Bioenergetics Flashcards
Law of thermodynamics
Energy cannot be created or destroyed
Calorie
Unit of food to measure the energy value of food.
Amount of energy to raise the temp of 1g of water by one degree.
Atwater energy values
Protein- 4
Carbs- 4
Fat- 9
Enzyme
Biological catalysts, usually named for the function they perform.
ATPase
Ase- identifies an enzyme
Waste products:
Adenosine diphosphate
Inorganic phosphate ion
Hydrogen
Phosphagen system
Maximize this system:
Low reps
Longer rest periods
ATP, 1-3 seconds, 90 second recovery
(Vert jump, 1RM)
Creatine phosphate, 10-15 seconds, 2-5 min recovery.
Glycolysis
Involves the breakdown of storage CHO’s (known as glycogen) found in muscle tissue or the liver into simple sugar (in the form of glucose) to produce energy.
__________the the only nutrient that can be used during anaerobic metabolism.
Glucose
Glycolysis
The ATP derived from the process can fuel max effort activities that last much longer- up to 90 seconds
The byproduct of CHO breakdown lactic acid, or (lactate) acts as a partial buffer for the hydrogen buildup to extend the period coworkers before the muscle becomes ischemic.
Improved performance in the glycolytic pathway
Lactate threshold
Recruitment of larger and faster motor units
Oxygen system delivery and utilization
Lactate and hydrogen clearance (off-gassing)
Lactate threshold
The highest intensity work that by product removal be matched by byproduct accumulation
As the duration of time an activity can be performed increases, the body shifts more and more toward aerobic metabolism
All metabolic systems are always active, their relative contributions simply shift.
The body does not turn one off, and turn one on. It is rather a fluid transitory shift.
Steady state
When the use of oxygen and energy meets demand, metabolic steady state is said to have been achieved.
BUT between transitions between metabolic systems, when shifts are necessary, cells do not receive sufficient energy from oxygen sources and must therefore borrow fuel from anaerobic sources. OXYGEN DEFICIT. (Debt)
EPOC
Oxygen consumption persists after exercise, due to periods of oxygen debt (when relatively higher intensities were employed) representing EPOC. Excess post exercise oxygen consumption.
EPOC allows the body to recover from the exercise stress and re-establish systemic homeostasis. Intense or long duration exercise increases the EPOC RESPONSE. Which can last up to 24 hours. This is crucial for trainers to understand and manipulate, as an increase in the EPOC response equates to heightened metabolism and therefore caloric expenditure for a given period of time after exercise
Aerobic metabolism
During ongoing activity the body must transition from anaerobic to aerobic metabolism to maintain adequate energy levels. Aerobic metabolism is initiated by pyruvate (left over from glycolysis, as it is transferred to the mitochondria within muscle cells. This entry starts the citric acid cycle or KREBS CYCLE where ATP is formed using oxygen and energy substrates. (Oxidative phosphorylation)
The efficiency of aerobic metabolism is dependent on:
Number of mitochondria
Concentration of aerobic enzymes inside mitochondria
Quantity of oxygen rich blood that can be delivered tot the muscle cells.
Unlike Anaerobic metabolism where only glucose can be used for fuel, during aerobic metabolism glucose, _________, and ________ can be used as necessary.
Glucose, fats, and protein.
Low level exercise ______ -_______ % of maximal aerobic capacity the body flies on fat metabolism for energy. This is called the fat burning zone BUT the total caloric expenditure is actually MINIMAL, and therefore not effective for weight loss.
40-60
Fats used as fuel must first be broken down into its individual parts from storage triglycerides.
Lipolysis, initiated by the enzyme lipase. Which splits triglycerides into a glycerol molecule and 3 bound fatty acids.
Fatty acids can bind with albumen to form free fatty acids so they can be transported to working tissues.
When free fatty acids enter muscle cells they’re are metabolized within the mitochondria
Beta oxidation.
Those who routinely engage in aerobic exercise enhance their ability to use lipids (due to increased mitochondrial and capillary density) which can improve glucose sparing and training capacity.
Increased work rates at >60% maximal aerobic capacity force a greater reliance on glucose metabolism through both anaerobic and aerobic pathways as energy is needed in a more rapid fashion.
Amino acids are liberated from protein sources (such as much in the body) during prolonged, high intensity, exercise. They are the building blocks for all proteins.
Cortisol liberates proteins from tissue, particularly branched chain amino acids, which are converted to sugar for fuel.
Low intensity exercise
Primarily sustained by lipid metabolism; glycogen use is minimal.
Elevated intensity, or intermittent high intensity exercise
Glycogen is rapidly depleted.
A lack of storage CHO is ultimately limiting factor for during any type of exercise.
But the rate of fatigue is accelerated with higher intensity, and/or longer duration exercise. OR low pre-exercise storage due to inadequate CHO intake or lack of recovery.
Acute peripheral fatigue
The body experiences an inability to supply sufficient energy to working muscles to met energy demand.
Central fatigue
(When carbohydrates or glucose is no longer available to properly fuel exercise, peripheral fatigue is joined by central fatigue.)
There is a reduction is neural drive to working muscles which results in a significant decline in force output.
Once central fatigue is reached, further exercise is futile, as the peripheral nervous system shuts down to preserve remaining CHO.
The physiological environment in tissues immediately post exercise allows for a significant increase in energy absorption
Cellular permeability and elevated hormone sensitivity allow for increased storage and uptake of glucose and protein I the first 3 hours after exercise.
Higher glycemic foods should be consumed during this period to allow for glucose availability within the 45 minute metabolic window immediately following exercise, when uptake capacity is at its greatest. This will maximize muscle and liver glycogen replenishment, optimizing recovery. Post exercise glycogen storage can be further enhanced with a CHO/protein meal with a 3:1 ratio. Due to the synergistic effects of CHO and protein on insulin. The protein will act as a permissive to enhance CHO uptake
