Exercise Physiology Exam 1 Study Guide

Work

Force × distance performed (measured in joules)

Power

Rate at which work is performed (work ÷ time; measured in watts)

Relationship between work and power

Power reflects how fast a given amount of work is performed

Ergometry

Measurement of work performed

Ergometer

Device used to measure work and power output during exercise

Purpose of ergometry in exercise physiology

Quantifies exercise intensity and energy expenditure

MET (metabolic equivalent)

Unit used to estimate energy expenditure relative to rest

1 MET

Energy cost of resting quietly

MET equivalent in VO2

3.5 mL O2·kg⁻¹·min⁻¹

Absolute VO2

Total oxygen consumption expressed in L/min

Relative VO2

Oxygen consumption expressed in mL/kg/min

Relationship between VO2 and METs

METs equal VO2 divided by 3.5

Relationship between VO2 and energy expenditure

Higher VO2 indicates higher caloric cost

Homeostasis

Maintenance of a stable internal environment

Negative feedback

Physiological response that restores balance

Physiology

Study of how body systems function

Exercise physiology

Study of acute and chronic physiological responses to exercise

Hormone chemical types

Peptide/protein steroid and amine hormones

Peptide hormones

Water soluble hormones that act through membrane receptors

Steroid hormones

Lipid soluble hormones that act through intracellular receptors

Amine hormones

Hormones derived from amino acids

Mechanism of water soluble hormones

Activate second messenger systems

Mechanism of lipid soluble hormones

Alter gene transcription

Epinephrine and norepinephrine

Increase heart rate blood flow and energy mobilization

Insulin during exercise

Decreases to allow greater glucose availability

Glucagon

Increases blood glucose levels

Cortisol

Promotes protein and fat breakdown

Growth hormone

Stimulates tissue growth and fat metabolism

Testosterone

Stimulates muscle protein synthesis

Nerve impulse transmission

Electrical conduction along axon and chemical transmission at synapse

Myelinated nerve fibers

Transmit impulses faster than unmyelinated fibers

Resting membrane potential

Electrical charge of a neuron at rest (approximately −70 mV)

Ion distribution at rest

High sodium outside cell and high potassium inside cell

Depolarization

Sodium enters the neuron

Repolarization

Potassium exits the neuron

Joint receptors

Provide information about joint position movement and pressure

Types of joint receptors

Ruffini endings Pacinian corpuscles Golgi type receptors and free nerve endings

Equilibrium and balance

Controlled by vestibular visual and proprioceptive systems

Central nervous system (CNS)

Brain and spinal cord

Peripheral nervous system (PNS)

All nerves outside the brain and spinal cord

Somatic nervous system

Controls voluntary skeletal muscle movement

Autonomic nervous system

Controls involuntary functions

Neurotransmitters

Chemicals released at synapses that transmit signals

Excitatory neurotransmitters

Increase likelihood of neuron firing

Inhibitory neurotransmitters

Decrease likelihood of neuron firing

EPSP

Excitatory postsynaptic potential that depolarizes neuron

IPSP

Inhibitory postsynaptic potential that hyperpolarizes neuron

Epimysium

Connective tissue surrounding the entire muscle

Perimysium

Connective tissue surrounding muscle fascicles

Endomysium

Connective tissue surrounding individual muscle fibers

Sarcomere

Functional unit of a myofibril

Actin

Thin filament in muscle fibers

Myosin

Thick filament in muscle fibers

Sliding filament theory

Muscle contraction occurs as actin slides over myosin

Role of calcium in contraction

Allows myosin to bind to actin

Isometric contraction

Muscle tension without length change

Concentric contraction

Muscle shortens while producing force

Eccentric contraction

Muscle lengthens while producing force

Type I muscle fibers

Slow twitch oxidative fibers with high fatigue resistance

Type IIa muscle fibers

Fast twitch oxidative glycolytic fibers

Type IIx muscle fibers

Fast twitch glycolytic fibers with high power output

Motor unit

Motor neuron and all muscle fibers it innervates

Disuse atrophy

Muscle wasting due to inactivity

Denervation atrophy

Muscle wasting due to loss of nerve supply

Sarcopenia

Age related loss of muscle mass and strength

Factors affecting muscle force

Motor unit recruitment fiber type muscle length and contraction velocity

Muscle fatigue

Decline in ability to produce force

Causes of muscle fatigue

Metabolite accumulation reduced calcium release and central fatigue

Muscle repair

Involves satellite cell activation and protein synthesis

Primary cause of muscle cramps

Neuromuscular fatigue

Unsupported causes of muscle cramps

Dehydration and electrolyte imbalance in most cases

Aging and skeletal muscle

Loss of type II fibers strength and power

Muscle fiber recruitment

Activation of muscle fibers based on force demands

Size principle

Motor units are recruited from smallest to largest

Strength gains in untrained individuals

Primarily neural adaptations

Strength gains in trained individuals

Greater contribution from muscle hypertrophy

Training principles

Overload specificity progression reversibility and individuality

Cross education

Strength gain in untrained limb after training opposite limb

FITT principle

Frequency intensity time and type of exercise

US physical activity guidelines aerobic

150-300 minutes moderate or 75-150 minutes vigorous activity per week

US physical activity guidelines strength

Muscle strengthening activities at least two days per week