10 response of the skeletal system to exercise; osteoporosis and fitness new

10-Response of the Skeletal
System to Exercise; Osteoporosis
and Fitness
Sport Nutrition
Dr. Siham Mohamed
Osman Gritly

objectives
• By the end of this lecture students should be able
to identify the following;
• The main functions of skeletal muscle
• types of skeletal muscles fibres and exercise
• The role of skeletal muscle in physical exercise
• Osteoporosis and exercise
Dr. Siham Mohamed Osman Gritly

The Skeletal System

The skeletal system consists of;
bones, ligaments and tendon
bones, ligaments
which connect bones
to other bones and
cartilage
Tendons connect
muscle tissue to
bone and although
more elastic than
ligaments, have a
greater strength than
muscle

A tendon connects muscle to bone. ligaments
are similar to tendons, but they connect bone to
bone and help to stabilize joints

• Synovial fluid joints produce an oil-like
substance called synovial fluid.
• It is produced by the synovial membrane
within our joints and is a short term or acute
response to exercise.

Main function of synovial fluid is to keep
cartilage lubricated and nourished

Four basic functions of skeletal system
• The skeletal system comprises of 206 bones
and provides four basic functions:
• Support for tissues and muscle
• Protection for vital organs
• Movement through bones and attached
muscles
• Storage for minerals and immature blood
cells

*1-Support for tissues and muscle
• Bones and cartilage that make up the skeleton
are the only rigid materials in the body.
• Bones and skeletal provide a framework and
points of attachment for many of the soft
tissues of the body.

*2-Protection for vital organs
• Skeletal muscles protect some of the vital
tissues and functional organs of the body.
examples are:
-Skull - protects the brain
-Vertebrae - protects the spinal cord
-Thoracic cage - protects the heart and lungs

*3-Movement through bones and
attached muscles
• during movement bones provide solid
structures to which muscles are attached.
• The joints allow movement between bones and
these movements are directly related to the
type of joint and range of motion.

• Joints fall into one of three categories:
• 1-Fixed fibrous (e.g. bones of the skull),
• 2-Slightly moveable (e.g. symphysis pubis)
• 3- Freely movable. Shoulder, hip, hinge joint, Knee,
elbow, fingers, toes, jaw, gliding- wrist, ankle,
vertebrae, - neck

1-Fixed fibrous (e.g. bones of the skull),

2-Slightly moveable (e.g. symphysis pubis)

3-Freely movable. Shoulder

*4-Storage for minerals and immature
blood cells
• In some bones, there is red marrow which
produces red blood cells, some white cells and
platelets.
• Minerals, especially calcium and phosphorous
are also stored in bones and can be distributed
to other parts of the body.

types of muscle fibres
• Skeletal muscles are composed of various types
of muscle fibres and based on metabolic and
contractile characteristics
• Skeletal muscles are used to create movement,
by applying force to bones and joints; via
contraction.
• 1-voluntarily contraction
• 2-involuntarily through reflexes.

the myofibrillar proteins
Myosin and Actin, two
proteins found in muscles
for contraction and
relaxation effect due to
nerve impulses
myosin (important
proteins that is
responsible for the ability
of muscle to contract).
actin (important proteins
that is responsible for the
ability of muscle to relax)

types of skeletal muscles fibres and
exercise
• there are three major types of fibres for
skeletal muscles: Type I, Type IIa andType
IIb .
• The types are differ in the mechanism they use
to produce ATP;
• the amount of each type of fibre varies from
muscle to muscle and from person to person.

Type I Red fibers. Slow oxidative (also called
slow twitch or fatigue resistant fibers).
 Large amounts of myoglobin (store oxygen) .
 Many mitochondria.
 Many blood capillaries.
 Generate ATP by the aerobic system, hence the
term oxidative fibers.
 Split ATP at a slow rate.
 Slow contraction velocity.
 Resistant to fatigue.
 Needed for aerobic activities like long distance
running (Marathon runners) .

• for endurance exercise
• rely on aerobic metabolism (oxidative
metabolism)

Type IIa Red fibers. Fast oxidative or (also called
fast twitch A or fatigue resistant fibers).
 Large amounts of myoglobin.
 Many mitochondria.
 Many blood capillaries.
 Large amount of glycogen.
 High capacity for generating ATP by oxidation. Split ATP
at a very rapid rate and, hence, high contraction
velocity
 Resistant to fatigue but not as much as slow oxidative
fibers.
 Needed for sports such as middle distance running and
swimming.

