Unit 3 Lecture 24

Question 1

What are the two things that affect muscle performance?

Answer 1

Power and Endurance

Question 2

Power = ?

Answer 2

Speed (velocity) x strength (force)

Question 3

Endurance = ?

Answer 3

Sustained activity (aerobic and anaerobic)

Question 4

What are the three fiber types?

Answer 4

Slow, intermediate and fast fibers

Question 5

Define slow fibers (Type I or SO)

Answer 5

slow contractions - slow myosin ATPase

High resistance to fatigue- relies on aerobic metabolism (high aerobic capacity, many mitochondria, high myoglobin content, dense capillary supply for O2 delivery)

Question 6

Define intermediate fibers (Type IIA or FOG)

Answer 6

relatively fast - intermediate myosin ATPase

Resistant to fatigue - primarily anaerobic (relies on glycolysis, but has higher aerobic capacity than FG fibers)

Question 7

Define fast fibers (Type IIX, or FG)

Answer 7

Rapidly contracts - fast myosin ATPase

Low resistance to fatigue - relies on anaerobic glycolysis (low aerobic capacity, few mitochondria, low myoglobin content)

Question 8

Define myoglobin

Answer 8

Large amino acid protein that binds/ releases one O2 at a time… responsible for muscles red color

Question 9

What is the common muscle composition in humans?

Answer 9

~ 50:50 mixture of fast and slow motor units in muscle

Question 10

Define hypertrophy

Answer 10

Increase number of myofibrils in muscle fibers makes muscles stronger

Question 11

Define hyperplasia

Answer 11

To grow a muscle by adding cells (mitosis)

• Skeletal muscle does NOT grow/strengthen through hyperplasia bc it doesn’t undergo mitosis

Question 12

Define atrophy

Answer 12

When muscles aren’t used -> weaker and lose myofibrils -> smaller muscle