1. Skeletal Muscle State possible sources of fatigue
Distinguish the different muscle fiber types.

2. SITES OF THE SOURCES OF FATIGUE
Origins of Localized Muscle Fatigue
SITES OF THE SOURCES OF FATIGUE
Central
Afferent Feedback
Psychological Motivation
Peripheral
Neural Transmission
Muscular Transmission
Muscular contraction
AP Propagation
cross-bridge interference

3. Depletion Theory of Fatigue:
Origins of Localized Muscle Fatigue
Depletion Theory of Fatigue:
Fatigue results from the depletion of metabolites necessary for energy production
ATP
Glucose
Oxygen
ADP or CP
Reaction Enzymes

4. Origins of Localized Muscle Fatigue
Accumulation Theory of Fatigue:
Lactic Acid and free H+ K+
NH3
Decreases membrane excitability
Decreases Ca++ affinity for Troponin
Decreases the release of Ca++
Obstructs glycolysis
Inhibits Aerobic Metabolism

5. Skeletal Muscle Fiber Types
innervating nerve is primary determinant of fiber type during development
a motor unit is composed of homogenous fibers
all human muscles contain mixture of three general fiber types
slow twitch (ST, oxidative, red)
fast twitch (FTa, fast-oxidative, red)
fast twitch (FTb, glycolytic, white)

6. Time Course of Contributions from Different Energy Sources
fast twitch glycolytic (white)
slow twitch oxidative (red)
Oxidative

7. Fiber Type Characteristics
Performance characteristics affected by:
Ca2+-ATPase
myosin ATPase speed
aerobic capacity (mitochondria, myoglobin, blood supply, fatigue resistance)
anaerobic capacity (glycolytic enzymes)
Be able to contrast the physiological characteristics of the three fiber types. Also, be able to explain how each of the bulleted items affects performance characteristics.

8. Muscle Movements ‘Not all force results in movement.’
Isotonic - (same force), muscle fibers create a force that moves a load. Muscle shortens or lengthens.
Isometric - (same distance), muscle fibers create changing force but does not move a load. Muscle length doesn’t change. Tendon collagen stretches out.
concentric – develops tension while shortening
eccentric – develops tension while lengthening
*(most muscle actions are a combination of these)