What is energy?
- It's the capacity for work.
- Energy reflects a dynamic state related to change.
- Increase in work > increase in energy transfer
Name at least 3 different types of energy.
Mechanical, Chemical, heat, light
Why is energy important for exercise?
It's required for chemical reactions to take place and muscles to contract. Basically need energy to move.
What are the 1st + 2nd Laws of Thermodynamics?
- 1st- conservation- energy cannot be destroyed or created.
- 2nd- Entropy- tendency of potential energy to kinetic energy of motion with a lower capacity for work.
How does the 1st + 2nd laws of thermodynamics apply to chemical reactions in the body?
- 1st- chemical energy=bonds of macronutrients that do not immediately dissipate as heat during energy metab. Which the MSK System changes into mech. energy.
- 2nd- Once changed into mech. energy, it dissipates into heat energy with a degradation in capacity for work.
Give examples of potential and kinetic energy in the body
What are coupled reactions?
- they contain Reducing agents- donates or loses e- as it oxidizes. and Oxidizing agents- reducing or gaining e-.
- Whenever oxidation occurs, so does reduction. when one gets an e the other loses an e
Why are coupled reactions necessary?
Used to power our metabolic energy systems.
are the three energy systems in the body?
Phosphogen (single enzyme system, uses creatine phosphate to resynth ATP from ADP) Glycolytic (catabolism of CHO to Pyruvate or Lactate) Oxidative (Krebs cycle, Oxidative Phosphorylation, ETC)
energy system generates ATP the fastest?
Phosphogen system, it involves transfer of high energy phosphates. Production peaks at 3-8 seconds, slows rapidly.
How long will the oxidative systems last (in theory)?
It uses oxygen, which is readily available in out atmosphere at all times (check if more)
What are the components of the phosphagen system?
Phosphocreatine, Creatine Kinase, Phosphates
is the primary role of energy metabolism in the body?
To produce ATP (that it?)
How does the phosphagen system affect the glycolytic and oxidative systems?
adenylate kinase and creatine kinase rxns produce AMP, Pi, and ADP which activate the initial stages of glycolysis and cellular oxidation/respiration pathways of the mito.
It is the catabolization of CHOs into pyruvate or lactate and produces ATp and NADH.
much energy do we derive from glycolysis (%)?
- ONly gives us 5% of total energy!
- 1 glucose= 2 Net ATP, 2 NADH Regularly small energy production.
What are the three phases of glycolysis?
1.ATP consumption 2. Splitting 3. ATP generation
How much net ATP do we derive from glycolysis?
1 glucose= 2 Net ATP
How else does glycolysis contribute to energy production?
Supplies 2 NADH, Produces energy in the Electrion Transport System
Does lactic acid exist in the human body? Why or why not?
- Lactic acid is not Lacatate!!
- LA- formed during anaerobic glycolysis, majority of it dissociates quickly into the acid salt Lactate.
- But also, may not exist because our bodies do not get acidic enough to form it, theres not enough H+ to cause lactate to exist as an acid and it raises pH.
Acidosis from lactate production may not be linked directly, it could be ATP hydrolysis or NADH + H+
- pK= -log pH
- every acid has a pK Pk is the equilibrium point of a pH. If a solution is 3.9. if you get far above, you get less and less acid. if 2 units, no more acid left. @ 5.9
- human body pH is 7.3
- so we can make lactic acid
Is lactate production “good” or “bad”? Why
Its good because it oxidizes NADH to NAD+, allowing glycolysis to continue and if you have an impaired ability to make lactate, exercise capacity drops. Lactate prod. represents an imbalance between glycolysis and mito. oxidation.
How does lactate threshold relate to endurance performance?
As we train, our LT delays toward a larger workload. (?)
What is the glycerol-phosphate shuttle? What is significant about it?
It is a Coenzyme shuttle used to transfer H+ from cytosol into mito. It's slow.
What are the two reduced co-enzymes produced during the glycolysis/krebs cycle? Why are they significant?
NADH in glycolysis and FADH2 in Krebs. NADH is too large and must be shuttled into mito. through a shuttle to transfer its H+ to FADH.
What is the name of the enzyme that catalyzes the reaction of pyruvate to acetyl CoA? What takes place in this reaction?
Enzyme PDH (pyruvate de-hydrogenase) catalyzes Coenzyme A with acetyl, and produces CO2 and NADH. It can also catalyze pyruvate into Acetyle CoA
Why is coenzyme A the workhorse of the Kreb’s cycle?
CoA, once in the mito is used in:
What is the function of the Kreb’s cycle?
to reproduce the reduced enzymes which will initiate the electron transport on the crytochromes.
