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Lecture 7

BPK 143 Lecture Notes - Lecture 7: Order Of Newfoundland And Labrador, Multifidus Muscle, Old Age


Department
Biomedical Physio & Kines
Course Code
BPK 143
Professor
Tony Leyland
Lecture
7

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FLEXIBILITY AND STRETCHING
Flexibility is the range of motion (ROM) around a joint and stretching is a component of
exercise programs. Being active and moving your joints through a full ROM will help you
maintain a reasonable amount of dynamic flexibility. Most people cannot rely on activity
alone to keep their flexibility in a good range. Sprains and bruises may increase scar tissue
build-up and reduce range of motion. Many activities do not require a full ROM of joints
and/or do not utilize all joints (e.g., running) which will limit your range of motion; for
these activities, a stretching routine may be required.
While aerobic exercise can reduce your risk of developing life-threatening illnesses such
as cardiovascular disease, strength and flexibility are also fundamental to health. As we
age, muscular strength, endurance, and flexibility, take on increasing importance. For
many people quality of life is badly diminished as a result of poor strength and flexibility.
People with chronic low back pain (LBP) and stooped postures might have been able to
reduce or eliminate their risk of developing these conditions if they had undertaken
lifelong resistance and flexibility training.
Dr. Cooper suggests that, by the time you are 50 years old, 50% of your training should be
resistance training. Many people lose independence and have to move into some form of
care due to limited strength and mobility. Adequate range of motion and strength are key
factors in maintaining your independence as you age.
Joint health.
Reduction of low-back pain and injuries.
Reduction of delayed onset muscle soreness (DOMS).
Pain relief.
Improved athletic performance.
Improved posture.
Benefits of stretching include the following:
It is common to suggest stretching as a possible mechanism to prevent onset of injury and
muscle soreness. They found that common stretching methods, like static and ballistic
stretches, decrease muscle performance, and evidence supporting the theory that being
flexible reduces risk of injury is inconclusive. Many sources claim that high levels of
flexibility do not reduce incidence of injury and, therefore, increasing ROM is not needed.
These results do not suggest that an optimal ROM is not needed. ROM must be adequate
for daily activities; if not, your daily quality of life will be negatively affected. Further, if
ROM diminishes to a large degree, problems like stooped postures resulting in low back
pain can occur. However, there is a strong genetic component to flexibility and some
argue that it is possible to maintain adequate ROM simply by moving through full ranges
of motion, without embarking on a specific and extensive stretching program.
WHAT DETERMINES FLEXIBILITY?
Some people have a greater range of motion than others simply because of the way
their bones are shaped. Different joint structures allow different ranges of motion.
One example is the limited circumduction (circling) range of the hip as compared
with the shoulder. The joint capsule also affects ROM.
Joint Structure and Your Skeleton
Normal activity and exercises through full ROM reduce the likelihood of a muscle
shortening, and a well-designed stretching program can actually lengthen the
muscle. Hypertrophy due to strength training results in sarcomeres (contractile unit
of the muscle) being laid down in parallel, thereby increasing the cross-sectional
area. With a stretching program, sarcomeres are laid down in series, increasing
muscle length.
Muscle Elasticity and Length
Reciprocal innervation This takes place when a muscle contracts, inhibiting
contraction of antagonist muscles; for example, when hip flexors contract, hip
extensors relax.
Muscle spindles These are sensory nerve endings in the muscle that detect
muscle length change and rate of change. Force applied to a muscle stimulates
muscle spindles, which activate protective reflexes and result in muscle
contraction (such as the knee jerk response to neurological testing procedures).
Golgi tendon organ Atendon organ that is located at the insertion where
the muscle fibres insert into the tendon. When the muscle generates force, the
sensory terminals are compressed and a signal is sent to the spinal cord which
signals the stretch reflex.
The nervous system plays a role in what range of motion you can achieve by
regulating muscle contraction.
Nervous System Activity
When I contract my hip flexors in a hamstring stretch, initially the muscle spindles in the
hamstring fire and the muscle contracts to protect it from an excessive stretch. If I hold the
stretch long enough, the stretch reflex diminishes and I can stretch the muscle out further.
This is why you must hold a static stretch for more than 20s to get the full benefit. You are
still contracting your hip flexors, so reciprocal innervation helps relax the hamstring once
the initial stretch reflex has passed.
TYPES OF STRETCHING
Static Stretching
Passive stretchingAn external force, such as gravity/push from a partner, moves
the limb into the new position, stretching the muscle. Passive stretching can also be
achieved with the help of stretch bands or mechanical devices. The more force
exerted on the limb, the less time it will take to get a substantial stretch, but
many are concerned that this increases the potential for injury. As long as the stretch
force is applied gradually, the risk of injury is low.
Active stretchingOccurs when you move your limb into position by contracting
the agonist muscle; no external force from a partner, gravity, or bands. This can
reduce the potential for injury.
The most common type of stretching is static stretching which encompasses various
techniques that lengthen a muscle to an elongated position (to point of discomfort), where
it is held in position statically for 2040s. During this holding period, participants may feel
a mild discomfort. When performed properly, static stretching lessens the sensitivity of
tension receptors, which allows the muscle to relax and be stretched to greater lengths.
There are two types of static stretchingpassive andactive.
Modified hurdler stretch in is an example of an active stretch as the hip flexors (agonists)
are being contracted to eventually stretch the hamstrings (antagonist). The lying
hamstring stretch as a passive stretch, because it is the latissimus dorsi and posterior
deltoid that are causing the stretch, and hence no reciprocal innervation of the hamstrings
due to agonist contraction.
Ballistic stretchingMomentum from body parts propels the muscle into an
extended range of motion, exceeding an individuals static, passive stretching
ability. These types of stretches are usually initiated by quite vigorous movements,
such as swinging the arm backwards to stretch the anterior deltoid and pectoralis
major. E.g. Leg swings/kicks
Dynamic stretchingThe movement into the stretch position is more controlled
and the fully stretched position is often held for 1-2s. In ballistic stretching, the limb
generally immediately recoils back from the extreme range of motion. Dynamic
stretching involves lower limb velocities than ballistic stretching. You can use limb
momentum to stretch a muscle more or less vigorously. You should be aware of the
potential dangers if you do not perform stretches properly.
