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

The Skeletal System



The skeletal system consists of;bones, ligaments and tendon

bones, ligaments which connect bones to other bones and cartilageTendons 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 velocityResistant 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 metabolismLarge 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 musclesMuscle 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.•


OsteoporosisOsteoporosis 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 ata 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

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

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