Type IIb White. Fast glycolytic (also called
fast twitch B or fatigable fibers).
 Low myoglobin content.
 Few mitochondria.
 Few blood capillaries.
 depend on anaerobic pathways (not oxygen
dependent) but also use oxidative metabolism
 Large amount of Creatine phosphate.
 Split ATP very quickly.
 Fatigue easily.
 Needed for sports like sprinting and Weightlifters.

• used for short bursts of speed and power
• more likely to accumulate lactic acid.

Effect of exercise on the skeletal system
• Exercise may improve to maintain healthy bones
• bone responds to mechanical stresses. When
mechanical stresses are applied, more mineral
salts are deposited and more collagenous fibres
are produced.
• The physiological response to exercise is
dependent on the intensity, duration and
frequency of the exercise as well as the
environmental conditions.

• During physical exercise, requirements for
oxygen and substrate in skeletal muscle are
increased, as are the removal of metabolites
and carbon dioxide.
• Chemical, mechanical and thermal stimuli
affect alterations in metabolic, cardiovascular
and ventilatory function in order to meet these
increased demands.

Skeletal muscle & physical exercise
• Physical exercises are generally grouped into
three types;
• Flexibility exercises, such as stretching, improve
the range of motion of muscles and joints.
• Aerobic exercises, such as cycling, swimming,
walking, skipping rope, rowing, running, hiking
or playing tennis, focus on increasing
cardiovascular endurance.
• Anaerobic exercises, such as weight training,
functional training, eccentric (unusual) training or
sprint (run), increase short-term muscle strength.

endurance exercise improves a number of factors
known to govern the FA flux and the oxidative capacity
of skeletal muscle.
• Such factors are:
• (1) blood flow and capillarization;
• (2) lipolysis of triacylglycerol (TAG) in adipose
tissue and circulating TAG and transport of FA
from blood plasma to the sarcoplasm;
• (3) availability and rate of hydrolysis of
intramuscular TAG;
• (4) activation of the FA and transport across the
mitochondrial membrane;

• (5) the activity of enzymes in the oxidative
pathway;
• (6) hormonal adaptations, i.e. sensitivity to
and insulin.

skeletal muscle is powered by one and only one compound...
adenosine triphosphate (ATP. However, the body stores only a
small quantity of this 'energy currency' within the cells and its
enough to power just a few seconds of all-out exercise. So the
body must replace or resynthesize ATP on an ongoing basis

Energy used by skeletal muscles
Muscle Metabolism
• Oxidative metabolism and anaerobic
metabolism are both used for provision of
energy during exercise
• Adenosine triphosphate (ATP) is the principal
high-energy phosphate molecule that enables
muscle contraction.
• Energy supplies to muscle are initially
provided from the immediate energy sources
of ATP and phosphocreatine

• Phosphocreatine (PCr) is another high-energy
compound containing a high-energy phosphate
bond that can be hydrolysed to provide energy
and resynthesize ATP:
• Skeletal muscle stores of PCr provide
quantitatively the greatest contribution to energy
provision in the first 10 s of high intensity
activities such as sprinting
• Oxygen delivery during strenuous exercise is
limited by cardiovascular function.

immediate energy for exercising muscles
• immediate energy - used in first 10-30
seconds of vigorous exercise; ATP creatine
phosphate (ATP-CP) system used;
• creatine phosphate contributes a phosphate
to ADP to make ATP; 1 creatine phosphate
(CP) = 1 ATP;
• all 3 skeletal fiber types use this system

short-term energy for exercising muscles
• short-term energy - used approx. 30 - 90
seconds into vigorous exercise;
• uses glycolysis to break down glucose to
pyruvate to lactate (lactic acid);
• 2 ATP; used by fast glycolytic fibers

long-term energy for exercising muscles
• long-term energy - used approx after 2 min of
vigorous exercise;
• uses glycolysis, citric acid cycle (kreb’s
cycle), and electron transport chain to fully
oxidize glucose;
• 1 glucose = 36 ATP (max);
• used by slow oxidative fibers and fast
oxidative fibers

Ossification
• -direct ossification
• Ossification is the process by which bone is formed.
• Some bones (e.g. the flat bones of the skull) are formed in
one stage from the connective tissue. This process is known
as intramembranous or direct ossification.
• -indirect ossification
• Other bones (e.g. short bones) are formed from the
cartilaginous cells during the development of embryo
• This process is known as endochondral or indirect
ossification - most bones are formed this way.
•