Ballistic and Dynamic Stretching
Dynamic stretching is advocated by many coaches, as a beneficial form of stretching that
is important during warm-up for sports involving intense, dynamic activity. During these
activities, muscles are used dynamically; hence, dynamic stretching should be part of a
warm-up routine.
Develops dynamic flexibility better. Most activities and movements are dynamic in
nature, so ballistic stretching adheres to the principle of specificity by stressing
muscle and connective tissues in manners in which they will be used.
Effectively stretches the muscle
Can be performed in unison during team warm-ups, which can help to promote
team camaraderie.
Less boring than static stretching.
The benefits of ballistic stretching include:
If you include ballistic (dynamic) stretching in your program or warm-up, you should
proceed with caution. Ballistic stretching initiates a stretch reflex that can reduce stretch
effectiveness. Also, the development of too much limb kinetic energy (a function of
velocity) can simply overpower the ability of tissues to absorb the energy, and can cause
rupture.
CONTROVERSY SURROUNDING FLEXIBILITY AND
STRETCHING
Researchers emphasize risk factors associated with low flexibility, and we should be
concerned about this component of fitness. Flexibility can be viewed on a continuum, and
we would all agree that no flexibility (anklosis, a stiffness/fixation of a joint through
surgery or disease) is highly undesirable. At the other end of the continuum, extreme
flexibility or instability can lead to dislocations, poor coordination, and increased risk of
joint, muscle, and connective tissue injury. There must be an optimum level of flexibility,
which will vary between individuals and sports.
In addition, strong evidence supports the notion that stretching can prevent injury is
lacking. People who possess greater flexibility have not been shown to be at a lower risk
of injury. Those possessing high flexibility, as well as those possessing low flexibility,
have been shown to be at higher risk of injury. There is some evidence to suggest that low
flexibility may increase the risk of muscle and tendon injury, whereas high flexibility may
increase the risk of ligament and cartilage injury. People with tight muscles benefit most
from stretching, while those with loose muscles should only perform mild stretching, if
any, and perhaps engage in more resistance training.
STRETCHING PRIOR TO EXERCISE (WARM-UP)
Warming-up prior to activity is essential, static stretching should not be a part of that
warm-up.
Shrier conducted a review to evaluate scientific evidence surrounding the hypothesis that
stretching immediately before exercise prevents injury. The study supports evidence that
stretching before exercise does not reduce the risk of injury. This study does not suggest
that a warm-up or increased flexibility is a problem or is ineffective in injury reduction;
the study was specific to the role of stretching prior to exercise.
In animals, immobilization or heating-induced increases in muscle compliance
(“stretch-ability”) causes tissues to rupture more easily.
Stretching before exercise should have no effect for activities in which excessive
muscle length is not an issue, such as jogging.
Stretching won’t affect muscle compliance during eccentric activity, when most
strains are believed to occur.
Stretching can produce damage to the structures within the muscle fibre.
Stretching appears to mask muscle pain in humans, and this may increase chances of
excessive exercise effort.
5 reasons why stretching before exercise would not prevent injuries:
Researchers caution against the improper use of static stretching in training as compared
with pre-competition warm-ups. Static stretching should be organized in a separate
routine from training and be used to increase soft tissue length, cautious with static
stretching prior to hard training as it may weaken the muscle leaving it prone to injury.
Not to perform any static stretching prior to matches, as static stretching weakens muscle
and further increases the chance of injury by reducing the amplitude of the stretch reflex.
Warm-up is designed to prepare you for the activity to come, reduce the chance of injury,
and improve performance, not improve flexibility. Even if you stretch before and after
training, these flexibility warm-up/cool down programs alone will not improve
flexibility.
The warm-up is not about training any particular component of fitness.
Found that female elite soccer players who performed static stretches prior to sprint tests
were slower than a group warming up with dynamic stretches. The players were slower
over 10 metres (acceleration) and 30 metres, and their top speed after 30 metres was
lower. This study then switched the warm-up protocols for both groups, and again, the
group performing static stretching was slower. The evidence shows that increased
compliance (stretch-ability) in the tendon (due to static stretching) increases the time
required to transmit force from muscle to bone.
"These findings provide evidence that static stretching exerts a negative effect on sprint
performance and should not be included as part of the preparation routine for physical
activity that requires sprinting.
Other studies have found that static stretching decreases muscle strength by as much as
30%. Also, stretching the muscles in one leg can reduce strength in the other leg, probably
because the central nervous system inhibits input due to the duration of the static stretch.
Again, you must incorporate such information into your specific exercise program. Static
stretching prior to jogging is unlikely to cause many problems, as jogging does not
involve extreme ranges of motion or very dynamic movements. Stretching is most
effective when the muscle is warm. It is better to stretch after your run when deep muscle
temperature is high, and the muscle and tendon are more compliant.
Safe dynamic stretching is the better type of stretching to do prior to dynamic power
activities such as tennis, rugby, soccer, volleyball, and basketball. The dynamic flexibility
component of this example would be very similar, for sports like football, tennis, rugby,
volleyball, tennis, and squash.
Dynamic Stretching
Internal and external hip rotations.
Walking lunges.
Pull knees to chest.
Deep squats (sumo stretches).
Quad stretches (heel to gluteals).
Toe touches—do not bounce down too aggressively.
High kick to opposite side (moderate speed).
(Hold for only a couple of seconds—you DO NOT want to diminish the stretch reflex.)
Goal Keeper Specific Warm-Up
Volleying balls directly to the keeper (waist to chest height).
Vary feed at keeperlow/high.
Feed to side requiring less than full dives (can be done off knees for younger athletes).
After the dynamic stretch, a player or coach needs to do some specific warm-up for the goalkeeper(s).
Conclude the warm-up with some small-sided games, long passing and/or shooting drills.
