Developing Flexibility and
Muscular Fitness
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At one time physical fitness programs consisted almost entirely
of strength and flexibility exercises.
Today, as the emphasis on balanced fitness grows, muscular
strength, muscular endurance, and flexibility are assuming new
importance.
They can enhance the ability to perform daily tasks and athletic
performance.
Muscular fitness makes it easier to perform routine activities
such as carrying groceries upstairs, lifting a child, and moving the
couch. It is perhaps the most important fitness component for
older adults because muscular fitness is essential for carrying out
activities of daily living that help maintain functional
independence.
Flexibility enables us to reach, bend, twist, and perform
movements without excessive tightness or stiffness.
Enhanced muscular fitness allows us to perform vigorous
activities with less risk of straining muscles or connective tissue,
and so it is important in the prevention and rehabilitation of
injuries.
FLEXIBILITY
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The ability to move the joints through their full range is an asset
that can be maintained throughout life.
As children, we are naturally flexible, but as we age, flexibility
tends to decrease.
Disuse, injury, excessive body fat, and muscle imbalances are
common factors in this loss of range of motion.
You can maintain youthful flexibility by incorporating stretching
into your regular workouts.
The flexibility exercises in this section are grouped as follows: a
basic fitness flexibility program with exercises for joggers,
walkers, aerobic dancers, cyclists, swimmers, and water exercisers
and examples of PNF partner-assisted stretches.
Benefits and Cautions
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Six main benefits can be gained from flexibility development:
• may decrease the risk of injury. When tight muscles restrict the natural range
of motion of a joint, the slightest unusual twist can cause a strain or pull,
such as a strained hamstring. Inflexibility also is a precipitating factor in
overuse injuries such as tendinitis, because inelastic muscles transfer excessive
stress to even less pliable connective tissue.
• counteracts age-related declines in flexibility.
• It decreases aches and pains. Tight, inflexible muscles pull unevenly across
joints, causing skeletal misalignment, poor posture, unnecessary fatigue, and
muscle and joint pain. Stretching can alleviate these problems.
• It increases the ability to move freely and easily and to perform activities
such as bending down to tie your shoes, scratching your back, and turning to
look back as you are driving.
• It enhances athletic performance. In racquetball, golf, tennis, volleyball, and
swimming, greater range of motion and ability to apply force through that
range of motion can confer a winning edge.
• It feels good. Stretching reduces muscular tension, promoting relaxation.
Types of Flexibility
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There are two basic types of flexibility: static and dynamic.
Static flexibility refers to the range of motion that can be
achieved through a slow, controlled stretch. Static stretching
techniques are those in which you slowly stretch a muscle to the
point of tension and hold, such as in holding a sitting hamstring
stretch. The stretching force is provided by gravity or the force
of one limb pulling on another. When a muscle is stretched and
held at a constant length, after a period of time there is a gradual
loss of tension and muscle lengthening
Dynamic flexibility is the range of motion achieved by quickly
moving a limb to its limits. Dynamic stretching programs employ
swinging or ballistic moves such as a high forward kick.
While both types of stretching can increase flexibility, static
stretching is preferred in health-related fitness programs because
it is highly effective and carries little risk of muscle or joint
Principles of Flexibility Development
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Both types of flexibility are specific to the joint; that is, flexibility in one leg
does not guarantee identical flexibility in the other leg, and flexibility in the
shoulders does not ensure flexibility in the lower back.
An individual's flexibility range for a particular joint is not only specific but
also partially genetically determined.
Flexibility is determined by joint structure and elasticity of muscle and
connective tissue.
While you may not be able to change your genetics, you can improve your
flexibility within your genetically determined range of motion.
Flexibility exercises are only part of a balanced fitness program. The goal is to
develop and maintain an adequate range of joint motion for ease of
movement in your daily activities.
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Flexibility gains are proportional to the overload
applied: to the frequency, intensity, and time (duration)
of stretching.
