Energy Metabolism - Lecture 12 Flashcards
What’s the composition of the air we inhale?
21% Oxygen
0.03% CO2
What’s the composition of the air we exhale?
17% Oxygen
3.3% CO2
To have more O2 delivered to the muscles…?
More capillaries can increase blood flow ultimately increasing oxygen delivery.
More mitochondria to deliver more oxygen
Large muscle mass requires more oxygen
Why is O2 low in expired air?
If a lot of oxygen is inhaled from air, then a sufficient amount will be extracted for the cells and other reasons before being exhaled
Where is oxygen mainly delivered to
It’s delivered to sites that need it more than others.
How does oxygen extraction work?
Oxygen follows a pressure gradient from high O2 pressure moving to low O2 pressure regions.
What is oxygen usage dependant on?
The bigger we are the more oxygen we require and use
What happens to the O2 in the muscles when exercising?
Concentration of oxygen in the muscles drop and that’s when oxygen is pulled into the muscle through diffusion
When and where is oxygen extracted?
Oxygen extraction at the capillaries and only at the tissue that are in need depending on its metabolic rate.
Fick’s Equation
VO2 = HR*SV (CaO2-CvO2)
- Calculates Oxygen consumption (VO2)
What is the CaO2 - CvO2 also known as from Fick’s Equation?
Oxygen extraction; the difference in oxygen in the arterials compared to the venous blood and how much oxygen was extracted and used in the muscle.
What does Fick’s Equation tell you?
The amount of oxygen used up for energy metabolism is equivalent to the cardiac output multiplied by the oxygen content in the arteries subtracted with the oxygen content in the veins.
VO2?
Volume of oxygen taken up and utilized by the body for energy metabolism.
How does O2 extraction become more useful as you exercise?
Mitochondria become more active (More oxygen consumption to make more ATP)
Oxygen usage increase when rate of muscle contraction…?
Increase; this causes the [O2] to drop in muscles.
Oxygen deficit
Work done anaerobically, which causes a lag in oxygen consumption at the beginning of a workout. Little bit of energy in muscles produce ATP without O2.
O2 debt
Oxygen that is used during recovery; Using the O2 that was not used at the beginning.
Why is knowing VO2Max important?
It’s a key determinant of health, predicting longevity
What’s the optimal situation for a good VO2
Deliver more blood rich with O2 and extract a greater proportion of the oxygen.
Relationship between Heart Rate and Oxygen Consumption?
Linear
Why is the relationship between HR and O2 Consumption important?
It can determine the intensity that you need to train. (If you want to train at 60% VO2Max then your Max HR should be 70%)
Age Predicted Max Heart Rate Equation
220-age
How accurate is the Max Predicted Heart Rate
Within the first 10-15 bpm.
Stroke Volume goes up with oxygen consumption and exercise
Stroke Volume and Exercise
How is the ventricles benefitting from SV increase?
Greater contractility, reduced peripheral resistance (increased ejection). Large left ventricular volumes
As oxygen consumption in the muscle goes up, it draws in O2 from the Hb molecule. At rest the muscle does not use much oxygen so not a lot needed.
Oxygen Extraction
Should testing for VO2Max be done on a treadmill?
It’s harder, more likely to get injured, but it gives true VO2 Max
Testing for VO2Max on a bike?
Less injury prone, but does not give you true VO2 Max.
Why does the treadmill give us a better VO2Max than bike
You use more muscles for oxygen consumption when on the treadmill.
Must be done in a progressive fashion. Start low and increase the task every 2 minutes
How to truly test for VO2Max
Step Protocol
Staying at a certain intensity for 2-3 minutes.
Why do some people suggest Step Protocol for VO2Max testing?
For some people with disease, we don’t want to blow past the oxygen deficit (lag).
What happens at the plateau of a graph showing your VO2 Max?
This is where work is done at the max and it’s not through oxygen consumption; using anaerobic metabolism.
What is a MET?
How much energy is required for an activity relative to rest
What is 1 MET equal to?
1 MET = 3.5mL o2/kg/min
What are MET’s Used for?
To find metabolic requirement for a given task; use this to prescribe exercise.
What age group typically has the highest VO2Max?
Late teens.
If you’re sedentary and overweight can you shift VO2Max?
Yes you can easily do it, but someone who is active will struggle.
What happens when your VO2Max gets lower than below 18?
Most likely to die. If you have a low VO2Max with a disease, certain death.
At peak exercise what fuels are we burning?
Carbohydrates
At lower intensity what fuel are we burning?
Fats
Why is excess fat not good for VO2Max?
It decreases VO2Max and increases obesity
Why is having little fat bad?
Increases anorexia and likeliness of dying. Must need some fat because it is energy dense.
If you want to burn off a few kilos of fat?
Need to burn several thousand calories.
Why do we need carbs for exercise?
Carbs are used for energy requirements, specifically glucose. Supports oxygen consumption. When doing anaerobic exercise, glycogen provides energy requirements
Energy stores in our body
We tap into them for our exercise performance.
Why don’t we burn protein?
If we don’t eat enough to produce energy from glucose and fat, the body resorts to burning muscles for energy which is a drawback.
How do we usually burn protein?
Overtraining or not enough eating.
What fuels are we predominantly burning?
Carbs and Fats
Amount of carbs and fats used during exercise?
It’s dependant on how hard you exercise
What are we burning at rest?
Fats
As you go harder in terms of intensity?
You tap more into Carbohydrates.
How do we burn fat?
If a little overweight with respect to fat, need to exercise at lower intensities
Fat Oxidation
The fats in our body and how they’re burned
Peak fat oxidation rate
Takes into account caloric expenditure during exercise and ratio between carbs and fat. It’s the body breaking down the fat in our body.
What happens when FOR increases?
As intensity of exercise increases FOR does too, meaning fat is being burned at a certain %VO2Max. But it starts to drop after a certain intensity and this is where we tap into carb storage
The longer you exercise for?
The more you tap into fat oxidation.
How does long amounts of exercise increase fat oxidation
Initial exercise does not use carbs and fats as it’s using oxygen deficit (ATP, phosphocreatine), but then you start to burn oxygen. Within first hour you burn muscle glycogen, but in order to burn fat the longer you exercise for the more fat you will burn.
How is VO2Max expressed?
It’s expressed per kilogram of your body mass; losing fat will increase VO2.
