume different foods and their bodies metabolize those nutrients.
what are the effects of exercise Duration on RQ( and substrate use)
The duration of exercise can have significant effects on the Respiratory Quotient (RQ), as well as on substrate utilization, which refers to the type of energy sources (carbohydrates, fats, or protein) the body relies on during physical activity. These effects depend on the intensity and duration of the exercise. Here’s how exercise duration can influence RQ and substrate use:
Depletion of Carbohydrate Stores: As exercise duration increases, the body’s carbohydrate stores, particularly muscle glycogen, become progressively depleted. This can lead to a greater reliance on fat for energy. The “hitting the wall” phenomenon in endurance sports occurs when glycogen stores are nearly exhausted, and the body shifts to predominantly fat oxidation.
graph on bottom of page 56 perfectly demonstrates this switch from carbohydrate to fat as exercise time gets longer
What are the effects of exercise intensity on RQ
Low-Intensity Exercise:
During low-intensity exercise, such as leisurely walking or slow cycling, the body relies primarily on aerobic metabolism.
Fat oxidation is the predominant energy source, as there is an ample supply of oxygen available to support the breakdown of fatty acids.
The RQ is lower, approaching 0.7, reflecting the utilization of fats for energy.
Moderate-Intensity Exercise:
During moderate-intensity exercise, such as brisk walking or jogging, the body increases its reliance on carbohydrates as well as fats.
Both fat and glycogen (stored carbohydrates) are used for energy, reflecting a mix of aerobic and anaerobic metabolism.
The RQ remains below 1.0, indicating the combined utilization of carbohydrates and fats.
High-Intensity Exercise:
During high-intensity exercise, such as sprinting or interval training, the body primarily relies on anaerobic metabolism.
Carbohydrates, particularly muscle glycogen, become the primary energy source.
The RQ may increase significantly above 1.0 due to the rapid production of carbon dioxide during anaerobic glycolysis.
what is the relationship between Exercise Intensity and Substrate Utilization in regards to RQ
Exercise Intensity and Substrate Utilization: Exercise intensity influences the balance between carbohydrate and fat utilization. As exercise intensity increases, there is a shift toward greater reliance on carbohydrates due to the need for rapid energy production. Conversely, lower-intensity exercise encourages the body to preferentially use fat as a fuel source because there is enough oxygen to support efficient fat oxidation.
what is the relationship between Duration and Intensity Interplay in regards to RQ
Duration and Intensity Interplay: The effects of exercise intensity on RQ interact with exercise duration.
Longer-duration, low- to moderate-intensity exercise allows for the gradual transition from carbohydrate to fat utilization as glycogen stores deplete.
Short, high-intensity efforts primarily rely on carbohydrates and can lead to a higher RQ.
what intensity of exercise is optimal for burning fat
mild, long exercise is best for lipid oxidation
below lactate threshold, yet high enough so that the energy expenditure is sufficiently high
Complete practice problems on page 60
where does norepinephrine come from
sympathetic drive
also known as the sympathetic nervous system activation or sympathetic tone, refers to the activity or stimulation of the sympathetic nervous system.
where does epinephrine come from
sympathetic drive
Catecholamines:
norepinephrine and epinephrine
where does glucagon and insulin come from
pancreas
glucagon = alpha cells in pancreas
insulin = beta cells in pancreas
Hormonal response to prolonged exercise and the effect of endurance training in regards to norepinephrine, epinephrine, glucagon and insulin
During prolonged exercise, the release of norepinephrine and epinephrine (also known as catecholamines) from the adrenal medulla and sympathetic nerve endings increases.
During prolonged exercise, glucagon levels may increase in response to low blood glucose levels and the need to maintain stable blood sugar levels.
Insulin levels typically decrease during exercise, especially during prolonged exercise, to prevent excessive uptake of glucose by muscles and allow more glucose to be available for other tissues.
Insulin decrease because sympathetic drive increases
