Quiz I
Dr. Hahesy
Fall 2012
Muscular Strength and Endurance
• Muscular strength is the amount of force a
muscle can produce with a single maximum
effort
– Muscular strength is usually assessed by measuring the
maximum amount of weight a person can lift one time (1 RM)
• Muscular endurance is the ability to resist fatigue
while holding or repeating a muscular
contraction
– Muscular endurance assessed by counting the maximum
number of repetitions of a muscular contraction a person can
perform to fatigue
• Well-developed muscles can assist with:
• Daily routines
• Protection from injury
• Enhancement of your overall well-being
Basic Muscle Physiology
• Muscles consist of individual muscle fibers
(cells) connected in bundles
• Muscle fibers are made up of smaller protein
structures called myofibrils
• Proper strength training causes individual
fibers to increase the number of myofibrils,
resulting in hypertrophy
• Inactivity can reverse this process, resulting
in atrophy
Skeletal Muscle Tissue
Slow and Fast Twitch Muscle
Fibers
• Slow-twitch fibers are:
• Fatigue resistant
• Don’t contract as rapidly and forcefully as fast-twitch
fibers
• Rely primarily on the aerobic energy system
• Fast-twitch fibers:
• Contract rapidly and forcefully
• Fatigue more quickly than slow-twitch fibers
• Rely more on the anaerobic energy system
Static vs. Dynamic Strength
Training
• Static (isometric) exercise involves a muscle contraction
without a change in the length of the muscle or joint angle
• An example is ‘pushing against a brick wall’
• Considered useful in strength building after an
injury/surgery
• Isometric contractions are usually held for 6 seconds
• Dynamic (isotonic) exercise involves a muscle contraction with
a change in the length of the muscle- Two types
• Concentric contraction- muscle shortens as it
works
• Eccentric contraction- muscle lengthens as it
works
Do You Need Supplements?
• Supplement manufacturers often make claims
about their products that will promote or
enhance sport performance or physique
• Most of these substances are ineffective and
expensive, as well as possibly dangerous
• Before purchasing and using these products,
find other resources that document these dietary
aids
What is Flexibility?
• Flexibility is the ability of a joint to move through
its normal range of motion
• It is a highly adaptable fitness component and
responds well when utilized as part of a fitness
program
• Flexibility is joint specific, meaning that you must
work all major joints, not just a few
Types of Flexibility
• There are two types of flexibility
• Static Flexibility: ability to hold an extended
position at one end in a joint’s range of motion
• Dependent on your ability to: tolerate stretched
muscles, joint structure, and tightness of connective
tissues
• Dynamic Flexibility: ability to move a joint through
its range of motion with little resistance
• Important for daily activities and sports
What Determines Flexibility?
• The flexibility of a joint is affected by the
following:
• Joint Structure (cannot be changed)
• Muscle Elasticity and Length
• The Nervous System
Types of Stretching Techniques
• Static Stretching- slow and steady
• Ballistic Stretching- bouncing at the end of
stretch
• Dynamic (Functional) Stretching- sport specific
• Proprioceptive Neuromuscular Facilitation
(PNF)- partner assisted
• Passive- hold your stretch against resistance or
force
• Active Stretching- hold your stretch with just your
antagonist muscle as resistance
Managing Low-Back Pain
• More than 85% of Americans experience back pain at
some time in their lives
• Lower-back pain is the second most common ailment in
the United States, headaches being number one
• Back pain can result from sudden traumatic injuries, but
is more often the result of:
– Weak and inflexible muscles
– Poor posture
– Poor body mechanics during activities
Causes of Back Pain
• Back pain can occur at any point along your spine
• Any excessive stress upon the spinal column can cause
injury and pain
• Underlying causes of back pain include:
• Poor muscle endurance and strength
• Excessive body weight
• Poor posture or body position at rest
• Poor posture body mechanics during activity
• Previous injuries
Preventing Lower-back Pain
• Lose weight, stop smoking, and reduce stress
• Avoid sitting, standing, or working in the same
position for too long
• Use a supportive seat and a medium-firm mattress
• Warm up thoroughly before exercising
• Progress gradually when improving strength and
fitness
• Do low-back exercises at least 3 days per week
• Emphasize muscular endurance
• Do not do full range of motion spine exercises early
in the morning
• Engage in regular endurance exercise
What Is Body Composition?
• Body composition is the body’s relative amounts of fat
mass and fat-free mass
• Body fat includes two categories:
– Essential fat is crucial for normal body functioning
• 3–5% of total body weight in males
• 8–12% of total body weight in females
– Nonessential fat is storage or adipose tissue
• 12-15% in males
• 20-27% in females
Body Composition
Body Composition of a typical man
and woman (20-24 years old)
Defining Overweight and Obesity
• Overweight is defined as total body weight
above the recommended range for good health;
range are set by population scales
• Obesity is defined as a more serious degree of
overweight, characterized by excessive
accumulation of body fat
• More than 67% of American adults are now
overweight
Problems Associated with Very Low
Levels of Body Fat
• Not considered as prevalent problem as obesity, too little body fat is
also dangerous
• Extreme leanness is linked to the following disorders:
• Reproductive
• Circulatory
• Immune system
• Eating disorders have been associated with low percentages of
body fat, especially in women
• Bulimia
• Anorexia Nervosa
Calculating Body Mass Index
• Body Mass Index (BMI) is a measure that can classify
risks, based on the concept that a person’s weight
should be proportional to height
–
–
–
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Underweight = 18.5 or less
Normal = 18.5 -24.9
Overweight = 25-29.9
Obesity = 30 or greater
• To determine this, body weight in kilograms is divided
by the square of height in meters
– BMI = body weight/ height squared
– Divide weight by 2.2 and height multiple by .0254
– 190 (2.2) / 70 (x.0254) = 86.36 / 3.16 = 27.33
• Elevated BMI is linked to increased risk of disease,
especially if associated with a large waist
circumference
The Cardiorespiratory System
• The cardiorespiratory system transports
oxygen, nutrients, and other key
substances to the organs and tissues that
need them
• It picks up waste products to where they
can be used or expelled
The Heart
• The heart has the following characteristics:
• 4 chambers
• Size of a fist
• Located just beneath the sternum
• Arteries carry blood away from the heart
• Veins carry blood back to the heart
• The average resting heart rate is between 60100 bpm (72 is the standard average)
Heart Rate
• You can improve your heart rate through
cardiorespiratory conditioning.
• Higher maximum heart rate
– You can exercise longer and at greater levels
• Lower resting heart rate
– The heart beats less beats per minute
– Can get into the 40’s or 50’s
Resting Heart Rates
• Males - 18-25 years of age
– 49-55 is excellent
– 56-61 is good
– 62-73 is average
Females - 18-25 years of age
- 54-60 is excellent
- 61-65 is good
- 66-73 is average
Maximum and Target Heart Rates
– Estimate your maximum heart rate (MHR)
• 220 – your age = MHR
– Multiply your MHR by selecting an appropriate range
of 65% - 90%
• People who are unfit should start at 55% of MHR
– Example: 20-year-old
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•
•
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MHR = 220 – 20 = 200
65% training intensity = 0.65 X 200 = 130 bpm
90% training intensity = 0.90 X 200 = 180 bpm
THR then is 130-180
Thursday
• Thursday we will have Quiz I in this room.
No working out that day.
• See you on Thursday!