Muscular Fitness

• 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.