The main thing now is to get game elements into the last part of the warm-up. “Where can I move to
support the ball carrier?” “I need to call for the ball,” etc. So this can be done in several ways.
. One group can play a little 5 vs. 2 keep-away (or possibly a little 3 vs. 3 game)
The research doesn’t really support the notion that dynamic stretching prevents injury. A
study showed reduced injury rates from a comprehensive warm-up, but this warm-up
only included running, strength, plyometrics, balance, and more running. The results
showed that this warm-up package significantly lowered the risk of injuries compared to
teams that warmed up in more traditional ways. Evidence supports warm-ups prior to
activity, but not static stretching.
You must treat stretching as a disruption of muscle homeostasis (resting state). People
expect strength training to stress the muscle and slightly damages muscle fibres and
connective tissues. The typical response to strength training is to increase the cross-
sectional area of the muscle by adding sarcomeres in parallel. With a stretching routine,
you are trying to force an adaptation that would add sarcomeres in series and increase
the length of the muscle. This takes work and will initially be disruptive to the muscle.
a minimum of 2-3 days per week;
holding each stretch for 2040s to mild discomfort; and
performing 3-4 repetitions per stretch.
All major muscles groups must be targeted.
The ACSM recommends static flexibility training with these variables:
Deltoid (anterior,medial, and posterior heads).
General back stretch (latissimus dorsi, erector spinae, and trapezius, including
lower, middle, and upper fibres; major and minor rhomboid).
Pectoralis major.
Biceps brachii (front of arm).Triceps (back of arm).
Abdominals (rectus abdominus)
Obliques.
Hip flexors (iliopsoas, rectus femoris).
Gluteus maximus.
Piriformis (this is slightly different stretch than the gluteus maximus stretch
above).
Quadriceps.
Hamstrings.
Thigh adductors
Thigh abductors
Tibialis anterior
Gastrocnemius
Soleus
You need only know one stretch for each muscle or muscle group (there are several
stretches for each muscle). For example for the Anterior Deltoid= doorway
stretch,seated,PNF, and wall.
Basic Stretching Program
Proprioceptive neuromuscular facilitation (PNF) is an advanced form of flexibility
training that involves both stretching and contraction of muscle groups. PNF stretching
was originally developed as a form of rehabilitation, and is very effective. It is excellent
for increasing flexibility and can also improve muscular strength.
There are many types of PNF stretching techniques, contract-relax or hold-relax is the
most common.In this procedure, the muscle group is positioned so that muscles are
stretched and under tension. The individual then contracts the stretched muscle group
for 5-6s while a partner/immovable object applies sufficient resistance to inhibit
movement, resulting in an isometric contraction. The contracted muscle group is then
relaxed, and a controlled stretch is applied for about 30s. The muscle group is allowed
30s to recover, and the process is repeated 2-4x.
When you stretch a muscle, the CNS produces some level of contraction (tension) in the
muscle to protect it from being over-stretched. This is why you need to hold a stretch
for at least 20s, as the CNS will allow the muscle to relax more as the stretch is
prolonged. The concept behind PNF stretching is that the muscle will more fully relax
after the isometric contractions. Hence PNF reduces the amount of tension the CNS
maintains in the muscle even more than in a traditional static stretch. If done properly
PNF stretching is the most effective form of stretching.
Use for problematic muscle groups
PNF stretching is effective and may increase ROM, but it may be uncomfortable. If
done improperly, it can result in injury. It is very important to communicate effectively
with your partner to reduce the chances of injury. Other disadvantages are that it takes
more time than other types of stretching, and athletes do report some pain and post-
stretching soreness.
Proprioceptive Neuromuscular Facilitation
Inflexibilities can easily cause injuries, such as poor hamstring flexibility leading to
back problems.
Common Orthopedic Inflexibilities
Joints have several muscles crossing them and some can move in many directions, so
you usually need to perform more than one stretch per joint. For example,
the gastrocnemius is a two-joint muscle crossing the ankle and knee. To stretch this
muscle, you should extend the knee and dorsiflex the ankle. The soleus does not cross
the knee and is best stretched with the knee flexed and the ankle dorsiflexed. The
shoulder can move in so many directions and has so many muscles crossing the joint
that several stretches are required.
Standing hamstring stretchesPut pressure and strain on the lower back.
Single or double-leg inverted hurdler’s stretchThis is when you sit on your
lower legs and lean backward to lay your back on the floor. This exercise can
result in over-stretching some tissues, crushing others, pinching nerves, and
jamming joints.
Full neck circlesNeck extension puts pressure on the cervical disks.
Arches and bridges (back hyperextension)Any hyperextension of the low back
can cause injury. Hyperextension of the low back can jam spinal joints together,
excessively squeezing spinal disks. This can also pinch nerve fibres that emerge to
form the sciatic nerve.
Standing torso twistProbably safe as a static stretch but, when performed
dynamically, there is a danger that the momentum gained can exceed the
absorbing capacity of tissues being stretched. Ligaments and joints in the lower
back are at risk if this exercise is performed too vigorously.
Gravity inversionA traction technique that requires special boots or frames.
The dangers of gravity inversion are probably limited to those with health
problems such as high blood pressure and glaucoma. This is because the exercise
will increase blood pressure and pulse, and also increase intraocular pressure
(pressure within the eye).
Some stretches should be avoided. The stretches in the following list, it is best to be on
the side of caution, especially if you are leading a group:
Additional Notes on Flexibility Exercises
BACK FITNESS
Avoiding back problems is a function of both adequate strength/endurance and
flexibility, which is why I have included a section on core conditioning.
The skeletal muscles that support the spinal column need to be strengthened and
balanced on all sides of the trunk. The unique feature of the core” is the spinal column
that it must support. The spine is an unstable stack of small bones, referred to as an
inverted pendulum (without ligament and muscular support, the spinal column would
collapse).
Muscles crossing the shoulder and muscles that attach the lower limb to the pelvis have to
be strong and flexible. If you take care of the strength and endurance of all major muscle
groups and maintain a good range of motion across major joints, you will be far less likely
to suffer from low back pain or other problems associated with the spinal column.
