Physical activity, physical performance, physical fitness, exercise and health

What is physical activity

Any movement done by skeletal muscle that uses energy

What is exercise

A PA that is structured and aimed at improving health

What is physical fitness

Ability to carry out tasks with vigor and alertness

What is FITT

Dose of PA determined by frequency, intensity, duration (time) and PA type

What is the distribution of cardiac output during rest vs during exercise

During rest: Majority to the liver and GI; exercise: To the muscle

What is fatigue

Reduced muscle power output caused by decrease in muscle force generation and shortening velocity

How does dehydration and electrolyte imbalance contribute to muscle cramp

Electrolyte imbalance causes discharge of ACh to motor end plate

How does altered neuromuscular control cause muscle cramps

Increased muscle spindle → Stimulate more motor neurons; GTO inhibition → Decreased inhibition 

What is the system the body uses to generate ATP (in chronological order)

Phosphagen system → Glycogen lactic acid system → Aerobic metabolism

Phosphagen system

Provides 8-10 seconds of energy using PCr

Glycogen lactic acid system

Provides 1.3-1.6 minutes of energy using glycogen/glucose

Aerobic metabolism

Provides unlimited energy using glucose and FFA

High jumping, 100 m dash, weight lifting is likely to use what metabolic system

High intensity exercise short duration → Phosphagen system

400 m dash, tennis and soccer is likely to use what metabolic system

High intensity exercise → Glycogen-lactic acid system

Marathon or jogging is likely to use what metabolic system

Low to moderate intensity exercise → Aerobic metabolism

Characteristic of type I fiber

Slow twitch; low force; small diameter; high MT density, high myoglobin, low myosin ATPase

Characteristic of type IIa fiber

Fast twitch; intermediate force; intermediate diameter; intermediate MT density, high myoglobin content, high myoglobin ATPase 

Characteristic of type IIb fiber

Fast twitch; large diameter, high myosin ATPase, low MT density, low myoglobin

Type I fiber function

Antigravity, weight bearing, sustained movement

Type IIa fiber function

Sustained locomotion

Type IIb and IIx fiber function

Burst power

mTOR function

Causes protein translation → Hypertrophy

PGC-1a function

MT protein transcription → MT biogenesis

What is motor unit aging

Older people have: Decrease alpha motor neuron, low recruitment, higher muscle fiber density → Less mobile and more fragile