Osteoporosis
Osteoporosis is a disease of the bones that affects men
and women, especially women beyond menopause
because estrogen helps to protect bone.
• Normal bone is composed of protein, collagen,
and calcium, all of which give bone its strength.
• Bones that are affected by osteoporosis can break
(fracture) with relatively minor injury that
normally would not cause a bone to fracture.
• The osteoporosis condition can be present without
any symptoms for decades

• Aging have an effects on bones;-
- Bones begin to lose calcium which lead to
condition known as osteoporosis.
- less protein is produced which alters the make-up
of bone and sometimes creates brittle or fragile
bones.
- Osteoarthritis (wear and tear inflammation) upon
weight bearing joints related to years of friction

type of osteoporosis
• type I osteoporosis: osteoporosis
• characterized by rapid bone losses, primarily of
trabecular bone. Women are most often the
victims of this type of osteoporosis
• and bone breaks may occur suddenly. Trabecular
bone becomes so fragile
• type II osteoporosis: osteoporosis
• characterized by gradual losses of both trabecular
and cortical bone.these bones become weaken,
breaks most often occur in the hip,

Trabecular bone is network of calcium-
containing crystals that fills the interior.
Cortical bone is the dense, ivory like bone that
forms the exterior shell

Electron micrograph of healthy trabecular bone.

Electron micrograph of trabecular bone affected
by osteoporosis

• To keep bones healthy, a person should engage in
weight training or weight-bearing endurance activities
(such as tennis and jogging or vigorous walking)
regularly.
• Regular physical activity combined with an adequate
calcium intake helps to maximize bone density in
adolescence.
• Adults can also maximize and maintain bone density
with a regular program of weight training.
• Even past menopause, when most women are losing
bone, weight training improves bone density.

Osteoporosis and Exercise
• Physical activity may be the single most
important factor supporting bone growth during
adolescence
• active bones are denser and stronger than
sedentary bones
• The benefit of exercise for osteoporosis has
mostly to do with decreasing the risk of falls,
probably because balance is improved and/or
muscle strength is increased
• most doctors recommend weight-bearing exercise,
such as walking, preferably daily.

Best Types of Exercise
• All exercise benefits your general fitness.
• Weight-bearing exercise is best for strengthening
bones. Here are some examples.
• Running and jogging
• Gymnastics
• Aerobics class -- step, dance and pump aerobics
• Weight lifting -- dumbbells, barbells, machines,
body weight exercises
• Team sports involving running and throwing --
basketball, football, baseball, softball, volleyball

• Individual sports involving running -- racket sports
• Walking (but less effective than running or
jogging)
• The least effective exercises for bones are:
• Swimming or water aerobics
• Cycling
• Other minimal weight-bearing exercise activities

Key risk factors for osteoporosis
• genetic factors,
• lack of exercise,
• lack of calcium and vitamin D,
• personal history of fracture as an adult, rheumatoid
arthritis,
• cigarette smoking,
• excessive alcohol consumption,
• low body weight, and family history of osteoporosis
• malabsorption (nutrients in the bowels are not
properly absorbed)
• low estrogen levels
• chemotherapy

• loss of the menstrual period (amenorrhea)
• chronic inflammation
• hyperthyroidism (excessive thyroid hormone)
• hyperparathyroidism (excessive parathyroid
hormone production causes too much calcium
to be removed from the bone)

• EXERCISE PHYSIOLOGY
• Theory and Application to Fitness and
Performance, 6th edition
• Scott K. Powers & Edward T. Howley
• Åstrand P-O, Rodahl K. Textbook of Work
Physiology—Physiological Bases of Exercise,
3rd Edn. McGraw–Hill Book Company, 1986

• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition
and Human Metabolism, fifth ed. WADSWORTH
• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th
ed, McGraw Hill
•
• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999.
Modern Nutrition in Health and Disease; Shils E Maurice,
Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th
edition
• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th
edition, W.B. Company

• MACKENZIE, B. (2001) Physiology - Skeletal
System [WWW] Available from:
http://www.brianmac.co.uk/physiol.htm
•

Flexibility;-Stretching activity that uses the major
muscle groups 2 to 7 days per week. Enough to develop
and maintain a full range of motion2 to 4 repetitions of
15 to 30 seconds per muscle group

Strength;-Resistance activity that is performed at
a controlled speed and through a full range of
motion2 or more nonconsecutive days per week.
Enough to enhance muscle strength and improve
body composition. 8 to 12 repetitions of 8 to 10
different exercises (minimum. Pull-ups, push-ups, weight
lifting,

biceps muscle exercises

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