Energy for Exercise

Biological WorkMuscle Contraction *Digestion & AbsorptionGland FunctionEstablishment of GradientsSynthesis of New Compounds

EnergyFirst Law of Thermodynamics

Conservation of Energy – Energy can not be “Created” or “Destroyed”Our body simply transforms energy

AdenosineTriPhosphate

“Fuel” for all processes in bodyFood energy → Rebuild more ATPATP – Chemical, Potential EnergyPhosphate bonds: “High Energy”

Phosphorylation

ATP ←→ ADP + P + ENERGY

CP ←→ C + P + ENERGY

ATP Re-synthesis

Aerobic vs. Anaerobic Energy

Aerobic: O2 requiring energy production

Anaerobic: No O2 required for energy

Anaerobic EnergyATP stores

Creatine Phosphate

Anaerobic glycolysis

ATP – CP Energy System

Small amount of ATP stored85 g in whole bodyMust be re-synthesizedCP: quick energy for ATP reboundCP stored in larger quantities

All out Exercise – 5 to 8 seconds

ATP – CP Energy System

Increasing [ATP – CP]Exhaust ATP – CP stores → AdaptationCreatine Monohydrate supplementation

Creatine MonohydrateWhat it does

Increases intracellular stores creatine phosphate.Increases anaerobic capacityDecreases accumulation of lactic acid*Delays onset of muscular fatigueIncrease water retention in muscle*

Creatine MonohydrateWhat it does NOT do:Make you stronger / fasterIncrease muscle massDecrease body fat %Increase aerobic capacity

Creatine MonohydrateSide Effects?Muscle cramps, pulls, strains, etc.DehydrationLiver / Kidney stressAtrophy of bank account

Anaerobic Glycolysis

6-Carbon Glucose → two 3-carbon pyruvic acidOccurs in “watery medium”5% of total ATP from glucose

1.) Chemical bonds broken

2.) H+ atoms are striped

3.) Two ATP formed

Anaerobic Glycolysis

Glucose

Pyruvic Acid (2)

Energy H+

Lactic Acid (2)

Acetyl Co-A (2)

CO2 & H+

Krebs

CycleCO2

H+

Energy ATP

ATP

Mitochondria

Inter Cellular Fluid

To ETC

Anaerobic

AerobicFatty Acids Amino Acids

Aerobic GlycolysisPyruvic Acid → Acetyl CoAAcetyl CoA → MitochondriaKrebs Cycle

Chemical breakdown of Acetyl CoA & fragments of proteins & Lipids

Frees H+ & Produces CO2

Generates small Amount of ATP

Aerobic GlycolysisKrebs CycleH+ → Electron Transport Chain

ETCH+ + Oxygen → H20 + Energy

Krebs

Cycle

Energy ATP

CO2

H+

Electron Transport

Chain

ATP

2H+ + O-- = H2O

100%

% Capacity of Energy System

10 sec 30 sec 2 min 5 min +

Energy Transfer Systems and Exercise

Aerobic Energy System

Anaerobic Glycolysis

ATP - CP

Aerobic Capacity

Capacity for aerobic resynthesis of ATP

O2 Uptake During Exercise

Oxygen Uptake: Use of oxygen by the cells for aerobic metabolism.

VO2 – ml O2/Kg/min.

VO2 max = Max O2 uptake possible by individualQuantification of Aerobic Capacity

VO2max

VO2max : Max Oxygen Uptake

Further increases in exercise intensity (further energy requirement), results in NO increase in VO2.

Additional energy is produced via anaerobic

glycolysis

VO2max

What Effects Energy Capacity ?

Diet (Glycogen stores, Metabolic State)

TrainingType of training, Altitude

GenderSupplements / DrugsGENETICS

Energy Systems and Exercise

Anaerobic / Aerobic Energy is always being produced

Exercise intensity / duration determines the ratio

Can be estimated with RER

RER aka RQRER = CO2 produced / O2 consumedCarbohydrate: Hydrogen to Oxygen (2:1) → RER = 1.00

C6H12O6 + 6O2 → 6 CO2 + 6 H2OLipid: Hydrogen > Oxygen (2:1) → RER = 0.7

Krebs

Cycle

Energy ATP

CO2

H+

Electron Transport

Chain

ATP

2H+ + O-- = H2O

Lactic Acid

Byproduct of Anaerobic Metabolism.

Glucose

Pyruvic Acid (2)

Energy H+

Lactic Acid (2)ATP

Lactic AcidCauses Fatigue

Irritation of local muscleDecreased pH of cellular environment & bloodstream

Training increases lactate tolerance and decreases lactate formation at any given workload (by 20-30%)

Blood Lactate Threshold

Point at which lactate begins to dramatically increase in the blood stream. (55% VO 2max)

Fatigue increases exponentiallyCaused by increase in anaerobic metabolism → Lactate production

Percent of VO 2 max

25% 50% 75% 100%

[Blood Lactate]

Untrained

Trained

Effect of Training on Blood Lactate / Lactate Threshold

LTLT

What Effects Lactic Threshold ?

GENETICSAerobic CapacityFiber Type

Training (adaptations..next slide)

Physiological )’s with Training (↓ Lactic Acid Build Up)

↑ in capillaries (↑ Density)↑ aerobic enzymes↑ mitochondria (# and size)↑ Pain tolerance to Lactic Acid

Blood Lactate Threshold

Lactate appearance in the bloodstream

POWERFUL predictor of aerobic exercise performance!Higher LT = Better performance; less LA buildup, less fatigue

Lactate ProcessingCori Cycle

Muscle Cell

Lactate

Pyruvate

Liver

Glucose

Lactate

Pyruvate

Glucose / Glycogen

RecoveryRecovery Oxygen Uptake

VO2 stays ↑ after exerciseReplenish ATP – CPReload hemoglobinSupply elevated energy needs to cardiovascular system

Increased O2 need 2o heat

Recovery (cont.)Lactic Acid Removal (Heavy Exercise)

Cori cycleReconversion in muscle cellLactate → Pyruvate → Glucose

Few seconds – few hours

Recovery (cont.)Light activity accelerates recovery

Increased blood flow to muscle, liver, and heartAll can oxidize lactate for energy