Be familiar with the monosaccharides, disaccharides, and polysaccharides.

Know distribution of glycogen storage.

•  Monosaccharides: 
• Glucose: (blood sugar)
• Fructose: (fruit sugar, converted to glucose in liver)
• Galactose:(combines with glucose to form breast milk sugar)

• ---

  Disaccharides: Sucrose: (glucose + fructose)
•  Lactose: (glucose + galactose)
•  Maltose: (glucose + glucose, found in alcohol)

• ---

   Polysaccharides:
• Plant form (fiber): RDI = 20-35g/day, slows CHO digestion, decreases blood sugar fluctuation.
• Animal form (glycogen):synthesized by glucogenesis via glycogen synthase. Broken down in glycogenolysis via phosphatase.

• ---

  Glycogen Storage: 
• Mostly skeletal muscle bed > Liver glycogen > blood (plasma glucose)

What are the recommend intakes of CHO for sedentary, active, and heavy exercising populations? 

• Sedentary: 40-50% total Kcal.

• ---

  Active: 60% (600g)

• ---

  Heavy aerobic: 70% (700g)

What tissues only use CHO for fuel?

Normal blood glucose level?

• Red blood cells, brain, nerves.

• ---

  Normal blood glucose = 80-12 mg/dl

Why is CHO preferred fuel for high intensity exercise? 

• Rapid supplier of ATP via oxidative processes. 
• Runs 2x rate of fat or protein. 
• Sole supplier of anaerobic.

Know the time frame for exercise-induced glycogen depletion.

• 1 hour intense = 55%

• ---

  2 hour intense = complete depletion (hitting the wall)

Be familiar with yellow handout illustrating what fuels are used for exercise at different relative intensities.

•  Low intensity: relies more on fat as a substrate, but still not primary fuel source.
  
• As intensity increases, depletion of glycogen stores increases, so does fat reliance.

Can diet influence muscle glycogen levels? 

How?

• YES

  ---

• CHO deficient diet leads to: Rapid decrease in muscle and liver glycogen
• Decreased performance in short term anaerobic exercise
• Decreased time to exhaustion
• 3 days low CHO will decrease exercise capacity. 

Provide examples for simple, compound, and derived lipids.

• Simple: Primarily triglycerides

• ---

  Compound: phospholipid 
• Found in cell membrane and myelin 
• Sloths have no myelin

• ---

  Derived: Simple + compound (cholesterol)

What are the differences between saturated and unsaturated fatty acids?

• Saturated:
• Saturated carbon atoms with single bond Hydrogen bonds. 
• Found in animal products and dairy fats. 
• Some come from plants 
• I.e. vegetable shortening
  

• ---

  Unsaturated:
•  

What is hydrogenation?

• Chemically breaking double bond C atom and loading it with single bond H.
• Taking oils to semi solid fat by adding hydrogen

Why is butter better to have in the diet than margarine?

Margarine has no cholesterol but has transfatty acids à Negative effects on serum lipoproteins (blood lipids) à Increase LDL, decrease HDL

What are the functions of cholesterol, and what are the components of cholesterol?

• Precursor to Vitamin D, adrenal hormones, and sex hormones. 
• Crucial in fetal development.

• ---

  Structural component of plasma membrane. 

What three things influence fat utilization?

Fitness, diet, and exercise

Does exercise training influence fat metabolism?

How?

Yes

After higher fitness level is attained, much more emphasis is placed on fat as a fuel source during low intensity exercise.

What is the RDI for protein and how much should athletes consume?

• Sedentary RDI:
•  0.8 g/kg/day for adults
•  0.9 - 1.0 g/kg BW/day for adolescents 

• ---

  Strength athlete RDI: 
• 1.4 - 1.8 g/kg BW/day 
• NRC does not recommend intake > 2x RDI.

• ---

  Endurance athlete RDI: 
• 1.2 - 1.4 g/kg BW/day

Does CHO intake influence protein metabolism?

• Yes, low CHO intake = high protein metabolism 
• Shown by high sweat urea nitrogen levels

Describe the physiological mechanism for “staleness”.

• Low CHO reserve = Utilizing fat as fuel source. 
• Fat cannot run crossbridge cycle as fast as CHO 
• Fat only has ½ the ATP production of CHO. 
• Complete glycogen reserves restored in no less than 20 hrs

What are some of the problems with nutritional intake for athletes in weight dependent sports?

• Diet often consists of high fat, high protein, low CHO. 
• Lack of sufficient vitamins and minerals reduces ATP cycle efficiency. 

Describe the ideal timing and content of a pre-competition meal, a meal immediately before exercise, and a post competition meal?  Defend your choices.

•  Pregame: 
• 3 hours, 3-5g CHO/kg body weight. 
• Avoid high lipid and protein.
   
• Benefit of high CHO pregame: 
• Replenish glycogen stores, faster absorption and digestion, less energy required to absorb and digest, serves as main energy for short-term anaerobic and high intensity aerobic exercise.

• ---

  Immediately before: 
• Low glycemic to prevent sugar spike which leads to poor performance.

• ---

   During exercise: 
• Recommended intake of CHO during high intensity long duration (>1hr) is 60 g/hr.  
   
• Benefit: 
• Spares muscle glycogen, maintains more optimal blood glucose levels, attenuates fatigue, and maintains sport skills in long competitions.

• ---

  Post exercise: 
• Ideally consumed 30-60 minutes post exercise 
• Blood flow and Insulin sensitivity are elevated in this timeframe. 
• Protein required (3 CHO: 1 protein ration). 
• Moderate to high glycemic index for glycogen replenishment. 

• Recommend 50-75g CHO every two hours until reaching 500g.

Describe and explain the blood glucose response to CHO intake immediately prior to exercise.

High glycemic will cause blood sugar spike after 30 minutes, resulting in poor performance.

How was the glycemic index developed? 

• Based on 50g of food and take series of blood samples over 2 hours 
• Not just one at the end of 2 hours 
• Glucose levels in blood samples are compared to 50g of pure glucose (100%).

What kind of glycemic index foods would a dieter want to consume for optimal weight reduction?

Low glycemic

Can feeding during exercise improve performance?

• Yes.

• ---

  During exercise: 
• Recommended CHO intake during high intensity long duration exercise (>1hr) is 60 g/hr.  
   
• Benefit: 
• Spares muscle glycogen
• Maintains more optimal blood glucose levels 
• Attenuates fatigue 
• Maintains sport skills (coordination) in long competitions.

What is blood osmolality?

• Osmolality = number of solutes in a solution. 

• ---

  Blood osmolality = 280 mosm/L

Know the ideal volume and solute concentration for a rehydrating drink/glycogen replacement?

• 5-8% CHO drink is ideal for rehydration 
• Gatorade = 6% CHO soln.

• ---

  Before competition: 
• 13-20 oz fluid.

• ---

  During: 
• 5-7 oz. every 15 min.

• ---

  Cardiac drift - Unnecessary rise of HR due to thicker blood 
• Caused by less fluid volume in plasma
• 94% of sweat volume comes from plasma.

Describe the influence of volume and osmolality on gastric emptying.

• Increased fluid volume = Compromise CHO absorption
• Increased CHO amount = Compromise water absorption

What is the law of thermodynamics?

• Energy cannot be created or destroyed.
• Released PE converts to KE

Describe and give several examples of exergonic and endergonic reactions.

• Exergonic 
• Releases energy in form of heat and ATP: 
• 
  

• ---

  Endergonic 
• Requires energy to form ATP:
• 
  

What is the role of enzymes and coenzymes in reactions?

• Enzyme (monogamous): 
• Catalyst that increases reaction rates (faster) and decreases activation energy (for less). 
• Not consumed or changed in reaction. 
• Typically end with “ase”. 
• Activation energy without enzymes is possible but MUCH harder.

