Lecture 7 - Muscular Fitness

Question 1

Why is muscular fitness important?

Answer 1

• Ability to perform activities of daily living (ADLs)
• Maintain functional independence as one ages
• Leisure time activities enjoyment (stress/fatigue)
• Decreases risk of low back problems, osteoporotic fractures & musculoskeletal injuries

Question 2

What are chronic benefits with resistance training?

Answer 2

• Muscle hypertrophy, Enhanced performance, Improved body composition, Increase self-esteem, Decreased BP, Increased bone density, Increased stores of muscle energy production materials

Question 3

What are acute benefits with resistance training?

Answer 3

• Increased BP
• Decreased energy stores
• Cause neural fatigue

Question 4

What is muscular strength?

Answer 4

• The ability of a group of muscles to exert a maximum force against a resistance in a single contraction

Question 5

What is muscular endurance?

Answer 5

• The ability of a muscle group to exert a submaxinal force for extended periods

Question 6

What is muscular power (speed-strength)?

Answer 6

• the ability of a group of muscles to perform high-intensity movements in short bursts

Question 7

What is an isometric (static) contraction?

Answer 7

• Tension in a muscle group with no movement at the joint (i.e., flexing, holding a weight)

Question 8

What is a concentric contraction?

Answer 8

• Tension in the muscle where the muscle shortens

Question 9

What is an eccentric contraction?

Answer 9

• tension in the muscle where the muscles lengthens

Question 10

What is an Isokinetic contraction?

Answer 10

• maximal contraction at a constant velocity

Question 11

What is mechanical advantage ?

Answer 11

• the ratio of the moment arm through which an applied force acts to that through which a resistive force acts
• A mechanical advantage >1.0 allows the applied (muscle) force to be less than the resistive force to produce an equal amount of torque
• A mechanical advantage of <1.0 is a disadvantage in the common sense of the term

Question 12

What are the 2 types of motor units?

Answer 12

• slow twitch (ST)
• fast twitch (FT)

Question 13

What is a slow twitch motor unit?

Answer 13

• Also called Type I & Slow Oxidative (SO)
• Appears “red” due to the increased capillaries & MYOGLOBIN (oxygen binding protein in muscle fibres) giving them a High oxidative capacity
• Smaller cross-sectional area (less force)
• Endurance rather than strength/power (fatigue resistant)

Question 14

What is a fast twitch motor unit?

Answer 14

• Also known as Type 2 X muscle fibers
• has 2 types:
• FTa or FOG (fast oxidative-glycolytic i.e., type IIa)
• FTb or FG (fast glycolytic i.e., type IIb)

Question 15

What is FTa or FOG (fast oxidative-glycolytic i.e., Type IIa) motor unit?

Answer 15

• Has high oxidative & glycolytic capabilities (pink in color)
• High number of mitochondria & glycolytic enzymes
• Some fatigue resistance

Question 16

What is FTb or FG (fast glycolytic i.e., type IIb) motor unit?

Answer 16

• White fibres (glycolytic enzymes)
• Large cross-sectional area (increased force)
• Good for strength and power (fatigable)

Question 17

What are the basics of neurophysiology?

Answer 17

• One α-motor neuron & all the muscle fibres it innervates
• “All or None” principle of recruitment: Creation of action potentials (AP’s)
• Gradation (degree) of force generation: Temporal summation (frequency of recruitment), Spatial summation (number of fibers recruited)