• Frequency: Stretch at least 2 to 3 days a week, daily if
possible. Greater flexibility is produced by more
frequent stretching.
• Intensity: Low-intensity stretching is best. Progress at
your speed.
Stretching is not competitive.
Flexibility changes from day to day, and on some days
you might not be able to stretch as far as you did the
day before.
Stretch slightly beyond the normal range of motion, to
the point of tension, and hold. Do not force a stretch.
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Time: The ACSM
recommends a 10- to 30second stretch, though
holding up to 60 seconds in a
cool-down stretch can
increase flexibility retention.
• Repetitions: At least four
10- to 30-second sustained
stretches for each muscle
group are recommended.
Guidelines for Flexibility Development
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Everyone can benefit from flexibility. To maximize the results from the time
invested, implement the following guidelines in your next stretching session:
• Warm up before stretching.
• After warm-up, use stretching as preparation for activity.
While some feel that stretching during warm-up decreases the risk of injury in
the activity that follows, there is no evidence that this is true.
Warm-up stretching is different from a planned program of stretching for
general flexibility. Warm-up stretching can be limited to what is essential,
avoiding overstretching. Stretch the muscle groups used in the activity, hold at
the point of tension for 10 seconds, and do not push for flexibility increases.
Any gains will be minimal due to the tightening effect of the workout that
follows.
Guidelines for Flexibility Development
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• Stretch for flexibility during cool-down. Muscles are warmest
and most elastic at this point. Stretching is easier. More
permanent changes in musclelengthening occur with low-force,
long-duration stretching if muscles are allowed to cool in a
stretched position. Cooling muscles before releasing tension
apparently causes muscle collagen (connective tissue), like
stretched taffy, to stabilize toward its new stretched length.
• Stop at the point of tension, not pain. Stretching to the point
of pain, or until muscles quiver, can risk overstretching injury.
• Stretch slowly and evenly, hold 10 to 30 seconds and release
slowly.
• Don't bounce. A slow sustained stretch is more effective.
• Incorporate 8 to 12 stretches into your program.
Guidelines for Flexibility Development
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Pay particular attention to body areas that are
least flexible and stretch them more often.
• Strive for muscle balance. When stretching
muscle on one side of a joint, stretch those on
the other side as well; for example, if you stretch
hamstrings, stretch quadriceps too.
Flexibility exercises
Other Programs for Enhancing
Flexibility
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Tai chi and yoga are very old yet newly popular
activities that can enhance flexibility and balance
as well as reduce stress.
Resistance Training: Benefits and
Cautions
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Resistance training can offer
additional benefits whether your
goal is health-related fitness or
improved athletic performance
Muscle is active, high-metabolic
tissue, while fat is storage tissue.
Resistance training increases muscle
mass, which increases the rate at
which you burn calories 24 hours a
day, not just during the workout.
This makes weight control easier
Injury Prevention
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Aerobic exercises such as jogging and aerobic dance
have the potential to cause injury through repetitive,
forceful impact against unyielding surfaces
Strong, flexible muscles and connective tissue can
better withstand the stress of many forceful landings
during a workout. When ligaments, tendons, muscle,
and bone are strengthened through muscular exercise,
the risk of injury is decreased.
Psychological Benefits
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While many people begin an exercise program
to improve appearance, many other less visible
but equally important effects may result.
Benefits in the emotional dimension of wellness
from regular exercise include feeling better,
decreased stress, decreased depression, and
enhanced self-esteem and self-confidence.
Social Benefits
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In addition to offering physical and psychological benefits, lifting with a
partner or friend offers social benefits.
There are many more opportunities for conversation and interaction when
you work out with someone than when you watch a movie.
Benefits at Any Age Regardless of your age, you can benefit from resistance
training. It is untrue that loss of strength is inevitable with age or that older
people cannot gain strength.
While the typical sedentary individual can lose up to 30 percent of his or her
muscle mass between the ages of 20 and 70, this loss is more from atrophy
due to disuse rather than from aging alone.