With more than 80% of North Americans experiencing back problems
There are many risk factors for poor back health, such as age, gender, physique, spinal
health, bone density (osteoporosis), low job satisfaction, lifting technique, conditioning,
and sedentary lifestyles. It is difficult to predict whether an individual will develop low
back pain; the number one risk factor is previous back pain or injury.
Most back problems do not occur due to lifting heavy objects. Many people have
rehabilitated their backs by resistance training. Think back to the principle of overload. If
you want to strengthen a tissue, you have to stress it and allow it to rebuild itself stronger.
People still believe back problems occur on the job due to heavy and frequent lifting.
While lifting, pulling, and pushing objects are major causes of work-related low-back
pain (LBP) and other musculoskeletal injuries, LBP is also common in work environments
where no lifting occurs, such as seated work. The pressure within the spinal discs is
higher when sitting than when standing; so it is not surprising that LBP is also caused by
non-work related movements and postures. So loading on the spine is not excessive, it is
constant for extended periods. That many people have poorly conditioned trunk
musculature.
Anatomy of the Spine
The spine is an inverted penduluma series of bones separated by fluid-filled disks,
which act as shock absorbers. Figure 7.4 is a mechanical analogue of the spine. The left
diagram depicts the pelvis as the stable floor into which the spine is anchored. Therefore,
as this stable anchor (the pelvis) is below the spinal column, stability can only be achieved
by the ligaments and muscles that support the spinal column (shown as springs in
Figure 7.4).
Note that all muscles that attach to the spine, and not just the muscles that originate and
end within the trunk, are relevant to understanding a core conditioning program.
Inflexibility affects your posture, which can cause back problems. In addition, just
focusing on strengthening trunk muscles is not necessarily going to prevent LBP. For
example, strong but short gluteals and hamstrings may be the cause of a person’s LBP,
rather than weak erector spinae muscles.
Figure 7.4. Mechanical analogue of the human spine
No single muscle is the most important muscle for stability, as the required pattern of
recruitment varies with each different movement pattern. The following in addition to
stabilizing the spine, each muscle group contributes to trunk movement.
Transverse abdominusForced expulsion (breathing).
Internal obliquesLateral flexion, rotation to same side and flexion of trunk.
External obliquesLateral flexion of trunk to same side, rotation to opposite side,
and flexion of trunk.
Rectus abdominusFlexion of trunk.
Abdominal Group
Erector spinaeTrunk extension.
MultifidusLateral flexion, extension, and hyperextension of the spine.
Quadratus lumboruminvolved in lumbar spine stabilization; largely isometric.
Latissimus dorsiSpine stabilizer enhanced by pulling to chest in lat pull-down
exercise.
Back Muscles
In addition, the hamstrings, quadriceps, pectorals, or any muscle with at least one
attachment on the trunk can cause problems to the back if weak and inflexible. Muscles
that are strong but short can also cause problems if they attach to the core.
Core Conditioning
Whenever you are upright in a gravitational field and/or move, you recruit your core
musculature. Therefore, training should include core conditioning. The core is more than
just the abdominal muscle group, which gets a lot of attention. When I discuss the core, I
mean the whole midsection of your body from groin to upper back and chest, including
sides. All muscles crossing onto the trunk are crucial in any program focused on the core.
All trainers agree that good core development is a type of functional training that will
enhance all human movement for all populations.
What exercises recruit the core? all movement will, if you let it. By this I mean not
slumping onto your spine and allowing all the load to be borne by passive tissues, such as
ligaments and joints. If you keep your trunk muscles engaged and supporting the spine,
you are core training. If I put a weight in my hands and press it overhead, I am applying
an upward force on the load. Now, if you know anything about mechanics, youll know
the load pushes you back. Why do you not move down? Because you effectively get
pushed into the ground, and the ground resists your downward motion. So the forces
from your shoulder and arm muscles used to accelerate the load upwards get transmitted
through your body to the ground. So performing an exercise like a press (shoulder press)
requires you to recruit core musculature to stabilize your spine.
Exercises like the deadlift and back-squat, allow you to pull and push so much weight, are
particularly challenging to the core. The challenge is to teach these movements correctly.
Once learned, they will probably be the best core exercises you’ll do, and at the same time
they will stimulate body strength like no other exercises. Safely loading your body with
large weights stimulates hormonal responses such as increased growth hormone,
testosterone, and insulin-like growth factor. This will help improve your hormonal
balance, strength, and core stability.
I’ll be honest and say I have a problem with the amount of exercises people do on Swiss
balls and Bosu balls. I agree that if you are sitting on an unstable surface, you will be
challenged to coordinate muscle activity and stabilize your core. However, the challenge
is not really like anything you’ll see in your everyday life and the forces being applied to
the core are low. These types of exercises challenge your motor controlthat much I agree
with. Being challenged this way is not an everyday occurrence, but I occasionally do ball
sit-ups, primarily for a change.
It is a heavy load for me and challenges my shoulder overhead press and, as explained
above, I have to control that force as it is transmitted through my spine. If I sit and press
on an unstable ball, I may only want to use 30-pound dumbbells (if that). Not only is this
less stress on my shoulders, it is less stress on my core. There may possibly be a greater
motor control challenge when I am on the ball, but strength is a component of fitness and
I can’t work in a high-weight, low rep-max range when on a ball. No matter how well
coordinated you are, if the load on your spine overwhelms your strength, the spine will
buckle. Mechanically stated, if the work done on the spine (energy applied) is greater than
the work the muscles can do to stiffen the spine, then the spine will buckle
I want to emphasize the need to train the entire core musculaturethe entire
cylinder. Spine stiffness (stability), is achieved by a complex interaction of stiffening
structures (muscles and ligaments) along the spine as well as those forming the torso wall.
Balancing stiffness on all sides of the spine is more critical to ensuring stability than
having high forces on a single side. Absolute endurance and strength is probably
secondary in importance to the relationship between muscle groups, as he believes muscle
imbalances are a primary cause of back problems. So, although lifting heavy is going to be
great for strength development and core stability, if you cant lift heavy, at least train all
four sides of your torso. That people with low back problems often have weaker extensor
strength relative to their flexor strength. This is not uncommon even among athletes, who
are likely to be better at sit-ups than at back extensions.