• ---

  Coenzyme (Co-Hoe): 
• Facilitates enzyme action by helping to bind substrate to enzyme (cobinder, carrier, helper) 
• i.e. Fe, Zn, vitamin B, Mg. 
• These are less specific than enzymes.

What are more specific in chemical reactions, enzymes or coenzymes?

Enzymes

What influences enzymatic activity?

pH & temperature

Provide examples of hydrolysis, condensation, oxidation, and reduction reactions.

• Hydrolysis: 
• Breaking (lysing) with water. 
• Ex: sucrose à glucose + fructose. 
• Dipeptide Hydrolyzed into amino acids. 
• Macro nutrients broken down to smaller forms with hydrolysis, making them more digestible.

• ---

  Condensation: 
• Removing water. 
• Example: Glucose + glucose à maltose

• ---

  Oxidation: 
• Losing electrons. 
• Ex: Lactate – electrons à pyruvate

• ---

  Reduction: 
• Gaining of electrons. 
• Ex: pyruvate +electrons à lactate

What is mass action effect?

• With increase in available substrates, the product formation will increase.
• Enzymes enable large increase in product formation with small changes in substrate concentration. 
• Less goes in but still large amount out

Why is it important to resynthesize ATP at the same rate as ATP consumption?

ATP cannot be eaten or stored (for more than 2-4 sec), so it must be continually resynthesized

How long does ATP power exercise?

2-4 sec of all out exercise

What are the PCr and adenylate kinase reactions?

• Adenylate Kinase reaction: 
• 2 ADP ß_{Adenylate kinase}à ATP + AMP

• ---

  Creatine Phosphate reaction: 
• PCr + ADP ß_{Creatine kinase}à Cr + ATP

How long does the PCr system power exercise?

• Cells store 4-6 times more PCr than ATP
• Provides energy for ~ 10 sec.

Describe efficiency and number of ATP generated by the oxidation of 1 mole of glucose.

• 1 mole of glucose = 686 Kcal 
• à CHO metabolism = 38% efficiency
• à 686 x 0.38 = 261 Kcal 
• Synthesis of 1 mole of ATP = 7.3 Kcal
• à 261 Kcal ÷ 7.3 Kcal = 36 ATP 
• Comes from glycolysis, citric acid cycle, and electron transport chain

What are the rate limiting enzymes of glycolysis?

• Step 1: 
• Hexokinase (in all cells)
• Glucokinase (only in liver) 
• 1 ATP consumed

• ---

  Step 2: 
• PFK (phosphofructokinase) 
• Most important rate limiting enzyme
• High levels of PFK found in type II fibers
• 1 ATP consumed

• ---

  Step 10: 
• Pyruvate kinase (end of glycolysis)

Where is ATP either produced or consumed in glycolysis?

• Step 1: 
• 1 ATP consumed

• ---

  Step 3: 
• 1 ATP consumed

• ---

  Step 7: 
• 2 ATP produced

• ---

  Step 10: 
• 2 ATP produced

Describe the fate of NADH + H⁺ in glycolysis in both presence and absence of O₂

• NADH + H­­⁺ cannot enter mitochondria of SM

• ---

  Aerobic: 
• In presence of oxygen NADH+H⁺ is converted to FADH₂
• → FADH₂ enters mitochondria and is oxidized.
• → Generates 2 ATP per side, 4 ATP total
• Terminal molecule = Pyruvate 

• ---

  Anaerobic: 
• If O₂ not present or not able to be utilized (RBC, IIx fibers): NADH+H⁺ cannot convert to FADH₂ 
• Due to lack of O₂
• → Donates 2 H⁺ to pyruvate to form lactate (added H⁺ molecules make it more acidic) 

What happens to FADH₂ in glycolysis?

• It enters the mitochondria and is oxidized
• → Produces 2 ATP per side
• → Forms pyruvate

How does glucose enter a skeletal muscle cell?

• Enters cell via translocation

• ---

  Higher concentrations of HK/GK, PFK, and PK speed up rate of glycolysis
• Hexokinase – Found in all cells
• Glucokinase – Only in liver
• Phosphofructokinase – MOST important rate limiting
• Pyruvate kinase

• ---

  Glucose is delivered to SM cells by facilitated diffusion via GLUT 4 
• Glucose transporter protein
• Found in liver, SM, and adipocytes.

• ---

  Translocation is triggered by insulin and muscle contractions. 
• Insulin levels very low during exercise. 
• Very sensitive immediately after

What continually forms lactate?

Red blood cells

What is typical resting value for lactate in the blood?

Approximately 1 mmol

Describe the mechanisms for lactate clearance.

• Oxidized by the mitochondria filled type I fibers (including the heart).

• ---

  Lactate shuttle:
• Lactate travels through bloodstream & picked up by type I fibers and stripped of 2 H⁺  
• Becomes pyruvate 
• Travels to the liver and converted back to glucose via gluconeogenesis 
• Since lactate/pyruvate are carbohydrates

Describe how lactate contributes to fatigue.

• Lactate ↓ blood pH 
• → Acidic blood ↓ enzyme activity 
• → Reduced enzyme activity ↓exercise intensity 
• i.e. increased fatigue

• ---

  Fatigue due to: 
• Reduced enzyme activation → Reduction in glycolysis → Decreased ATP production

What is gluconeogenesis?

• Anaerobic activity (or RBC) produces lactate in muscle
• à Veins carry lactate to the liver
• à Lactate converted to pyruvate
• à Pyruvate to glucose
• à Arteries carries glucose to SM (or stored as glycogen)

Where does glycolysis, CAC, and OP occur in cells?

• Glycolysis: 
• Occurs in the cytoplasm

• ---

  CAC: 
• Occurs in mitochondria  
• Type I fibers (dark meat)

• ---

  OP: 
• Occurs in mitochondria

What are the rate limiting enzymes for the CAC?

• Step 1: 
• Pyruvate dehydrogenase

• ---

  Step 2: 
• Citrate synthase

• ---

  Step 9: 
• Succinate dehydrogenase

Where is NADH + H⁺ and FADH₂ produced in the CAC?

• Step 1: 
• Produces 1 NADH + H⁺

• ---

  Step 5: 
• Produces 1 NADH + H⁺

• ---

  Step 7: 
• Produces 1 NADH + H⁺

• ---

  Step 9: 
• Produces 1 FADH₂

• ---

  Step 11: 
• Produces 1 NADH + H⁺

For each molecule of glucose, how many ATP are produced during glycolysis, the CAC, and OP?

• Glycolysis:
• Direct = 2ATP
• 2 FADH₂ 
• Yields 4 ATP

• ---

  CAC:
• Direct = 2 ATP

• ---

  OP:
• 8 NADH + H⁺ 
• Yields 24 ATP
• 2 FADH₂ 
• Yields 4 ATP

• ---

  36 total ATP molecules per 1 glucose molecule 
• Only 4 ATP are produced directly

Describe the storage capacity (Kcal) of fat compared with CHO.

• Triglycerides in adipocytes (stored fat in cells): 
• 50,000-100,00 Kcal

• ---

  Intramuscular TG (marbling): 
• 3,000 Kcal

• ---

  CHO: 
• 2,000 Kcal

What is lypolysis, the products it produces, and the catalyzing enzyme?

• Lypolysis - Fat breakdown

• ---

  TG + 3 H₂O → Glycerol and 3 fatty acids

• ---

  Catalyzed with Hormone Sensitive lipase (HSL)

What are two fates of glycerol?

• If glycogen is low: 
• Glycerol → Glucose 
• Process of gluconeogenesis

• ---

  If ATP is req’d: 
• Glycerol → 3-phosphoglyceraldehyde → 
• → CAC (via glycolysis) → OP → 1 glycerol = 
• Yields 19 ATP (from glycerol backbone)

Name the end product of b-oxidation (AKA fat metabolism in mitochondria).