Where does the Kreb’s cycle take place?
In the mitochondria
Does the Kreb’s cycle produce any ATP?
No. not directly
What are the coupled reactions in the oxidative system?
Electron transport system and Phosphorlylation (H+ flow through the Fo-Fi complex-- a protein, creates energy from high to low concentration of H+ from outermembranous to intramembranous.)
What is the electron transport system?
It takes place in the mito intramembranous space. Powered by FADH2 and NADH from krebs, the cytochromes produce H+
What is the function of the electron transport system?
To produce ATP through oxidizing reduced coenzymes.
What is the significance of oxygen in the electron transport system?
the reduced coenzyme carrier molecules transfer H+ to the ETC, ATP forms when H+ bind to O2. so ATP is in the form of H2O? cool
What is lipolysis?
A process that breaks down triaglycerides into free fatty acids and glycerol.
What is the oxidative process by which FFA are catabolized?
- Beta Oxidation- ffa catabolyzes in mito, produces acetyl-CoA, NADH, FADH
- Process: successive splitting of 2-C acyl fragments from the long chain of fatty acid. ATP phosphorylates the rxns, H2O is added, H+ pass to NAD+ and FAD, and the acyl frags joins with CoA to form Acetyl CoA. This continues till the entire FFA degrades into Acetyl CoA to go into citric cycle.
exercise where is the primary amount of fat derived from in the body?
All cells store fat, but Adipose Cells are the major supplier. Adipocytes specialize in storing + synthing triaglycerides. which make up 95% of adipocyte vol.
What is the shuttle system used to carry FFA into the mitochondria?
- Carnitine acyltransferase- catalyzes transfer of an acyl group to carnitine to form acylcarnitine which can cross mito membrane.
- Only long chain FFA need this, short + medium can diffuse freely into mito.
What do FM and FFM stand for?
Fat Free Mass- muscle, bones, organs, water, blood, basically everything but fat.
FM- Fat mass
How is the Archimedes principle used to asses body composition?
- Hydrostatic weighing.
- AP- obj loss of weight in water=vol. water displaced.
- More lean=higher body density
- Caveat- differs w/ age/gender/ethnicity/physical activity level. 1.7% error. Also, account for lung vol. + residual lung vol.
- Density is BM/Vol
- True mass= Ma-Mw/Dw
What is gluconeogensis? Where does it take place?
In the liver primarily, we make our own CHO from C residues of generally A.A., glycerol, pyruvate, lactate.
What are the two primary gluconeogenic processes that take place during exercise?
- Cori Cycle- Liver takes lactate out of blood and makes glucose.
- Glucose-Alanine cycle- series of reactions in which amino groups and carbons from muscle are transported to the liver
Work is force times distance. So, work put out over a distance. Measured as Kg-m
is power different from work?
- Power is Work over time.
- Force X Distance/ Time. Measured as Watts or kg-m/time
power from a Monark cycle ergometer for a person turning 60 rpm with 2Kg of
What is the difference in direct and indirect calorimetry?
Direct calorimetry is Heat Production, which is not practical for exercise because you need tons of equipment to measure.
Indirect C.- We measure O2 which equals energy expenditure
What is the major assumption in indirect calorimetry?
All energy releasing reactions in humans ultimately depend on O2 use.
What does STPD stand for and what is it used for? What are the standard conditions?
- Standard Temp. and Pressure, Dry.
- Standard conditions are 0 Celsius, 760 mmHg
- Used for standardization of measurement for indirect calorimetry
How do we assess caloric expenditure during exercise?
- We collect expired gas (O2,CO2 and N2) in a bag through a 2 way valve. We analyze for [O2], [CO2] and VE. We use RER to find kcal/LO2
- Step 1.
- VE(STPD)=VE*[273/(273+C)]*[(Pbar-47)/760 Torr]
- Step 2.
- Step 3. VO2=(VI*.2093)-(VE*FEO2)
- Step 4. VCO2=(VE*FECO2)-(VI*0.0003)
- Step 5. RER=VCO2/VO2
- Step 6. Kcal/min=Kcal/L*VO2
What is RER?
RER is respiratory exchange rate, measured by VCO2/VO2. Similar to RQ. aka nonprotein RQ?
Why is knowing RER important during indirect calorimetry?
Helps us determine kcal/min. Reflects pulmonary exchange of CO2 and O2 under differing physiologic and metabolic conditions.
What is the Haldane exchange and what is it used for?