Core musculature is often engaged isometrically. When you strike a tennis or golf ball, or
throw a baseball, you rotate the trunk quickly; for most other activities, you actually use
the core musculature to stabilize the trunk as forces are transmitted through them. This
was the example used for the shoulder press. Planks are excellent exercises where you
hold a position for a set period of time (or until fatigue). Planks are isometric exercises
where the core muscles have to work against gravitational forces to maintain a straight
spine.
BACK INJURY, INTRA-ABDOMINAL PRESSURE, AND
LIFTING BELTS
Most spinal-disk herniations occur at the disks between the lowest two lumbar vertebrae
(L4 and L5) or between the lowest lumbar and the top sacral vertebra (L5 and S1). The
high incidence of injury in these regions is due to the large compressive forces
experienced at L4/L5 and L5/S1 during lifting. Whenever you hold a weight in your
hands or on your shoulders and incline your trunk forward, there is a great torque about
the lower spinal discs due to the large distance between your lower back and the weight.
The back muscles have a low mechanical advantage because the perpendicular distance
from the spinal erector muscle’s line of action to the spinal disks is much lower (about 6
cm) than the horizontal distance from the weight to the disks. As a result, your muscles
must exert forces that are much greater than the weight being lifted (10x or more). These
forces tend to squeeze spinal discs between adjacent vertebral bodies.
To minimize L5/S1 compressive forces and ligament strain, you should use a flat-back
lifting posture, as opposed to a rounded-back posture. A slightly arched back has been
found to be superior to a rounded back in terms of minimizing injury to the vertebrae,
discs, facet joints, ligaments, and muscles of the back. In addition, low back muscles are
able to exert much higher forces when you arch your back slightly rather than rounding it.
When you round your back, the erector spinae muscles turn off’ and more of the load is
borne by the spinous ligaments. This increases the risk of both ligament and disk injury.
When rounding the back, the anterior (front) edges of the vertebral bodies tend to squeeze
the front portions of the spinal discs. In contrast, extreme backward arching results in
squeezing of the posterior (back) portions of the discs. This uneven squeezing of spinal
discs increases the risk of disc rupture.
INTRA-ABDOMINAL PRESSURE AND LIFTING BELTS
When the diaphragm and deep muscles of the torso contract, pressure is generated within
the abdominal cavity. Because the cavity is mainly composed of incompressible fluid, the
resulting volume under pressure has been described as a fluid ball, which aids in
supporting the spinal column during lifting. This support may significantly reduce both
the forces required by the erector spinae muscles to perform a lift and the associated
compressive forces on the discs.
For exercise that is not stressing the back, do not wear a belt at all.
For exercise that is directly stressing the back, refrain from wearing a belt during
lighter sets but wear one during near-maximal and maximal sets. The sets
performed without a belt allow the deep abdominal muscles to receive a training
stimulus so that they are capable of generating sufficient intra-abdominal pressure
on their own. This should reduce the chance of low back injury.
Weightlifting belts have been shown to increase intra-abdominal pressure during lifting
and are therefore probably effective in improving lifting safety. However, it should be
cautioned that, if you do all lifting with a belt, the deep abdominal muscles that produce
intra-abdominal pressure might not get enough of a stimulus to develop optimally. This
being the case, if you become accustomed to wearing a belt, you may risk injury to the
muscles or discs of your lower back if you are required to perform a lift without a belt.
This is because your abdominal muscles may not be capable of generating enough intra-
abdominal pressure to significantly reduce erector spinae muscle forces. Conservative
recommendations for wearing a belt include the following:
EXERCISE AND BACK PAIN
I cannot say enough about the importance of exercise in preventing and rehabilitating
back pain. It is estimated that 95% of people with back pain can be helped by exercise.
This is because a lot of injuries to the back are soft-tissue injuries. For example, adequate
muscle strength and a proper balance of this strength will support the spine, reduce strain
on the ligaments, and help maintain correct posture. Good flexibility also allows for
correct posture. In addition, cardiovascular exercise helps with everyday mobility (joints
can deteriorate with lack of movement).
The following lists show conditions that can benefit from exercise, as well as conditions
that are not helped by exercise. Note that even a fractured spine can be helped by exercise
once the acute phase of the injury is over.
Muscular strains or weakness.
Ligament sprains or inflammation.
Disc degeneration.
Facet joint arthritis.
Osteoporosis of the spine.
Sacroiliac joint disorders.
Recovery phase of a fractured spine.
Weak back due to poor body maintenance.
Back Problems Helped by Exercise
The overload principle shows us that the only way to strengthen the core is to stress the
core. Sitting on a chair spinning your legs isn’t going to achieve that objective. They have
never trained athletes and other individuals. Many doctors will tell you that squats are
bad for your knees, but nearly all strength and conditioning coaches will tell you the
opposite.
Flexibility: is the range of motion around a joint
Stretching: is an component of an exercise program
Define both flexibility and stretching.1.
Improved joint health.
Reduction of low-back pain and injuries.
Reduction of delayed onset muscle soreness (DOMS).
Pain relief.
Athletic performance.
Improved posture.
Relaxation.
Additional potential benefits such as:
List four benefits of maintaining adequate range of motion (flexibility).2.
Some people have a greater range of motion than others simply because of
the way their bones are shaped. In addition, different joint structures allow
different ranges of motion. One example is the limited(circling) range of the
hip as compared with the shoulder. The joint capsule also affects ROM.
Joint Structure and Your Skeleton
Normal activity and exercises through full ROM reduce the likelihood of a
muscle shortening, and a well-designed stretching program can actually
lengthen the muscle. Hypertrophy due to strength training results
in sarcomeres being laid down in parallel, thereby increasing the cross-
sectional area. With a stretching program, sarcomeres are laid down in
series, increasing muscle length.