• Acetyl-CoA
• Splits 2 carbon-acyl fragments from fatty acid chain 
• → Joins the 2 carbon-acyl fragments with co-enzyme A

Compare ATP production from CHO vs. fat on both rate and amount of production.

• Fat:
• 18 chain FA will produce 147 ATP
• Yield per molecule of neutral fat: 
• 19 ATP (from 1 molecule glycerol) + 441 ATP (from 3 molecules of 18-chain FA) = 460 ATP
• Occurs during light exercise, but not with high intensity
• Due to HI needing ATP faster than β-oxidation / lypolysis can provide.
• Only delivered / utilized ½ as fast as CHO

• ---

  CHO:
• Metabolizes twice as fast as fat.
• 1 mole of glucose yields 36 ATP 
• 38% efficient of glucose oxidation
• Oxidative phosphorylation is 90% of ATP production
• 40% efficiency

Describe situations when protein becomes a source of ATP generation.

• Long-term endurance
• Chronic glycogen depletion

What is the difference between glucogenic and ketogenic amino acids?

• Glucogenic: 
• Can either be oxidized or converted to glucose

• ---

  Ketogenic: 
• Converted to acetyl-CoA and can either: 
• Become TG or 
• Enter CAC.

• ---

  Some AA enter CAC directly
• Deanimation occurs for all  possibilities
• Removal of NH₂ 

What is deamination?

• Removal of nitrogen (amine group : NH₂) from AA
• Liver is main site 
• → NH₂ excreted in urine
• H₂O follows NH₂ 
• → Dehydration occurs
• High protein diet requires more water intake

How is excess CHO intake converted to fat?

****

• If glycogen stores in liver and muscle are saturated, excess CHO intake will convert to fat for storage
• Via Pentose Phosphate pathway

• ---

  Excess CHO converted to pyruvate 
• → Pyruvate enters mitochondria 
• → Excess citrate produced 
• → Converted out of mitochondria to fat in cytosol.

Can it be counter productive for a strength athlete to consume large quantities of protein?

• Yes, it can be stored as fat (cytosol in cell) via excess citrate production in CAC
• Excess AA absorbed and sent to liver 
• → Deaminated to pyruvate 
• → Excess citrate produced 
• → Converted out of mitochondria to fat in cytosol & 
• Converted to fatty acids.

• ---

  Also dehydration can occur from excess protein diet

What is meant by fat burns in a CHO flame? 

• Fat is converted to acetyl-CoA 
• Via β-oxidation
• → Acetyl-CoA must combine with Oxaloacetate to begin CAC.
• → Oxaloacetate must be generated from CHO via Pyruvate Carboxylase.

• ---

  Therefor, any fat metabolism requires some level of CHO metabolism and fat can never be burned exclusively.

Composition of air at sea level and altitude.

- 20.93% at sea level and high altitude

- ↓ total barometric pressure with altitude

o Leads to ↓ PO₂ in air

o Less pressure gradient between air and lung → Less likely to flow into lungs

§ ↓ PO₂ in lung → PO₂ ↓ in bloodstream

- Blood transported at altitude has less O₂ bound to the Hb

↑ elevation = ↓ oxygen in Hb

Describe Henry’s Law. How does the law relate to the amount of gas you can dissolve in blood?

- ↑ Diffusion - ↑ solubility, pressure gradient, & surface area

↓ Diffusion - ↑ wall thickness

What is a concentration gradient and how does it influence the movement of gas molecules?

• Pressure of a gas in one area vs another area.
  
• Increased gradient = increased diffusion

Understand and explain the oxygen-hemoglobin dissociation curve as it relates to altitude exposure.

- As altitude increases, oxy-hemoglobin decreases

- Takes 2 weeks to adapt to altitude up to 7,000 feet

o Additional week for every 2,000 feet above 7,000

What is the ventilatory response to being at altitude?

- Cannot get as much O₂ per breath due to ↓ pressure gradient

o Breathing rate ↑ (hyperventilation) due to drop in arterial PO₂

Since pulmonary system is not a limiting factor for maximal exercise → Not much change at altitude

Explain the CV responses to both submaximal and maximal exercise.

- CO = HR x SV

- Sub-max:

o Sub-max HR ↑ 50% above sea level HR

§ With each beat (SV) the blood carries less O₂ to working SM

§ (Requires much higher HR to do same work load of sea level)

· Due to ↓ in arterial PO₂

o Cannot load as much O­₂ on to Hb

o SV may decrease slightly

§ Due to dehydration effect via hyperventilation → losing H­₂O in breath

o Net effect on sub-max CO is ↑ by as much as 50%

o a-vO₂ difference at altitude

§ ↓ O₂ per 100 mL of blood

§ Extraction of O₂ still = 50%

· a-vO₂ difference ↓ at altitude due exclusively to less O­₂ in arterial blood

CO ↑ at altitude

o [Large ↑ in CO] x [small ↓ a-vO₂ difference] = [Large ↑ VO₂]

Higher oxygen volume needed to do same workload of sea level

- Maximal:

o HR → No change

o SV → No change

o CO → No change

o A-vO₂ difference = ↓

o CO x (a-vO₂ difference) = VO₂-max ↓

§ VO₂-max ↓ 1.5% - 3% for every 1,000 feet above 5,000 feet

· Mt. Everest = 70% ↓ in VO₂-max

o Sea level = 45 mL/kg/min

o Everest = 13.5 mL/kg/min

Decreased VO₂ Max resulting from A-VO₂ difference

Understand and explain the Fick equation.

VO₂ = [CO] x [a-vO₂ difference]

- Oxygen extraction is 50% regardless of altitude

o Lack of oxygen delivery at altitude results in ↓ [a-vO₂ difference]

§ Due to drop in arterial PO₂

NOT due to exchange difference since it still remains 50%

Describe changes to blood (i.e., PV and EPO) that occur at altitude.

- Erythropoietin (EPO):

o Responsible for RBC formation

o Synthesized by kidney → RBC release from bone marrow ↑

§ ↑ within 15 hours due to ↓ arterial PO₂

· Results in ↑ RBC number (polycythemia)

o Polycythemia = ↑ Hb

§ Instantly makes a better endurance athlete (in moderation)

§ Altitude ↓ % saturation of O₂ on Hb

· Polycythemia makes up for ↓ % saturation

- ↑ in PV due to ↑ in EPO → Keeps blood from becoming too thick

↑ altitude = ↓ O₂ saturation on Hb → Corrected with ↑ RBC → makes up for ↓ saturation

Describe the cellular adaptations. What is 2,3 DPG? How does it function?

-

↑ capillary density (months)

o ↓ O₂ diffusion distance

o ↑ transit time (going past working SM)

- Small ↑ to mitochondrial density (months)

- ↑ aerobic enzyme activity (i.e. Succinate Dehydrogenase, Citrate Synthase) (weeks)

- ↑ concentration of 2,3 DPG (oxygen lube) (2-4 weeks)

- 2,3 DPG helps O­₂ unbind from Hb so that O₂ can be utilized by SM

o Yields ↑ a-vO₂ difference

§ Dumping more O₂ off into the tissue thanks to 2, 3 DPG

All adaptations are driven by the PO₂ ↓

Describe the principle of Live High, Train Low (LHTL).

- Altitude is an ergogenic aid → Helps human performance without cheating

- Positive benefits of chronic altitude exposure:

o ↑ EPO à ↑ RBC count à ↑ O₂ delivery to tissue

o ↑ capillary density à ↓ O₂ diffusion distance

o ↑ mitochondrial density à Enhanced aerobic metabolism

o ↑ aerobic enzyme activity à Enhanced aerobic metabolism

o ↑ concentrations of 2, 3 DPG à Enhances O₂ delivery into the tissue

- Drawbacks:

o Cannot train at same exercise intensity as sea level

o Sea level = train at 78% of VO₂-max

o Altitude = train at 39% of VO₂-max

§ 50% ↓

o Training at altitude causes detraining

- Live high – get benefits of altitude exposure

- Train low – avoid drawbacks

How does an athlete accomplish LHTL, and is it an effective training paradigm.

