- Muscle fitness has two components namely
muscular strength and muscular endurance
o Strength
is the amount of force you can produce with a single maximal effort of a muscle
group
o Muscular
endurance is the capacity of the skeletal muscles continue contracting over a
long period of time
- Characteristics of Skeletal Muscle
o Excitability
(Responsiveness) – Muscles can be stimulated by electrical, chemical and
physical means
o Contractibility
– a muscle responds to stimuli by contracting
- There are three distinct types of muscle
fibers, slow-twitch (Type 1), fast-twitch (Type IIb) and (Type IIa)
o The
slow-twitch fibers are generally red in color. Slow twitch fibers generate less
tension but are more resistant to faigue. Low intensity, longer duration
o Fast-twitch
fibers are generally white in color. They generate greater tension than slow
twitch fibers, but they fatigue more quickly. High intensity, shorter duration
o Some
people inherit a higher percentage of one muscle fiber to another
- Type of Muscle Contraction
o Agonist
– the prime mover; the muscle which performs the movement
o Antagonist
– the muscle that performs the opposing movement to that of the agonist
o Synergists
– synergistic muscles are those which aid in a movement
o Fixators
– muscles which work to keep a part from moving; stabilizers; neutralizers.
o Flexion
– bending a joint to decrease the angle between the two bones or two body parts
o Extension
- bending a joint to increase the angle between the two bones or two body parts
o Dorsiflexion
– Bending of the foot that causes the toe to point upward.
o Plantar
Flexion - Bending of the foot that causes the toe to point downward.
o Abduction
– moving the body part away from the midline of the body
o Adduction
– moving the body towards the midline the body
o Medial
Rotation – moving the body parts around its axis (inward rotation)
o Lateral
Rotation - moving the body parts around its axis (outward rotation)
o Pronation
– turning the palm of the hand downward
o Supination
– turning the palm of the hand upward
- Major Muscle Groups
o Back
Muscles
1. Trapezius – the triangular muscle that extends from the neck to the
shoulders and mid back
2. Latissimi dorsi – major muscle that extends from armpits along both
sides of the small of the back
o Chest
Muscles
1. Pectoralis – fan like muscles that protect the upper rib cage
2. Subclavius – small, cylindrical muscle between the collarbone and
first rib
o Shoulder
Muscles
1. Deltoids – thick large, triangular muscles that run from the top of
the shoulders into the upper arm
2. Trapezius - the triangular muscle that extends from the neck to the
shoulders and mid back
o Arm
Muscles
1. Biceps – beginning below the top of the shoulder and ending slightly
below the elbow
2. Triceps – triangular muscle that extends from the top of the
shoulders to the elbow
3. Forearms – flexors ad extensor muscles that enable the curling of
the wrist
o Leg
Muscles
1. Quadriceps – four muscles that comprise the front of the thigh and
allow extensions of the knee and flecing of the hips
2. Gluteals – gluteus maximus and minimus enable extensions of the hip
and knee
3. Hamstrings – three muscles at rear of leg used for
flexing knee and extending hip.
4. Soleus – larger of the two calf muscles, helps
with jumping and shifting of weight
5. Gastrocnemius – gastroc is the part of the calf
that helps from the correct foot postion.
Abdominals
1. Rectus Abdominis – along muscle that extends the
length of the abdomen. It pulls the upper torso towards the hips when the body
is slightly flexed at the waist.
2. Internal and External Obliques – muscles that run
along sides of torso. These muscles contract to tilt and twist the torso from
side to side.
Progressive
Resistance Exercise – is a type of physical activity done with the intent of
improving muscle fitness. Weight training
Muscular
Endurance – is defined as one’s ability to perform many repetitions with a
sub-maximum resistance over a given period of time
Absolute
Endurance – muscular endurance measured by the maximum number of repetitions
one can perform against a given resistance. The number of times you can lift a
50 pound bag.
Relative
Muscular Endurance – is measured by the maximum number of repetitions one can
perform using a given percent of absolute strength. The number of time you can
lift 50 percent of your absolute strength.
- You have the ability to resist fatigue.
You have the ability to repeat a movement without getting tired.
- Two Types of Muscular Endurance
o Dynamic
Endurance – is defined as a muscle’s ability to contract and relax repeatedly.
o Static
Endurance – is a muscle’s ability to remain contracted for a long period of
time
o Muscular
endurance is related to cardiovascular endurance, but it is not the same thing
- Muscular Strength – is the ability or
capacity of a muscle or muscle group to ecert a maximal force against
resistance, one time through a full range of motion
- Absolute Strength – the maximum amount of
force one can exert. The maximum number of pounds or kilograms that can be
lifted on one attempt
- Relative Strength – amount of force that
one can exert in relation to one’s bodyweight or per unit of muscle
You need strength to increase work capacity, to decrease chance of
injury, to prevent poor posture and perhaps to save a life in an emergency
situation.
- Different Types of Contraction
o Isotonic
Contractions – muscles to change length as it contracts thus causes movement of
a body part
o Concentric
Contractions – are those which cause the muscle to shorten as it contracts
o Isometric
Contractions – there is no change in the length of the contracting muscle. When
the muscle force is greater than the restrictive force, the muscle shortens,
resulting in a concentric contraction (positive contraction)
o Eccentric
Contraction When the muscle force is
less than the resistive force, the muscle lengthens, resulting in an eccentric
(negative contraction)
o Isokinetic
Contractions – similar to isotonic, muscle changes length but isokinetic
contractions produce movements of a constant speed.
- Strength Factors
o Sex
– testosterone (60 – 85 % of the absolute strength of men)
o Age
– maximum strength is usually reached in the twenties and typically declines
with age
o Limb
Length – leverage factors enhance effective force output
o Muscle
Length – some people have long muscles with short tendon attachments, while
others have short muscles with long tendon attachment
- Health benefits of Muscle Fitness and
Resistance Exercise
o Reduces
Risk for Injury
o People
with good muscle fitness are less likely to suffer joint injuries
o Muscles
balance in important in reducing the risk for injury
o Good
posture and reduced risk for back problems
o Lack
of fitness of the abdominal and low back muscles is particularly related to
poor posture and potential back problems
o Improved
athletic performance. Many sports depend on strength and muscular endurance.
There are jobs requiring muscular strength and endurance
o Good
muscle Fitness is associated with wellness and quality of life
o You
can work efficiently and effectively thus has reserve energy to enjoy leisure
time
o Reduced
risk for osteoporosis – resistance exercises provide a positive stress on the
bones
o Contributes
to weight control – muscles burns calories at rest, so extra muscle built
through PRE can contribute to increased resting and basal metabolism
o A
pound of fat uses or burns 2-3 calories per day
o Each
pound of muscle gained, a person can burn approximately 35 to 50 calories more
per day.