Muscle Elasticity and Length
Reciprocal innervation This takes place when a muscle contracts,
inhibiting contraction of antagonist muscles; for example, when hip
flexors contract, hip extensors relax.
Muscle spindles These are sensory nerve endings in the muscle that
detect muscle length change and rate of change. Force applied to a
muscle stimulates muscle spindles, which activate protective reflexes
and result in muscle contraction (such as the knee jerk response to
neurological testing procedures).
Golgi tendon organ Atendon organ that is located at the insertion
where the muscle fibres insert into the tendon. When the muscle
generates force, the sensory terminals are compressed and a signal is
sent to the spinal cord which signals the stretch reflex.
The nervous system plays a role in what range of motion you can achieve by
regulating muscle contraction.
Nervous System Activity
What factors contribute to the range of motion of a joint?3.
Sprains and bruises accumulated during exercise may increase scar tissue build-
up and actually reduce range of motion. From experience, most soccer players do
not have excellent ankle flexibility due to the number of times they are kicked on
the ankle and lack of stretching. This frequent stress increases the likelihood that
they will develop scar tissue. Many activities do not require a full ROM of joints
and/or do not utilize all joints (e.g., running) which will limit your range of
motion; for these activities, a stretching routine may be required.
How can exercise limit flexibility?4.
Ballistic stretchingMomentum from body parts propels the muscle into an
extended range of motion, exceeding an individuals static, passive stretching
ability. These types of stretches are usually initiated by quite vigorous
movements, such as swinging the arm backwards to stretch the anterior deltoid
and pectoralis major.
Dynamic stretchingThe movement into the stretch position is more controlled
and the fully stretched position is often held for one or two seconds. In ballistic
stretching, the limb generally immediately recoils back from the extreme range of
motion obtained. Dynamic stretching involves lower limb velocities than ballistic
stretching. No matter how you define dynamic and ballistic stretching, you can
use limb momentum to stretch a muscle more or less vigorously. You should be
aware of the potential dangers if you do not perform stretches properly.
Dynamic stretching is advocated by many coaches, trainers, and researchers as a
beneficial form of stretching that is especially important during warm-up
for sports involving intense, dynamic activity. During these activities, muscles are
used dynamically; hence, dynamic stretching should be part of a warm-up
routine.
Compare static and ballistic stretching. Which method is better and why?5.
Static stretching during a warm-up reduces injuries is not accurate. Warming-up
prior to activity is essential, static stretching should not be a part of that warm-up.
In animals, immobilization or heating-induced increases in muscle
compliance (“stretch-ability) causes tissues to rupture more easily.
Stretching before exercise should have no effect for activities in which
excessive muscle length is not an issue, such as jogging.
Stretching won’t affect muscle compliance during eccentric activity, when
most strains are believed to occur.
Stretching can produce damage to the structures within the muscle fibre.
Stretching appears to mask muscle pain in humans, and this may increase
chances of excessive exercise effort.
Evidence surrounding the hypothesis that stretching immediately before exercise
prevents injury. The study concluded that scientific literature supports
epidemiological evidence that stretching before exercise does not reduce the risk of
injury. This literature review suggests five reasons why stretching before exercise
would not prevent injuries:
Researchers and coaches caution against the improper use of static stretching in
training as compared with pre-competition warm-ups. Argued that static
stretching should be organized in a separate routine from training and be used to
increase soft tissue length. He argues, correctly in my view, that caution must be
used when doing static stretching prior to hard training as it may weaken the
muscle leaving it prone to injury. Instead he argues athletes should use
"facilitated" or "dynamic" stretching.
Static stretching weakens muscle and further increases the chance of injury by
reducing the amplitude of the stretch reflex. The warm-up is designed to prepare
you for the activity to come, reduce the chance of injury, and improve
performance, not improve flexibility. Even if you stretch before and after training,
these flexibility warm-up/cool down programs alone will not improve flexibility.
The purpose of a warm-up is to prepare your body for the exercise to follow.
Where during a soccer, tennis, football, or rugby game would you hold a 20-
second stretch? The warm-up is not about training any particular component of
fitness.
Female elite soccer players who performed static stretches prior to sprint tests
were slower than a group warming up with dynamic stretches. The players were
slower over 10 metres (acceleration) and 30 metres, and their top speed after 30
metres was lower. This study then switched the warm-up protocols for both
groups, and again, the group performing static stretching was slower. The
evidence from this and other studies shows that increased compliance (stretch-
ability) in the tendon (due to static stretching) increases the time required to
transmit force from muscle to bone. Basically, static stretching slows you down
(for a period of time immediately afterward). "These findings provide evidence
that static stretching exerts a negative effect on sprint performance and should
not be included as part of the preparation routine for physical activity that
requires sprinting.”
Other studies have found that static stretching decreases muscle strength by as
much as 30%. Also, stretching the muscles in one leg can reduce strength in the
other leg, probably because the CNS inhibits input due to the duration of the
static stretch.
Static stretching prior to jogging is unlikely to cause many problems, as jogging
does not involve extreme ROM or very dynamic movements. Stretching is most
effective when the muscle is warm, yet you often see runners performing static
stretching before their run, prior to their muscles being really warmed up. It is
better to stretch after your run when deep muscle temperature is high, and the
muscle and tendon are more compliant.
Discuss the arguments for and against including static stretching in a warm-up routine.6.
It develops dynamic flexibility better. Most activities and movements are
dynamic in nature, so ballistic stretching adheres to the principle of
specificity by stressing muscle and connective tissues in manners in which
they will be used.
Shown to be effective.
It can be performed in unison during team warm-ups, which can help to
promote team camaraderie.
It can be less boring than static stretching.
The benefits of ballistic stretching include the following:
If you decide to include ballistic (dynamic) stretching in your program or warm-
up, you should proceed with caution. Ballistic stretching initiates a stretch reflex
that can reduce stretch effectiveness. Also, the development of too much limb
kinetic energy (a function of velocity) can simply overpower the ability of tissues
to absorb the energy, and can cause rupture.
Discuss the arguments for and against including ballistic stretching in a warm-up
routine.
7.