-

Natural environments:

o Live at altitude and drive to sea level to train

- Artificial environments:

o Hyperbaric chamber

§ ↓ barometric pressure

· true simulation of altitude

o Altitude tent:

§ ↓ O₂ %

§ Same barometric pressure as sea level

· Less realistic simulation of altitude

· More time spent inside tent = greater benefits of positive adaptation

- Yes, this is an effective training paradigm

- Minimize amount of time spent at sea level

o Only down to train

- Minimal elevation for performance benefit is 6,000 feet

o 6,000 feet = PO₂ of 60mmHg

§ Threshold stimulus for ↑ EPO production

- Measurable effects of LHTL can be seen in as little as 8 full days

Understand orthostatic hypotension. How does this affect astronauts?

-

Orthostatic hypotension: large drop in BP upon standing

o More frequent in those with naturally low BP

o Particularly common in paraplegic / those in wheelchair

- For astronauts:

o Affects after return because in zero gravity blood doesn’t pull to legs (puff upper body and face)

Upon return the blood pressure is thrown off from more blood in legs

Be able to describe human and animal models for microgravity.

-

Human models:

o Head-down bed rest

§ “Removal” of gravitational pressure (spine and venous return)

o Wheelchair confinement and paraplegics

o Immobilization

§ Casting of limbs to remove load but not recruitment

· Arm in cast at 75-80 degrees can still be loaded, but not recruited (weighted)

o Parabolic flights

§ Vomit comet

- Animal models:

o Hind limb suspension

§ Used to remove mechanical load of rodent hind limb muscles

Impact of no load on SM → Major atrophy

Explain mechanism of microgravity-induced fluid loss (i.e., plasma volume).

-

Decreased fluid volume

o Fluid shift toward upper body due to no gravity

o Heart temporarily enlarges to handle “blood flood” (eccentric hypertrophy)

§ EDV & venous return ↑

o Body eliminated perceived excess fluid/blood volume via:

§ ↑ urine output

§ ↓ thirst

Both result in decreased total body water

How is heart size affected in microgravity? How does this adaptation occur?

-

Overall reaction in zero gravity is a decrease in heart size (all 4 chambers) after initial increase

- Heart atrophies for the remainder of time in zero gravity

Due to not working against gravity (no mechanical load)

Describe how changes to RBC number occur.

- RBC count ↓ in microgravity

- Hematocrit (RBC : Plasma Volume ratio) remains similar

o If no RBCs were lost, hematocrit would ↑ (due to ↓ plasma volume from ↑ urine output)

RBC ↓ and Plasma ↓ = Same ratio

o

- RBC count ↓ due to ↓ EPO (Erythropoietin)

o Kidney does not produce as much EPO during microgravity since there is less stimulus on bone marrow

o EPO drops almost 50% within 2 days of microgravity

o Upon return to earth, EPO levels shoot up to ~36 (mUnits/ml) in first day

Decrease and level off to around 20 (mUnits/ml) over 2 weeks

What are the bone adaptations to microgravity?

-

1% loss per month in bone mass during microgravity exposure

o Law of initial value for women → Start with less, lose less

- Due to loss of calcium

o On earth, small intestine absorbs 250-500 mg of Ca²⁺ for every 1000 mg consumed

§ Far more calcium in dark leafy green vegetables than dairy

o In microgravity there is ↓absorption of Ca²⁺ and ↑ fecal excretion

§ No stimulus (load on bones) to utilize the calcium

· Weight bearing aerobic exercise, or resistance training is the stimulus required to promote calcium synthesis.

· → no exercise / training = expensive poop

· → Important for woman past 50 to lift weights to prevent bone loss

Normal gravitational loading promotes Ca²⁺ absorption

Describe changes, and mechanisms for, the decreases in skeletal muscle CSA and fiber type transformations.

-

Microgravity virtually eliminates load on anti-gravity muscles:

o ↓ muscle mass / CSA in only 11 days of microgravity exposure

o ↓ in force production (strength)

§ Force goes down because mass goes down

§ Major atrophy takes a while to recover from in general

· 2 weeks post-mission = only 85% maximal explosive power compared to pre-mission

o Alters MHC (myosin heavy chain) isoforms in an effort to maintain power

§ After 11 days microgravity exposure:

· ↓ in type I fibers

· ↑ in type IIa fibers

· No change in IIx fibers

§ ↓ Power due to force ↓ a lot

Slight ↑ in velocity due to changing from type I fibers to type IIa fibers

Be able to discuss the general time course of changes (i.e., what happens first), CV, bone, muscle, and fluid loss

-

Fluids (blood) falls first (10%) – several days

- Muscle mass falls second (15-18%) – Approx. 2 weeks

- Bone mass falls slowest (15-17%) – One to five months

o Changes occur from soft tissue to hard

- Cardiac index of deconditioning will increase inversely to blood

Know that it increases since it is Deconditioning

Discuss the current countermeasures that are used during space flight.

-

Non-motorized treadmill for walking and running

o Harness and bungee tether system

o Creates the effect of 0.5 to 0.7 g

o Monitor HR data and sent to Johnson space center in Texas via telemetry

o Alters biomechanics of gait, which reduces ability to maintain target HR

§ → Due to difficulty to walk / run on

- Cycle ergometry / human centrifuge

o Generates gravity , but downfall is the size of it

o Centrifuge produces >1g via rotation

o Two pedal rotations moves you to 360 degrees

o Generates a maximum of 5 g

§ 7 g makes most people faint

o Frequent use can help maintain good amount of muscle mass and blood volume

o Exercise plus g acceleration → augmented HR compared with exercise alone

o Mechanism: increased g pulls blood to lower extremity causing heart to work harder to distribute blood → increased load

o Could attenuate heart atrophy

§ Pulling blood AWAY from heart increases load by increasing BPM

- Rowing

- Upper and lower body multi-joint resistance exercise

o Hydraulic resistance

o Thera-bands / bowflex type machines

o Mechanisms of action

§ Load on bone → increased Ca²⁺ absorption

§ Load on skeletal muscle → increased CSA

· If not increased, then at least maintain muscle

List and describe the mechanisms of heat gain and heat loss.

-

Heat gain:

oBasal metabolic rate:

§ The lowest metabolic rate necessary to sustain life

§ Metabolism (burning of calories) only 20% efficient

§ Heat is the major byproduct of metabolism

oMuscular activity

§ Increased metabolism due to increased activity

oHormones

§ Can ↑ or ↓ metabolic rate

· Example: LH ↑ core temperature by ~ 2 degrees Celsius

oThermic effect of food:

§ Following meal breakdown and storage of food yields ↑ heat production

oPostural changes:

§ Sustained muscular contractions with standing

· Using more energy by contraction posture muscles

oHeat loss:

§ Radiation → Gaining of heat without direct contact

· Ex: heat gain from sun

§ Conduction → Loss/gain of heat via direct contact

· Ex: heat from stove to pan or from human to cold object

§ Convection → Loss/gain of heat to air or water around you

· Ex: windy day, hot tub, or cold lake

§ Evaporation → Loss of heat via evaporation of sweat

· Sweating is NOT what cools you off, it is the evaporation of sweat that cools

Harder to evaporate sweat at higher humidity since there is a higher gradient to go against

What is the primary mechanism of heat loss in high temperatures?

