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Chapter 4: Muscular Strength and Endurance
LEARNING OBJECTIVES
After reading this chapter, the student will be able to:
 Describe the basic physiology of muscles and explain how strength training affects muscles.
 Define muscular strength and endurance and describe how they related to wellness.
 Assess muscular strength and endurance.
 Apply the FITT principle to create a safe and successful strength training program.
 Describe the effects of supplements and drugs that are marketed to active people and athletes.
 Explain how to safely perform common strength training exercises using free weights and
machines.
KEY TERMS AND DEFINITIONS
muscle fiber A single muscle cell, usually classified according to strength, speed of contraction, and
energy source.
myofibrils Protein structures that make up muscle fibers.
hypertrophy An increase in the size of a muscle fiber, usually stimulated by muscular overload, as
occurs during strength training.
atrophy A decrease in the size of muscle fibers.
hyperplasia An increase in the number of muscle fibers.
slow-twitch fibers Red muscle fibers that are fatigue-resistant but have a slow contraction speed and
a lower capacity for tension; usually recruited for endurance activities.
fast-twitch fibers White muscle fibers that contract rapidly and forcefully but fatigue quickly;
usually recruited for actions requiring strength and power.
power The ability to exert force rapidly.
motor unit A motor nerve (one that initiates movement) connected to one or more muscle fibers.
muscle learning The improvement in the body’s ability to recruit motor units, brought about through
strength training.
tendon A tough band of fibrous tissue that connects a muscle to a bone or other body part and
transmits the force exerted by the muscle.
ligament A tough band of tissue that connects the ends of bones to other bones or supports organs in
place.
testosterone The principal male hormone, responsible for the development of secondary sex
characteristics and important in increasing muscle size.
repetition maximum (RM) The maximum amount of resistance that can be moved a specified
number of times.
repetitions The number of times an exercise is performed during one set.
static (isometric) exercise Exercise involving a muscle contraction without a change in the muscle
length
dynamic (isotonic) exercise Exercise involving a muscle contraction with a change in the muscle
length
concentric muscle contraction An isotonic contraction in which the muscle gets shorter as it
contracts.
eccentric muscle contraction An isotonic contraction in which the muscle lengthens as it contracts;
also called a pliometric contraction.
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Chapter 4
constant resistance exercise a type of dynamic exercise that uses a constant load throughout a
joint’s entire range of motion.
variable resistance exercise A type of dynamic exercise that uses a changing load, providing a
maximum load throughout the joint’s entire range of motion.
eccentric (pliometric) loading Loading the muscle while it is lengthening; sometimes called
negatives.
plyometrics Rapid stretching of a muscle group that is undergoing eccentric stress (the muscle is
exerting force while it lengthens), followed by a rapid concentric contraction.
speed loading Moving a load as rapidly as possible.
isokinetic The application of force at a constant speed against an equal force.
spotter A person who assists with a weight training exercise done with free weights.
set A group of repetitions followed by a rest period.
agonist A muscle in a state of contraction, opposed by the action of another muscle, its antagonist.
antagonist A muscle that opposes the action of another muscle, its agonist.
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