Physiology of Strength Training

1
Physiology of Strength Training

• Part 1 Muscle Function

2
Skeletal Muscle Anatomy

• 660 muscles
• Approximately 45 of body weight
• 75 water, 20 protein (12 myofibullar and 8
  enzymes, etc) 5 inorganic salts
• Largest organ system
• End organ for the primary support systems
  involved in exercise

3
Skeletal Muscle Anatomy

• Basement membrane outer most membrane
• Plasma membrane or sarcolemma
• Satellite cells between membranes
• growth, development, adaptation
• under stress they are responsible for hypertrophy
  and hyperplasia
• Multi-nuclei
• 200-300 nuclei per millimeter
• 85-95 within the scaroplasm
• 5-15 in the basement membrane
• Tremendous potential for gene alterations

4
Skeletal Muscle Anatomy

• Muscle
• Fascicle
• Fibers

5
Skeletal Muscle Structure

• Epimysium, Endomysium, and Perimysium converge to
  form tendons and are very elastic

6
Skeletal Muscle Anatomy

• Muscle
• Fascicle
• Fibers
• Myofibrils
• Myofilaments
• Actin
• Myosin

7
(No Transcript)
8
Skeletal Muscle Anatomy
9
Skeletal Muscle Anatomy -Myofibrils
10
Skeletal Muscle Anatomy Sarcomere
11
(No Transcript)
12
Skeletal Muscle Anatomy Myofilaments
13
Skeletal Muscle Anatomy

• What are the three proteins that make up actin?
• Actin, tropomyosin, and troponin
• What is the function of actin?
• What is the function of tropomyosin?
• What is the function of tropoin?

14
Skeletal Muscle Anatomy
15
Skeletal Muscle Anatomy

• Myosin is also referred to as the thick
  myofilament
• Myosin heads
• What does myosin use its heads for?

16
Skeletal Muscle Anatomy

• Myosin
• Actin
• M-line proteins
• Titin/Nebulin

17
(No Transcript)
18
Muscle Strength

• Where is the strength of a muscle generated?
• Muscle strength comes from the interaction of
  myosin and active
• How is the strength of a muscle generated?

19
Muscle ContractionGenerating Force

• Stimulation
• Calcium
• Actin/Myosin
• Sliding
• Energy/ATP

20
Muscle Contraction Stimulation
21
Motor Unit

• What is a motor unit?
• One motor nerve
• All the muscle fibers (cells) that it stimulates
• Example. 14
• Actual MU range from 110s to 11000s

22
Neuromuscular Junction

• How does a nerve stimulate a muscle fiber?
• Neurotransmitter substance
• Acetylcholine (ACh)

23
Neuromuscular Junction

• Acetylcholine (acetate and choline)
• Reuptake of choline
• Fatigue?
• Supplement?

24
Depolarization and Action Potential

• Acetycholine
• Sodium gates open
• Depolarization
• Action Potential
• Propagation of Action Potential
• Sarcolemma
• T-tubules

25
Muscle Contraction Calcium

• After the T-tubule, where does the action
  potential go?
• What is stored in the sarcoplasmic recticulum?
• Where does the calcium go?
• FYI Too much lactic acid may block Ca release.

26
(No Transcript)
27
Muscle Contraction Actin/Myosin

• Ca binds to troponin
• Troponin causes tropomyosin to shift or move
• This uncovers the active sites on the actin.
• Once uncovered, the myosin heads will attach to
  the active site

28
(No Transcript)
29
Muscle Contraction Sliding

• What does the myosin head do once it attaches?
• This is called a power stroke.
• What happens to the actin?
• The myosin breaks away, reattaches, power stroke
• In this case, what happens to the sarcomere?

30
(No Transcript)
31
(No Transcript)
32
Actin and Myosin Interaction
Charged myosin head and covered active sites.
1.
2.
Uncovered active site myosin head attaches.
3.
Power stroke sliding actin inward myosin head
uncharged.
4
ATP separates and recharges myosin head.
33
Muscle Contraction Energy

• What is ATP?
• What does it provide?

34
ADP P Energized
ADP P energy
New ATP
35
Muscle Relaxation

• What is needed in order to have the muscle stop
  contracting?
• Stop the impluse
• Re-store the calcium
• How? Calcium pump
• What powers the calcium pump?

36
Summary of Muscle Contraction

• 1. Motor Impulse
• 2. Neurotransmitter Substance
• 3. Action potential via Na and K
• 4. Calcium released exposing active sites
• 5. ATP split forming high energy myosin

37
Summary of Muscle Contraction
6. Myosin attaches to actin forming a
crossbridge 7. Stored energy released and
crossbridge movement (Power Stroke) 8. ATP breaks
myosin from actin 9. ATP splits forming high
energy myosin
38
(No Transcript)
39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
Quick Time Movie

• Yellow Calcium
• Green ATP
• Gray ATPase
• A Quick Time Movie of the contraction process can
  be download at the 5230 Web Page

43
Muscle Strength

• So far
• ...Where and how is the strength of a muscle
  generated?
• Next
• .What makes a muscle stronger?
• Acute increase
• Chronic increase