-

Evaporation is the only means to lose heat and depends upon:

o Surface exposed

o Temperature and relative humidity

o Air currents

- Sweat must evaporate to be effective

o Importance of fans (air circulation) in a gym to help evaporate sweat

Radiation, conduction, and convection are all ineffective

Describe ways to conserve heat and disperse excess heat.

-

Conservation:

o Vascular adjustments

§ Cutaneous (right below skin) cold receptors constrict peripheral blood vessels

· Periphery → Core

· Conserves heat, prevents blood from going to periphery, keeping core warm

o Muscular activity

§ Shivering (skeletal muscle contraction)

o Hormonal output

§ Epinephrine and Norepinephrine (short term)

§ T₃ (active form) and T₄ (thyroxin – secreted by thyroid)

- Dispersion:

o Circulation

§ Shunt blood to surface (skin) 15-20% of CO is directed to skin in extreme heat

· About 1/5 of blood goes to skin to vent heat

o Evaporation

§ Sweating begins within first 30 sec of extreme exercise

§ Cooled blood returns to core to absorb additional heat

o Hormonal adjustments

§ One bout of exercise in heat

· Aldosterone ↑ yields sodium conservation → more dilute sweat

Water follows sodium

Describe hypothalamic regulation of body temperature

-

Regulation of body temperature

o Heat sensors (skin) sense environmental heat stress and feedback to hypothalamus

o Hypothalamus signals peripheral vessel dilation and sweating

How does a fluid volume shift (i.e., ECF and ICF) help to attenuate the sweat-induced reductions in plasma volume?

-

Circulatory adjustments

o Redistribution of blood flow to periphery

o Loss of plasma volume via sweat

§ Reduced SV

§ Effort to maintain CO → Sub max HR is ↑

· Cardiac drift

§ Maximal exercise CO is ↓ as HR can no longer compensate

§ Blood to periphery + ↓ plasma volume = ↓ EDV → SV ↓

§ Performance max test can get true HR

· A true max HR can be overcome during cardiac drift

o Attempt to maintain cardiac output

§ Plasma volume (PV) is ↓

§ Attempt to restore PV via shift of fluid from ECF (outside of cell) to ICF (inside of cell)

§ Shift partially restores PV

· Definitely not a long term solution

· Much less effective in man than women since men have a disadvantage for keeping themselves cool

Cannot compensate for massive sweat-induced fluid loss

Describe the performance-related decrements as a result of dehydration.

-

Dehydration:

o Thirst mechanism is inefficient to maintain hydration

o One hour moderate exercise = 0.5 to 1.0 L of sweat loss

o Dehydration:

§ Compromises evaporative cooling (less PV to move to periphery)

§ Decreases sweat rate

- For every 1 L of sweat loss, HR increases 8 bpm

- Most people typically are 2% dehydrated everyday

- Monitor urine color

- 3% dehydration (4.5 lbs on 150 lb person) during 1 mile run

o 3% performance decrease

- 4% dehydration (6lbs on a 150 lb person):

o Yields 50% ↓ in time to exhaustion

22% ↓ VO₂ max

Is glycerol effective?

-

Endurance athletes have ↑ blood glycerol

- Causes:

o ↓ urine output

o CHO preservation

§ Glycerol is component of triglycerides → burn more fat as fuel

· Carnitine palmytyl transferase → Beta oxidation

Animal and human studies show SOME improvement in hydration levels and performance

Why does a sports drink with an osmotic load not quench thirst?

-

Sports drinks contain Na⁺ → Stimulates thirst → Drink more → Rehydrate better

o Body wants to stay within a very narrow sodium range

o Typical sports drink contain 10-25 mmol/L of Na⁺

Which is better to drink during long-term endurance events, Gatorade or water?

- Water is not bad, just not optimal for rehydration

o If exercising more than 60 minutes → Drink Gatorade

Much better for rehydration

What is the optimal way to become heat acclimatized?

- 2-4 hours per day of heat exposure

- First few sessions include 15-20 min of low intensity work

Must be adequately hydrated

What physiological parameters are beneficially altered by heat acclimatization?

-

Graph explanation:

o Initial: rectal temp ↑, HR ↑, sweat loss ↓

o With time: rectal temp ↓, HR ↓, sweat loss ↑

§ Sweat loss goes up, causing more evaporation, bringing body temp down

§ Getting used to heat causes less stress on the body, bringing HR down

- Mechanism:

o Increase in fluid regulatory hormones

§ Aldosterone – Na⁺ conserving ↑ (aids in H₂O retention)

§ Vasopressin – H₂O retention ↑

o Increase in total body H₂O

§ ↓ rectal temp – due to more H₂O to store heat (car radiator)

§ ↓ HR – due to increased PV

↑ sweat rate – due to ↑ total body water

How does training status (i.e., level of fitness) influence acclimatization?

- With fitness:

o Sweating begins at lower core temp

§ Begins sooner after onset of exercise

o Produce ↑ volume of more dilute sweat

o PV ↑ (due to ↑ in aldosterone and vasopressin)

↑ skin (heat dispersion) and GI (gastric emptying) blood flow

Does gender influence acclimatization?

- No

- Women sweat less than men, despite having more heat activated sweat glands per unit area of skin

- Sweat smaller volumes

- Begin sweating at higher core temp

- Tend to have larger external surface area per unit of mass

Favorable to dissipate heat via convection (loss of heat to air)

Describe heat cramps/heat exhaustion/heat stroke.

-

Cramps:

o Likely related to:

§ Substantial electrolyte loss due to sweating

· Loss of Na⁺ and K⁺ usually during exercise

· Loss of Ca²⁺

§ Hypnatremia (excess H₂O intake)

· Diluting sodium too much

o Treatment:

§ Salt or electrolyte pills = potential stomach distress

§ Electrolyte drinks = better solution

- Exhaustion

o Related to H₂O volume depletion

o Reduced peripheral blood flow leads to beginning of decreased sweat output

§ Initiation of hypothalamic regulatory breakdown (hypothalamus shutdown = dead)

- Stroke

o Most serious heat stress condition

o Requires immediate medical attention

o Absence of sweating, skin becomes dry and hot

o Core temp > 105 F

o Hypothalamus shutdown = complete loss of thermoregulatory function

§ Body doesn’t know what temp it is or how hot → Stops sweating

o Diagnosis

§ Blood sample assay for constituents not normally found in blood

Liver mitochondrial and cardiac enzymes due to cell lysis (explosion)

Are humans better adapted to handle heat, cold water, or cold air?

- Humans have less capacity to acclimate to cold than to heat

o Much more population density around hot places vs cold

- Water dissipates heat 25x faster than air

o Submax swimming at 64 F requires additional 500 ml/min of O₂ compared to 79 F

§ Due to shivering

o Can become hypothermic in <1 hour in 67 F H₂O

Clothing does not insulate in H₂O

List the means of heat loss in a cold environment.

-

R Radiation – lower environmental temp than skin temp

o Heat given off to environment

- Convection – wind carries away heat (wind chill)

o Standing outside at 45 F vs riding a bike at 45 F

Evaporation (sweat) and conduction (hand to cold surface) not major heat loss factors

List and describe the mechanisms of heat production in a cold environment.

-

Exercise

o High intensity produces adequate metabolic heat (moving green house)

§ Metabolic heat is byproduct of inefficient metabolic processes

· Keeps you warm in the cold

o Convective heat loss

§ Riding is different than running in the cold due to heat loss from convection

· Need to wear more clothes when riding or working at higher intensity

- Eating (thermic effect of food)

o Breakdown of CHO, fat, and protein requires shunting of blood to stomach (core)

§ Converting foodstuffs into storage forms of fuel

· Glycogen and Triglycerides

§ High fat density food increases duration of thermic effect

- Shivering

o Rapid skeletal muscle contraction

o Begins at trunk and jaw

o Can be at intensity of ~ 10.5 – 18.0 ml/kg/min

§ Intensity determined by body mass

§ Large man can shiver at a higher intensity than an 80 yr old woman who is exercising

- Vasoconstriction

o Surface arterioles constrict, ↓ skin blood flow

o Attempt to ↓ heat loss via convection and radiation

o Less gradient between skin temp and environmental temp

§ More fat = lower skin temp as arterioles are “buried” further beneath skin

Fat people’s skin feels colder in the winter (it is colder)

Describe cold-induced vasodilation.

