Muscle Fiber Types and Bioenergetics

Question 1

how do we measure the composition of fiber types?

Answer 1

muscle biopsy and laboratory analysis

Question 2

what muscle fiber type has a bigger diameter?

Answer 2

type IIx

Question 3

characteristics of type I fibers

Answer 3

• contract more slowly
• more efficient
• more mitochondria
• myoglobin (O2 carrier)
• resistant to fatigue
• recruited more frequently than IIa or IIb
• have a high capillary density
• primary fuel is fat and carbohydrates
• ATPase activity = lowest
• colour: dark red
• diameter: intermediate

Question 4

characteristics of type IIb or IIx fibers (fast-twitch glycolytic)

Answer 4

• develop force more quickly
• little aerobic energy supply and rely on anaerobic mechanisms
• fatigue more quickly
• major fuel = creatine phosphate
• ATPase activity = highest
• colour: white
• diameter: wide

Question 5

characteristics of type IIa fibers (fast-twitch oxidative (intermediate))

Answer 5

• have fast twitch characteristics
• possess both aerobic and anaerobic energy generating capabilities
• major fuel = glycogen
• ATPase activity = moderate
• colour: red
• diameter: narrow

Question 6

What is the first law of thermodynamics?

Answer 6

• energy can neither be created nor destroyed, only transfer from one form to another

Question 7

what is bioenergetics?

Answer 7

• the flow of energy in a biological system
• we have energy that we get from different sources that we convert to use in different ways

Question 8

where does our energy/fuel come from?

Answer 8

• 3 main macronutrients (aka substrates)
• breakdown of these ‘substrates’ is referred to as metabolism

Question 9

does exergonic reactions have negative free energy (delta G)?

Answer 9

yes because energy is being released

(endergonic is the opposite)

Question 10

what is catabolism?

Answer 10

breakdown of larger into smaller molecules
- exergonic

(anabolism is the opposite)

Question 11

where does ATP come from?

Answer 11

substrate metabolism

Question 12

what does ATP do?

Answer 12

• muscle contraction
• protein synthesis
• digestion
• active transport

Question 13

more ATP available / produced = ?

Answer 13

greater capacity for movement/exercise performance

Question 14

How does ATP contribute energy for contraction of muscle?

Answer 14

• energizing the myosin head
• phosphate molecule is lysed (cut) and energy is released and goes to the myosin head and allows the cross bridge to go though that power stroke and produce force

Question 15

what is meant by “ATP is a renewable energy source”?

Answer 15

it can be replenished
- ADP can repackage itself into ATP to be used again

Question 16

how does each energy system differ?

Answer 16

these systems differ in the RATE at which they can produce ATP and the CAPACITY / YIELD of ATP they can produce

Question 17

what is required for breakdown of many molecules in the body (catabolic processes)

Answer 17

enzymes

Question 18

what is a sign that a molecule is an enzyme?

Answer 18

it ends with “-ase”

Question 19

what are the three main energy systems?

Answer 19

• ATP-CP (highest RATE of ATP production)
• Glycolysis
• Oxidative (highest CAPACITY to produce ATP)

Question 20

what is the ATP-CP system used for? What is its fuel? what duration of exercise uses this? is oxygen required?

Answer 20

• immediate energy (type IIx)
• very HIGH RATE of ATP production
• VERY LOW CAPACITY of ATP production
• fuel is creatine phosphate
• fuel is depleted after maximal exercise lasting about 10-15 minutes
• oxygen is NOT required
• ATP and PCr are stored intramuscularly