PHYS ED 32 Lecture Notes - Lecture 4: Heredity, Bench Press, Motor Unit
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24 Oct 2013
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Lecture 4:
Muscular Strength: usually assessed by measuring the maximum amount of weight a
person can lift one time. e.g. taking 1 RM for the bench press
Muscular Endurance: usually assessed by counting the maximum number of
repetitions of a muscular contraction a person can do (e.g. push-ups) or the maximum
amount of time a person can hold a muscular contraction. e.g. curl-up test, push-up test,
squat endurance test
Benefits of Muscular Strength and Endurance:
Improved performance of physical activities
Injury prevention
Improved body composition
Enhanced self-image and quality of life
Improved muscle and bone health with aging
Prevention of chronic disease
Skeletal Muscle Tissue
muscle fascicle (bundle of fibers) muscle fiber (all) myofibril
Sarcomere – basic unit of muscle; composed of long, fibrous proteins that slide
past each other when the muscles contract and relax
o Protein filaments
o Sliding filaments
o Theory: filaments slide and contract when energy is used
Myosin and Actin
o Muscle proteins responsible for elastic and contractile properties of
muscle
Basic Muscle Physiology
Hypertrophy: larger size of individual muscle fiber (via lifting, working out)
Atrophy: muscle gets small and shriveled
Slow Twitch (endurance athletes) vs. Fast Twitch (sprinters)
Slow Twitch
o Resist fatigue
o Don’t contract as rapidly and forcefully as fast twitch fibers
o Rely primarily on the aerobic energy system
Fast Twitch
o Fatigue more quickly than slow-twitch fibers
o Contract rapidly and forcefully
o Rely more on the anaerobic energy system
Typical Muscle Fiber Composition in Elite Athletes
% Slow Fibers
% Fast Fibers
Sport
Type I
Types IIx and IIa