Nitrogen exchange. N2 is inert. Any change in its conc. in expired air reflects # of O2 remoed from inspired air are not replaced by the same # of CO2 produced by metab. VI can be determined from VE using the ratio of N2 expired and N2 inspired. Ultimately used to calc the RQ.
What percentage of carbohydrate and fat are being utilized when the RER is 0.9?
- Using the graph, CHO- 64.2% and Fat- 35.8%
- How else can I find out?
What would the RER be if someone were catabolizing only carbohydrate?
How many Kcals are there in a gram of carbohydrate? Fat?
- CHO- 4 kcal/g
- Fat- 9 kcal/g
How much is the recommended daily intake for protein?
RDI= 0.8g/kg of BW
much is the recommended protein intake for athletes?
1.2-3.0 g/Kg of BW still depends on kcal intake/expenditure
How much carbohydrate intake is recommended following exercise?
GLycogen resynth after exercise is important.
What is the recommended procedure for glycogen loading?
Begin @ moderate CHO, high training volume, then increase CHO and decrease trainin for Glycogen Supercompensation.
Will high fat diets improve performance?
May stimulate adaptive responses that augment fat use, but no reliable research on benefits of consistent high fat diet. Lots of health risks, shown to improve it, but high CHO improves so much more, not worth it?
What are the disadvantages to high fat diets?
Heart disease more?
What are the best dietary recommendations for athletes?
- Protein- 1.2-1.8g/kg BW
Can RER ever be greater than 1.0?
Rare, when a person gains body fat through excessive dietary CHO intake, or hyperventilation?
What are the three areas in the lung
- Conducting Zone- move air to lung. No respiration takes place here. includes Mouth, Nose, Larynx, Trachea.
- Respiratory Zone- site of gas exchange, respiration, not ventilation.
- Pulmonary Circulation Zone- Network of blood vessels that surround the lung. High capillary density.
What is the difference between ventilation and respiration?
- Ventilation is movement of air. VE= frequency (breath/min) * TV (L)
- includes VA
- Respiration is gas exchange.
Calculate VE knowing TV = 0.8 L/min and Bf = 13 breathes/min. What is the calculated alveolar ventilation?
- VE=13 breaths/min * .8 L/min
- VE= 10.4L/min
What is the inspired partial pressure for O2? Why does it decrease in the alveoli?
- PO2- 159 mmHg
- Decreases to 103 mmHg in the alveoli because O2 flows from lungs to blood for transport, alveolar air contains avg of 14.5% O2.
Why is an understanding of pressure gradients important for understanding gas exchange?
- Exchange of gases between the lungs and blood and gas movement at the tissue level progress passively by diffusion, depending on their Pressure Gradient.
- The pressure differences between alveolar and pulmonary blood gases creates the driving force for gas diffusion across the pulmonary membrane.
What is the [Hb] for men and women?
Calculate arterial content of O2 for women at 98% saturation. At 90% saturation (~ 10,000 ft)
CaO2=[Hb]*O2/g Hb * Hb-O2 Sat.
What is the oxy-hemoglobin dissociation curve? What can cause shift in the curve?
- its a curve on the graph of Hb saturation over PAO2.
- Heat, pH and CO2 can shift the curve
What is the primary chemical driver for ventilation at rest and low exercise intensity
variations of PO2, PCO2, pH and temperature activate neural units in the medulla and arterial system to adjust ventilation
How is CO2 transported?
- 3 ways:
- 1. small amount in physical solution of plasma.
- 2. Combined with hemoglobin within the RBC
- 3. As plasma bicarbonate.
What is pH
Our body is 7.5, it measures acidity and alkalidity
What factors effect pH?
- Rate of acid production.
- Concentration of HCO3- and other bases or acids.
- Renal excretion of acids and bases.
How does ventilation play a role in acid-base balance?
Hyperventilation reduces PCO2, therefore reduces acidity and hypoventilation allows build up of PCO2, adding to acidity.
At the onset of exercise how the lung adapt to the increased need to ventilate?
- Inspiration- volume inc and pressure decreases.
- Expiration- Volume dec. and pressure inc.
What is the ventilation threshold?
- The point where pulmonary ventilation increases disproportionately relative to increase in O2 consumption during graded exercise.
- The point we begin to ventilate at a faster rate during exercise.
How does the control of ventilation change during higher intensities?
- pulmonary ventilation no longer links tightly to O2 demand.
- The maximal amount of O2 the body is able to uptake during a specific period. VO2 provides a quantitative measure of a person's capacity for aerobic ATP resynthesis. Represents physical performance
What is VO2 max and what does it represent?
It's maximal O2 consumption.
What are the two ways to express VO2
Absolute = oxyL/min Relative= oxymL/kg of body weight/min