-

Occasional bolus of blood to extremities (fingers and toes) in attempt to eliminate frostbite and decrease cell damage.

Where blood goes, heat follows

Body responses to cold.

-

Resting HR does NOT change

- Resting SV ↑

o ↑ venous return as a result of ↓ skin blood flow

- Cardiac output ↑

- Cold water immersion

o Instant ↑ in norepinephrine (instant ↑ in HR, BP, and ventilation)

§ Due to rapid ↓ in T_sk

Results in vasoconstriction

What are the modifiers to cold environment?

- Body composition

o Less fat = more T_cr falls

o More fat = more T_sk falls

§ Skinny = core (down) → Fat = Skin (down)

- Physical fitness

o With ↑ VO₂ max, metabolic rate rises (shivering response)

o Potentially due to ↑ muscle mass

- Gender

o Women lose heat rapidly (compared to men with same fat %)

§ Less muscle mass

More surface area

Describe the mechanisms for acclimatization to a cold environment.

-

Metabolic:

o ↑ heat production via ↑ shivering

- Insulation response:

o ↑ in vasoconstriction = ↓ in T_sk (skin temp) = less radiation and convection heat loss

- Sympathetic nervous system:

↑ norepinephrine = ↑ vasoconstriction and ↓ skin temp (and ventilation ↑)

Should college students drink alcohol to stay warm in the Shoe? Defend your answer.

-

No

- Decreased blood glucose (insulin response) → ↓ shivering → ↓ heat production → T_cr (core temp)

No sugar → no fuel to shiver → giving off excess heat via vasodilation (alcohol) → Drop core temp

Define and give examples of endocrine, paracrine, and autocrine.

-

Endocrine:

o Secretion that acts on any tissue in the body (typically distal from secreting gland) with appropriate receptor

§ Hypothalamus

- Paracrine:

o Secretion that acts on tissues in the local area

§ Secretions from pancreas acts on the spleen

- Autocrine:

o Secretion that acts on the tissue that provided the secretion

SM releases calcium telling it contract

Describe and give an example of the cAMP second messenger system.

- Binding of hormone to receptor sites may activate the enzyme adenylate cyclase

o Plasma membrane level

- Andelylate cyclase catalyzes the reaction

o ATP → cAMP

- cAMP then acts as a second messenger to activate protein kinases that alter cellular activity

o Ex: Glucogon promotes glycogen degradation to glucose within the muscle

ATP -->cAMP-->Protein kinase

- Hormones in the blood bind to receptors in the lipid bilayer on surface of the cell

- Hormone bonds to receptor

o Activates adenylate cyclase in the cell (hormone turns on adenylate cyclase)

- Adenylate cyclase stimulates ATP to turn into cAMP

o cAMP is 2^nd messenger INSIDE the cell

o → Tells protein kinase to start working

o → Glucogon promotes glycogen → Glucose degradation within the muscle

The effectiveness of a hormone depends upon what three things?

- Hormone concentration in the blood

- Sensitivity of receptor for the hormone (i.e. type II diabetes)

o ↑ regulation

o ↓ regulation

Number of target cell receptors

Concentration of a hormone in the blood is dependent on what five things?

-

Quantity of hormone synthesized

- Rate of secretion into the blood

- Rate of catabolism (half-life or consumption)

- Quantity of transportation proteins present for some hormones

o GH – might secrete a lot of growth hormone but lack the transporter to carry it around, GH is not utilized or effective

Fluctuations in plasma volume (dilution or concentration)

Describe the cellular actions of both IGF-1 and GH.

- IFG-1 and GH combine to:

o Promote cell division – muscle hypertrophy

o Facilitate protein synthesis

§ ↑ amino acid transport into cells → transports protein into cells

§ Stimulate RNA formation to ↑ protein synthesis

o Slow CHO breakdown

§ ↓ insulin mediated cellular glucose uptake

· → instead gets taken up by SM and stored as glycogen

§ ↑ glycogen storage via gluconeogenesis

o Increases lipolysis

§ Stimulate FFA release from adipocytes

· ↑ reliance of fat as fuel

o Once FFAs and glycerol leave fat cells and get into blood they are able to be used as fuel and broken down

o GH will be released as long as you’re exercising, but the amount of GH released is dependent on fitness level and exercise intensity level

§ The fitter you are and the higher relative exercise intensity you work, bigger release of GH

GH can stimulate muscle hypertrophy but target organ is the liver and liver releases IGF-1 (insulin like growth factor) which is very involved in muscle hypertrophy

Describe the negative feedback loop of TSH (thyroid stimulating hormone).

- Secreted by anterior pituitary gland

o Regulates hormone secretion by thyroid gland

- Acts on thyroid

o Thyroid hormones

§ T3 (triiodothyronine) and T4 (thyroxine)

§ Function to ↑ metabolism of cell via ↑ enzyme activity

§ Assist with growth and development – thyroid levels decrease with age ↑ in T4 with exercise

- TSH comes from anterior pituitary

- Causes release of T4 from thyroid

o ↑ metabolism

- Feeds back negatively on pituitary to stop release of TSH

Due to ↑ in T4 and metabolism

What are the primary actions of thyroid hormone (i.e., T3 and T4).

- Increase in metabolism via ↑ enzyme activity → Increasing heat → Metabolizing fuel faster

- Assist with growth and development

How does ADH affect hydration levels?

- Anti-diuretic hormone (vasopressin) → CONSERVE water

o Increases water reabsorption by the distal tubules of the kidneys

o Exercise ↑ ADH secretion due to sweating

§ Losing a lot of water during exercise but if intensity is high enough, AHD will be secreted to help preserve water

· This is why with prolonged exercise if not hydrating properly, sweating will slow down to dehydration → leading to increased body temp → Danger of heat stroke

· ↓ secretion in response to fluid overload yields ↑ to urine output

Leads to peeing out less and sweating more

Be able to explain in detail how epinephrine alters glycogenolysis and lypolysis.

-

Epinephrine and norepinephrine both come from adrenal medulla (catecholamines)

o Epinephrine:

§ ↑ glycogenolysis – glycogen to glucose

§ ↑ lipolysis via ↑ HSL (hormone sensitive lypase) – breaking down fat

o Norepinephrine:

§ ↑ lipolysis via HSL

o Both epi and norepi ↑ with ↑ exercise intensity – as intensity ↑ you need more fuel, so secretion ↑

o Both epi and norepi deal with utilizing things as fuel

§ Important to exercise

Describe the relationship between epinephrine and lactate.

- Epinephrine rises with exercise intensity (75%) intensity

o Utilizes glucose

Since lactate ↑ with intensity and is a CHO → Epinephrine uses lactate as fuel

What is the renin-angiotensin-aldosterone cascade? How does it influence plasma volume?

-

Adrenal cortex

o Blood flow to kidney is ↓ during exercise

o → kidney releases renin

o → activated production of angiotensin II and III

o → A-II and A-III stimulate aldosterone secretion from adrenal cortex (on top of kidney)

o → aldosterone stimulates Na⁺ and H₂O reabsorption in distal tubules of kidneys

o →Na⁺ and H₂O ↓ and K⁺ ↑ in urine

o → plasma volume, CO, and BP ↑

o Organ blood flow is ↓ during exercise → less blood in kidney

o Causes kindey to release renin → causes activation of AII AIII production

o Stimulates adrenal cortx to secrete aldosterone

o Aldosterone causes body to reabsorb Na⁺ and water

o → Urine has ↓ water / Na⁺

§ ↑ K⁺ in urine

o → PV ↑ (↑ EDV due to water reabsorption)

o → CO ↑ (due to ↑ EDV)

→ BP ↑ (due to ↑ EDV so higher pressure)

Through what pathway does cortisol increase glucose availability?