Adequate levels of muscular strength are particularly important to older
adults to maintain their functional independence and quality of life.
Several studies including people in their 70s, 80s, and 90s participating in
resistance training have shown that they increased muscle mass, more than
doubled their strength, and improved their functional mobility and ability to
perform daily living activities.
Disadvantages and Cautions
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Although resistance training has
many benefits, it does have
disadvantages.
Resistance training is not a complete
exercise program because it does not
develop cardiorespiratory endurance.
As in any physical activity, injury is
possible if you are careless or ignore
safety procedures. You may have
trouble accessing equipment.
Also, you can expect some mild
muscle soreness during the first week
of the program.
Muscle Function
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Muscles are made of individual muscle fibers
bound together and sheathed in connective
tissue. They end in a tendon that connects the
muscle to a bone.
Resistance training increases the size and
strength of both fiber types as well as their
ability to exert force. Muscles cannot expand and
push.
Movement is produced as muscle contracts,
shortens, and pulls on bones across a joint.
As a muscle on one side of a bone contracts,
muscles on the other side must relax to allow
movement to occur. The contracting muscle that
initiates movement is called the agonist.
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Biceps curl demonstrating muscle function.
Muscle Fiber Recruitment
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When a muscle contracts, only the number of muscle fibers required for that
momentary effort will shorten.
Individual muscle fibers cannot contract partially. They are working as hard as
possible or not at all. This is called the all-or-nothing principle.
On each subsequent contraction, more fibers must be recruited to continue to
lift the same weight. After several muscle contractions, enough fibers are
fatigued that the muscle temporarily can no longer generate the same effort in
what is called temporary muscular failure.
Muscle fibers increase strength only if they are stimulated by intensity of
effort.
If your goal is to develop maximal muscular strength, try to recruit, or
activate, as many muscle fibers as possible by working a muscle to a state of
temporary muscular failure.
If you are working for health-related fitness levels, a less intense effort is
adequate.
Muscle Atrophy and Hypertrophy
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Muscles adapt to the load placed on them. When the load increases over time,
muscular strength and endurance improve. When muscles are not used, they
grow weaker, stiffen, and atrophy, or shrink in size.
A dramatic example of muscle atrophy occurs when a person has an injured
limb in a cast for several weeks. When the cast is removed, the muscles of the
affected limb are noticeably smaller. Increasing amounts of exercise over time
are necessary to rebuild muscle strength, size, and flexibility.
When muscles are stimulated by an increased workload, they grow stronger
and muscle fibers experience hypertrophy, or increase in size.
This increase occurs in both men and women and is proportional to muscle
mass. The average man has about twice the muscle mass of the average
woman, and so hypertrophy in men is more pronounced.
Gender Differences
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Some women worry that they will develop big shoulders or massive, masculine
musculature because of weight training.
This myth is reinforced by televised images of women's body-building competitions.
Be assured that shoulder width, like hip width, is influenced by genetics and that
significant muscle gains require hours of strenuous weight lifting for many months.
Men have a greater potential for muscle hypertrophy than women do because men
have higher levels of sex hormones such as androgen and testosterone, which promote
muscle growth.
Some of the strongest women athletes are gymnasts, who have very feminine
physiques.
Weight training is also popular with TV and movie stars who exercise to maintain a fit,
toned appearance and help control weight. Be assured that massive muscles don't
occur by accident or with a 20- to 30-minute muscle-toning workout twice a week.
Types of Resistance Training Programs
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Two basic types of muscular exercise are static
(isometric) and dynamic (isotonic). Different
resistance programs have been developed for
each type.
Static (Isometric) Exercise
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Static (isometric) exercise is
exercise in which the muscle
contracts but does not change
length and little or no movement
occurs
However, these exercises are not
widely used because resistance is
applied at only one point in your
range of motion, and thus strength
development is limited.
