06: Power of Muscle Contraction

How is power provided for muscle contraction

• Stored Phosphagens

• Glycolysis

• Aerobic metabolism

Types of phosphagens stored for muscle contraction

• ATP (low)

• Creatine phosphate (high)

How do phosphagens provide energy

Hydrolysis of a phosphate bond

Which phosphagen storage is tapped first for fast muscle contraction

CrP

How is CrP used to create energy

CrP + ADP → Creatine + ATP

Enzyme that is crucial for utilization of CrP

Creatine Kinase

High levels of Creatine Kinase in serum are indicative of what condition

Muscle damage

T/F: supplementing creatine for performance animals is useful

False, a couple extra contractions probably won’t help

Pros of glycolysis for energy generation

• Fast

• Anaerobic

Cons of glycolysis for energy generation

• Low yield

• Produces lactate

When do muscles rely on glycolysis for energy

High intensity, anaerobic activity

Most efficient way to produce ATP

Oxidative phosphorylation

Where does OxP happen

Mitochondria

When do muscles rely on OxP for energy

Low intensity aerobic activity

How does pyruvate get processed in the mitochondria

Loses a carbon to become Ac CoA

How is Ac COA processed in the mitochondria

Fed into TCA cycle

How does the TCA cycle produce energy

Produces electron carriers with hydrogens that are harvested in the ETC

What actually produces the ATP when processing glucose

H+ flowing down concentration gradient at and of ETC through ATP synthase

What happens if pyruvate can’t be fed into the TCA cycle

Gets converted to lactate

Which protein in the ETC is the most saturable (bottleneck)

Q (quinone, ubiquinone)

What is the primary source of ROS in the body

MITOCHONDRIA

Intracellular oxidizable substrates (what to use instead of glucose)

• Glycogen

• TGs

Intracellular oxidizable substrates pros and cons

• Pros: don’t have to mobilize

• Cons: can only store so much

Extracellular oxidizable substrates pros and cons

• Pro: larger storage

• Con: have to mobilize

Different signals for energy mobilization to muscle cells

• Contraction

• Insulin