What are the pancreatic hormones? From what cell types are they secreted? What is their action?

-

Insulin and glucagon → Function to regulate blood glucose

- Insulin:

o Secreted from beta-cells of pancreas at high blood sugar

§ Regulate glucose entry into nearly all tissues

§ Promotes glycogen synthesis (storing glycogen in liver and SM)

- Glucogon:

o Produced at low blood glucose

o Secreted from alpha-cells

Promotes glycogenolysis (breakdown of glycogen)

Describe the mechanism through which insulin/exercise promotes glucose entry into skeletal muscle cells and liver.

- Insulin activates glucose transporter protein in SM (glut-4)

o Glut-4 is responsible for glucose transport across plasma membrane

- Insulin causes movement of GLUT-4 from center of cell to PM

- Once at PM, GLUT-4 binds with glucose to transport it into cell

o Exercise causes the same events (because of SM contraction)

§ Contraction causes uptake of GLUT-4 protein

GLUT-4 → Reason insulin not needed during exercise

How is the insulin response to carbohydrate intake different between rest and exercise? Explain your answer.

- During prolonged exercise, blood insulin ↓

o Epinephrine ↑ with exercise

o Inhibits insulin release from pancreas

- CHO intake during exercise minimizes insulin as compared to CHO intake at rest

During exercise glucose transported into cell via contraction-induced GLUT-4 translocation

Describe the differences between type I and type II diabetes.

-

Type I:

o Born with condition

o Severe compromise in production of insulin

o Auto-immune dysfunction → Beta-cells attack themselves

o Requires exogenous insulin

- Type II:

o Typically adult onset but not always

§ Happening much younger than ever before

o Skeletal muscle insulin resistance

§ Cells don’t respond to insulin as well but still can be affected by it

§ Causes beta-cells to produce more insulin to overcome resistance

o Slightly compromised insulin secretion

§ Over time beta-cells get burnt out from excess production and just stop producing insulin all together

Normal to high plasma insulin levels

What are the characteristics of Syndrome X?

-

Conglomeration of coronary artery disease factors that have positive loop feedback on each other

o Nutrient excess

§ ↑ saturated fat

o Obesity

o Insulin resistance

o Hypertension

o Dyslipidemia

§ High cholesterol, high glycerol

What are the characteristics of Syndrome X?

Conglomeration of coronary artery disease factors that have positive loop feedback on each other

o Nutrient excess

§ ↑ saturated fat

o Obesity

o Insulin resistance

o Hypertension

o Dyslipidemia

§ High cholesterol, high glycerol

Is exercise beneficial for Syndrome X and type II diabetics?

- Yes:

- ↑ insulin receptor sensitivity

o ↑ fitness requires less hormone release due to ↑ receptor sensitivity

- ↑ caloric utilization

- Encourages weight reduction

- ↑ HDL levels

- ↓ LDL levels

- ↓ blood pressure

What evaluation, of the two discussed in class, is the most appropriate for assessing the PCr system? 

Defend your answer.

• Stair sprinting test is a more accurate PCr measurement since it incorporates the time 
• → Giving actual power output.

• ---

  Power = [Mass (kg) x Distance (m)] ÷ Time (sec)
• Performed up 6 steps, 3 at a time (always use same staircase)
• Typical rise is ~1.05 m
• All participants must start from same distance before first step

• ---

  Jump has low correlation with test scores and ATP-PCr capacity since power is only generated with feet on the ground (only a fraction of the action)

Understand how Wingate test is performed and know the definitions of peak power, relative peak power, and anaerobic fatigue.

• Assesses anaerobic glycolysis
• Substantial lactate accumulation can be close to 20 mMol/L
• Non-weight bearing test on arm-crank or bike
• Workload based on body mass 
• More body mass = more SM CSA
• Pedal as fast as possible for 30 sec.

• ---

  Results:
• Peak power - Highest power generated in 3-5 sec 
• Typically at beginning
• Relative peak power - Peak power ÷ Body mass
• Power curve decline 
• Anaerobic fatigue
• Typically very weak in endurance athletes
• Anaerobic fatigue - Percentage decline in power during test 
• Rate of power decline
• Fatigue index = how fast it drops off

Define MLSS. 

What is the relationship between RA and RD at MLSS exercise intensity?

• Maximal lactate steady state (MLSS):
• Equilibrium between lactate rate of appearance (RA) in the blood and lactate rate of disappearance (RD) from the blood. 

• ---

  (RAIN Rarely Does Fall)

What is the relationship between RA and RD at MLSS exercise intensity?

• RA = RD: Lactate steady state in an equilibrium

• ---

  RA>RD: Accumulation of lactate in blood
• Produced primarily by type IIx fibers

• ---

  RA<RD: Elimination of lactate from blood
• Lactate oxidized by heart, type I fibers (lactate shuttle), converted to glucose in the liver (gluconeogenesis)

Be able to explain how an MLSS evaluation is performed. 

• Test lasts 30 min.
• Lactate values taken throughout, but doesn’t account for first 10 min since [LA] ↑ most in that time.
• Measured via finger blood stick

• ---

  Measured through series of separate constant workload tests
• Day 1:VO₂ Max test
• Day 3: Constant workload test (slightly ↑ intensity than day 1)
• Day 5: Constant workload test (slightly ↑ intensity than day 3 )
• Day 7: Constant workload test (slightly ↑ intensity than day 5) 
• → If drifted above 1mMol more than day 5 → RA>RD → Day 5 result is MLSS

• ---

  Test with highest power output where [LA] does not change by >1 mMol in the last 20 min is the MLSS
• Very reliable, but very time consuming

What is the value of knowing your MLSS?

• Retest every couple months (4-6 weeks ideally) to check for improvements
• Training within threshold of MLSS will increase it
• ↑ MLSS → Higher [LA] can be tolerated without exhaustion

Be able to describe each of the components of the equation for measuring O2 consumption.

• VO₂ (L/min) = (V_I X %O_2I) – (V_E X %O­2_E­)
• (V_I) X (% O_2In) = (Volume inhaled) X ⁽% of oxygen in the air)
• O₂ breathed IN
• (V_E) X (% O_2Ex­) = (Volume exhaled) X (% of oxygen in the air)
• O₂ breathed OUT

• ---

  Subtract expired O₂ from room air = amount of O₂ consumed
• Typical resting VO₂ is 5 L/min

Describe how exercise modality can influence VO2max.

• Variations depend on:
• Muscle mass used (arm-crank vs. bike vs. treadmill vs cross country skiing)
• Skill of individual for specific modality
• Coordination is required to skillfully perform certain activities
• Lack of skill requires more energy consumption

• ---

  Sedentary:
• Treadmill - Most individuals rate highest VO₂ max since everyone knows proper mechanics of walking/running  
• Most reliable

• ---

  Cyclist:
• Bike or treadmill will provide highest VO₂ max
• Skill on bike will make up for more SM used in running
• Professional cyclists are the exception of treadmill having highest VO₂ max value

Explain the criteria for VO2max achievement.

• Primary:
• Leveling off of VO₂

• ---

  Secondary:
• Blood lactate > 8mMol/L
• Reached age prediction
• Max HR
• VCO₂/VO₂
• Respiratory exchange rate (RER) > 1.15
• Starts at 0.7 (burning fat as fuel)
• 1.0 is burning only CHO as fuel

Have a “feel” for how much genetics and training influence VO2max.

