Download Chapter 4 - Mr-Corrente

Chapter 4
Question Bank for Written Student Assessment and
Evaluation
Answers to Chapter Discussion Questions
Question #1
The major types of muscle contraction and two examples of each are:
Static contraction—force exerted against an external load is equal or weaker; e.g. the iron cross
in gymnastics and floor grips in judo
Dynamic contraction—internal and external forces are unbalanced ;e.g. bicep curl, bench press
Isometric contraction—there is no visible change in muscle length even though the muscle has
undergone muscle contraction; e.g. pushing against a wall, arm wrestling with someone of same
strength
Auxotonic contraction—contraction of variable/increasing tension; e.g. bicep curl with free
weights and lateral arm raise with free weight
Isotonic contraction—contraction of variable length but same/unchanging muscle tension; e.g.
slow, controlled arm extension with an extremely heavy barbell, slow, controlled leg extension
with an extremely heavy barbell
Isokinetic contraction—contraction of same speed over the entire range of motion; e.g. arm
flexion and leg extension using dynamometers
Concentric contraction—contraction during which muscle shortens; e.g. shortening of biceps
during flexion of a bicep curl and shortening of quadriceps during leg extension of leg curl
Eccentric contraction—contraction during which muscle lengthens; e.g. lengthening of biceps
during extension of a bicep curl and lengthening of quadriceps during leg flexion of leg curl
Plyocentric contraction—isotonic concentric contraction from a stretched position; e.g. leaping
and bounding
Question #2
During the static contraction internal force exerted against an external load is equal or weaker,
resulting in no movement. In contrast, during the dynamic contraction internal force exerted
against an external load is stronger, resulting in movement.
Question #3
The larger the cross-section area the more myofibrils are present in the muscle. Since myofibrils
are the active/contractile unit of muscle contraction, having more myofibrils will result in greater
amount of myofibril recruitment during muscle contraction, thus resulting in greater muscle
force.
Question #4
The factors that influence muscle contraction and an example of each are:
Joint angle—it is harder to lift the same weight at a small angle than at about ninety degree angle
Muscle cross-sectional area—weightlifters can lift more weight than marathon runners
Speed of movement—the force developed during extremely fast velocities is lower than that
developed during optimal velocities
Muscle fibre type—muscles that are composed mostly of slow-twitch fibres (e.g. soleus) will
produce less force than the same muscle mass composed mostly of fast-twitch fibres (e.g. rectus
femoris)
Age—80-year-old man can generate less force than 40-year-old man of the same mass
Gender—female can generate less force than a male of the same mass
Question #5
Absolute strength is the maximum amount of force one can produce regardless his/her body mass
(absolute strength=maximal force). Relative strength is the maximum amount of force one can
produce in proportion to his/hers body mass (relative strength=maximal force/body mass)
Question #6
Strength refers to the ability of the athlete to perform maximal voluntary muscular contraction in
order to overcome powerful external resistance. Power, often referred as speed-strength, is the
ability of the athlete to overcome external resistance by developing a high rate of muscular
contraction. Muscular endurance is the ability of an athlete to resist fatigue in strength
performance of long duration.
Question #7
Power or speed –strength depends is the ability of the athlete to overcome external resistance by
developing a high rate of muscular contraction. Generally, the stronger the individual the more
power he or she can generate.
Question #8
The number of repetitions that can be performed against a high-resistance is dependent on
maximal strength. That is, the greater an athlete’s maximal strength, the greater the muscular
endurance at a particular load (as a percentage of 1RM).
Question #9
As one ages, his/her muscular strength decreases due to the age-associated muscle loss or
wastage (i.e. sarcopenia).