Intensity: Hold the stretch to mild discomfort
Duration: 20-40 seconds, 3-4 repetitions
Frequency: 2-3 days per week minimum
How do the concepts intensity, duration and frequency apply to stretching programs?8.
Sternocleidomastoid: (Neck retraction stretch) Stand or sit. Pull head back as far
possible and down slightly. Hold stretch.
Trapezius (Upper): (Upper trapezius stretch) Grasp wrist or hand from behind
and pull arm to opposite side. Tilt head away from lowered shoulder by
positioning ear toward front of opposite shoulder. Hold stretch. Repeat to other
side.
Anterior Deltoid: (Doorway front deltoid stretch) Stand at end of wall or in
doorway facing perpendicular to wall. Position palm on surface of wall slightly
lower than shoulder. Bend elbow slightly. Turn body away from positioned arm.
Hold stretch. Repeat with opposite arm.
Posterior Deltoid: (Fixed bar rear deltoid stretch) Face stationary bar. Grasp
stationary bar with one hand approximately face height. Rotate body so upper
arm is positioned across neck. Turn body into upper arm. Hold stretch. Repeat
with opposite arm.
Latissimus Dorsi: (Fixed bar back stretch) Stand facing stationary bar. Grasp
stationary bar with one hand approximately waist height. Bend over allowing
hips to fall back. Slightly lean torso toward stretched arm. Hold stretch. Repeat
with opposite side.
Pectoralis Major: (Doorway chest stretch) Stand at end of wall or in doorway
facing perpendicular to wall. Place inside of bent arm on surface of wall. Position
bent elbow shoulder height. Turn body away from positioned arm. Hold stretch.
Repeat with opposite arm.
Triceps: (Overhead triceps stretch) Stand facing stationary bar. Grasp stationary
bar with one hand approximately waist height. Bend over allowing hips to fall
back. Slightly lean torso toward stretched arm. Hold stretch. Repeat with opposite
side.
Iliopsoas: (Lunging hip flexor) Lunge with one foot far behind other foot. Squat
down with chest high, straightening hip of rear leg by pushing hips down and
forward. Hold stretch. Repeat with opposite side.
Abdominals (rectus abdominus): (Lying prone abdominis stretch) Lie prone on
mat or floor. Position hands on floor to sides of shoulders. Push torso up keeping
pelvis on floor. Hold stretch.
Abdominals (internal and external obliques): (Lying cross over stretch) On floor
or mat, lie supine with arms extended to sides. Lift one leg straight up. Lower leg
to opposite side toward hand. Hold stretch. Repeat with opposite side.
Erector Spinae:
Gluteus Maximus: (Lying glute stretch) Lie on floor or mat. Bend knees with feet
on floor. Cross lower leg over thigh of other leg. Grasp foot and knee with both
hands. Pull leg toward torso. Hold stretch. Repeat with opposite leg.
Quadriceps: (Lying piriformis stretch) Lie on floor or mat. Lift one leg and grasp
ankle and knee with both hands. Pull thigh toward torso while keeping knee over
torso. Hold stretch. Repeat with opposite leg.
Hamstrings: (Lying hamstring stretch) Lie on back and lift knee up. Grasp behind
thigh near knee with both hands. Pull knee close to chest. Extend knee while
maintaining knee close to chest. Hold stretch. Repeat with opposite leg.
Tibialis Anterior: (Standing shin stretch) Stand and touch wall or stationary
object for balance. Grasp forefoot behind. Pull forefoot to lower back. Hold
stretch. Repeat with opposite side.
Gastrocnemius: (Floor board straight leg calf stretch) Face wall with both knees
slightly bent. Position fore foot on wall with heel on floor. Straighten knees and
lean body toward wall. Hold stretch. Repeat with opposite leg.
Soleus: (Wall bent knee calf stretch) Place both hands on wall with arms
extended. Lean against wall with one leg bent forward and other leg extended
back. Bend rear knee slightly, positioned foot directly forward, and place heal to
floor. Lower knee until just before heel raises. Hold stretch for 20 seconds. Repeat
with opposite leg.
Describe a stretching exercise that would be effective at stretching the muscles listed
below.
9.
Proprioceptive neuromuscular facilitation (PNF) is an advanced form of
flexibility training that involves both stretching and contraction of muscle groups.
PNF stretching was originally developed as a form of rehabilitation, and is very
effective. It is excellent for increasing flexibility and improving muscular strength.
The most common PNF stretching technique is contract-relax or hold-relax. In
this procedure, the muscle group is positioned so that muscles are stretched and
under tension. The individual then contracts the stretched muscle group for 5-6s
while a partner/immovable object applies sufficient resistance to inhibit
movement, resulting in an isometric contraction. The contracted muscle group is
then relaxed, and a controlled stretch is applied for about 30s. The muscle group
is allowed 30s to recover, and the process is repeated 2-4x.
Briefly explain what is meant by Proprioceptive Neuromuscular Facilitation (PNF)
stretching.
10.
Single or double-leg inverted hurdler’s stretchThis is when you sit on your
lower legs and lean backward to lay your back on the floor. This exercise can
result in over-stretching some tissues, crushing others, pinching nerves, and
jamming joints.
Describe a flexibility/warm-up exercises that are considered to be potentially
dangerous to the knee joint. Explain why the exercise is considered to be potentially
harmful to the knee joint.
11.
Standing hamstring stretchesPut pressure and strain on the lower back
Full neck circlesNeck extension puts pressure on the cervical disks.
Arches and bridges (back hyperextension)Any hyperextension of the low back
can cause injury. Hyperextension of the low back can jam spinal joints together,
excessively squeezing spinal disks. This can also pinch nerve fibres that emerge to
form the sciatic nerve.
Standing torso twistProbably safe as a static stretch but, when performed
dynamically, there is a danger that the momentum gained can exceed the
absorbing capacity of tissues being stretched. Ligaments and joints in the lower
back are at risk if this exercise is performed too vigorously.
Describe two flexibility/warm-up exercises that are considered to be potentially
dangerous to the lower back. Explain why each exercise is considered to be potentially
harmful to the lower back.