Also, it is difficult to know how
much force is being exerted, and so
strength gains are not as easy to
observe as they are when
equipment is being used.
However, static exercises can be
useful in strengthening muscles
after an injury, when dynamic
movement would be painful or
even increase injury.
Dynamic (Isotonic) Exercise
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Dynamic (isotonic) exercise is exercise in which the
muscle contracts and shortens and movement occurs.
Most daily activities, such as pushing, pulling, and
lifting, are dynamic.
Dynamic exercise programs can be done with free
weights, exercise machines, elastic resistance, or
calisthenics such as crunches and push-ups. Advantages
of dynamic exercise are that it strengthens through a
full range of motion, the load is measurable, and a
variety of isotonic programs are available.
Dynamic exercise involves two types of
muscle contractions: concentric and
eccentric
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In a concentric contraction, a muscle shortens as it overcomes
resistance. For example, a weight is lifted as the biceps contract
during the lifting phase of a biceps curl.
Eccentric contraction occurs when a muscle lengthens and
contracts at the same time, gradually allowing a force to
overcome muscular resistance; for example, the biceps contract
eccentrically during the lowering phase of a biceps curl.
Eccentric contraction is a beneficial component of strength
development because it makes up half of the muscular effort.
The same muscles are involved in eccentric and concentric
contractions, and so lowering should be done in a smooth,
controlled manner for maximal benefit and to prevent potential
injury from dropping the weight
Principles of Resistance Training
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Strength gains are proportional to the load
applied and the frequency and intensity of
effort. Basic principles of resistance training
include progressive overload, specificity, and
recovery.
Progressive Overload
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Progressive overload is the most important principle of resistance training.
To stimulate a muscle to increase strength or endurance, it must gradually be
overloaded or forced to work at a higher than normal effort.
Either the number of lifts (repetitions) performed or the amount of weight
(load or resistance) must gradually be increased or recovery time between
exercises must be decreased. Increasing the number of repetitions or
decreasing rest increases muscular endurance. Increasing the weight lifted
increases strength.
General programs increase load and repetitions until a desired maintenance
goal is reached. You must exercise two to three times a week to improve
muscular fitness. Significant strength gains require at least 8 consecutive
weeks of training.
To maintain strength, one intense workout is adequate for health fitness.
Athletes will need to train at least twice a week to maintain fitness in the offseason.
Specificity
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The speed of contraction, range of motion,
amount and type of resistance, and number and
type of exercise are a few of the variables that
determine the results of strength training.
If you desire a specific result, such as an
increase in muscle mass, your program must be
designed and executed to produce that result.
Recovery
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Exercise stimulates a muscle to take in more protein and
nutrients and undergo changes that increase its ability to contract
forcefully.
After a workout, you will be weaker, not stronger, due to fatigue.
Improvement occurs during recovery, which gives the muscle
fibers time to repair and grow.
This requires more recovery time than for the cardiorespiratory
system. Strength workouts are best done with 2 to 3 days of rest
between sessions to allow recovery and improvement to occur.
Lifting may be done more frequently, using a split routine with
the upper body one day and the lower body the next
Guidelines for Resistance Training
Programs
Safety Guidelines for Resistance
Training
Major muscles of the body.
Basic Resistance Training Programs
There are many types of resistance-training
programs. The type of program you select
will depend on your goals and the type of
equipment (if any) you plan to use
Free weight exercises
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There are many ways to develop muscular strength and endurance. While
weight training is an excellent program, it is not always convenient.
The abdominal and core strengthening, hip and thigh, and upper-body
programs require no special equipment. Partner exercises add a social
dimension to a workout.
Elastic resistance produces results without bulky equipment and is easy to
take with you for exercise on a trip.
While weights add intensity to a workout, they are not always necessary when
the goal is to shape and tone.
Muscles develop firmness by working against a resistance, and that resistance
can be your body weight.
These programs emphasize muscular endurance rather than strength by
increasing time in contraction or reps. .
Elastic resistance exercises.