• 50-60% is determined by heredity

• ---

  Going from sedentary to highly fit can ↑ VO₂ max by 25%

Describe the mechanisms for how gender influences VO2max.

• Males ~15-30% higher VO₂ max

• ---

  Body composition:
• M ~ 15% fat : F ~ 25% fat
• M have greater SM mass
• SM is what consumes O_2­

• ---

  Hemoglobin (Hb):
• Carries O₂ on RB
• M have ~ 10-15% more due to ↑ testosterone

Be able to convert from relative to absolute VO2max and vice versa.

• Absolute: L/min

• ---

  Relative: mL/kg of body mass/min
• At max consumption
• Body mass = lean tissue body mass (which consumes O₂)
• Makes it possible to compare different body sizes

• ---

  Conversion of relative to absolute: 
• Multiply by kg of body mass and 100 mL

How does age and level of physical activity interact to influence VO2max?

• Decreasing body fat % will ↑ relativeVO₂ max
• Does not change absolute VO₂ max
• Importance of leanness for aerobic athlete

• ---

  Age:
• Sedentary: ↓ by 10% per decade (after 30)
• Master athletes: ↓ by 5% per decade (after 30)

Be able to describe the four VO2max prediction tests discussed in class. 

Consider what prediction test you would recommend for a variety of different populations.

• All should be second option to VO₂ max test

• ---

  Walking Test:
• 1 mile on level surface
• Measure time
• Measure HR at end
• Consider age, weight, and gender
• Modertely predictive of VO_{2­ max}

• ---

  Step test:
• 3 minutes on 16.25” box
• Both feet up, both feet down = 1 cycle
• Males = 24/min
• Females = 22/min
• Measure HR from 5-20 sec post exercise
• Fitter people recover HR faster
• Requires moderate level of fitness to perform

• ---

  Endurance run:
• 12 min run for distance
• Distance alone gives prediction of VO₂ max
• Less predictive of VO₂ max than walk test
• Due to only consideration being distance covered

• ---

  Sub-max VO_2:
• VO₂ max test (mask and all)
• Any modality
• VO₂ measured
• Subject not taken to max
• HR data taken between 120 and 170 BPM
• Max HR is estimated
• Slow ↑ = fit 
• Quick ↑ = unfit
• Most effective prediction test since VO₂ is actually collected

What is the specificity principle?

• Athletes:
• High intensity anaerobic training can benefit endurance athletes
• Still need adequate training volume to achieve optimum results.
• Adaptation takes place only in trained SM
• Benefit not transferred to untrained SM

• ---

  General fitness:
• Any aerobic training can improve health and cardiac function

What are the mechanisms (enzymes) for how training can improve the PCr system, glycolysis, and aerobic metabolism (CAC/OP)?

• PCr:
• Creatine kinase (CK) and myosin ATPase increase with training
• CK: (PCr + DP) →^CK→(Cr + ATP)
• M-ATPase: (ATP) →^M-ATPase→(ADP + Pi)

• ---

  Glycolysis:
• Endurance training
• ↑ in hexokinase (first step glycolysis)
• ↑ slightly in PFK (most important RLE in glycolysis)
• Resistance training
• Minimal magnitude change if hexokinase and PFK change

• ---

  CAC:
• ↑ in citrate synthase (CS) and succinate dehydrogenase (SDH)
• Due to ↑ in number and size of mitochondria
• Not due to ↑ in function of mitochondria
• Changes only occur with aerobic training
• Resistance training doesn’t use CAC → does not change enzymes

• ---

  OP:
• Exact same as CAC
• Only difference is cytochrome-c & cytochrome-a instead of CS & SDH

What is the magnitude of change one can expect to see in the enzymes?

• For CAC and OP, the enzymes roughly double after 5 months of resistance training

• ---

  ↑ slightly in PFK

How does lactate clearance improve?

• Lactate clearance ↑ in endurance training due to increase RD
• RD ↑ via  ↑ in gluconeogenesis
• oxidation by type I fibers and cardiac cells
• ↑ mitochondria (more mitochondria = more lactate oxidation)
• ↑ number of lactate transporters (must have transporters to deliver lactate to mitochondria)
• ↑ lactate into type I fibers and cardiac cells

Describe the mechanism within b-oxidation for how training increases fat metabolism.

• Carnitine palmityl transferase (CPT)
• Β-oxidation RLE
• Important for cutting up fatty acid carbon chains.
• ↑ in CPT means better ability to use fat as fuel source
• Pre-training levels = 0.48 μMol/g/min
• Post-training levels = 0.86 μMol/g/min

Describe the reversibility principle.

• Detraining occurs rapidly
• 1-2 weeks significantly reduces metabolic and exercise capacity
• 3 months results in total loss

• ---

  20 day confined bedrest resulted in VO­₂ max and stroke volume ↓ 25% each
• ~1% per day for both

Understand all of the anatomy of respiration.

• Air enters trachea 
• Becomes 100% humidified and is body temperature, filtered)
• → Air down to bronchi 
• Point of entry into lung
• → Bronchi branch into bronchioles
• → Air conducted into alveoli 
• Gas exchange occurs in alveoli

• ---

  Conducting zone
• anatomic dead space
• Trachea
• Air transport
• Primary bronchus
• Warming
• Bronchus
• Humidification
• Bronchus
• Filtration
• Bronchi
• Respiratory zone
• Location of gas exchange
• 2.5-3 L
• Surfactant production

Ventilation anatomy and dynamics.

• Lung size varies between 4 & 6 L
• Depends on body size
• Surface area ~ half a tennis court

• ---

  Rest:
• A single RBC remains in pulmonary capillary for 1.0 sec

• ---

  Maximal exercise:
• A pint of blood goes through pulmonary capillaries in 1.0 sec

Characteristics of alveoli 

• Largest blood supply of any organ
• Millions of short, thin walled capillaries lying very close to alveoli
• Permits diffusion of O₂ and CO₂

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  Rest:
• Every minute 250 mL of O₂ out of alveoli into blood
• 200 mL of CO₂ enter alveoli from blood

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  Exercise:
• Multiply by 25

What is Fick’s Law of gas diffusion?  Explain all of the regulators.

• Gas diffusion is dependent on 4 things:

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  Amount of surface “contact” between alveoli capillary (stays constant)
• ↑ “contact” area = ↑ diffusion
• 0.3 μm between alveoli and capillary

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  Pressure gradient between alveoli and capillary (stays constant)
• ↑ gradient = ↑ diffusion
• Changes with altitude

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  Contact area thickness (stays constant)
• Inversely proportional to pressure gradient 
• ↑ “contact” area thickness = ↓ diffusion
• Smoking increases area thickness

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  Solubility of gas
• ↑ solubility = ↑ diffusion
• CO₂ diffuses 20x faster than O₂ due to solubility
• O₂ must bind to RBC
• Mucus in alveoli reduces diffusion of gas
• Dependent on particular gas

How does inspiration and expiration occur?

• Inspiration:
• Diaphragm contracts and lowers
• Primary muscle for inspiration
• Contracts, flattens, and moves ↓
• → Volume of thoracic cage ↑
• →Thoracic pressure becomes 5mmHg < atmospheric pressure
• → Air enters lung
• → During exercise, abdominal & external intercostal muscles contribute

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  Expiration:
• Diaphragm relaxes and rises
• Mostly passive at rest and light exercise due to:
• Recoil of stretched lung tissue
• Relaxation of diaphragm
• During exercise abdominal and internal intercostal muscles forcefully reduce thoracic cavity
• → Volume of thoracic cage ↓
• → Thoracic pressure becomes > atmospheric pressure
• → Air exits lung

What is surfactant and what is the function it plays during respiration?