12.
Cervical, thoracic, lumbar, sacral, coccygeal
Name the five regions of the spinal column.13.
More than 80% of North Americans experiencing back problems in their lifetime,
back fitness is an important issue. There are many risk factors for poor back
health, such as age, gender, physique, spinal health, bone density (osteoporosis),
low job satisfaction, lifting technique, conditioning, and sedentary lifestyles. It is
difficult to predict whether an individual will develop low back pain; the number
one risk factor is previous back pain or injury. So, if you have already had an
episode of back pain, you are at a high risk for developing back pain again in the
future. But those of you who haven’t had any back problems should not be
complacent.
What percentage of the population in Canada will experience back problems during
their lifetime?
14.
List two muscles from the abdominal group and two from the back group. What two
sets of muscles are responsible for lateral flexion, and spinal rotation?
15.
Transverse abdominusForced expulsion (breathing).
Internal obliquesLateral flexion, rotation to same side and flexion of trunk.
External obliquesLateral flexion of trunk to same side, rotation to opposite
side, and flexion of trunk.
Rectus abdominusFlexion of trunk.
Abdominal Group
Erector spinaeTrunk extension.
MultifidusLateral flexion, extension, and hyperextension of the spine.
Quadratus lumborumHighly involved in lumbar spine stabilization; largely
isometric.
Latissimus dorsiSpine stabilizer enhanced by pulling to chest in lat pull-down
exercise.
Back Muscles
The best way to train the core is to challenge the whole core musculature, training
should include core conditioning. The core is more than just the abdominal
muscle group, which tends to get a lot of attention. When I discuss the core, I
mean the whole midsection of your body from groin to upper back and chest,
including sides. All muscles crossing onto the trunk are crucial in any program
focused on the core. Without good core development, you will not be able to
move and react efficiently, whether you are a cross-country runner, football
player, or senior citizen. All trainers agree that good core development is a type
of functional training that will enhance all human movement for all populations.
Exercises like the deadlift and back-squat, allow you to pull and push so much
weight, are particularly challenging to the core. The challenge is to teach these
movements correctly. Once learned, they will probably be the best core exercises
youll do, and at the same time they will stimulate body strength like no other
exercises. Safely loading your body with large weights stimulates hormonal
responses such as increased growth hormone, testosterone, and insulin-like
growth factor. This will help improve your hormonal balance, strength, and core
stability
Discuss the best way to challenge and train your core musculature.16.
Planks are excellent exercises where you hold a position for a set period of time
(or until fatigue). Planks are isometric exercises where the core muscles have to
work against gravitational forces to maintain a straight spine. The front plank,
which is a general core exercise but challenges flexors (abdominals) more
specifically.
Describe the front plankexercise17.
If you do all your lifting with a belt, the deep abdominal muscles that produce
intra-abdominal pressure might not get enough stimulus to develop optimally.
This being the case, if you become accustomed to wearing a belt, you may risk
injury to the muscles or discs of your lower back if you are required to perform a
lift without a belt. This is because your abdominal muscles may not be capable of
generating enough intra-abdominal pressure to significantly reduce erector
spinae muscle forces.
A friend who weight-trains with you always wears a back belt. He argues he has never
been hurt while using it. What would be your response to him?
18.
Chapter 7: Flexibility and Core Conditioning
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FLEXIBILITY AND STRETCHING
Flexibility is the range of motion (ROM) around a joint and stretching is a component of
exercise programs. Being active and moving your joints through a full ROM will help you
maintain a reasonable amount of dynamic flexibility. Most people cannot rely on activity
alone to keep their flexibility in a good range. Sprains and bruises may increase scar tissue
build-up and reduce range of motion. Many activities do not require a full ROM of joints
and/or do not utilize all joints (e.g., running) which will limit your range of motion; for
these activities, a stretching routine may be required.
While aerobic exercise can reduce your risk of developing life-threatening illnesses such
as cardiovascular disease, strength and flexibility are also fundamental to health. As we
age, muscular strength, endurance, and flexibility, take on increasing importance. For
many people quality of life is badly diminished as a result of poor strength and flexibility.
People with chronic low back pain (LBP) and stooped postures might have been able to
reduce or eliminate their risk of developing these conditions if they had undertaken
lifelong resistance and flexibility training.
Dr. Cooper suggests that, by the time you are 50 years old, 50% of your training should be
resistance training. Many people lose independence and have to move into some form of
care due to limited strength and mobility. Adequate range of motion and strength are key
factors in maintaining your independence as you age.
Joint health.
Reduction of low-back pain and injuries.
Reduction of delayed onset muscle soreness (DOMS).
Pain relief.
Improved athletic performance.
Improved posture.
Relaxation.
Benefits of stretching include the following:
It is common to suggest stretching as a possible mechanism to prevent onset of injury and
muscle soreness. They found that common stretching methods, like static and ballistic
stretches, decrease muscle performance, and evidence supporting the theory that being
flexible reduces risk of injury is inconclusive. Many sources claim that high levels of
flexibility do not reduce incidence of injury and, therefore, increasing ROM is not needed.
These results do not suggest that an optimal ROM is not needed. ROM must be adequate
for daily activities; if not, your daily quality of life will be negatively affected. Further, if
ROM diminishes to a large degree, problems like stooped postures resulting in low back
pain can occur. However, there is a strong genetic component to flexibility and some
argue that it is possible to maintain adequate ROM simply by moving through full ranges
of motion, without embarking on a specific and extensive stretching program.
WHAT DETERMINES FLEXIBILITY?
Some people have a greater range of motion than others simply because of the way
their bones are shaped. Different joint structures allow different ranges of motion.
One example is the limited circumduction (circling) range of the hip as compared
with the shoulder. The joint capsule also affects ROM.
Joint Structure and Your Skeleton
Normal activity and exercises through full ROM reduce the likelihood of a muscle
shortening, and a well-designed stretching program can actually lengthen the
muscle. Hypertrophy due to strength training results in sarcomeres (contractile unit
of the muscle) being laid down in parallel, thereby increasing th